rTMS and Retraining in Focal Hand Dystonia (DSS)

This study is exploring a new experimental procedure in dystonia called repetitive transcranial magnetic brain stimulation (TMS) combined with rehabilitation. The purpose of the study is to determine whether repetitive TMS is effective as a treatment to reduce symptoms in dystonia as demonstrated by improved motor performance.

BACKGROUND: Though the etiology of focal hand dystonia (FHD) is uncertain, two primary factors implicated in the development of dystonic symptoms are excessive cortical excitability and impaired sensorimotor processing. OBJECTIVE: The purpose of this study was to determine the functional efficacy and neural effects of a Dual intervention of rTMS and sensorimotor retraining. Our working hypothesis is: subjects receiving the combined intervention will (1) display significantly improved handwriting measures; (2) report significant improvement in daily functional ability; (3) display reduced hand cramping compared; and (4) demonstrate reduced corticospinal excitability after the Dual intervention when compared to the rTMS+ stretching and massage (Sham) intervention. METHODS: A randomized, single-subject, multiple baseline design with crossover is used for this study that will examine ten subjects with FHD with two interventions: five days of low-frequency 1 Hz rTMS + sensorimotor retraining (Dual intervention) vs. rTMS + stretching and massage (Sham). The rTMS is applied to the premotor cortex at 1 Hz at 90% resting motor threshold for 1200 pulses. For sensorimotor retraining, a subset of the Learning-based Sensorimotor Training program was followed.

focal hand dystonia (FHD), repetitive transcranial magnetic stimulation (rTMS), sensorimotor retraining

First phase of treatment: Repetitive transcranial magnetic stimulation (rTMS) and sensorimotor retraining (SMR). Second phase of treatment: rTMS and control treatment (CTL) (CTL therapy consisted of non-specific therapy that includes stretching, massage, range of motion).

First phase of treatment: Repetitive transcranial magnetic stimulation (rTMS) with non-specific therapy that includes stretching, massage, range of motion. Second phase of treatment: rTMS and sensorimotor retraining (SMR).

For sensorimotor retraining, a subset of the Learning-based Sensorimotor Training program was followed

Symptom severity was assessed using the global rating of change (GROC). For the GROC, participants were asked to identify between one to three functions most impacted by focal hand dystonia. At posttest 1 they were then asked to select a rating of perceived change that represented the level of function compared to baseline. Perceived change consisted of a ±7 point Likert scale (+7= a very great deal better, 0= no change, -7= a very great deal worse).

The Arm Dystonia Disability Scale (ADDS) is a survey where participants rate task difficulty for activities such as writing, handling utensils, and buttoning on a scale of 1-4 (1 = no difficulty ,4 = not able or marked difficulty). This is a subjective assessment of impairment due to focal hand dystonia. Scores are determined using an equation: total points scored, divided by the maximum possible (23), multiplied by the quotient by 90 and subtract from 90%. Scores range from 0%-90% with higher scores indicating more function.

Examinations included two point discrimination. Two-point discrimination threshold was completed using a Disk-Criminator™. Participants were asked to reply "one" or "two" after each presentation. Static and dynamic stimuli were presented to the index and ring fingers bilaterally, meaning it was presented as a static stimuli or it was slowly swept across the skin (dynamic).

Cortical silent period (CSP) testing was completed during an isometric contraction of the target muscle whereby the motor evoked potential is followed by a short duration of electromyographic quiescence. The maximal voluntary contraction for finger abduction was recorded using a custom strain gauge placed around the index finger. Real-time visual feedback was given on a laptop screen to project the force produced by the participant and 20% of the maximum of three trials was calculated and displayed on a target line. For the CSP, participants were asked to contract until the target line was met, then a single transcranial magnetic stimulation pulse was delivered to the motor cortex. Ten trials were collected with a short rest period to prevent fatigue. CSP duration was calculated in milliseconds (ms). CSP EMG data were first rectified, and then a 10-ms moving average calculation was applied to the data. The onset of the CSP was set as the time point of the delivery of the TM

Digitized handwriting was assessed using a computerized tablet (WACOM Co., Ltd., japan) with MovAlyzeR® (Neuroscript LLC, Tempe, AZ) hardware and software. Participants used a custom modified digitized pen (Kiko Software, Netherlands) to write in a self-selected pace and style on the tablet with real-time visual feedback. Writing tasks included "My country tis of thee" at a self-selected pace, repeated eight times. Data were sampled at 215 Hz (resolution: 5080 lpi, accuracy: ±0.01 pressure range: 0-800 g). Writing samples were segmented by points of minimal velocity into single strokes for analysis. Pressure for each stroke was automatically calculated within the software.

Video recordings were made as participants wrote on a pad of paper with pen. Participants were asked to draw a series of 10 loops across the pad of paper followed by "The dog is barking" and their signature, each repeated four times. A physician blinded to participant allocation rated recordings. Scoring criteria were adapted from a standardized writer's cramp rating scale (WCRS) (Wissel et al., 1996), rating pathological flexion or extension at the wrist, fingers and elbow, presence of tremor, dystonic posture, writing speed and latency of dystonic symptoms. Final scores are expressed as a rating listed as a movement score.

Participants completed the full SF-36 assessment with subsection of interest: "physical functioning".

Inclusion Criteria: Greater than 18 years of age Symptoms of focal hand dystonia or writer's cramp Exclusion Criteria: History of seizure or other neurologic disorder

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Kimberley TJ, Borich MR, Arora S, Siebner HR. Multiple sessions of low-frequency repetitive transcranial magnetic stimulation in focal hand dystonia: clinical and physiological effects. Restor Neurol Neurosci. 2013;31(5):533-42. doi: 10.3233/RNN-120259.

Kimberley TJ, Schmidt RL, Chen M, Dykstra DD, Buetefisch CM. Mixed effectiveness of rTMS and retraining in the treatment of focal hand dystonia. Front Hum Neurosci. 2015 Jul 9;9:385. doi: 10.3389/fnhum.2015.00385. eCollection 2015.