Kirsten E. Zeuner

Sensory training for patients with focal hand dystonia

Some patients with focal hand dystonia have impaired sensory perception. Abnormal sensory processing may lead to problems with fine motor control. For patients with focal hand dystonia who demonstrate sensory dysfunction, sensory training may reverse sensory impairment and dystonic symptoms. We studied the efficacy of learning to read braille as a method of sensory training for patients with focal hand dystonia. Sensory spatial discrimination was evaluated in 10 patients who had focal hand dystonia and 10 age‐ and gender‐matched controls with a spatial acuity test (JVP domes were used in this test). Clinical dystonia evaluation included the Fahn dystonia scale and time needed to write a standard paragraph. Each individual was trained in braille reading at the grade 1 level for 8 weeks, between 30 and 60 minutes daily, and was monitored closely to ensure that reading was done regularly. Both controls and patients demonstrated improvement on the spatial acuity test. Patients showed a significant mean difference from baseline to 8 weeks on the Fahn dystonia scale. Sixty percent of the patients shortened the time they needed to write a standard paragraph. Improved sensory perception correlated positively with improvement on the Fahn dystonia scale. We conclude that training in braille reading improves deficits in spatial discrimination and decreases disability in patients with focal hand dystonia.

Enhanced tactile spatial acuity and cortical processing during acute hand deafferentation

Acute deafferentation of a limb results in bilateral cortical reorganization, but the behavioral consequences of this phenomenon are unknown. Here we found rapid improvements in tactile spatial acuity and changes in cortical processing for the left hand during cutaneous anesthesia of the right hand. The site-specific improvement in tactile spatial acuity may represent a behavioral compensatory gain.

Motor training as treatment in focal hand dystonia

Focal hand dystonia may arise as a result of aberrant plasticity from excessive repetitive use. Improvement might be possible with appropriate motor training. Focusing on trying to decrease abnormal overflow of movement to fingers not involved in a task, we developed a motor training program for individualized finger movements. Ten patients with writers cramp participated in the motor training program. Evaluation was done with the Fahn dystonia scale, kinematic analysis of handwriting, transcranial magnetic stimulation (TMS), and electroencephalography (EEG). Clinical improvement of dystonia was significant using the Fahn dystonia scale, and 6 patients reported an improvement in writing. The handwriting analysis showed a trend for improvement after training in simple exercises. There were no changes in cortical excitability measured by TMS and EEG. Whereas this method of motor training for 4 weeks led to mild subjective improvement and some improvement in handwriting, it is not sufficient to reverse motor cortex abnormalities measured by TMS and EEG. Published 2004 John Wiley & Sons

Accelerometry to distinguish psychogenic from essential or parkinsonian tremor

The authors measured postural wrist tremor with accelerometry in patients with psychogenic (n = 6), essential (n = 11), and parkinsonian (n = 12) tremor. Tremor was measured in one hand, while the other hand either rested or tapped to an auditory stimulus at 3 and 4 or 5 Hz. Psychogenic tremors showed larger tremor frequency changes and higher intraindividual variability while tapping. Accelerometry may differentiate psychogenic from essential and parkinsonian tremor.

Manual activity shapes structure and function in contralateral human motor hand area

From longitudinal voxel-based morphometry (VBM) studies we know that relatively short periods of training can increase regional grey matter volume in trained cortical areas. In 14 right-handed patients with writers cramp, we employed VBM to test whether suppression (i.e., immobilization) or enhancement (i.e., training) of manual activity lead to opposing changes in grey matter in the contralateral primary motor hand area (M1(HAND)). We additionally used transcranial magnetic stimulation (TMS) to evaluate concurrent changes in regional excitability. Patients were recruited from a clinical trial which was designed to improve handwriting-associated dystonia. Initially the dystonic hand was immobilized for 4 weeks with the intention to reverse faulty plasticity. After immobilization, patients accomplished a motor re-training for 8 weeks. T1-weighted MRIs of the whole brain and single-pulse TMS measurements of the resting motor threshold (RMT) were performed every 4 weeks. Immobilization of the right hand resulted in a relative grey matter decrease in the contralateral left M1(HAND) along with a decrease in corticomotor excitability as indexed by an increase in RMT. Subsequent training reversed the effects of immobilization, causing an increase in regional grey matter density and excitability of left M1(HAND). The relative changes in grey matter correlated with the relative shifts in RMT. This prospective within-subject VBM study in task-specific hand dystonia shows that the grey matter density of M1(HAND) is dynamically shaped by the level of manual activity. This bi-directional structural plasticity is functionally relevant as local grey matter changes are mirrored by changes in regional excitability.

Sensory training as treatment for focal hand dystonia: a 1-year follow-up.

In a prior study, 10 patients with focal hand dystonia learned braille reading as sensory training for 8 weeks. Practice time was 30 to 60 minutes daily. They improved both their spatial acuity using the Grating Orientation Discrimination Task (GOT) and their dystonia using the Fahn scale. Three patients continued training for 1 year. Patients showed further improvement in the GOT, writing a standard paragraph, and self‐rating scales. Sensory training lasting longer than 8 weeks may lead to continued improvement.

How to assess motor impairment in writer's cramp

Writers cramp is a task‐specific hand dystonia affecting handwriting. Clinical scores such as the Arm Dystonia Disability Scale (ADDS) or Writers Cramp Rating Scale (WCRS) as well as kinematic analysis of handwriting movements have been used to assess functional impairment in affected patients. In 21 patients with writers cramp and healthy controls, we analyzed the kinematics of writing and cyclic drawing movements. We rated the severity of dystonia using the ADDS and WCRS and correlated the clinical scores with movement kinematics. Mean stroke frequency was significantly reduced in dystonic patients. Drawing movements showed more frequently a decrease in stroke frequency than handwriting movements. During circle drawing, mean vertical peak velocity was more variable in patients relative to controls, indicating an impaired ability to reproduce the same kinematic pattern over time. An increase in vertical writing pressure was only observed during handwriting but not during circle drawing and may reflect a compensatory effort to stabilize the pencil. Kinematic measures and individual ADDS and WCRS scores did not correlate with each other. The lack of correlation is not surprising as ADDS, WCRS, and kinematic analysis probe different aspects of motor impairment. The ADDS characterizes how dystonia affects a set of fine manual tasks, whereas the WCRS scores the manifestation of dystonia during handwriting. Therefore, the clinical scores and kinematic analysis of handwriting provide complementary insights into motor impairment. Future studies need to address which combination of clinical scores and kinematic measures are most appropriate to quantify impairment in writers cramp.

Motor re‐training does not need to be task specific to improve writer's cramp

Previous studies showed a beneficial effect of motor re‐training in task‐specific hand dystonia. Here we examined whether re‐training needs to specifically focus on the task affected by dystonia. 21 patients with writers cramp were randomly assigned to two types of re‐training: One group of patients trained drawing and writing movements using a pen attached to the bottom of a finger splint. The second group used therapeutic putty to train finger movements without exercises of drawing and writing movements. Training lasted for 8 weeks. Before re‐training, affected hand and forearm were immobilized for 4 weeks to facilitate the responsiveness to re‐training. Dystonia was assessed during handwriting using the Writers Cramp Rating Scale. Although no clinical improvement was observed immediately after immobilization, 8 weeks of re‐training improved task‐specific dystonia relative to baseline (P = 0.005). Both training modalities were equally effective. More severely affected patients benefited most. There was no correlation between disease duration and the individual treatment response. Re‐training also improved hand function as indexed by the Arm Dystonia Disability Scale (P = 0.008). Kinematic handwriting analysis showed that re‐training lowered vertical force level and enhanced the fluency of handwriting. We conclude that re‐training does not need to specifically focus on the task affected by dystonia to be clinically effective.

Effect of ethanol on the central oscillator in essential tremor

We investigated the effects of ethanol and diazepam on the central, mechanical, and mechanical reflex components of tremor in patients with essential tremor (ET). A double‐blind crossover study (ethanol or diazepam) was conducted on 2 separate days. Dose of ethanol or diazepam was calculated in each individual according to height, weight, and age in 10 patients with ET. The postural tremor amplitude at the wrist was recorded using a three‐dimensional accelerometer placed on the dorsum of the hand. Electromyogram (EMG) was recorded with surface electrodes placed on the forearm extensors and flexors. To separate central and mechanical (reflex) components, a 500‐g weight was placed on the dorsum of the hand during a second tremor measurement. Tremor recordings were done at baseline and 30, 60, 90, and 120 minutes after drug ingestion. Ethanol and diazepam blood levels were measured at baseline and after 20, 40, 80, and 120 minutes. Blood ethanol and diazepam levels were highest after 40 and 80 minutes. The amplitude of the central component 60 minutes after ingestion of ethanol was decreased significantly (P = 0.029) compared with diazepam. Our findings suggest that the improvement in tremor after ethanol ingestion was due, at least in part, to an effect on a central oscillator.

Provocation of Parkinsonian tremor.

Classical Parkinsonian rest tremor typically fluctuates over time and can be provoked by stressful situations. We quantified and compared the influence of different provocation methods on classical rest tremor severity. The effect of counting backwards from 100, tapping of the contralateral foot and a Stroop test on the Unified Parkinsons Disease Rating Scale (UPDRS) III rest tremor scores and the accelerometrically measured tremor amplitudes (total power) were analyzed in 18 patients with Parkinsons disease and a Type I tremor. Each of the three provocation methods increased the UPDRS III rest tremor score by 1–2 and the total power by 1–2 orders of magnitude compared with baseline (P < 0.001). The maximal effect was reached on average after 2–3 minutes of provocation. The effects were not significantly different. Provocations clearly influence the result of clinical rest tremor ratings, with the kind of provocation being of minor importance. We therefore suggest that each assessment of Parkinsonian rest tremor should include a systematic provocation and this should be formally included in future versions of the UPDRS.