Use of Botulinum Toxin in Upper-Limb Tremor: Systematic Review and Perspectives

• Published in: Toxins Vol. 16; no. 9; p. 392
• Main Authors: Motavasseli, Damien, Delorme, Cécile, Bayle, Nicolas, Gracies, Jean-Michel, Roze, Emmanuel, Baude, Marjolaine
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 13.09.2024; MDPI
• Subjects: ataxia; Botulinum toxin; Botulinum Toxins - adverse effects; Botulinum Toxins - therapeutic use; Botulinum Toxins, Type A - administration & dosage; Botulinum Toxins, Type A - adverse effects; Botulinum Toxins, Type A - therapeutic use; cerebellar; Clinical trials; dystonic tremor; Effectiveness; essential tremor; Flexors; Humans; Kinematics; Labels; Limbs; Multiple sclerosis; Neuromuscular Agents - adverse effects; Neuromuscular Agents - therapeutic use; Optimization; Oral administration; Patients; Quality of life; Randomized Controlled Trials as Topic; Side effects; Systematic Review; Toxins; Treatment Outcome; Tremor; Tremor (Muscular contraction); Tremor - drug therapy; Tremors; Upper Extremity; Wrist; botulinum toxin; tremor; ataxia; action tremor; cerebellar; dystonic tremor; resting tremor; essential tremor
• ISSN: 2072-6651; 2072-6651
• DOI: 10.3390/toxins16090392

Tremor is the most common movement disorder, with significant functional and psychosocial consequences. Oral medications have been disappointing or limited by side effects. Surgical techniques are effective but associated with risks and adverse events. Botulinum toxin (BT) represents a promising avenue but there is still no double-blind evidence of efficacy on upper limb function. A systematic review on the effects of BT in upper-limb tremor was conducted. A systematic search of the literature was conducted up to July 2023, including the keywords "botulinum toxin" and "tremor". All randomized controlled trials (RCTs) and open-label studies were analyzed. Independent reviewers assessed their methodological quality. There were only eight published RCTs and seven published open-label studies, with relatively small sample sizes. This review suggests that BT is more effective when injections are patient-tailored, with analyses based on clinical judgement or kinematics. Subjective and objective measures frequently improve but transient weakness may occur after injections, especially if wrist or fingers extensors are targeted. A number of studies had methodological limitations. The authors discuss how to optimize tremor assessments and effects of BT injection. Controlled evidence is still lacking but it is suggested that distal "asymmetric" BT injections (targeting flexors/pronators while sparing extensors/supinators) and proximal injections, involving shoulder rotators when indicated, may avoid excessive weakness while optimizing functional benefit.