Abstract

A 57-year-old male presented to the endocrinology service with a 2 month history of weight loss of 10 kg, sweatiness, confusion and disturbed sleep. He was hypertensive and tachycardic. Investigations for phaeochromocytoma were initiated. He developed pneumonia and respiratory failure requiring admission to an intensive treatment unit. A neurology opinion was sought following agitation and confusion. Marked muscle wasting with apparent fasciculation was obvious. ALS was considered. EEG suggested moderate to severe encephalopathy. Brain MRI had high signal in the basal ganglia. Electromyography showed doublets, triplets and multiplets. Serum had voltage-gated potassium (VGK)-channel antibodies. CT chest, abdomen and pelvis revealed no malignancy. Marked clinical improvement and a parallel fall in VGK-channel antibody titre followed treatment with steroids and plasmaphaeresis. Six months later, recovery was maintained. First described in 1890, the classical presentation of Morvan's syndrome—hyperhidrosis, neuromyotonia and encephalopathy is extremely rare. It is of historical importance in prompting the recognition of potentially reversible VGK-channel antibody-related encephalopathies, and has been associated with thymoma, small cell lung cancer and prostate cancer. This case illustrates the potential to mimic motor neurone disease and the importance of the neurophysiologist in the electrophysiological characterisation of apparent fasciculations.