Bilateral subthalamic nucleus deep brain stimulation for refractory total body dystonia secondary to metabolic autopallidotomy in a 4-year-old boy with infantile methylmalonic acidemia: case report.

The methylmalonic acidemias (MMAs) are a group of inborn errors of metabolism resulting in the accumulation of methylmalonic acid in body tissues and fluids. A recognized complication of MMA is bilateral liquefaction of the globus pallidi, resulting in a fulminant total body dystonia of childhood often refractory to medical treatment. This case of total body dystonia due to MMA in a 4-year-old boy had been medically refractory for 15 months. Complete metabolic destructive liquefaction of the pallidi, that is, autopallidotomy, necessitated an alternative, bilateral subthalamic nucleus (STN) target for deep brain stimulation (DBS) with a marked improvement in dystonia and reduction in pain. The case illustrates the efficacy of STN DBS in this condition and the technical challenges in targeting the STN in a small child.