Kinesigenic Dyskinesia in a Case of Voltage-Gated Potassium Channel–Complex Protein Antibody Encephalitis

Abstract

To describe the first case (to our knowledge) of voltage-gated potassium channel-complex protein antibody encephalitis with kinesigenic dyskinesia and cramp-fasciculation syndrome. Case report. Hospitalized care. A 38-year-old man with a history of bronchial asthma, eczema, vitiligo, and immune complex mesangiopathic glomerulonephritis presented with abnormal movements. Clinical examination, magnetic resonance imaging, single-photon emission computed tomography, electromyography and nerve conduction studies, video-electroencephalographic monitoring, plasmapheresis exchange therapy, and intravenous immunoglobulin administration. Clinical examination revealed paroxysmal kinesigenic dyskinesia and fasciculations. Magnetic resonance imaging of the brain revealed a left caudate and left putamen increased signal lesion on T2-weighted and fluid-attenuated inversion recovery sequences as well as increased flow in the same region on single-photon emission computed tomographic scans. Electromyography and nerve conduction studies revealed significant afterdischarges, cramp potentials, and continuous motor activity. The video-electroencephalographic monitoring revealed no epileptiform discharges. The patient dramatically improved after 5 plasmapheresis exchange treatments and a course of intravenous immunoglobulin at 2 gm/kg over 5 divided doses. To our knowledge, this is the first report of paroxysmal kinesigenic dyskinesia with voltage-gated potassium channel-complex protein antibody encephalitis associated with the cramp fasciculation syndrome.