title: A Case of Morvan Syndrome Mimicking Amyotrophic Lateral Sclerosis With Frontotemporal Dementia.
abstract: BACKGROUND
  Morvan syndrome is a rare autoimmune/paraneoplastic disorder involving antibodies to the voltage-gated potassium channel complex. It is defined by subacute encephalopathy, neuromuscular hyperexcitability, dysautonomia, and sleep disturbance. It may present a diagnostic dilemma when trying to differentiate from amyotrophic lateral sclerosis with frontotemporal dementia.
  
  
  METHODS
  A 76-year-old man with a history of untreated prostate adenocarcinoma was evaluated for subacute cognitive decline, diffuse muscle cramps, and hyponatremia.
  
  
  RESULTS
  MRI demonstrated atrophy most prominent in the frontal and temporal regions. Electromyography (EMG) demonstrated diffuse myokymia/neuromyotonia. Polysomnography lacked REM and N3 sleep. Paraneoplastic panel detected antibodies to voltage-gated potassium channel complex (CASPR2 subtype).
  
  
  CONCLUSIONS
  It is difficult to differentiate between Morvan syndrome and amyotrophic lateral sclerosis with frontotemporal dementia with examination and neuroimaging alone. There may be a link between Morvan syndrome and prostate adenocarcinoma which could help with screening/diagnosis. The authors found that laboratory and neurophysiological tests are indispensable in diagnosing and treating Morvan syndrome.
authors.affiliation: *Department of Neurology, Johns Hopkins Hospital, Baltimore, MD; and ‡Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Brin
authors.initials: B
authors.lastname: Freund
authors.forename: Manoj
authors.initials: M
authors.lastname: Maddali
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Lloyd
mesh_terms: D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D001323:Autoantibodies; D001921:Brain / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D004576:Electromyography; D057180:Frontotemporal Dementia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology; D024642:Potassium Channels, Voltage-Gated / Q000276:immunology; D013595:Syringomyelia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000276:immunology / Q000503:physiopathology
chemical_list: D001323:Autoantibodies; D024642:Potassium Channels, Voltage-Gated