A case report of deleterious SGCE myoclonus: dystonia successfully treated with pallidal deep brain stimulation

Abstract

SGCE (epsilon (ε)-sarcoglycan gene) myoclonus-dystonia (SGCE M-D) is a pleiotropic neuropsychiatric disorder with an autosomal dominant mode of inheritance, variable severity, and incomplete penetrance. There have been few reports of patients with SGCE M-D who have been successfully treated with deep brain stimulation (DBS). This case report presents a missense mutation (c.289>T) inherited in a Northeastern Asian family affected by SGCE M-D. The individuals with the condition exhibited clinical manifestations of generalized myoclonus accompanied by sustained cervical dystonia. A 38-year-old woman had a history of generalized dystonia myoclonus with paroxysmal jerks for the past 10 years. The symptoms gradually worsened over the years, affecting her entire body and interfering with most of her daily activities. Genetic testing identified a single base deletion in exon 3 of the SGCE gene, which was considered the genotype underlying her phenotypic symptoms. After failed attempts with oral medications as an outpatient, she underwent DBS targeting the globus pallidus internus (GPI). Her symptoms significantly improved after the activation of the stimulator. Our case supports the beneficial effect of GPI-targeted DBS in patients who are unresponsive to oral medications and have a genetically confirmed M-D phenotype.