Cerebellar repetitive transcranial magnetic stimulation (rTMS) for essential tremor: A double-blind, sham-controlled, crossover, add-on clinical trial

Abstract

Background: There is controversial evidence about the effect of cerebellar low-frequency stimulation in patients with essential tremor (ET). Objectives: In this study we assessed safety and effectiveness of 1 Hz (low-frequency) cerebellar repetitive transcranial magnetic stimulation (rTMS) on tremor severity in patients with essential tremor in a sham-controlled crossover trial. Methods: A total of 23 patients assigned into two groups to receive either sham (n ¼ 10) or rTMS (n ¼ 13) treatment, with crossing over after a two-month washout period. Intervention consisted of 900 pulses of 1 Hz rTMS at 90% resting motor threshold or the same protocol of sham stimulation over each cerebellar hemisphere for 5 consecutive days. Tremor severity was assessed by Fahn-Tolosa-Marin (FTM) scale at baseline and at days 5, 12 and 30 after intervention. The FTM consists of 3 subscales including tremor severity rating, performance of motor tasks, and functional disability. Carry-over and treatment effects were analyzed using independent samples t-test. Results: There was no significant improvement in the total FTM scores in rTMS compared to the sham stimulation on day 5 (p ¼ 0.132), day 12 (p ¼ 0.574), or day 30 (p ¼ 0.382). Similarly, FTM subscales, including tremor severity rating, motor tasks, and functional disability did not improve significantly after rTMS treatment. Mild headache and local pain were the most frequent adverse events. Conclusion: Although cerebellar rTMS seems to have acceptable safety when used in ET patients, this study could not prove any efficacy for it in reduction of tremor in these patients. Larger studies are needed to evaluate efficacy of this therapeutic intervention and to provide evidence about the optimal stimulation parameters.

Transcranial Magnetic Stimulation in Tremor Syndromes: Pathophysiologic Insights and Therapeutic Role

“…This study also demonstrated restoration of CTC connectivity on the fMRI (38). However, two other low frequency rTMS studies with a similar 5day paradigm found no significant difference between active and sham stimulation conditions (41,42).…”

Cerebellar rTMS and PAS effectively induce cerebellar plasticity

“…Also, the size of the cerebellum renders specific stimulation of certain parts problematic. The exact stimulation regions are not specified in many studies 50,72,77,[80][81][82][83] . Also, certain measurements such as CBI cannot be elicited in every person, or are not tolerated, so that these participants had to be excluded in previous studies.…”

“…To induce plasticity, we used procedures previously described to be effective in inducing plasticity in the cerebellum. In experiment 1, 1 Hz rTMS 50 , PAS 17 , cTBS 44,51 , and anodal tDCS [64][65][66] was used. 1 Hz rTMS was administered with 90% RMT for 20 min using a Magstim Rapid magnetic stimulator (Magstim Company, Whitland, Dyfed, UK) 50 .…”

“…studies, i.e. 1 Hz rTMS 50 , PAS 17 , cTBS 51 and tDCS 32 . The order of the four plasticity techniques was randomized and they were applied at least one week apart from each other.…”

Wearable Peripheral Electrical Stimulation Devices for the Reduction of Essential Tremor: A Review

“…Various types of non-invasive central stimulation may provide further treatment options for essential tremor. Trans cranial magnetic stimulation of the cerebellum has been studied in a small number of patients, and demonstrates acute motor improvement in essential tremor; however, not all studies have shown significant improvements compared to sham stimulation and whether long-lasting improvements can occur is uncertain [ 61 ], [ 62 ]. Another form of central stimulation, trans cranial direct current stimulation has shown a significant improvement in TETRAS scores in 6 essential tremor patients after a 15 session treatment course spanning across a 50 day period [ 63 ].…”