Morvan’s syndrome associated with voltage-gated K channel antibodies

Abstract

Neuromyotonia, or Isaacs’ syndrome, is a syndrome of continuous muscle fiber activity caused by hyperexcitability of peripheral nerves.1 Patients present with myokymia, muscle stiffness, cramps, impaired muscle relaxation, and hyperhidrosis. Rarely, these patients also develop an encephalopathy characterized by confusion, insomnia, hallucinations, and agitation.1-5 Neuroimaging results and CSF are usually normal. The EEG typically shows generalized slowing. The triad of neuromyotonia, hyperhidrosis, and encephalopathy is called Morvan’s syndrome. A 62-year-old man presented with a 6-week history of insomnia, malaise, anorexia, hyperhidrosis, and burning pain in both feet. He developed an unsteady gait, drowsiness, fluctuating confusion, generalized headache, and vomiting 3 days before presentation. Five months earlier he was treated for legionella pneumonia. He had presented 15 years earlier with an acute confusional state and vomiting. The cause of these earlier symptoms was not found, but he recovered fully. He was afebrile and there was no meningismus. He was drowsy and intermittently confused. His …