Brin Freund1, Manoj Maddali, Thomas E Lloyd. 1. *Department of Neurology, Johns Hopkins Hospital, Baltimore, MD; and ‡Johns Hopkins University School of Medicine, Baltimore, MD.
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.
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.
Authors: Sumanth Shivaram; Madhu Nagappa; Doniparthi V Seshagiri; Anita Mahadevan; Yashwanth Gangadhar; T N Sathyaprabha; Vijay Kumavat; Rose D Bharath; Sanjib Sinha; Arun B Taly Journal: Ann Indian Acad Neurol Date: 2021-03-31 Impact factor: 1.383