Cerebellar repetitive transcranial magnetic stimulation versus propranolol for essential tremor

Abstract

Background: Propranolol, a nonselective beta-adrenergic blocker, has long been used as one of the standard treatments for essential tremor (ET). Repetitive transcranial magnetic stimulation (rTMS) has also been used for a long time as a substitution therapy for ET patients. Objective:The main aim of this study was to evaluate the antitremor effect of 1-Hz (low-frequency) cerebellar rTMS and compare it to the use of propranolol in ET patients. Methods:In this single-blinded, randomized, controlled pilot study, a total of 38 patients with ET were randomized into two groups. One group (n = 20) received 1200 pulses of 1-Hz rTMS at an intensity of 90% of the resting motor threshold to the bilateral cerebellar region for 10 days. Another group (n = 18) received oral propranolol for 30 days. The initial dose was 30 mg/day, which was increased to 60 mg/day after 5 days, then to 90 mg/day on the 11th day, and continued thereafter for 20 days. The Fahn-Tolosa-Marin (FTM) clinical scale was assessed at baseline and at days 5, 10, and 30 to evaluate tremor severity, specific motor tasks, and functional disability.Results: Low-frequency rTMS of the cerebellum significantly improved tremor severity, specific motor tasks (writing, spiral drawing, and pouring), and FTM total scores on days 10 and 30. Nevertheless, we found no significant difference in functional disability at any point in time (p > .05). There were no statistically significant differences in FTM Part A, Part B, Part C scores and total scores of patients in propranolol group on days 5 and 10 compared with before treatment (p > .05). However, FTM total scores and FTM Part A, Part B, and Part C scores were significantly improved for patients when the dose of propranolol was 90 mg/day on day 30. Our study showed that there was no statistically significant difference in the total FTM scores and FTM Part A, Part B, and Part C scores between rTMS and propranolol on days 5, 10, and 30 (p > .05).

Essential Tremors: A Literature Review of Current Therapeutics

“…In a randomized controlled trial conducted in China, patients receiving rTMS therapy were given a total of 600 pulses, 20 pulses for 30 seconds followed by 5 second break. This study demonstrated improvement in FTM scores including parts A and B only after being subjected to 20-minute rTMS sessions for 10 days, with effects lasting up to 20 days [30]. This indicated that tremor severity was reduced without significant improvement in functional disability in daily living.…”

“…rTMS is a non-invasive brain stimulation (NIBS) therapy [30]. In this way, stimulating electrodes placed strategically near the patient's scalp create a magnetic field by producing small electrical currents.…”

“…The phenomenon of cerebellar inhibition has been known for years, wherein the magnetic stimulus applied to the cerebellum causes inhibition of the contralateral primary cortex through cerebello-thalamo-cortical (CTC) connections. This inhibition is caused by the use of low-frequency currents (less than one Hz), in contrast to high-frequency currents (five Hz and more), which cause cortical excitation [30]. On either side, coils are stationed tangentially to the cranial surface at a point distanced one-third from the inion on an imaginary line joining the inion and mastoid process.…”

“…On either side, coils are stationed tangentially to the cranial surface at a point distanced one-third from the inion on an imaginary line joining the inion and mastoid process. With respect to the midline, coils are given an angulation of 45° with the current flowing in the downward direction [30,31]. Fahn Tolosa Marin clinical scale (FTM), having a total point of 156, has been widely used to evaluate tremor effects.…”

“…Fahn Tolosa Marin clinical scale (FTM), having a total point of 156, has been widely used to evaluate tremor effects. It includes three subscales; Part A (tremor severity/amplitude), Part B (specific motor task assessment such as writing, spiral drawing, and pouring water with both hands), and Part C (functional disability measurement in activities of daily living) [30]. In a randomized controlled trial conducted in China, patients receiving rTMS therapy were given a total of 600 pulses, 20 pulses for 30 seconds followed by 5 second break.…”