Systemic adverse events following botulinum toxin A therapy in children with cerebral palsy.

Aim: We studied the incidence of incontinence and respiratory events in children with cerebral palsy who received injections of botulinum toxin A (BoNT-A).

Method: We used multivariable logistic regression to investigate relationships between (BoNT-A) dose, Gross Motor Function Classification System (GMFCS) level, and the incidence of bladder or bowel incontinence, unplanned hospital admission, emergency department consultation or prescription of antibiotics for respiratory symptoms, and diagnosis of upper respiratory tract infection.

Results: Of 1980 injection episodes in 1147 children (mean age 4y 7mo, SD 1y 10mo, range 9mo-23y), 488 (25%) were in children with unilateral involvement and 1492 (75%) in children with bilateral involvement. At the time of injection 440 (22.2%) of children were at GMFCS level I, 611 (30.9%) were at level II, 330 (16.7%) were at level III, 349 (17.6%) were at level IV, and 250 (12.6%) were at level V. The incidence of serious adverse events was low, with 19 episodes of incontinence (1% of injection episodes) and 25 unplanned hospital admissions due to respiratory symptoms (1.3%). Incontinence typically resolved spontaneously 1 to 6 weeks after injection. The incidence of adverse events was associated with GMFCS level and dose of BoNT-A.

Interpretation: The incidence of serious adverse events was low but suggests systemic spread as well as a procedural effect. We recommend reviewing upper dose limits for children at all GMFCS levels, particularly those at levels IV and V with a history of aspiration and respiratory disease. In these children, alternatives to mask anaesthesia may be particularly important.