A Case of Morvan Syndrome Mimicking Amyotrophic Lateral Sclerosis With Frontotemporal Dementia. Issue 4 (June 2016)

• Record Type: Journal Article
• Authors: Freund, Brin; Maddali, Manoj; Lloyd, Thomas E.
• Is Part Of: Journal of clinical neuromuscular disease. Volume 17:Issue 4(2016:Jun.)
• Publication Date: 2016-06
• Subjects: Morvan syndrome -- myokymia -- neuromyotonia -- amyotrophic lateral sclerosis -- frontotemporal dementia -- voltage-gated potassium channel; Neuromuscular diseases -- Periodicals; 616.744005
• DOI: 10.1097/CND.0000000000000118
• Languages: English
• ISSNs: 1522-0443

Abstract

Abstract: Introduction: 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.