Objective: To describe a group of patients with an upper limb tremor refractory to per os medications and receiving Botulinum NeuroToxin type A (BoNT-A) injections.

Background: Among off-label indications, the efficacy of BoNT-A regarding upper limb tremor is controversial. According to the litterature, BoNT-A is able to reduce the amplitude of the tremor, but the functional benefit is not clearly demonstrated. Methodological pittfalls (incomplete muscular targeting, fixed dose regimen, evaluation performed after a single injection) and weakness following the injections may explain this paradox.

Methods: We examined retrospectively the medical observation of the patients treated in our department with BoNT-A injections for an upper limb tremor from january 2016 to may 2017. Clinical and epidemiological data were recorded for descriptive statistics. Improvement one month after the injections was studied according to the Quality of life Essential Tremor (QUEST), the Essential Tremor Embarrassment Assessment (ETEA) and the Clinical Global Impression-Improvement (CGI-I). The Shapiro–Wilk test was used to study the normality of data distribution, and comparisons were performed using Student’s t test.

Results: Forty-five patients (27 men,18 women) were included. Mean age: 64.1+/-16.3 years. Etiologies: essential tremor (ET) (n=22); Holmes tremor (HT) or cerebellar tremor (CT) secondary to a focal lesion (HT) (n=14); idiopathic, dystonic tremor (n=5); primary writing tremor (n=3); Parkinson’s disease (n=1). Mean BoNT-A posology (onabotulinumtoxinA units): 139.2+/-94.2 U (ET: 122.5+/-82.3 U; HT+CT: 203.8+/-113.0 U). The improvement after one month was recorded in 31 patients, including 17 ET and seven HT. Previous cycles of injections: 12.5+/-13.1. Main side effetcs: muscular weakness (22.6%); pain (12.9%). CGI-I was unchanged in 9.7%, minimally improved in 29.0%, much improved in 32.3% and very much improved in 29.0% of the patients. ETEA and QUEST were ameliorated on the whole population (QUEST and ETEA: p<10-3), in the ET subgroup (QUEST and ETEA: p<10-3) and in the HT group (ETEA: p=0.004; QUEST: p=0.007).

Conclusions: Our results indicate it is possible to improve daily life activites with BoNT-A in patients with an upper limb tremor, irrespective of its etiology. The study was performed in patients receiving BoNT-A injections for a long time, allowing to adjust the strategy of injections. This suggests to perform a double-blind, placebo-controlled study including several cycles of BoNT-A injections.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/botulinum-toxin-injections-improve-daily-life-activities-in-patients-with-upper-limb-tremor/