Onabotulinumtoxin A injections: a safety review of children with clubfoot under 2 years of age at BC Children's Hospital.

Background: Pediatric indications for Onabotulinumtoxin A extend beyond treatment of skeletal muscle conditions. Each of the indications for Onabotulinumtoxin A use have adverse events reported in the past. The aim of this study was to review dverse events in children less than 2 years of age who were treated with Onabotulinumtoxin A injections as part of equinus foot deformity, in the setting of clubfoot at British Columbia's Children Hospital.

Methods: A retrospective review of all clubfoot patients at British Columbia's Children Hospital, less than 2 years of age, who received a Onabotulinumtoxin A injection for equinus correction, between September 2000 and December 2012 was conducted. Data collected included demographics, clinical diagnosis, treatment history, ankle range of motion and any adverse event noted by the clubfoot team or reported by the families.

Results: A total of 239 eligible subjects (361 feet) had received 523 Onabotulinumtoxin A injections before the age of 2 years. There was only one adverse event reported out of the 523 Onabotulinumtoxin A injections (adverse events rate of 0.19%) given at British Columbia's Children Hospital. However, this adverse event was not found related to the Onabotulinumtoxin A injection.

Conclusions: Onabotulinumtoxin A appears to be safe with respect to the adverse events, for use in children under 2 years of age with the diagnosis of clubfoot when dosed at 10 units per kilogram. However, the dose of Onabotulinumtoxin A and underlying diagnosis should always be kept in mind.