Tolerance of early pallidal stimulation in pediatric generalized dystonia.

The authors report on 2 cases of pediatric generalized dystonia with a DYT1 mutation; the patients, an 11-year-old girl and a 9-year-old boy, underwent chronic, pallidal deep brain stimulation (DBS) of the globus pallidus internus (GPi). The dystonic postures in both cases showed dramatic improvements with pallidal DBS, but each patient's symptoms gradually recurred within a year, irrespective of exhaustive readjustments of the stimulation settings. After the recurrence of the dystonic symptoms, the DBS leads were replaced within the GPi in one patient (Case 1) and additional DBS leads were implanted into the bilateral subthalamic nuclei in the other patient (Case 2). Neither measure produced any further clinical benefit, and the patient in Case 2 died of status dystonicus 2 days after reoperation. These findings suggest that early pallidal DBS for pediatric dystonia is indeed effective, although there are some cases in which its therapeutic effect is lost. One possible reason may be the ability of the preadolescent brain to tolerate chronic electrical stimuli during the active maturation process.