Psychometric Properties of a Digital Goniometer in Upper and Lower Cervical Range of Motion Measurement.

OBJECTIVE: The purpose of this study was to examine the intrarater reliability and criterion validity of a digital goniometer for measuring cervical range of motion including an active sitting version of the cervical flexion rotation test, an important clinical measure for capturing upper cervical dysfunction. METHODS: A cross-sectional study (n = 18; 78% women) examined total cervical and upper cervical active ranges of motion (flexion, extension, side bending, rotation) measured concurrently using 3 measurement methods (a digital goniometer, the cervical range-of-motion instrument, and 3-dimensional motion analysis). Intraclass correlation coefficient (2,1), Pearson correlation coefficients (digital goniometer versus 3-dimensional motion analysis), and minimum detectable change were calculated. RESULTS: There was moderate to excellent intrarater reliability for the digital goniometer and good to excellent criterion validity of the digital goniometer for all cervical motions except left lateral flexion which was moderate (0.70). The sitting upper cervical flexion rotation test showed good to excellent reliability and validity. The minimal detectable change for the digital goniometer ranged from 3 to 8 degrees across cervical motions. CONCLUSION: In individuals without neck pain, a digital goniometer device was a reliable, valid, and an easy-to-administer clinical tool for measuring total cervical range of motion as well as for capturing upper cervical motion.

Predicting the number of physical therapy visits and patient satisfaction in individuals with temporomandibular disorder: A cohort study.

BACKGROUND: Temporomandibular disorders (TMD) can be challenging to manage for clinicians and patients alike. It is unclear which factors are associated with prolonging conservative care and patient dissatisfaction with treatment outcomes. OBJECTIVES: To examine factors collected during a physical therapy (PT) evaluation in a cohort of individuals with TMD to determine factors associated with an increased number of PT visits and reduced patient satisfaction. METHODS: Records of 511 patients referred to PT over 18 months were reviewed to extract 27 variables to develop a predictive model. Outcomes were patient satisfaction following PT and number of PT visits. Linear and zero inflated negative binomial regressions were used, and a multivariate regression model was built for both outcomes. RESULTS: Two factors were associated with both lower patient satisfaction and an increased number of PT visits: higher patient rated functional neck disability and a greater number of healthcare professionals seen. Other factors associated with patient satisfaction were duration of symptoms, subluxation, and referral from an oral surgeon. Only patient rated functional neck disability score was a significant predictive factor in the multivariate model. Factors associated with number of PT visits were gender, educational level, time between initial visit and discharge, number of pain areas, bruxism, biopsychosocial factors, dizziness, pain rating, and presence of neck pain. In the multivariate model, gender, number of healthcare professionals seen, and resting pain rating were significant predictors of number of PT visits. CONCLUSION: Considering key factors on initial evaluation, specifically functional neck disability and the number of prior healthcare professionals seen before starting PT, can help to predict a higher number of PT visits and reduced patient satisfaction with outcomes.

Effects of 2 Years of Exercise on Gait Impairment in People With Parkinson Disease: The PRET-PD Randomized Trial.

BACKGROUND AND PURPOSE: This study presents a secondary analysis from the Progressive Resistance Exercise Training in Parkinson Disease (PRET-PD) trial investigating the effects of progressive resistance exercise (PRE) and a Parkinson disease (PD)-specific multimodal exercise program, modified Fitness Counts (mFC), on spatial, temporal, and stability-related gait impairments in people with PD. METHODS: Forty-eight people with PD were randomized to participate in PRE or mFC 2 times a week for 24 months; 38 completed the study. Gait velocity, stride length, cadence, and double-support time were measured under 4 walking conditions (off-/on-medication, comfortable/fast speed). Ankle strength was also measured off- and on-medication. Twenty-four healthy controls provided comparison data at one time point. RESULTS: At 24 months, there were no significant differences between exercise groups. Both groups improved fast gait velocity off-medication, cadence in all conditions, and plantarflexion strength off-/on-medication. Both groups with PD had more gait measures that approximated the healthy controls at 24 months than at baseline. Plantarflexion strength was significantly associated with gait velocity and stride length in people with PD at baseline and 24 months, but changes in strength were not associated with changes in gait. DISCUSSION AND CONCLUSIONS: Twenty-four months of PRE and mFC were associated with improved off-medication fast gait velocity and improved cadence in all conditions, which is important because temporal gait measures can be resistant to medications. Spatial and stability-related measures were resistant to long-term improvements, but did not decline over 24 months. Strength gains did not appear to transfer to gait.Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, http://links.lww.com/JNPT/A161).

Distinct functional and macrostructural brain changes in Parkinson's disease and multiple system atrophy.

Parkinson's disease (PD) and the parkinsonian variant of multiple system atrophy (MSAp) are neurodegenerative disorders that can be difficult to differentiate clinically. This study provides the first characterization of the patterns of task-related functional magnetic resonance imaging (fMRI) changes across the whole brain in MSAp. We used fMRI during a precision grip force task and also performed voxel-based morphometry (VBM) on T1 -weighted images in MSAp patients, PD patients, and healthy controls. All groups were matched on age, and the patient groups had comparable motor symptom durations and severities. There were three main findings. First, MSAp and PD had reduced fMRI activation in motor control areas, including the basal ganglia, thalamus, insula, primary sensorimotor and prefrontal cortices, and cerebellum compared with controls. Second, there were no activation differences among the disease groups in the basal ganglia, thalamus, insula, or primary sensorimotor cortices, but PD had more extensive activation deficits throughout the cerebrum compared with MSAp and controls. Third, VBM revealed reduced volume in the basal ganglia, middle and inferior cerebellar peduncles, pons, and throughout the cerebrum in MSAp compared with controls and PD, and additionally throughout the cerebellar cortex and vermis in MSAp compared with controls. Collectively, these results provide the first evidence that fMRI activation is abnormal in the basal ganglia, cerebellum, and cerebrum in MSAp, and that a key distinguishing feature between MSAp and PD is the extensive and widespread volume loss throughout the brain in MSAp.

Resting state functional magnetic resonance imaging in Parkinson's disease.

Neuroimaging advances over the past several decades have provided increased understanding of the structural and functional brain changes that occur with Parkinson's disease (PD). Examination of resting state functional magnetic resonance imaging (rs-fMRI) provides a noninvasive method that focuses on low-frequency spontaneous fluctuations in the blood-oxygenation-level-dependent signal that occurs when an individual is at rest. Several analysis methods have been developed and used to explore how PD affects resting state activity and functional connectivity, and the purpose of this review is to highlight the critical advances made thus far. Some discrepancies in the rs-fMRI and PD literature exist, and we make recommendations for consideration in future studies. The rs-fMRI technique holds promise for investigating brain changes associated with the motor and nonmotor symptoms of PD, and for revealing important variations across large-scale networks of the brain in PD.

Real time ultrasound imaging shows changes in deep neck flexor activation during exercise in individuals with mechanical neck pain.

BACKGROUND: Deep neck flexor muscle atrophy and increased superficial neck muscle activation are associated with disability and pain intensity in individuals with neck pain. There is a lack of evidence to support direct assessment of deep neck flexor muscles in a non-invasive way during exercise performance to help determine the effectiveness of different neck strengthening exercises. OBJECTIVE: Compare longus colli (LC) and sternocleidomastoid (SCM) activation between individuals with and without neck pain using real time ultrasound (RTUS) during a series of craniocervical exercises. METHODS: This cross-sectional cohort study recruited 10 control and 10 neck pain participants to complete four deep neck flexor activation activities involving varying levels of craniocervical flexion. Dimensions of the LC and SCM were measured using RTUS at rest and during exercise. Independent t-tests assessed baseline differences and analysis of variance examined activation changes. RESULTS: At rest, the neck pain group had significantly smaller cross-sectional area and thickness of the LC compared to the control group (p< 0.05). During exercise, the neck pain group showed significantly larger increases in LC thickness and cross-sectional area across exercise compared to the control group, with no differences in SCM activation between groups. CONCLUSIONS: Despite atrophy, individuals with neck pain can activate their deep neck flexor muscles appropriately without activating their superficial neck flexor muscles in a supine series of craniocervical flexion exercise as measured by non-invasive ultrasound imaging.

Prevalence and impact of signs and symptoms of temporomandibular disorders in dental students and faculty.

OBJECTIVES: Temporomandibular disorders (TMD) affect individuals undergoing increased stress, for example, dental professionals. No study to date has compared dental students and faculty in TMD manifestation. This cross-sectional study compared prevalence, risk factors, and impact on daily activities of self-reported TMD signs/symptoms between dental students and faculty at a predoctoral dental school, and between preclinical (first- to second-year) and clinical (third- to fourth-year) students. METHODS: A REDCap survey was sent to dental students and faculty, assessing TMD signs/symptoms (TMD Symptom Questionnaire), pain intensity (Chronic Graded Pain Scale), jaw function (Jaw Function Limitation Scale), parafunctions (Oral Behavioral Checklist), previous TMD treatments, anxiety/depression symptoms (Patient Health Questionnaire), perceived stress (Perceived Stress Scale), and sleep quality (RU-SATED Scale). Outcomes were compared between groups using chi-square and t-tests, adjusting for covariates with analyses of covariance (ANCOVA). RESULTS: Data derived from N = 145 participants (N = 108 students, N = 37 faculty). Dental students reported significantly higher prevalence (90.1% vs. 75.7%, p = 0.020) and greater number of TMD signs/symptoms (5.3 ± 3.5 vs. 3.0 ± 2.7, p < 0.001) compared to faculty. Students reported significantly more parafunctional activities (p = 0.000), jaw-strain episodes (prolonged mouth opening, p = 0.007), higher stress level (p = 0.008), and lower sleep quality (p = 0.002) than faculty. Difference in number of TMD signs/symptoms was maintained after adjusting for stress, sleep quality, and parafunctional/jaw-strain activities. Clinical students utilized significantly more often evidence-based TMD treatment compared to preclinical students. CONCLUSIONS: High prevalence of self-reported TMD was observed among dental students and faculty, with students reporting higher prevalence and impairment despite working in the same environment. Findings underscore the importance of education on preventive measures early in dental training to address contributing factors and TMD management.

Diffusion tensor imaging of Parkinson's disease, atypical parkinsonism, and essential tremor.

Diffusion tensor imaging could be useful in characterizing movement disorders because it noninvasively examines multiple brain regions simultaneously. We report a multitarget imaging approach focused on the basal ganglia and cerebellum in Parkinson's disease, parkinsonian variant of multiple system atrophy, progressive supranuclear palsy, and essential tremor and in healthy controls. Seventy-two subjects were studied with a diffusion tensor imaging protocol at 3 Tesla. Receiver operating characteristic analysis was performed to directly compare groups. Sensitivity and specificity values were quantified for control versus movement disorder (92% sensitivity, 88% specificity), control versus parkinsonism (93% sensitivity, 91% specificity), Parkinson's disease versus atypical parkinsonism (90% sensitivity, 100% specificity), Parkinson's disease versus multiple system atrophy (94% sensitivity, 100% specificity), Parkinson's disease versus progressive supranuclear palsy (87% sensitivity, 100% specificity), multiple system atrophy versus progressive supranuclear palsy (90% sensitivity, 100% specificity), and Parkinson's disease versus essential tremor (92% sensitivity, 87% specificity). The brain targets varied for each comparison, but the substantia nigra, putamen, caudate, and middle cerebellar peduncle were the most frequently selected brain regions across classifications. These results indicate that using diffusion tensor imaging of the basal ganglia and cerebellum accurately classifies subjects diagnosed with Parkinson's disease, atypical parkinsonism, and essential tremor and clearly distinguishes them from control subjects.

Effect of Starting Posture on Three-Dimensional Jaw and Head Movement.

Objectives: The effect of body posture on movement of the jaw and head has not yet been clearly established. The relationship between jaw and head movement has implications for conditions such as temporomandibular joint disorders which can be associated with neck pain. The purpose of this quasi-experimental study was to examine the effect of starting posture on three-dimensional movement of the jaw and head, and to examine the relationship between head and jaw movement during mouth opening. Material and Methods: Fourteen healthy participants performed jaw opening to comfortable and maximal amounts from three starting body postures (neutral, slumped, upright) while three-dimensional movement of the head, jaw, and trunk was tracked. Separate repeated measures analyses of variance analyses examined the effect of posture on jaw and head rotation and translation, and Pearson product moment correlations examined the relationship between jaw opening and head rotation. Results: Body posture significantly influenced maximal opening but not comfortable opening (P < 0.0033). There was a positive relationship between head extension and maximum opening in an upright posture (r = 0.74, P = 0.006), and head extension and comfortable opening in neutral and upright postures (r = 0.75 to 0.93, P < 0.0033), although there was no relationship between head extension and jaw opening in a slumped posture when opening comfortably. Conclusions: Posture can affect three-dimensional movement of the jaw when opening. Negating the normal head extension that occurs with mouth opening when in a slumped posture has implications for the development of temporomandibular and neck problems in some individuals.

Predicting grip force amplitude involves circuits in the anterior basal ganglia.

The ability to grip objects allows us to perform many activities of daily living such as eating and drinking. Lesions to and disorders of the basal ganglia can cause deficits in grip force control. Although the prediction of grip force amplitude is an important component of performing a grip force task, the extant literature suggests that this process may not include the basal ganglia. This study used functional magnetic resonance imaging (fMRI) to explore the functional brain mechanisms underlying the prediction of grip force amplitude. The mean force and duration of force did not vary across prediction levels. As anticipated, the reaction time decreased with the level of grip force predictions. In confirmation of previous studies, the parieto-frontal and cerebellar circuits increased their fMRI signal as grip force predictability increased. In addition, the novel finding was that anterior nuclei in the basal ganglia such as caudate and anterior putamen also had an fMRI signal that increased with the level of grip force prediction. In contrast, the fMRI signal in posterior nuclei of the basal ganglia did not change with the level of prediction. These findings provide new evidence indicating that anterior basal ganglia nuclei are involved in the predictive scaling of precision grip force control. Further, the results provide additional support for the planning and parameterization model of the basal ganglia by demonstrating that specific anterior nuclei of the basal ganglia are involved in planning grip force.

Basal ganglia hypoactivity during grip force in drug naïve Parkinson's disease.

The basal ganglia (BG) are impaired in Parkinson's disease (PD), but it remains unclear which nuclei are impaired during the performance of motor tasks in early-stage PD. Therefore, this study was conducted to determine which nuclei function abnormally, and whether cortical structures are also affected by early-stage PD. The study also determined if cerebellar hyperactivity is found early in the course of PD. Blood oxygenation level dependent activation was compared between 14 early-stage drug-naïve PD patients and 14 controls performing two precision grip force tasks using functional magnetic resonance imaging at 3 T. The grip tasks used in this study were chosen because both tasks are known to provide robust activation in BG nuclei, and the two tasks were similar except that the 2-s task required more switching between contraction and relaxation than the 4-s task. The 4-s task revealed that PD patients were hypoactive relative to controls only in putamen and external globus pallidus, and thalamus. In the 2-s task, PD patients were hypoactive throughout all BG nuclei, thalamus, M1, and supplementary motor area. There were no differences in cerebellar activation between groups during either task. Regions of interest analysis revealed that the hypoactivity observed in PD patients during the 2-s task became more pronounced over time as patients performed the task. This suggests that a motor task that requires switching can accentuate abnormal activity throughout all BG nuclei of early-stage, drug-naive PD, and that the abnormal activity becomes more pronounced with repeated task performance in these patients.

Blood oxygenation level-dependent activation in basal ganglia nuclei relates to specific symptoms in de novo Parkinson's disease.

To aid the development of symptomatic and disease modifying therapies in Parkinson's disease (PD), there is a strong need to identify noninvasive measures of basal ganglia (BG) function that are sensitive to disease severity. This study examines the relation between blood oxygenation level-dependent (BOLD) activation in every nucleus of the BG and symptom-specific disease severity in early stage de novo PD. BOLD activation measured at 3 T was compared between 20 early stage de novo PD patients and 20 controls during an established precision grip force task. In addition to the BG nuclei, activation in specific thalamic and cortical regions was examined. There were three novel findings. First, there were significant negative correlations between total motor Unified PD Rating Scale and BOLD activation in bilateral caudate, bilateral putamen, contralateral external segment of the globus pallidus, bilateral subthalamic nucleus, contralateral substantia nigra, and thalamus. Second, bradykinesia was the symptom that most consistently predicted BOLD activation in the BG and thalamus. Also, BOLD activation in the contralateral internal globus pallidus was related to tremor. Third, the reduced cortical activity in primary motor cortex and supplementary motor area in de novo PD did not relate to motor symptoms. These findings demonstrate that BOLD activity in nuclei of the BG relates most consistently to bradykinesia and functional magnetic resonance imaging has strong potential to serve as a noninvasive marker for the state of BG function in de novo PD.

Effects of visual gain on force control at the elbow and ankle.

Visual feedback is essential when minimizing force fluctuations. Varying degrees of somatotopic organization have been shown in different regions of the brain for the upper and lower extremities, and visual feedback may be processed differently based on the body effector where feedback-based corrections are used. This study compared the effect of changes in visual gain on the control of steady-state force at the elbow and ankle. Ten subjects produced steady-state isometric force to targets at 5 and 40% of their maximum voluntary contraction at seven visual gain levels. Visual gain was used effectively at both joints to reduce variability of the force signal and to improve accuracy, with a greater effect of visual gain at the elbow than the ankle. Visual gain significantly decreased the regularity of force output, and this effect was more pronounced at the elbow than the ankle. There were accompanying changes in the proportion of power in the 0-4, 4-8, and 8-12 Hz frequency bins of the force signal across visual gain at the elbow. Changes in visual gain were accompanied by changes in both agonist and antagonist electromyographic (EMG) activation at the elbow. At the ankle joint, there were only changes in agonist EMG. The results suggest better use of visual information in the control of elbow force than ankle force and this improved control may be related to the changes in the pattern of agonist and antagonist activation.

Effect of Injury Prevention Programs on Lower Extremity Performance in Youth Athletes: A Systematic Review.

BACKGROUND: Understanding how existing youth injury prevention programs affect specific modifiable injury risk factors will inform future program development for youth athletes. OBJECTIVE: To comprehensively evaluate the effects of injury prevention programs on the modifiable intrinsic risk factors associated with lower extremity performance in youth athletes. DATA SOURCES: This systematic review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A systematic search of the literature was performed using multiple databases (PubMed, EBSCOhost [including CINAHL, Medline, and SPORTDiscus], and PEDro). Secondary references were appraised for relevant articles. Article types included randomized or cluster randomized controlled trials and randomized cohort designs with youth athletes engaged in organized sports, along with outcomes that included at least 1 physical performance outcome measure. STUDY SELECTION: Eight studies met inclusion and exclusion criteria and were reviewed by 2 independent reviewers, with a third consulted in the case of disagreement, which was not needed. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: Included studies underwent review of methodological quality using the Physiotherapy Evidence Database scale. RESULTS: Studies included mixed-sex samples of youth athletes who predominantly participated in soccer at different skill levels. The FIFA 11+ series was the most commonly used injury prevention program. Among studies, the mean percentage of improvement identified was 11.3% for force generation, 5.7% for coordination, 5.2% for posture, and 5.2% for balance. The lowest mean percentage improvement was in speed (2.2%). Endurance was not significantly affected by any of the programs. CONCLUSION: This systematic review shows that injury prevention programs improve several modifiable intrinsic risk factors of lower extremity performance among youth athletes, particularly force generation. However, several intrinsic risk factors were either not significantly affected or specifically addressed by existing programs.

Temporomandibular disorder content in the curricula of physical therapist professional programs in the United States.

Objective: To describe the status of entry-level physical therapist (PT) education related to the diagnosis and management of temporomandibular disorders (TMD) in accredited, entry-level United States PT programs. Methods: An electronic survey explored specific TMD diagnostic and management curricular content, including the use of evidence-based diagnostic criteria, opportunities for students to interact with individuals with TMD, and faculty qualifications. Results: Eighty-four programs completed the survey. TMD content is covered in the entry-level PT curriculum of almost all (98.8%) responding programs. Content specifically related to TMD averaged 12 h across program respondents (range 1.5-50 h). The majority (68%) of respondents utilized established evidence-based diagnostic criteria. Discussion: Consistent entry-level education guidelines related to TMD and additional post-professional education opportunities are necessary to ensure that patients with TMD are not underserved by the profession of PT by newly graduated PTs.

Outcomes and patient satisfaction following individualized physical therapy treatment for patients diagnosed with temporomandibular disc displacement without reduction with limited opening: A cross-sectional study.

OBJECTIVE: To investigate physical therapy treatment outcomes and patient satisfaction in patients with a diagnosis of disc displacement without reduction with limited opening (DDWoR wLO). METHODS: Records of 97 patients with DDWoR wLO who received physical therapy in one outpatient clinic were used in this cross-sectional study. Outcomes included number of visits, maximum active interincisal opening, self-reported pain, and patient satisfaction. RESULTS: The average number of physical therapy visits per patient was 5.5, and there were significant improvements in pain rating and interincisal opening following physical therapy. Effect sizes for these comparisons were large (>1.0). Mean patient satisfaction responses across all symptom areas was consistent with patients being more than less satisfied following treatment. DISCUSSION: Individualized physical therapy treatment is an effective conservative intervention to improve mouth opening, reduce pain, and provide patient satisfaction in patients with one specific sub-type of temporomandibular disorder (TMD), DDWoR wLO.

Changes in the relationship between movement velocity and movement distance in primary focal hand dystonia.

The authors examined the relationship between movement velocity and distance and the associated muscle activation patterns in 18 individuals with focal hand dystonia (FHD) compared with a control group of 18 individuals with no known neuromuscular condition. Participants performed targeted voluntary wrist and elbow flexion movements as fast as possible across 5 movement distances. Individuals with FHD were slower than controls across all distances, and this difference was accentuated for longer movements. Muscle activation patterns were triphasic in the majority of individuals with FHD, and muscle activation scaled with distance in a similar manner to controls. Cocontraction did not explain movement slowing in individuals with dystonia, but there was a trend toward underactivation of the 1st agonist burst in the dystonic group. The authors concluded that slowness is a consistent feature of voluntary movement in FHD and is present even in the absence of dystonic posturing. Underactivation of the 1st agonist burst appears to be the most likely reason to explain slowing.

Effects of STN DBS on memory guided force control in Parkinson's disease (June 2007).

This study examined the control of elbow force in nine patients with Parkinson's disease when visual feedback was available and when visual feedback was removed to determine how medication (Meds) and unilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) affect memory guided force control. Patients were examined in each of four treatment conditions: 1) off treatment; 2) Meds; 3) STN DBS; and 4) Meds plus STN DBS. With visual feedback available, there was no difference in force output across treatment conditions. When visual feedback was removed force output drifted under the target in both the off-treatment and the Meds conditions. However, when on STN DBS or Meds plus STN DBS force output drifted above the target. As such, only STN DBS had a significant effect on force output in the vision removed condition. Increased force output when on STN DBS may have occurred due to disruptions in the basal ganglia-thalamo-cortical circuitry. We suggest that modulation of output of the internal segment of the globus pallidus by STN DBS may drive the effect of STN DBS on memory guided force control.

Disc displacement without reduction with limited opening: A clinical diagnostic accuracy study.

PURPOSE: The purpose of this study is to explore the diagnostic accuracy and clinical utility of an examination by a physical therapist using a clinical patient population for diagnosing a specific sub-type of disc displacement (DDWoR wLO) compared to the imaged disc position. METHODS: Data from 46 patients with a clinical diagnosis of DDWoR wLO (92 clinical examinations and MRI records) were collected. Clinical diagnosis was made based on predefined diagnostic criteria, and the MRI diagnosis was made based on the MRI radiology report obtained from the dental provider. A McNemar test was used to determine whether the outcomes of the clinical and MRI diagnoses differed significantly, and sensitivity, specificity, likelihood ratios, predicative values, 95% confidence intervals, and the overall diagnostic accuracy were computed. RESULTS: There was high sensitivity (85%), moderate but unacceptable specificity (73%), and acceptable overall diagnostic accuracy (80%) for using predefined criteria in the diagnosis of DDWoR wLO. The likelihood ratios and predictive values supported the clinical utility of the criteria used for diagnosing DDWoR wLO. CONCLUSION: This is the first study to characterize diagnostic accuracy by a physical therapist of a specific sub-type of TMD in a clinical patient population rather than a research based population. The results suggest that while sensitivity and the overall diagnostic accuracy were acceptable, specificity was lower than acceptable and these findings are discussed in relation to clinical utility of using diagnostic criteria in a clinical setting against a gold standard of MRI.

Rate of force production and relaxation is impaired in patients with focal hand dystonia.

One factor, which may contribute to slowed movement in dystonia, is impairment in controlling the voluntary rate of motor output. This study examined the ability of patients with focal hand dystonia to rapidly turn force on and off at the wrist and elbow joints. Dystonic patients were slower than controls in rapidly turning on force from rest at both joints, passively relaxing force and rapidly reversing force output from a steady-state flexion contraction. Adding a preload did not improve the ability of dystonic subjects to rapidly turn on force. These results support the idea that dystonia is a disorder of impaired motor cortical activation, possibly due to basal ganglia dysfunction.