Safety and Efficacy of Botulinum Toxin in the Treatment of Self-Biting Behavior in Lesch-Nyhan Disease.

Background: Lesch-Nyhan disease (LND) is a disease of purine metabolism linked to chromosome X due to the absence or near-absence of enzyme hypoxanthine-guanine phosphoribosyltransferase. Patients with LND have a compulsive autoaggressive behavior that consists of self-mutilation by biting.
Methods: The objective of this study was to explore the safety and efficacy of botulinum toxin (BoNT) injected into the masticatory muscles and biceps brachii to reduce self-mutilation in patients with LND. We retrospectively analyzed six patients with LND who were treated with BoNT to prevent automutilatory behavior.
Results: The patient ages when started on treatment with BoNT were 4, 4.5, 6.6, 7.9, 13.9, and 32.3 years. Patients received a mean number of injections of 20, ranging from 3 to 29, over a period that ranged from 1.5 to 7.1 years. The maximum total dose of Botox was 21.3 units/kg mean and the maximum total dose of Dysport was 37.5 units/kg mean. A total of 119 injections were performed. Of these 113 (95%) were partially or completely effective. Only three of 119 injections (2.5%) produced adverse effects.
Conclusions: Botulinum toxin is useful and safe for the treatment of self-biting behavior in patients with LND.
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