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    A comparison of the effects of imposed extension and flexion movements on Parkinsonian rigidity. Xia R,Markopoulou K,Puumala S E,Rymer W Z Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology OBJECTIVE:To test a hypothesis that Parkinsonian rigidity is more pronounced in imposed extension than flexion movement. METHODS:Twelve Parkinsonian subjects (both "Off" and "On" medication states) and seven control subjects participated in the protocol, in which a servomotor imposed wrist flexion and extension. Rigidity was quantitatively evaluated by the rectified torque integral with time, i.e., temporal score, and by the torque integral with joint angle, i.e., work score, for extension and flexion, respectively. RESULTS:In the "Off" state, the imposed extension induced a significantly higher resistance than did flexion. Dopaminergic medication significantly reduced the temporal score associated with imposed extension, and significantly decreased the work score of both movements. Compared with controls, the scores were higher for patients in the "On" state. CONCLUSIONS:Rigidity is more readily elicited in extension movement. The distinction is not evident in clinical practice, whereas it can be clearly revealed with the application of biomechanical analyses. SIGNIFICANCE:This distinction may prove to be a standard feature of rigidity. The procedures may be helpful in diagnosis and useful in evaluating new treatments and developing rehabilitation programs. 10.1016/j.clinph.2006.06.176
    Enhancement of parkinsonian rigidity with contralateral hand activation. Powell Douglas,Hanson Nicholas,Threlkeld A Joseph,Fang Xiang,Xia Ruiping Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology OBJECTIVE:Quantify the enhancement of parkinsonian rigidity associated with a contralateral activation maneuver. METHODS:Twelve subjects with PD and eight controls participated in the study protocol. Subjects' tested hand was displaced by a servo-motor throughout wrist flexion and extension motions of 60° without and with a concurrent gripping activation in the contralateral hand, referred to as Passive and Active conditions, respectively. Subjects with PD were tested in both OFF-MED and ON-MED states. Rigidity was quantified by integrating torque with position during both flexion and extension (torque resistance). ANOVA was performed to assess the effect of contralateral activation on rigidity. RESULTS:PD patients had significantly (0.038) enhanced torque resistance in OFF-MED compared to healthy controls and ON-MED. In the Active condition, differences in torque resistance were magnified (p=0.002). Medication substantially reduced differences in torque resistance between controls and PD patients in the Passive and Active conditions. CONCLUSIONS:A contralateral activation maneuver substantially increases rigidity in patients with PD, specifically the OFF-MED state. Rigidity is reduced with the application of dopaminergic medication, even with the presence of a contralateral activation maneuver. SIGNIFICANCE:These data support the use of a contralateral activation maneuver as a tool in the diagnosis of PD. 10.1016/j.clinph.2011.01.010
    Relationship between electromyographic activity and clinically assessed rigidity studied at the wrist joint in Parkinson's disease. Meara R J,Cody F W Brain : a journal of neurology The electromyographic (EMG) patterns recorded from wrist muscles during manually applied, repetitive flexion and extension movements of the wrist joint, used for simultaneous clinical assessment of rigidity, were studied in patients with Parkinson's disease and healthy subjects. Recordings were made whilst patients/subjects attempted voluntarily to relax the muscle of the arm whose wrist joint was manipulated. Individual patients were investigated before and at varying times after their routine daily medication as their clinical rigidity underwent associated modulations. It was often possible to induce additional alterations in clinical rigidity by instructing patients to perform an activation or Jendrassik-like manoeuvre (clenching the contralateral fist). In rigid patients, the approximately sinusoidal wrist displacements (60 deg, 1-1.5 Hz) typically elicited pronounced, cyclic modulations of EMG activities in wrist flexors and extensors; increases in EMG activity were phase-locked to the respective periods of muscle stretch. Stretch-related EMG activity reduced or disappeared as rigidity was abolished by drug therapy. The EMG patterns of patients showing cogwheel rigidity featured discrete, phasic bursts superimposed upon more generalized stretch-related increases in activity. In healthy subjects, showing no clinical rigidity, the pronounced cyclic modulations of EMG activity characteristic of rigid patients were absent during similar manually applied wrist displacements. Quantitative EMG measurements for individual patients, made 'on' and 'off' medication and as their rigidity fluctuated, indicated that mild (grade 1) and moderate (grade 2) rigidity was consistently associated with increased stretch-related activity compared with non-rigid conditions. Pair-wise statistical analysis indicated such increases in EMG to be significant. Similarly, the ratios of EMG activities in the stretched versus released muscles were significantly greater for grades 1 and 2 rigidity than in the absence of rigidity. Overall, the present findings support the view that enhancement of stretch reflex activity has a major role in the genesis of parkinsonian rigidity. 10.1093/brain/115.4.1167
    Analysis of viscoelastic properties of wrist joint for quantification of parkinsonian rigidity. Park Byung Kyu,Kwon Yuri,Kim Ji-Won,Lee Jae-Ho,Eom Gwang-Moon,Koh Seong-Beom,Jun Jae-Hoon,Hong Junghwa IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society This study aims to analyze viscoelastic properties of the wrist in patients with Parkinson's disease (PD) in comparison with the clinical score of severity. Forty-five patients with PD and 12 healthy volunteers participated in this study. Severity of rigidity at the wrist was rated by a neurologist just before the experiment. Wrist joint torque resistive to the imposed movement was measured. Three different models, (identical in structure, only different in the number of parameters for extension and flexion phases) were used in identification of viscoelastic properties: 1) one damping constant and one spring constant throughout all phases, 2) two damping constants for each phase and one spring constant throughout all phases, and 3) two damping constants and two spring constants for each phase. Normalized work and impulse suggested in the literature were also calculated. Spring constants of different models and phases showed comparable correlation with rigidity score ( r=0.68-0.73). In terms of the correlation of damping constant with clinical rigidity score, model 1 ( r = 0.90) was better than models 2 and 3 ( r=0.59 - 0.71). These results suggest that the clinical rigidity score is better represented by the mean viscosity during both flexion and extension. In models with two dampers (model 2 and 3), the damping constant was greater during extension than flexion in patients , in contrast that there was no phase difference in normal subjects. This suggests that in contrast with normal subjects, phase-dependent viscosity may be an inherent feature of PD. Although work and impulse were correlated with clinical rigidity score ( r = 0.11 - 0.84), they could not represent the phase-dependent rigidity inherent in PD. In conclusion, the viscosity of model 1 would be appropriate for quantification of clinical ratings of rigidity and that of model 2 for distinction of PD and also for investigation of phase-dependent characteristics in parkinsonian rigidity. 10.1109/TNSRE.2010.2091149
    Wrist rigidity assessment during Deep Brain Stimulation surgery. Costa Pedro,Rosas Maria José,Vaz Rui,Cunha João Paulo Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference Parkinson's Disease (PD) patients often need Deep Brain Stimulation (DBS) surgery when they become intolerant to drugs or these lose efficiency. A stimulation electrode is implanted in the basal ganglia to promote the functional control of the deregulated dopaminergic motor pathways. The stimulation target is defined by medical imaging, followed by electrophysiological inspection for fine electrode position trimming and electrical stimulation tuning. Intra-operative stimulation of the target and the evaluation of wrist rigidity allows to choose the stimulation parameters which best alleviate PD symptoms without side effects. Neurologists impose a passive wrist flexion movement and qualitatively describe the perceived decrease in rigidity under different voltages, based on its experience and with subjectivity. We designed a novel, comfortable and wireless wearable motion sensor to classify the wrist rigidity by deriving a robust signal descriptor from angular speed values and a polynomial mathematical model to classify signals using a quantitative continuous scale. The descriptor significantly (p<0.05) distinguished between non-rigid and rigid states, and the classification model labelled correctly 83.9% of the evaluated signals against the blind-agreement of two specialists. Additionally, we developed a methodology to detect cogwheel rigidity from the angular speed signal with high sensitivity (0.93). Our system provides a reliable evaluation of wrist rigidity, improving upon the inherent subjective clinical evaluation while using small, simple and easy to use motion sensor. 10.1109/EMBC.2015.7319128
    A portable system for quantitative assessment of parkinsonian rigidity. Dai Houde,Otten Bernward,Mehrkens Jan Hinnerk,D'Angelo L T Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference Rigidity is one of the primary symptoms of Parkinson's disease. Passive flexion and extension of the elbow is used to assess rigidity in this study. An examiner flexes and extends the subject's elbow joint through a rigidity assessment cuff attached around the wrist. Each assessment lasts for 10 seconds. Two force sensor boxes and an inertial measurement unit are used to measure the applied force and the state of the elbow movement. Elastic and viscous values will be obtained through a least squares estimation with all the data. 9 healthy subjects were tested with this system in two experimental conditions: 1) normal state (relaxed); 2) imitated rigidity state. Also the subjects were performed the assessment task with different frequencies and elbow movement ranges. The imitated rigidity action increases viscosity and elasticity. The effect sizes (Cohen's d) of the viscosity and elasticity between normal state and imitated state are 1.61 and 1.36 respectively, which means the difference is significant. Thus, this system can detect the on-off fluctuations of parkinsonian rigidity. Both wrist movement angle and frequency have small effect on the viscosity, but have elevated effect on the elasticity. 10.1109/EMBC.2013.6611066
    Quantitative evaluation of parkinsonian rigidity during intra-operative deep brain stimulation. Kwon Yuri,Park Sang-Hoon,Kim Ji-Won,Ho Yeji,Jeon Hyeong-Min,Bang Min-Jung,Koh Seong-Beom,Kim Jong-Hyun,Eom Gwang-Moon Bio-medical materials and engineering This study aims at the quantification of fine change in parkinsonian rigidity at the wrist during deep brain stimulation (DBS) using a portable measurement system and objective mechanical measures. The rigidity of fourteen limbs was evaluated during DBS surgery. The resistive torque to imposed movement was measured for every setting where a reduction in rigidity was perceived by a neurologist. Quantitative mechanical measures derived from experimental data included viscoelastic properties, work, impulse and mechanical impedance. Most mechanical measures could discriminate the optimal setting from baseline (electrode at stereotactic initial position without electrical stimulation) and the highest significance was achieved by viscous damping constant (p<0.001). Spearman correlation coefficients between mechanical measures and clinical score for multiple settings (averaged for 14 limbs) were 0.51-0.77 and the best correlation was shown for viscosity (ρ=0.77 ± 0.22). The results suggest that intraoperative quantification of rigidity during DBS surgery is possible with the suggested system and measures, which would be helpful for the adjustment of electrode position and stimulation parameters. 10.3233/BME-141040
    Associations between quantitative mobility measures derived from components of conventional mobility testing and Parkinsonian gait in older adults. Buchman Aron S,Leurgans Sue E,Weiss Aner,Vanderhorst Veronique,Mirelman Anat,Dawe Robert,Barnes Lisa L,Wilson Robert S,Hausdorff Jeffrey M,Bennett David A PloS one OBJECTIVE:To provide objective measures which characterize mobility in older adults assessed in the community setting and to examine the extent to which these measures are associated with parkinsonian gait. METHODS:During conventional mobility testing in the community-setting, 351 ambulatory non-demented Memory and Aging Project participants wore a belt with a whole body sensor that recorded both acceleration and angular velocity in 3 directions. We used measures derived from these recordings to quantify 5 subtasks including a) walking, b) transition from sit to stand, c) transition from stand to sit, d) turning and e) standing posture. Parkinsonian gait and other mild parkinsonian signs were assessed with a modified version of the original Unified Parkinson's Disease Rating Scale (mUPDRS). RESULTS:In a series of separate regression models which adjusted for age and sex, all 5 mobility subtask measures were associated with parkinsonian gait and accounted for 2% to 32% of its variance. When all 5 subtask measures were considered in a single model, backward elimination showed that measures of walking sit to stand and turning showed independent associations with parkinsonian gait and together accounted for more than 35% of its variance. Cross-validation using data from a 2(nd) group of 258 older adults showed similar results. In similar analyses, only walking was associated with bradykinesia and sway with tremor. INTERPRETATION:Quantitative mobility subtask measures vary in their associations with parkinsonian gait scores and other parkinsonian signs in older adults. Quantifying the different facets of mobility has the potential to facilitate the clinical characterization and understanding the biologic basis for impaired mobility in older adults. 10.1371/journal.pone.0086262
    Relation between changes in long-latency stretch reflexes and muscle stiffness in Parkinson's disease--comparison before and after unilateral pallidotomy. Hayashi R,Hashimoto T,Tada T,Ikeda S Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology OBJECTIVE:To study the effects of posteroventral pallidotomy on both the size of long-latency stretch reflex (LLR) and the muscle stiffness in the wrist flexor muscles. PATIENTS AND METHODS:Eleven consecutive patients (right-handed, 6 men and 5 women) underwent left-side microelectrode-guided pallidotomy. The LLR of the contralesional forearm was studied at baseline and 2-3 months after surgery while patients continued to take their optimal medical regimens ('on' period). Patients were instructed not to respond to the perturbation (passive mode) or to oppose the mechanical extensor perturbation (active mode). RESULTS:The stretch reflex evoked by extension perturbations of the wrist consisted of a short-latency reflex (M1) and an LLR (M2). Pallidotomy had no effects on the size of M1 components in both passive and active mode and on that of M2 component in the passive mode, however, it significantly reduced M2 component in the active mode (P<0.05). The inherent muscle stiffness over 60 ms period of mechanical stretch was not influenced by pallidotomy in any experimental condition (preoperative vs. postoperative or passive mode vs. active mode). The hand displacement following M2 component increased significantly after pallidotomy in both passive (P<0.005) and active mode (P<0.05). The inverted value of the displacement following M2 component correlated with the size of M2 component (r=0.60, P<0.001). CONCLUSIONS:Pallidotomy decreased the transcortical reflex gain, probably at cortical level, and consequently reduced muscle stiffness.
    The effect of Trager therapy on the level of evoked stretch responses in patients with Parkinson's disease and rigidity. Duval Christian,Lafontaine Denis,Hébert Jacques,Leroux Alain,Panisset Michel,Boucher Jean P Journal of manipulative and physiological therapeutics OBJECTIVE:To quantify changes of evoked stretch responses (ESR) in the most rigid arm of patients with Parkinson's disease (PD) after Trager therapy. METHODS:Gentle rocking motion associated with this type of manual therapy was imparted to the upper limbs and body of 30 patients for 20 minutes. A pretest and 2 posttests (at 1 and 11 minutes after the treatment, respectively) were performed, consisting of electromyographic (EMG) recordings of the flexor carpi radialis and extensor digitorum communis while the patient's wrist was passively flexed and extended with an amplitude of 60 degrees and a frequency of 1 Hz. Patients received the treatment on the most rigid side of their bodies (ipsi-group) or on the contralateral side (contra-group). Half of patients in each group received the treatment while lying supine on a massage table (ipsi- and contra-supine) or sitting in a chair (ipsi- and contra-sitting). RESULTS:In general, the level of ESR were reduced by 36% immediately after treatment and remained 32% lower than pretest values 11 minutes after treatment (F = 41.45, P <.05). Patients who received the treatment lying supine benefited from a 42% reduction of ESR (F = 4.07, P <.05). The side on which the treatment was performed did not significantly influence the outcome of the treatment (F = 0.50, P >.05). However, post hoc analysis of the triple interaction (test x side x position) indicated that the sitting position was much less efficient for sustained contralateral effect (P >.05). CONCLUSIONS:Results from the present study strongly suggest that it is possible to modify the level of ESR by using Trager therapy. This stretch reflex inhibition may induce a reduction of the muscle rigidity seen in these patients. The present results may eventually lead to the development of a specific complementary therapy for patients with Parkinson's disease and rigidity. 10.1067/mmt.2002.126469
    Unilateral subthalamic nucleus stimulation has a measurable ipsilateral effect on rigidity and bradykinesia in Parkinson disease. Tabbal Samer D,Ushe Mwiza,Mink Jonathan W,Revilla Fredy J,Wernle Angie R,Hong Minna,Karimi Morvarid,Perlmutter Joel S Experimental neurology BACKGROUND:Bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves motor function in Parkinson disease (PD). However, little is known about the quantitative effects on motor behavior of unilateral STN DBS. METHODS:In 52 PD subjects with STN DBS, we quantified in a double-blinded manner rigidity (n=42), bradykinesia (n=38), and gait speed (n=45). Subjects were tested in four DBS conditions: both on, left on, right on and both off. A force transducer was used to measure rigidity across the elbow, and gyroscopes were used to measure angular velocity of hand rotations for bradykinesia. About half of the subjects were rated using the Unified Parkinson Disease Rating Scale (part III) motor scores for arm rigidity and repetitive hand rotation simultaneously during the kinematic measurements. Subjects were timed walking 25 feet. RESULTS:All subjects had significant improvement with bilateral STN DBS. Contralateral, ipsilateral and bilateral stimulation significantly reduced rigidity and bradykinesia. Bilateral stimulation improved rigidity more than unilateral stimulation of either side, but there was no significant difference between ipsilateral and contralateral stimulation. Although bilateral stimulation also increased hand rotation velocity more than unilateral stimulation of either side, contralateral stimulation increased hand rotation significantly more than ipsilateral stimulation. All stimulation conditions improved walking time but bilateral stimulation provided the greatest improvement. CONCLUSIONS:Unilateral STN DBS decreased rigidity and bradykinesia contralaterally as well ipsilaterally. As expected, bilateral DBS improved gait more than unilateral DBS. 10.1016/j.expneurol.2008.01.024
    Quantitative assessment of Parkinson's disease deficits. Zhang T,Wei G,Yan Z,Ding M,Li C,Ding H,Xu S Chinese medical journal OBJECTIVE:To quantitatively analyze the tremor and rigidity due to Parkinson's disease. METHODS:38 patients with Parkinson's disease (PD) ranging in age from 45 to 72 years and 211 normal subjects aged from 16 to 76 years were investigated. The frequency and range of tremor, the muscle tone of the upper limbs in elbow were detected by a computerized video motion detecting system and a new invented apparatus which can detects skeletal muscle tone. RESULTS:For the PD patients, the frequency of resting tremors was detected in 4 to 6 per second. For extensor and flexor in the PD patients, the value of muscle tone was higher than that of normal subjects and the value of muscle tone in flexor was higher than that of extensor. The rigidity increased gradually with repeat passive movement. The curves of rigidity were shown on computer screen or printed out. The data of rigidity were compared with the M-A Scale. A patient who was suspected to suffer from PD above by the equipments and found the muscle tone was higher than normal. In another PD patient the rigidity was obvious at one side and the muscle tone in "normal side" was also high. These equipments were used to record changes of rigidity and tremor in one more PD patient taking with different drugs in order to see the drug effect. CONCLUSION:Quantitative methods are useful to analyse the motion disorders due to PD.
    Flexor and extensor muscle tone evaluated using the quantitative pendulum test in stroke and parkinsonian patients. Huang Han-Wei,Ju Ming-Shaung,Lin Chou-Ching K Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia The aim of this study was to evaluate the flexor and extensor muscle tone of the upper limbs in patients with spasticity or rigidity and to investigate the difference in hypertonia between spasticity and rigidity. The two experimental groups consisted of stroke patients and parkinsonian patients. The control group consisted of age and sex-matched normal subjects. Quantitative upper limb pendulum tests starting from both flexed and extended joint positions were conducted. System identification with a simple linear model was performed and model parameters were derived. The differences between the three groups and two starting positions were investigated by these model parameters and tested by two-way analysis of variance. In total, 57 subjects were recruited, including 22 controls, 14 stroke patients and 21 parkinsonian patients. While stiffness coefficient showed no difference among groups, the number of swings, relaxation index and damping coefficient showed changes suggesting significant hypertonia in the two patient groups. There was no difference between these two patient groups. The test starting from the extended position constantly manifested higher muscle tone in all three groups. In conclusion, the hypertonia of parkinsonian and stroke patients could not be differentiated by the modified pendulum test; the elbow extensors showed a higher muscle tone in both control and patient groups; and hypertonia of both parkinsonian and stroke patients is velocity dependent. 10.1016/j.jocn.2015.07.031
    A novel method for systematic analysis of rigidity in Parkinson's disease. Endo Takayuki,Okuno Ryuhei,Yokoe Masaru,Akazawa Kenzo,Sakoda Saburo Movement disorders : official journal of the Movement Disorder Society We propose a novel system that analyzes the components of rigidity in Parkinson's disease (PD) usually perceived by physicians, in a very simple and systematic way for routine clinical practice. Our system is composed of two compact force sensors, a gyroscope, and EMG surface electrodes. Muscle tone was assessed in 24 healthy elderly subjects and 27 PD patients by passive extension and flexion of the elbow joint with ramp-and-hold trajectory. Torque and angle data in the dynamic phase were used to calculate "elastic coefficients" in extension and flexion, and the mean value of torque in each dynamic phase at each joint angle (defined as "Bias") was also calculated. The muscle activity index in the static phase (EMG Index) was obtained for both biceps brachii (BB) and triceps brachii (TB) muscles. "Elastic coefficients," sum of the "difference of Bias" and "EMG Index" for BB all correlated well with UPDRS score. Based on our results, Parkinsonian rigidity consists of both an "elastic" component and a "difference of Bias" component, and neurologists may assess greater rigidity when either one or both components are high in value. The EMG index was useful for differentiating PD patients with slight rigidity from healthy elderly adults. 10.1002/mds.22752
    Neck rigidity in Parkinson's disease patients is related to incomplete suppression of reflexive head stabilization. Anastasopoulos Dimitri,Maurer Christoph,Nasios Gregory,Mergner Thomas Experimental neurology Muscle rigidity in PD (Parkinson's disease) patients represents an involuntary increase in muscle tone that stands out upon passive rotation of a joint. The pathophysiology of rigidity is still not well understood. We measured head-trunk torque in PD patients and normal controls during transient passive head rotations by means of servomotors under the instruction to the subjects to relax the neck muscles. We observed that rotation onset was followed by an initial rapid rise in resistive torque, similarly in both subject groups. It then leveled off or declined in controls. With PD patients, in contrast, the rise continued roughly proportional to head eccentricity almost until the end of the rotation. These observations led us to the hypothesis that the initial rise in torque represents reflexive head stabilization that normal subjects in the course of the rotational stimulus are able to suppress, whereas PD patients are less effective in doing so. The hypothesis was implemented into a dynamic control model of active and passive head rotation. Model simulations successfully reproduced the torque responses of normal subjects and PD patients in the present and previous studies. 10.1016/j.expneurol.2009.03.010
    Trunk muscle strength, but not trunk rigidity, is independently associated with bone mineral density of the lumbar spine in patients with Parkinson's disease. Pang Marco Y C,Mak Margaret K Y Movement disorders : official journal of the Movement Disorder Society Previous literature suggested that muscle forces applied to the skeleton may be an important factor in increasing bone mineral density (BMD). This purpose of this study was to determine whether trunk rigidity and trunk muscle strength were associated with lumbar spine BMD in patients with Parkinson's disease (PD). Forty-three PD patients and 29 controls participated in this study. Dual-energy X-ray absorptiometry was used to measure lumbar spine BMD of PD patients. Additionally, an isokinetic dynamometer was used to evaluate trunk rigidity and trunk muscle strength of all subjects. The results showed that PD patients had significantly lower trunk muscle strength, but more trunk rigidity than controls by 46.6 and 162.8%, respectively (P < 0.001). In bivariate correlation analysis, lumbar spine BMD was significantly related to trunk muscle strength (r = 0.475, P = 0.001), but not trunk rigidity (r = 0.271, P = 0.079). In multiple regression analysis, after adjusting for relevant factors, only trunk muscle strength remained independently associated with lumbar spine BMD, accounting for 10.0% of the variance (R(2) = 0.342, F(5,) (37) = 3.838, P = 0.007). Trunk muscle strength, but not trunk rigidity, is independently associated with lumbar spine BMD in patients with PD. Further randomized controlled studies are required to determine whether trunk muscle strengthening exercise is effective in enhancing lumbar spine BMD. 10.1002/mds.22531
    Analysis of interactive effect of stretch reflex and shortening reaction on rigidity in Parkinson's disease. Xia Ruiping,Sun Junfeng,Threlkeld A Joseph Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology OBJECTIVE:To examine the correlation between rigidity and interaction of stretch reflex and shortening reaction during passive movements of the wrist and to compare this correlation with that between rigidity and stretch reflex alone. METHODS:Twelve subjects with Parkinson's disease participated in the study in Off-medication and On-medication states. A servomotor imposed wrist flexion and extension within +/-30 degrees at velocities 50 and 280 degrees/s, while joint torque and EMG of the wrist flexors and extensors were recorded. Rigidity was quantified by integrating torque with joint angle, i.e., objective rigidity (OR) score, for extension and flexion, respectively. The interaction between EMG responses was estimated by calculating a ratio of normalized EMG in stretched to shortened muscles for both movements. RESULTS:The OR scores were more strongly correlated with the EMG ratios than with EMG of the stretched muscles alone. The strongest and significant correlation was found between the OR score and EMG ratio during the extension at high velocity in the Off-medication (r=0.792, p=0.002). CONCLUSIONS:Both stretch reflex and shortening reaction are important determinants of rigidity. SIGNIFICANCE:Study findings provide new insight into mechanistic descriptions of rigidity and have implications for development and evaluation of interventions. 10.1016/j.clinph.2009.05.001
    Effect of rasagiline as adjunct therapy to levodopa on severity of OFF in Parkinson's disease. Stocchi F,Rabey J M European journal of neurology BACKGROUND:The LARGO study demonstrated that rasagiline 1 mg/day as adjunct to levodopa significantly reduces OFF time to the same magnitude as adjunct entacapone. This substudy of LARGO aimed to assess the effect of rasagiline and entacapone on the motor symptoms of PD during the practically defined OFF state. METHODS:LARGO was a randomized, double-blind, multicenter trial that assessed the efficacy and safety of rasagiline (1 mg/day), entacapone (200 mg with each levodopa dose), and placebo in 687 levodopa-treated PD patients with motor fluctuations. A substudy of LARGO measured UPDRS motor scores in the practically defined OFF state in 32 rasagiline, 36 entacapone, and 37 placebo patients. RESULTS:Treatment with rasagiline produced a significant improvement over placebo of 5.64 units in UPDRS motor OFF score (P = 0.013 vs. placebo). By contrast, the effect of adjunct entacapone was not significant (P = 0.14 vs. placebo). Whereas rasagiline also showed a trend in reducing the UPDRS-ADL OFF score (P = 0.058 vs. placebo), no such trend was noted for entacapone (P = 0.26 vs. placebo). Retrospective analysis, using the Bonferroni correction, of UPDRS motor subdomains further revealed that rasagiline, but not entacapone, significantly improved bradykinesia (P < 0.001) and showed trends for improvements in facial expression, speech, and axial impairment during OFF time. CONCLUSIONS:This study provides the first objectively measured evidence that adjunct rasagiline 1 mg/day is effective in reducing the severity of motor symptoms in the OFF state. This suggests a continuous effect of rasagiline 1 mg/day throughout the day and night and is consistent with its extended duration of therapeutic action. 10.1111/j.1468-1331.2011.03512.x
    Higher muscle passive stiffness in Parkinson's disease patients than in controls measured by myotonometry. Marusiak Jarosław,Kisiel-Sajewicz Katarzyna,Jaskólska Anna,Jaskólski Artur Archives of physical medicine and rehabilitation OBJECTIVE:To assess muscle passive stiffness in medicated Parkinson's disease patients using myotonometry. DESIGN:Case-control study. SETTING:Kinesiology laboratory. PARTICIPANTS:Women with Parkinson's disease (PD) (n=8) and healthy matched elderly women (controls) (n=10) (mean age: PD, 77+/-3y; controls, 77+/-4y). INTERVENTIONS:Not applicable. MAIN OUTCOME MEASURES:Passive stiffness of relaxed biceps brachii (BB) muscle was measured using myotonometry. Additionally, surface electromyographic and mechanomyographic signals were recorded from the muscle at rest, and amplitude of those signals was analyzed offline. RESULTS:The values of BB muscle passive stiffness were significantly (P=.004) higher in PD than in the controls, with a statistically significant influence of parkinsonian rigidity score (Unified Parkinson's Disease Rating Scale) on intergroup differences (P<.001). The Spearman correlation coefficient rho value showed a significant (P=.005) positive relationship (rho=.866) between the parkinsonian rigidity score and passive stiffness values of BB in PD. The groups did not differ significantly in the electromyogram amplitude (P=.631) and mechanomyogram amplitude (P=.593) of the BB muscle, and values of these parameters did not correlate significantly with rigidity score (P=.555, P=.745, respectively) in the patients. CONCLUSIONS:Myotonometer is a sensitive enough tool to show that PD patients have higher muscle passive stiffness than healthy controls. 10.1016/j.apmr.2010.01.012
    Axial rigidity and quality of life in patients with Parkinson's disease: a preliminary study. Cano-de-la-Cuerda Roberto,Vela-Desojo Lydia,Miangolarra-Page Juan Carlos,Macías-Macías Yolanda,Muñoz-Hellín Elena Quality of life research : an international journal of quality of life aspects of treatment, care and rehabilitation PURPOSE:Rigidity is a cardinal symptom of Parkinson's disease (PD) and is often clinically assessed by passively flexing and extending a patient's limb. Objective measurements had been employed to examine rigidity in PD subjects, including wrist, elbow, knee and trunk. This study aimed to investigate the relationship between an objective measurement of trunk rigidity and health-related quality of life (HRQoL) and functional status in patients with mild to moderate PD. METHODS:An isokinetic dynamometer Biodex System 3 was employed to assess trunk rigidity in 36 PD patients. HRQoL was assessed with the EuroQol-5D and Parkinson's Disease Questionnaire-39 items (PDQ-39). Functional status was measured with the Schwab and England scale. RESULTS:Trunk rigidity was correlated with the HRQoL assessed with the mobility, cognition and stigma PDQ-39 domains and the total PDQ-39 scores. No correlations were found among trunk muscle tone assessed with the isokinetic dynamometer and the EuroQoL-5D. Functional status was correlated with the trunk extensors rigidity at all angular velocities. CONCLUSION:The results from this study suggest that the axial motor impairments impact on QoL and functional status in patients with PD. Further studies are needed with quantitative devices for axial rigidity assessment to determine the relationship between trunk rigidity in PD patients with higher disease severity and HRQoL scales. 10.1007/s11136-010-9818-y
    Myometry revealed medication-induced decrease in resting skeletal muscle stiffness in Parkinson's disease patients. Marusiak Jarosław,Jaskólska Anna,Koszewicz Magdalena,Budrewicz Sławomir,Jaskólski Artur Clinical biomechanics (Bristol, Avon) BACKGROUND:Based on combined analysis of clinical assessment of parkinsonian rigidity (constant resistance force generated during passive movement in a joint), electromyography and/or dynamometry many studies showed objectively that anti-parkinsonian medication decreases the rigidity in Parkinson's disease (PD). Rigidity-related changes in resting muscle stiffness (changed muscle's mechanical property related to its structural changes and changed neural drive) in PD patients have been revealed by myometry, a simple, sensitive, and reliable method for measuring mechanical properties in human soft tissues. However, an application of myometry in estimation of medication effects on the PD rigidity-related muscle stiffness has not been reported yet. Therefore, our study aimed to assess medication-induced changes in resting muscle stiffness in PD patients using myometry. METHODS:We measured resting muscle stiffness by myometry and recorded a surface electromyogram of relaxed biceps brachii, brachioradialis and triceps brachii muscles in ten patients with PD (age: 51-80 years; Hoehn and Yahr stage: 2.5-4) during medication on-phase (when subjects felt best comfort and fitness after medication: Levodopa, Piribedil, Ropinirol) and medication off-phase (12h after withdrawal of the medication). FINDINGS:Our patients had significantly lower myometric stiffness and electromyogram amplitude in all tested muscles, and also lower clinical rigidity scores during the medication on-phase compared with the medication off-phase. INTERPRETATION:Myometry revealed that anti-parkinsonian medication decreases not only rigidity in PD, but also rigidity-related stiffness in resting skeletal muscles in PD patients. These findings show that myometry can enrich neurological practice, by allowing objective and reliable assessment of parkinsonian rigidity treatment effectiveness. 10.1016/j.clinbiomech.2012.02.001
    [Quantitative measurement of axial rigidity, functional status and health-related quality of life in patients with Parkinson's disease]. Cano de la Cuerda Roberto,Vela Lydia,Miangolarra-Page Juan Carlos,Macías-Macías Yolanda,Muñoz-Hellín Elena Revista de neurologia INTRODUCTION:Rigidity is a cardinal symptom of Parkinson's disease (PD). Clinically, rigidity is usually assessed by passively flexing and extending a patient's limb. Few studies have assessed rigidity in trunk muscles in PD patients. AIMS:To develop an objective measurement to quantify trunk rigidity in PD patients, and to examine its relationship with disease severity using the Hoehn and Yahr staging score (HY) and the Unified Parkinson's Disease Rating Scale III (UPDRS-III), disease duration, functional status with the Schwab & England activities of daily living scale and health related quality of life (HRQoL) was assessed with the European Quality of Life-5 Dimensions and Parkinson's Disease Questionnaire-39 items (PDQ-39). PATIENTS AND METHODS:An isokinetic dynamometer Biodex System 3 was employed to assess trunk rigidity in 36 PD patients. Passive trunk flexion and extension at 3 angular velocities, 30 degrees/s, 45 degrees/s and 60 degrees /s were applied and resistive torques were recorded as trunk flexor and extensors rigidity. RESULTS:Significant correlations between trunk flexors-extensors tone and HY staging score, UPDRS-III, disease duration and functional status at 30 degrees/s, 45 degrees/s and 60 degrees/s were obtained. Trunk rigidity was correlated with the HRQoL assessed with the PDQ-39. CONCLUSIONS:Our results suggest that the 30 degrees/s, 45 degrees/s and 60 degrees/s angular velocities of this objective method was valid to assess trunk rigidity and was correlated with disease severity, disease duration, functional status and HRQoL in PD patients.
    Reduced muscle strength is the major determinant of reduced leg muscle power in Parkinson's disease. Paul S S,Canning C G,Sherrington C,Fung V S C Parkinsonism & related disorders BACKGROUND:Reduced muscle power (speed × strength) is associated with increased fall risk and reduced walking speed in people with Parkinson's disease (PD) as well as in the general older population. This study aimed to determine the relative contribution of motor impairments (bradykinesia, tremor, rigidity and weakness) to reduced leg muscle power in people with PD. METHODS:Eighty-two people with PD were tested while "on" medication. Leg extensor muscle strength and muscle power were measured using pneumatic variable resistance equipment. Lower limb bradykinesia, rigidity and tremor were measured using the Movement Disorders Society-sponsored Unified Parkinson's Disease Rating Scale. Associations between motor impairments and leg muscle power were examined using linear regression. RESULTS:Univariate models revealed that muscle strength (R(2) = 0.84), bradykinesia (R(2) = 0.05) and rigidity (R(2) = 0.05) were significantly associated with leg muscle power, while tremor was not. A multivariate model including bradykinesia, tremor, rigidity, muscle strength, age and gender explained 89% of the variance in leg muscle power. This model revealed reduced muscle strength to be the major determinant of reduced muscle power (β = 0.7), while bradykinesia was a minor contributor to reduced muscle power (β = -0.1), even when accounting for age and gender. CONCLUSIONS:The findings that reduced strength and bradykinesia contribute to reduced muscle power in people with PD tested "on" medication suggest that these impairments are potential targets for physical interventions. 10.1016/j.parkreldis.2012.05.007
    Linear and nonlinear tremor acceleration characteristics in patients with Parkinson's disease. Meigal A Yu,Rissanen S M,Tarvainen M P,Georgiadis S D,Karjalainen P A,Airaksinen O,Kankaanpää M Physiological measurement The purpose of the study was to evaluate linear and nonlinear tremor characteristics of the hand in patients with Parkinson's disease (PD) and to compare the results with those of healthy old and young control subjects. Furthermore, the aim was to study correlation between tremor characteristics and clinical signs. A variety of nonlinear (sample entropy, cross-sample entropy, recurrence rate, determinism and correlation dimension) and linear (amplitude, spectral peak frequency and total power, and coherence) hand tremor parameters were computed from acceleration measurements for PD patients (n = 30, 68.3 ± 7.8 years), and old (n = 20, 64.2 ± 7.0 years) and young (n = 20, 18.4 ± 1.1 years) control subjects. Nonlinear tremor parameters such as determinism, sample entropy and cross-sample entropy were significantly different between the PD patients and healthy controls. These parameters correlated with the Unified Parkinson's disease rating scale (UPDRS), tremor and finger tapping scores, but not with the rigidity scores. Linear tremor parameters such as the amplitude and the maximum power (power corresponding to peak frequency) also correlated with the clinical findings. No major difference was detected in the tremor characteristics between old and young control subjects. The study revealed that tremor in PD patients is more deterministic and regular when compared to old or young healthy controls. The nonlinear tremor parameters can differentiate patients with PD from healthy control subjects and these parameters may have potential in the assessment of the severity of PD (UPDRS). 10.1088/0967-3334/33/3/395
    Amplitude- and velocity-dependency of rigidity measured at the wrist in Parkinson's disease. Powell Douglas,Threlkeld A Joseph,Fang Xiang,Muthumani Anburaj,Xia Ruiping Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology OBJECTIVE:Quantify the effects of increased amplitude and rate of muscle stretch on parkinsonian rigidity. METHODS:Eighteen subjects with Parkinson's disease participated in this study. Subjects' tested hand was passively displaced through 60° and 90° ranges of wrist flexion and extension at velocities of 50°/s and 280°/s in both treated and untreated conditions. Joint angular position, resistance torque, and surface electromyography (EMG) of the wrist flexors and extensors were recorded. Rigidity was quantified by normalized work scores and normalized angular impulses for flexion and extension, separately. Reflex responses of stretched and shortened muscles were quantified by mean EMG and EMG ratio. A series of ANOVAs was performed to determine the effect of amplitude, velocity and medication on selected variables. RESULTS:Both work scores and angular impulses revealed that the larger displacement amplitude and the higher velocity were associated with significantly greater rigidity, increased EMG ratio and mean EMG of stretched muscles. Dopaminergic medication was not associated with a reduction in rigidity. CONCLUSIONS:Parkinsonian rigidity is modulated by the amplitude and rate of muscle stretch. SIGNIFICANCE:These findings shed light on the biomechanical underpinnings and physiological characteristics of rigidity and may inform clinical rigidity assessment in Parkinson's disease. 10.1016/j.clinph.2011.08.004
    Neural and nonneural contributions to wrist rigidity in Parkinson's disease: an explorative study using the NeuroFlexor. Zetterberg H,Frykberg G E,Gäverth J,Lindberg P G BioMed research international OBJECTIVE:The NeuroFlexor is a novel method incorporating a biomechanical model for the measurement of neural and nonneural contributions to resistance induced by passive stretch. In this study, we used the NeuroFlexor method to explore components of passive movement resistance in the wrist and finger muscles in subjects with Parkinson's disease (PD). METHODS:A cross-sectional comparison was performed in twenty-five subjects with PD with clinically identified rigidity and 14 controls. Neural (NC), elastic (EC), and viscous (VC) components of the resistance to passive extension of the wrist were calculated using the NeuroFlexor. Measurements were repeated during a contralateral activation maneuver. RESULTS:PD subjects showed greater total resistance (P < 0.001) and NC (P = 0.002) compared to controls. EC and VC did not differ significantly between groups. Contralateral activation maneuver resulted in increased NC in the PD group but this increase was due to increased resting tension. Total resistance and NC correlated with clinical ratings of rigidity and with bradykinesia. CONCLUSIONS:The findings suggest that stretch induced reflex activity, but not nonneural resistance, is the major contributor to rigidity in wrist muscles in PD. The NeuroFlexor is a potentially valuable clinical and research tool for quantification of rigidity. 10.1155/2015/276182
    REM sleep without atonia is associated with increased rigidity in patients with mild to moderate Parkinson's disease. Linn-Evans Maria E,Petrucci Matthew N,Amundsen Huffmaster Sommer L,Chung Jae Woo,Tuite Paul J,Howell Michael J,Videnovic Aleksandar,MacKinnon Colum D Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology OBJECTIVE:Increased muscle activity during rapid eye movement (REM) sleep (i.e. REM sleep without atonia) is common in people with Parkinson's disease (PD). This study tested the hypotheses that people with PD and REM sleep without atonia (RSWA) would present with more severe and symmetric rigidity compared to individuals with PD without RSWA and age-matched controls. METHODS:Sixty-one individuals participated in this study (41 PD, 20 controls). An overnight sleep study was used to classify participants with PD as having either elevated (PD-RSWA+) or normal muscle activity (PD-RSWA-) during REM sleep. Quantitative measures of rigidity were obtained using a robotic manipulandum that passively pronated and supinated the forearm. RESULTS:Quantitative measures of forearm rigidity were significantly higher in the PD-RSWA+ group compared to the control group. Rigidity was significantly more asymmetric between limbs in the PD-RSWA- group compared with controls, while there was no significant difference in symmetry between the control and PD-RSWA+ groups. CONCLUSION:In people with mild to moderate PD, RSWA is associated with an increased and more symmetric presentation of upper limb rigidity. SIGNIFICANCE:Dysfunction of brainstem systems that control muscle tone during REM sleep may contribute to increased rigidity during wakefulness in people with PD. 10.1016/j.clinph.2020.04.017
    Analysis of antagonistic co-contractions with motorized passive movement device in patients with Parkinson's disease. Kwon Yuri,Kim Ji-Won,Ho Yeji,Jeon Hyeong-Min,Bang Min-Jung,Eom Gwang-Moon,Koh Seong-Beom Bio-medical materials and engineering Patients with Parkinson's disease (PD) suffer from an increased resistance to passive movement of a joint, called as rigidity. Stretch reflex and shortening reaction were suggested to be associated to the rigidity, however, the mechanism is still poorly understood. We hypothesized that the co-contraction of antagonistic muscle pairs is enhanced in patients with PD and this induces resistance persisting throughout its range of motion. To test the hypothesis, we developed a motorized device for application of passive movement of the wrist joint and investigated the co-contraction of muscles during passive movement. It consisted of a servo motor connected to a rotating axis with a timing belt, load cell for the measurement of resistance, and other elements for the fixation of arm and hand. Repetitive passive movement was applied to the wrist joint of patients. Co-contraction of antagonistic muscle pairs was significantly greater in patients than in normal subjects (p<0.001), suggesting that the enhanced co-contraction is associated with the mechanical resistance during passive movement, i.e. rigidity. Co-contraction during extended state was greater than the other states (p<0.001), which implies that the length-feedback mechanism may play the important role in co-contraction. 10.3233/BME-141042
    Quantitative Measurement of Rigidity in Parkinson´s Disease: A Systematic Review. Ferreira-Sánchez María Del Rosario,Moreno-Verdú Marcos,Cano-de-la-Cuerda Roberto Sensors (Basel, Switzerland) Rigidity is one of the cardinal symptoms of Parkinson´s disease (PD). Present in up 89% of cases, it is typically assessed with clinical scales. However, these instruments show limitations due to their subjectivity and poor intra- and inter-rater reliability. To compile all of the objective quantitative methods used to assess rigidity in PD and to study their validity and reliability, a systematic review was conducted using the Web of Science, PubMed, and Scopus databases. Studies from January 1975 to June 2019 were included, all of which were written in English. The Strengthening the Reporting of observational studies in Epidemiology Statement (STROBE) checklist for observational studies was used to assess the methodological rigor of the included studies. Thirty-six studies were included. Rigidity was quantitatively assessed in three ways, using servomotors, inertial sensors, and biomechanical and neurophysiological study of muscles. All methods showed good validity and reliability, good correlation with clinical scales, and were useful for detecting rigidity and studying its evolution. People with PD exhibit higher values in terms of objective muscle stiffness than healthy controls. Rigidity depends on the angular velocity and articular amplitude of the mobilization applied. There are objective, valid, and reliable methods that can be used to quantitatively assess rigidity in people with PD. 10.3390/s20030880
    Face-referenced measurement of perioral stiffness and speech kinematics in Parkinson's disease. Chu Shin Ying,Barlow Steven M,Lee Jaehoon Journal of speech, language, and hearing research : JSLHR PURPOSE:Perioral biomechanics, labial kinematics, and associated electromyographic signals were sampled and characterized in individuals with Parkinson's disease (PD) as a function of medication state. METHOD:Passive perioral stiffness was sampled using the OroSTIFF system in 10 individuals with PD in a medication ON and a medication OFF state and compared to 10 matched controls. Perioral stiffness, derived as the quotient of resultant force and interoral angle span, was modeled with regression techniques. Labial movement amplitudes and integrated electromyograms from select lip muscles were evaluated during syllable production using a 4-D computerized motion capture system. RESULTS:Multilevel regression modeling showed greater perioral stiffness in patients with PD, consistent with the clinical correlate of rigidity. In the medication-OFF state, individuals with PD manifested greater integrated electromyogram levels for the orbicularis oris inferior compared to controls, which increased further after consumption of levodopa. CONCLUSIONS:This study illustrates the application of biomechanical, electrophysiological, and kinematic methods to better understand the pathophysiology of speech motor control in PD. 10.1044/2015_JSLHR-S-13-0293
    Development and Pilot Testing of a Novel Electromechanical Device to Measure Wrist Rigidity in Parkinson's Disease. Zito Giuseppe A,Gerber Stephan M,Urwyler Prabitha,Shamsollahi Mohammad J,Pal Natassja,Benninger David,Nef Tobias Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference Quantitative assessment of the muscle tone is important when studying patients with neurological disorders such as Parkinson's disease (PD). For the assessment of therapeutic progress, quantitative and objective outcome measures are needed. This article presents a novel electromechanical device to monitor the quantitative rigidity of the wrist joint against passive movement. The novel device is equipped with an electrical motor to move the wrist joint in a flexion-extension manner with different velocity profiles. The accuracy of the device was measured in terms of position, velocity and torque accuracy. The feasibility of the measurement procedure was tested in a pilot study with four PD patients and 12 healthy controls (HC), at velocities of 10 °/s,50 °/s, and 100 °/s. {The position and velocity of the developed device were (0.005 ± 0.105)° and (0.734 ±0.276) °/s, unloaded, and (0.003 ± 0.113) ° and (0.013 ± 0.038) °/s, loaded with a relaxed arm, respectively. The torque accuracy was (15.029 ± 2.235) mNm. The comparison of the median rigidity between the PD patients and HC showed significant differences at all tested velocities, during both flexion and extension movements. This device proved to have sufficient accuracy and sensitivity to precisely measure the interaction torque at the wrist joint and to differentiate PD rigidity from normal muscle tone. The device, thus provides a quantitative and objective measure of rigidity in PD. 10.1109/EMBC.2018.8513422
    Increased muscle belly and tendon stiffness in patients with Parkinson's disease, as measured by myotonometry. Marusiak Jarosław,Jaskólska Anna,Budrewicz Sławomir,Koszewicz Magdalena,Jaskólski Artur Movement disorders : official journal of the Movement Disorder Society BACKGROUND:Based on Davis's law, greater tonus of the muscle belly in individuals with Parkinson's disease can create greater tension in the tendon, leading to structural adjustment and an increase in tendon stiffness. Our study aimed to separately assess passive stiffness in the muscle belly and tendon in medicated patients with Parkinson's disease, using myotonometry. METHODS:We tested 12 patients with Parkinson's disease and 12 healthy matched controls. Passive stiffness of muscle belly and tendon was estimated by myotonometry, electromyography, and mechanomyography in relaxed biceps and triceps brachii muscles. RESULTS:Compared with controls, patients with Parkinson's disease had higher stiffness in the muscle belly and tendon of the biceps brachii and in the tendon of the triceps brachii. In patients with Parkinson's disease, there was a positive correlation between muscle belly stiffness and parkinsonian rigidity in the biceps brachii. CONCLUSION:Patients with Parkinson's disease have higher passive stiffness of the muscle belly and tendon than healthy matched controls. 10.1002/mds.23841
    QAPD: an integrated system to quantify symptoms of Parkinson's disease. Patel Vrajeshri,Burns Martin,Pourfar Michael,Mogilner Alon,Kondziolka Douglas,Vinjamuri Ramana Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference The complex prevalence of Parkinson's disease (PD) symptoms has pushed research towards assessment tools that can assist in their quantification. There remains a need for a system capable of measuring symptoms during various tasks at multiple motor levels (kinematics and electromyography). In this paper, we present the development and initial validation of a quantitative assessment tool for Parkinson's disease (QAPD), a system designed to assist researchers and clinicians in the study of PD. The system integrates motion tracking, data gloves, and electromyography to collect movement related data from multiple body parts. As part of the system, a custom MATLAB® based toolbox has been designed to quantify bradykinesia, tremor, micrographia, and muscle rigidity using both standard and contemporary data analysis techniques. We believe this system can be a useful assessment tool to assist clinicians and researchers in diagnosing and estimating movement dysfunction in individuals with PD. 10.1109/EMBC.2016.7591073
    Ultrasound strain elastography in assessment of resting biceps brachii muscle stiffness in patients with Parkinson's disease: a primary observation. Gao Jing,He Wen,Du Li-Juan,Li Shuo,Cheng Ling-Gang,Shih George,Rubin Jonathan Clinical imaging The aim of this study was to evaluate the feasibility of ultrasound strain elastography (SE) for the assessment of resting biceps brachii muscle (BBM) stiffness in patients with Parkinson's diseases (PD). From May 2014 to December 2014, we prospectively performed SE of BBM in 14 patients with PD and 10 healthy controls. Based on the Unified Parkinson's Disease Rating Scale for scoring muscle rigidity (UPDRS, part III), muscle rigidity scores in 14 patients with PD included 3 patients with high rigidity (UPDRS III-IV) and 11 patients with low rigidity (UPDRS I-II). Ultrasound strain was represented by the deformation of the BBM and subcutaneous soft tissues that was produced by external compression with a sand bag (1.5 kg) tied onto an ultrasound transducer. Deformation was estimated with two-dimensional speckle tracking. The difference in strain ratio (SR, defined as mean BBM strain divided by mean subcutaneous soft tissue strain) between PD and healthy controls was tested by unpaired t test. The correlation between SR and muscle rigidity score was analyzed by Pearson correlation coefficient. The reliability of SR in assessment of BBM stiffness was tested using intraclass correlation coefficient. In our result, the SR in PD and healthy controls measured 2.65±0.36 and 3.30±0.27, respectively. A significant difference in SR was noted between the healthy controls and PD (P=.00011). A negative correlation was found between SR and UPDRS rigidity score (r=-0.78). Our study suggests that the SR of BBM to reference tissue can be used as a quantitative biomarker in assessing resting muscle stiffness associated with muscle rigidity in PD. 10.1016/j.clinimag.2015.12.008
    Axial hypertonicity in Parkinson's disease: direct measurements of trunk and hip torque. Wright W G,Gurfinkel V S,Nutt J,Horak F B,Cordo P J Experimental neurology A cardinal feature of Parkinson's disease (PD) is muscle hypertonicity, i.e. rigidity. Little is known about the axial tone in PD or the relation of hypertonia to functional impairment. We quantified axial rigidity to assess its relation to motor symptoms as measured by UPDRS and determine whether rigidity is affected by levodopa treatment. Axial rigidity was measured in 12 PD and 14 age-matched controls by directly measuring torsional resistance of the longitudinal axis to twisting (+/-10 degrees ). Feet were rotated relative to fixed hips (Hip Tone) or feet and hips were rotated relative to fixed shoulders (Trunk Tone). To assess tonic activity only, low constant velocity rotation (1 degrees /s) and low acceleration (<12 degrees /s(2)) were used to avoid eliciting phasic sensorimotor responses. Subjects stood during testing without changing body orientation relative to gravity. Body parts fixed against rotation could translate laterally within the boundaries of normal postural sway, but could not rotate. PD OFF-medication had higher axial rigidity (p<0.05) in hips (5.07 N m) and trunk (5.30 N m) than controls (3.51 N m and 4.46 N m, respectively), which did not change with levodopa (p>0.10). Hip-to-trunk torque ratio was greater in PD than controls (p<0.05) and unchanged by levodopa (p=0.28). UPDRS scores were significantly correlated with hip rigidity for PD OFF-medication (r values=0.73, p<0.05). Torsional resistance to clockwise versus counter-clockwise axial rotation was more asymmetrical in PD than controls (p<0.05), however, there was no correspondence between direction of axial asymmetry and side of disease onset. In conclusion, these findings concerning hypertonicity may underlie functional impairments of posture and locomotion in PD. The absence of a levodopa effect on axial tone suggests that axial and appendicular tones are controlled by separate neural circuits. 10.1016/j.expneurol.2007.07.002
    Responses to anterior and posterior perturbations in Parkinson's disease with early postural instability: role of axial and limb rigidity. Colebatch James G,Govender Sendhil Experimental brain research We studied 12 patients with Parkinson's disease (PD): 6 with postural instability (Hoehn and Yahr Stage 3) and 6 without (Stage 2 or 2.5), using a quantitative test based on the clinical pull test. Their findings were compared with those for 12 healthy controls. The patients on their usual medications were pulled either forwards or backwards at the level of the shoulders and asked not to take a step in a series of five trials. Acceleration was monitored for the upper trunk, sacrum, and both tibias. EMG was measured in soleus and tibialis anterior (TA) muscles in all and for thigh and truncal muscles in a subgroup. A target of 0.2 g trunk acceleration was used, but smaller perturbations were used in very unstable patients. All the Stage 3 patients lost balance in at least one trial for the posterior perturbations but none for the anterior ones. None of the Stage 2 patients lost balance. There was increased tonic EMG and agonist activity but no difference in EMG onset or initial force production compared to healthy controls. For posterior perturbations, there were two related disorders that separated the PD patients from controls. There was a significantly higher ratio of sacral-to-applied acceleration and both PD groups showed reduced knee acceleration and shortened latency, more so for the Stage 3 group. The increased sacral-to-C7 acceleration ratio was correlated with the tonic level of activation of the hamstrings (HS), quadriceps, and lumbar paraspinal muscles (PS), while the tibial acceleration latency was also correlated with the level of tonic PS activation. We also found that the size of balance responses, 0-200 ms post-perturbation, correlated significantly with the level of tonic activation in nearly all the muscles studied. We confirmed that PD patients show greater instability posteriorly than anteriorly to applied perturbations. Our findings support increasing axial and limb rigidity as the cause of the impaired pull test rather than postural bradykinesia and suggest that tonic truncal and thigh muscle activation may be an important underlying cause. 10.1007/s00221-019-05553-8
    Isokinetic dynamometry as a technologic assessment tool for trunk rigidity in Parkinson's disease patients. Cano-de-la-Cuerda Roberto,Vela-Desojo Lydia,Miangolarra-Page Juan Carlos,Macías-Macías Yolanda NeuroRehabilitation BACKGROUND:Rigidity is a cardinal symptom of Parkinson's disease (PD). There are few studies that have assessed rigidity with objective tools in PD patients. OBJECTIVE:This study aimed to develop an objective measurement to quantify trunk rigidity in PD patients with a technology device and to investigate the relationship between this objective assessment and to examine its relationship with disease severity (Hoehn and Yahr staging score and the Unified Parkinson's Disease Rating Scale III) disease duration, functional status (Schwab & England activities of daily living scale) and health related quality of life (European Quality of Life-5 Dimensions and Parkinson's Disease Questionnaire-39 items) in patients with mild to moderate PD. METHODS:An isokinetic dynamometer Biodex System 3 was employed to assess trunk rigidity in 36 PD patients. Passive trunk flexion and extension at 3 angular velocities, 30°/s, 45°/s and 60°/s were applied and resistive torques were recorded as trunk flexor and extensors rigidity. RESULTS:Significant correlations between trunk flexors-extensors tone and clinical status, disease duration and functional status at 30°/s, 45°/s and 60°/s were obtained. No correlations were found among trunk muscle tone assessed with the isokinetic dynamometer and the EuroQoL-5D. Trunk rigidity was correlated with the HRQoL assessed with the mobility, cognition and stigma PDQ-39 domains and the total PDQ-39 scores. CONCLUSION:Our results suggest that the 30°/s, 45°/s and 60°/s angular velocities of this objective technology method were a valid assessment for trunk rigidity and were correlated with disease severity, disease duration, functional status and HRQoL in PD patients. 10.3233/NRE-141142
    Using wearables to assess bradykinesia and rigidity in patients with Parkinson's disease: a focused, narrative review of the literature. Teshuva Itay,Hillel Inbar,Gazit Eran,Giladi Nir,Mirelman Anat,Hausdorff Jeffrey M Journal of neural transmission (Vienna, Austria : 1996) The potential of using wearable technologies for the objective assessment of motor symptoms in Parkinson's disease (PD) has gained prominence recently. Nonetheless, compared to tremor and gait impairment, less emphasis has been placed on the quantification of bradykinesia and rigidity. This review aimed to consolidate the existing research on objective measurement of bradykinesia and rigidity in PD through the use of wearables, focusing on the continuous monitoring of these two symptoms in free-living environments. A search of PubMed was conducted through a combination of keyword and MeSH searches. We also searched the IEEE, Google Scholar, Embase, and Scopus databases to ensure thorough results and to minimize the chances of missing relevant studies. Papers published after the year 2000 with sample sizes greater than five were included. Studies were assessed for quality and information was extracted regarding the devices used and their location on the body, the setting and duration of the study, the "gold standard" used as a reference for validation, the metrics used, and the results of each paper. Thirty-one and eight studies met the search criteria and evaluated bradykinesia and rigidity, respectively. Several studies reported strong associations between wearable-based measures and the gold-standard references for bradykinesia, and, to a lesser extent, rigidity. Only a few, pilot studies investigated the measurement of bradykinesia and rigidity in the home and free-living settings. While the current results are promising for the future of wearables, additional work is needed on their validation and adaptation in ecological, free-living settings. Doing so has the potential to improve the assessment and treatment of motor fluctuations and symptoms of PD more generally through real-time objective monitoring of bradykinesia and rigidity. 10.1007/s00702-019-02017-9
    Automated assessment of symptom severity changes during deep brain stimulation (DBS) therapy for Parkinson's disease. Angeles Paolo,Tai Yen,Pavese Nicola,Wilson Samuel,Vaidyanathan Ravi IEEE ... International Conference on Rehabilitation Robotics : [proceedings] Deep brain stimulation (DBS) is currently being used as a treatment for symptoms of Parkinson's disease (PD). Tracking symptom severity progression and deciding the optimal stimulation parameters for people with PD is extremely difficult. This study presents a sensor system that can quantify the three cardinal motor symptoms of PD - rigidity, bradykinesia and tremor. The first phase of this study assesses whether data recorded from the system during physical examinations can be used to correlate to clinician's severity score using supervised machine learning (ML) models. The second phase concludes whether the sensor system can distinguish differences before and after DBS optimisation by a clinician when Unified Parkinson's Disease Rating Scale (UPDRS) scores did not change. An average accuracy of 90.9 % was achieved by the best ML models in the first phase, when correlating sensor data to clinician's scores. Adding on to this, in the second phase of the study, the sensor system was able to pick up discernible differences before and after DBS optimisation sessions in instances where UPDRS scores did not change. 10.1109/ICORR.2017.8009462
    Hypometria and bradykinesia during drawing movements in individuals with Parkinson's disease. Broderick Michael P,Van Gemmert Arend W A,Shill Holly A,Stelmach George E Experimental brain research To address the hypothesis that Parkinson's disease (PD) patients have deficits in controlling acceleration, a drawing task was used in which target size, frequency, and weight of pen were manipulated. In accordance with previous results, it was found that, relative to controls, PD patients produced movements at the required frequency, but moved significantly slower, produced less acceleration, and drew smaller-than-required stroke sizes. This resulted in smaller-than-required movement amplitudes, suggesting that hypometria and bradykinesia in drawing and/or handwriting are related. Patients were found to perform similarly to controls when the target size was 1 cm. However, their performance became more dissimilar at greater stroke lengths. In addition to the aforementioned effects it was found that movement amplitude error was less when the pen was 20 times heavier than the normal pen and that the increased load may dampen abnormal limb-stiffness characteristics induced by PD. 10.1007/s00221-009-1925-z
    Parkinson's Disease: Basic Pathomechanisms and a Clinical Overview. Noyce Alastair,Bandopadhyay Rina Advances in neurobiology PD is a common and a debilitating degenerative movement disorder. The number of patients is increasing worldwide and as yet there is no cure for the disease. The majority of existing treatments target motor symptom control. Over the last two decades the impact of the genetic contribution to PD has been appreciated. Significant discoveries have been made, which have advanced our understanding of the pathophysiological and molecular basis of PD. In this chapter we outline current knowledge of the clinical aspects of PD and the basic mechanistic understanding. 10.1007/978-3-319-57193-5_3
    Axial rigidity is related to the risk of falls in patients with Parkinson's disease. Cano-de-la-Cuerda Roberto,Vela-Desojo Lydia,Miangolarra-Page Juan Carlos,Macías-Macías Yolanda NeuroRehabilitation BACKGROUND:Rigidity is a cardinal symptom of Parkinson's disease (PD) and is often clinically assessed by passively flexing and extending a patient's limb. Objective measurements had been employed to examine rigidity in PD subjects, including wrist, elbow or knee. OBJECTIVE:This study aimed to investigate the relationship between an objective measurement of trunk rigidity and risk of falls in patients with mild to moderate PD. METHODS:An isokinetic dynamometer Biodex System 3 was employed to assess trunk rigidity in 36 patients with mild to moderate PD at a University Department in a cross-sectional study. Risk of falls was measured by the Get Up & Go test (GU&G). Disease severity (Hoehn and Yahr staging score and the Unified Parkinson's Disease Rating Scale III), disease duration and functional status (Schwab & England activities of daily living scale) were also evaluated. RESULTS:Significant correlations between trunk extensors rigidity at 45°/s and 60°/s and risk of falls were obtained. A correlation between trunk extensors tone at 30°/s and the GU&G test almost reached significant almost reached statistical significance (r = 0.306; p = 0,066). Significant correlations between trunk flexors-extensors tone and clinical status, disease duration and functional status at 30°/s, 45°/s and 60°/s were also obtained. CONCLUSION:The results from this study suggest that the axial rigidity is related to the risk of falls in patients with mild to moderate PD. Further studies are needed with quantitative devices for axial rigidity assessment to determine the relationship between trunk rigidity in PD patients with higher disease severity and risk of falls. 10.3233/NRE-171444
    Reduced performance in balance, walking and turning tasks is associated with increased neck tone in Parkinson's disease. Franzén Erika,Paquette Caroline,Gurfinkel Victor S,Cordo Paul J,Nutt John G,Horak Fay B Experimental neurology Rigidity or hypertonicity is a cardinal symptom of Parkinson's disease (PD). We hypothesized that hypertonicity of the body axis affects functional performance of tasks involving balance, walking and turning. The magnitude of axial postural tone in the neck, trunk and hip segments of 15 subjects with PD (both ON and OFF levodopa) and 15 control subjects was quantified during unsupported standing in an axial twisting device in our laboratory as resistance to torsional rotation. Subjects also performed six functional tests (walking in a figure of eight [Figure of Eight], Timed Up and Go, Berg Balance Scale, supine rolling task [rollover], Functional Reach, and standing 360-deg turn-in-place) in the ON and OFF state. Results showed that PD subjects had increased tone throughout the axis compared to control subjects (p=0.008) and that this increase was most prominent in the neck. In PD subjects, axial tone was related to functional performance, but most strongly for tone at the neck and accounted for an especially large portion of the variability in the performance of the Figure of Eight test (r(OFF)=0.68 and r(ON)=0.74, p<0.05) and the Rollover test (r(OFF)=0.67 and r(ON)=0.55, p<0.05). Our results suggest that neck tone plays a significant role in functional mobility and that abnormally high postural tone may be an important contributor to balance and mobility disorders in individuals with PD. 10.1016/j.expneurol.2009.06.013
    New Sensor and Wearable Technologies to Aid in the Diagnosis and Treatment Monitoring of Parkinson's Disease. Monje Mariana H G,Foffani Guglielmo,Obeso José,Sánchez-Ferro Álvaro Annual review of biomedical engineering Parkinson's disease (PD) is a degenerative disorder of the brain characterized by the impairment of the nigrostriatal system. This impairment leads to specific motor manifestations (i.e., bradykinesia, tremor, and rigidity) that are assessed through clinical examination, scales, and patient-reported outcomes. New sensor-based and wearable technologies are progressively revolutionizing PD care by objectively measuring these manifestations and improving PD diagnosis and treatment monitoring. However, their use is still limited in clinical practice, perhaps because of the absence of external validation and standards for their continuous use at home. In the near future, these systems will progressively complement traditional tools and revolutionize the way we diagnose and monitor patients with PD. 10.1146/annurev-bioeng-062117-121036
    Patterns of grey matter loss associated with motor subscores in early Parkinson's disease. Li Xingfeng,Xing Yue,Martin-Bastida Antonio,Piccini Paola,Auer Dorothee P NeuroImage. Clinical Classical motor symptoms of Parkinson's disease (PD) such as tremor, rigidity, bradykinesia, and axial symptoms are graded in the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) III. It is yet to be ascertained whether parkinsonian motor symptoms are associated with different anatomical patterns of neurodegeneration as reflected by brain grey matter (GM) alteration. This study aimed to investigate associations between motor subscores and brain GM at voxel level. High resolution structural MRI T1 scans from the Parkinson's Progression Markers Initiative (PPMI) repository were employed to estimate brain GM intensity of PD subjects. Correlations between GM intensity and total MDS-UPDRS III and its four subscores were computed. The total MDS-UPDRS III score was significantly negatively correlated bilaterally with putamen and caudate GM density. Lower anterior striatal GM intensity was significantly associated with higher rigidity subscores, whereas left-sided anterior striatal and precentral cortical GM reduction were correlated with severity of axial symptoms. No significant morphometric associations were demonstrated for tremor subscores. In conclusion, we provide evidence for neuroanatomical patterns underpinning motor symptoms in early PD. 10.1016/j.nicl.2017.11.009
    A palm-worn device to quantify rigidity in Parkinson's disease. Perera Thushara,Lee Wee-Lih,Jones Mary,Tan Joy L,Proud Elizabeth L,Begg Angus,Sinclair Nicholas C,Peppard Richard,McDermott Hugh J Journal of neuroscience methods BACKGROUND:Parkinsonian rigidity is identified on clinical examination as resistance to passive movement. Measurement of rigidity commonly relies on ordinal rating scales (MDS-UPDRS), however instrumented objective measures may provide greater mechanistic insight. NEW METHOD:We present a palm-worn instrument to objectively quantify rigidity on a continuous scale. The device employs a miniature motor to flex the third digit of the hand about the metacarpophalangeal joint whilst transducers record flexion/extension forces. We aim to determine congruence with the MDS-UPDRS, investigate sensitivity to the impact of deep brain stimulation (DBS) and contralateral movement, and make comparisons with healthy individuals. Eight participants with Parkinson's disease underwent evaluation during conditions: on and off DBS, and with and without contralateral limb movement to activate rigidity. During each DBS condition, wash-in/out effects were tracked using both our instrument and two blinded clinical raters. Sixteen healthy volunteers (age-matched/young) served as controls. RESULTS:Rigidity measured using our instrument had moderate agreement with the MDS-UPDRS and showed differences between therapeutic state, activation conditions, and disease/healthy cohorts. Rigidity gradually worsened over a one-hour period after DBS cessation, but improved more rapidly with DBS resumption. COMPARISON WITH EXISTING METHODS:Previous attempts to quantify rigidity include manual approaches where a clinician is required to manipulate limbs while sensors passively gather information, or large automated instruments to move the wrist or elbow. CONCLUSION:Given its ability to track changes in rigidity due to therapeutic intervention, our technique could have applications where continuous measurement is required or where a suitably qualified rater is absent. 10.1016/j.jneumeth.2019.02.006
    The effect of subthalamic stimulation on viscoelastic stiffness of skeletal muscles in patients with Parkinson's disease. Rätsep Tõnu,Asser Toomas Clinical biomechanics (Bristol, Avon) BACKGROUND:Myotonometric evaluation of viscoelastic stiffness of skeletal muscles has been proposed to document the effect of surgical or pharmacological treatment on rigidity in patients with Parkinson's disease. The aim of the study was to analyze the changes of viscoelastic stiffness induced by deep brain stimulation. METHODS:Fifteen patients in an advanced stage of Parkinson's disease participated in the study. The study took place in the off-medication conditions after one night of drug withdrawal. The Unified Parkinson's Disease Rating Scale was used for clinical assessment of the disease. Myotonometry was used to measure viscoelastic stiffness in the resting muscles before and directly after passive wrist movements, commonly used for clinical evaluation of rigidity. The measurements were repeated during the stimulation-on and stimulation-off periods and compared with fifteen healthy control persons. FINDINGS:The clinical scores for wrist rigidity improved from 3.0 (1-4) to 0.93 (0-2) (P<0.05) due to brain stimulation. The mean values of viscoelastic stiffness were similar before and after passive wrist movements, but the differences between the patients with high vs. low rigidity values (354.9 vs 310.2N/m; P<0.05) and in stimulation-off vs. stimulation-on conditions (342.7 vs 310.5N/m; P<0.05) were significant only if the measurements had been performed after passive wrist movements. INTERPRETATION:Effective deep brain stimulation and increased rigidity can significantly change viscoelastic stiffness in the resting muscles in patients with Parkinson's disease, especially if evaluated after passive wrist movements. This paper supports the use of myotonometry for objective quantification of parkinsonian rigidity at rest. 10.1016/j.clinbiomech.2017.03.012
    Tension-referenced measures of gastrocnemius slack length and stiffness in Parkinson's disease. Tan Benedict,Double Kay L,Burne John,Diong Joanna Movement disorders : official journal of the Movement Disorder Society BACKGROUND:It is not known how passive muscle length and stiffness contribute to rigidity in Parkinson's disease. The objective of this study was to compare passive gastrocnemius muscle-tendon slack length and stiffness at known tension in Parkinson's disease subjects with ankle rigidity and in able-bodied people. METHODS:Passive ankle torque-angle curves were obtained from 15 Parkinson's disease subjects with rigidity and 15 control subjects. Torque-angle data were used to derive passive gastrocnemius length-tension data and calculate slack length and stiffness of the gastrocnemius muscle. Between-group comparisons were made with linear models. RESULTS:Gastrocnemius muscle-tendon slack lengths (adjusted between-group difference, 0.01 m; 95% CI, -0.02 to 0.04 m; P = 0.37) and stiffness (adjusted between-group difference, 15.7 m ; 95% CI, -8.5 to 39.9 m ; P = 0.19) were not significantly different between groups. CONCLUSIONS:Parkinson's disease subjects with ankle rigidity did not have significantly shorter or stiffer gastrocnemius muscles compared with control subjects. © 2016 International Parkinson and Movement Disorder Society. 10.1002/mds.26530
    Efficacy of oral administration of licorice as an adjunct therapy on improving the symptoms of patients with Parkinson's disease, A randomized double blinded clinical trial. Petramfar Peyman,Hajari Fatemeh,Yousefi Gholamhossein,Azadi Samar,Hamedi Azadeh Journal of ethnopharmacology ETHNOPHARMACOLOGICAL RELEVANCE:Licorice preparations are used as neuroprotective remedies in Persian ethnomedicine, in order to prevent from disabilities in neurodegenerative conditions like Parkinson's disease (PD). AIM OF THE STUDY:This study was designed to determine the licorice (root of Glycyrrhiza glabra L.) effectiveness as an adjunct treatment in the PD management. MATERIAL AND METHODS:In this double-blinded trial, 128 patients were assessed for eligibility criteria. Seventy-eight patients were ineligible and 11 of them refused from participating. Thirty-nine PD patients (YAHR staging ≤ 3) were divided into two groups by random. The patients received oral licorice or placebo syrups with a dose of 5 cc, twice a day for 6 months. High-performance liquid chromatography and spectrophotometric instruments determined licorice syrup constituents. The patients' situation for Unified Parkinson's rating scale (UPDRS) was assessed every 6 weeks for the duration of six months. In addition, patients' blood pressure, blood glucose, sodium and potassium levels, quality of life and dizziness were determined. RESULTS:Six weeks after intervention, total UPDRS, daily activities and tremor were significantly improved with a considerable effect size. A significant better motor test and rigidity scores were observed 4 months after licorice intake (p > 0.05). No electrolyte abnormality, significant changes in blood pressure or blood glucose levels were observed during the study. Each 5cc of syrup contained 136 mg of licorice extract with 12.14 mg glycyrrhizic acid, and also 136 μg of polyphenols. CONCLUSION:The licorice intake could improve the symptoms in PD patients without serious adverse events. 10.1016/j.jep.2019.112226
    Influence of dopaminergic treatment on resting elbow joint angle control mechanisms in patients with Parkinson's disease - a preliminary report. Marusiak Jarosław,Jaskólska Anna,Budrewicz Sławomir,Koszewicz Magdalena,Andrzejewska Renata,Kisiel-Sajewicz Katarzyna,Jaskólski Artur Acta of bioengineering and biomechanics PURPOSE:Heightened tonic stretch reflex contributes to increased muscle tone and a more-flexed resting elbow joint angle (EJA) in patients with Parkinson's disease (PD). Dopaminergic medication restores central nervous system (CNS) functioning and decreases resting muscle electrical and mechanical activities. This study aimed to evaluate the effects of dopaminergic medication on parkinsonian rigidity, resting EJA, resting electrical activity (electromyography, EMG) and mechanical properties (myotonometry, MYO) of elbow flexor muscles and the associations of EJA with these muscles resting electrical activity and mechanical properties in PD patients. We also evaluated a relationship between dopaminergic treatment dose and these outcome measures values. METHODS:Ten PD patients (age 68 ± 10.1 years; body mass 70 ± 16.8 kg; height 162 ± 6.6 cm; illness duration 9 ± 4.5 years) were tested during medication on- and off-phases. Resting EJA, myotonometric muscle stiffness (S-MYO) and root mean square electromyogram amplitude (RMS-EMG) were recorded from relaxed biceps brachii and brachioradialis muscles. Based on the above parameters, we also calculated the EJA/S-MYO ratio and EJA/RMS-EMG ratio. Parkinsonian rigidity was assessed using the motor section of the Unified Parkinson's Disease Rating Scale. RESULTS:EJA, EJA/S-MYO ratio, and EJA/RMS-EMG ratio were increased and S-MYO, RMS-EMG, and parkinsonian rigidity were decreased during the medication on-phase compared with the off-phase. In addition, the dopaminergic treatment dose was negatively correlated with S-MYO and RMS-EMG, and positively correlated with EJA/SMYO and EJA/RMS-EMG ratios. CONCLUSIONS:We conclude that dopaminergic medication- induced improvements in resting elbow joint angle in tested patients with PD are related to changes in their muscle electrical and mechanical properties.
    Does Postural Rigidity Decrease during REM Sleep without Atonia in Parkinson Disease? Arnaldi Dario,Latimier Alice,Leu-Semenescu Smaranda,De Carli Fabrizio,Vidailhet Marie,Arnulf Isabelle Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine STUDY OBJECTIVES:Rigidity is a muscle hypertonia typical of Parkinson disease (PD), whereas rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by abnormally increased muscle tone during REM sleep (REM sleep without atonia) and enacting dream behaviors. Because movements are not bradykinetic during RBD in patients with PD, we investigated whether the background, wake postural rigidity is attenuated during REM sleep without atonia, in absence of movement. METHODS:The amplitude of levator menti (postural muscle) electromyographic activity during relaxed evening wakefulness (considered as reference) and sleep (N2, N3, atonic REM sleep, and quiet REM sleep without atonia) was measured in 20 patients with PD (with and without RBD), 10 patients with idiopathic RBD patients and 10 healthy subjects. RESULTS:The chin tone amplitude progressively decreased from wake to N2, N3, and atonic REM sleep in the four groups, but the highest amplitude was observed in PD patients with RBD during atonic REM sleep. Furthermore, chin muscle tone amplitude did not attenuate from wake to REM sleep without atonia in patients with both PD and RBD but dramatically attenuated (by 40% on average) in patients with idiopathic RBD. CONCLUSIONS:The high amplitude of chin muscle tone in PD with RBD (but not in idiopathic RBD) during REM sleep with and without atonia suggests that both PD-related hypertonia and RBD-related enhanced muscle tone coexist during REM sleep, together affecting chin muscle tone. Consequently, some rapid RBD movements likely start against a rigid postural tone. 10.5664/jcsm.5882
    Classification of resistance to passive motion using minimum probability of error criterion. Chan H C,Manry M T,Kondraske G V Annals of biomedical engineering Neurologists diagnose many muscular and nerve disorders by classifying the resistance to passive motion of patients' limbs. Over the past several years, a computer-based instrument has been developed for automated measurement and parameterization of this resistance. In the device, a voluntarily relaxed lower extremity is moved at constant velocity by a motorized driver. The torque exerted on the extremity by the machine is sampled, along with the angle of the extremity. In this paper a computerized technique is described for classifying a patient's condition as 'Normal' or 'Parkinson disease' (rigidity), from the torque versus angle curve for the knee joint. A Legendre polynomial, fit to the curve, is used to calculate a set of eight normally distributed features of the curve. The minimum probability of error approach is used to classify the curve as being from a normal or Parkinson disease patient. Data collected from 44 different subjects was processes and the results were compared with an independent physician's subjective assessment of rigidity. There is agreement in better than 95% of the cases, when all of the features are used.