Objective: To assess the effect of 5 days of transcranial direct current stimulation (tDCS) on spiral drawing in Writer’s Cramp patients.

Background: Writer’s cramp (WC) is a focal hand dystonia where handwriting is severely affected due to abnormal posturing of hand muscles. Imaging studies have revealed hyperactivity of sensorimotor and premotor cortical regions of brain, implying maladaptive plasticity. Few studies using tDCS on focal hand dystonia show inconsistent results. However, 5 days of cathodal tDCS can help reduce cortical activity. Moreover, it is relatively inexpensive and non-invasive and might hold promise as a technique for alleviating symptoms in WC.

Methods: 2 WC patients, based on MDS consensus for classification of dystonia, have to date been recruited to the study. 2mA of cathodal or sham stimulation was administered via carbon-rubber electrodes over the contralateral premotor-motor cortex (PM-M) area for 20 minutes, for 5 consecutive days. The patients were asked to draw spirals on a Wacom® digitizing tablet, before and after tDCS. They were made to practice the task before the main recording. Pullman’s experiment was run using MovAlyzeR® software. Average velocity, axial pen pressure, and normalized jerk (a measure of fluency) were chosen as variables for analysis.

Results: Patient 1: Average velocity before tDCS was 1.03± 0.47 cm/s, and 1.46± 0.49 cm/s (p<0.001) on the last day, post-tDCS. No significant change in pen pressure was seen. Normalized jerk was 5390 ± 4371.04 cm/s3 and 2681 ± 1557.6 cm/s3 (p=0.035) pre- and post-tDCS, respectively. Sham stimulation showed no significant change. Patient 2: Average velocity was 3.15 ± 0.78 cm/s at baseline and 2.28 ± 0.355 cm/s after tDCS (p<0.001). The pressure before and after tDCS was 491 ± 51.46 and 391 ± 23.41, respectively (p<0.001). Normalised jerk before the treatment was 382 ± 478.11 cm/s3 before and 586 ± 630.45 cm/s3 after tDCS (p=0.025). In sham, velocity and normalised jerk were not significantly altered following treatment, but the pen pressure decreased post-tDCS.

Conclusions: Both the patients responded differently; while speed and fluency improved in patient 1, patient 2 showed improvement in axial pen pressure after 5 days of tDCS. However, more studies are needed to identify the responding group of patients, and the ideal set of stimulation parameters to obtain the desired effects.

« Back to 2018 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/effect-of-multiple-sessions-of-transcranial-direct-current-stimulation-in-writers-cramp-does-it-hold-promise/