Deep Brain Stimulation for Generalized Dystonia from Secondary Carnitine Deficiency: A Case Report and Literature Review

Abstract

Background: Carnitine deficiencies result from a metabolic disorder of fatty acid β-oxidation and may lead to organic acidemia, which are thought to be associated
with dystonia, epilepsy, autism, and developmental delay. Pharmacotherapy has been the dominant therapy, while many refractory patients still require other
treatment. Deep brain stimulation (DBS) of the globus pallidus internus (GPi) has been found to be effective for medically refractory primary dystonia and now it has
been proposed to be used for an acquired dystonia from mitochondrial metabolic disorder.
Objective: We present the first case of carnitine deficiency treated with DBS for dystonia and investigate the efficacy and safety of DBS treatment in acquired
dystonia from organic acid metabolic disorder.
Methods: The patient was born with secondary carnitine deficiency who had an onset of generalized seizures at age 4.5 months and developed general dystonia at
age 14. Multiple medical therapies have failed to adequately control her symptoms, therefore she received GPi DBS at age 26. In addition, we performed a literature
review of this therapy in the treatment of inherited organic acid metabolic disorder.
Results: Our patient’s dystonia has resolved without side effects post-DBS surgery, but intermittent spastic symptoms along with severe pain in her lower
extremity persist. Concerning the 14 cases from our literature review, 13 of them received GPi DBS, and had an improvement in motor symptoms. One patient with
methylmalonic acidemia received STN DBS and had marked improvement in dystonia and reduction in pain afterwards. Overall, DBS efficacy was lower than in
treatment of primary dystonia.
Conclusion: DBS has become an effective therapy in refractory acquired dystonia from inherited organic acid metabolic disorder. More prospective studies are
needed to determine the eligibility and efficacy of this surgical therapy in these cases.