Deep brain stimulation for the treatment of childhood dystonic cerebral palsy

Abstract

Object: Deep brain stimulation (DBS) for dystonic cerebral palsy (CP) has rarely been reported, and its efficacy, though modest when compared with that for primary dystonia, remains unclear, especially in the pediatric population. The authors present a small series of children with dystonic CP who underwent bilateral pallidal DBS, to evaluate the treatment's efficacy and safety in the pediatric dystonic CP population.

Methods: The authors conducted a retrospective review of patients (under the age of 18 years) with dystonic CP who had undergone DBS of the bilateral globus pallidus internus between 2010 and 2012. Two of the authors independently assessed outcomes using the Barry-Albright Dystonia Scale (BADS) and the Burke-Fahn-Marsden Dystonia Rating Scale-movement (BFMDRS-M).

Results: Five children were diagnosed with dystonic CP due to insults occurring before the age of 1 year. Mean age at surgery was 11 years (range 8-17 years), and the mean follow-up was 26.6 months (range 2-42 months). The mean target position was 20.6 mm lateral to the midcommissural point. The mean preoperative and postoperative BADS scores were 23.8 ± 4.9 (range 18.5-29.0) and 20.0 ± 5.5 (range 14.5-28.0), respectively, with a mean overall percent improvement of 16.0% (p = 0.14). The mean preoperative and postoperative BFMDRS-M scores were 73.3 ± 26.6 (range 38.5-102.0) and 52.4 ± 21.5 (range 34.0-80.0), respectively, with a mean overall percent improvement of 28.5% (p = 0.10). Those stimulated at least 23 months (4 patients) improved 18.3% (p = 0.14) on the BADS and 30.5% (p = 0.07) on the BFMDRS-M. The percentage improvement per body region yielded conflicting results between rating scales; however, BFMDRS-M scores for speech showed some of the greatest improvements. Two patients required hardware removal (1 complete system, 1 unilateral electrode) within 4 months after implantation because of infections that resolved with antibiotics.

Conclusions: All postoperative dystonia rating scale scores improved with pallidal stimulation, and the greatest improvements occurred in those stimulated the longest. The results were modest but comparable to findings in other similar series. Deep brain stimulation remains a viable treatment option for childhood dystonic CP, although young children may have an increased risk of infection. Of particular note, improvements in the BFMDRS-M subscores for speech were comparable to those for other muscle groups, a finding not previously reported.

Keywords: BADS = Barry-Albright Dystonia Scale; BFMDRS-D = Burke-Fahn-Marsden Dystonia Rating Scale–disability; BFMDRS-M = BFMDRS-movement; CP = cerebral palsy; DBS = deep brain stimulation; GPi = globus pallidus internus; HIE = hypoxic-ischemic encephalopathy; IPG = implantable pulse generator; PD = Parkinson's disease; QALY = quality-adjusted life year; cerebral palsy; deep brain stimulation; dystonia; functional neurosurgery; pediatrics.