title: Myopathic EMG findings and type II muscle fiber atrophy in patients with Lambert-Eaton myasthenic syndrome.
abstract: OBJECTIVE
  Lambert-Eaton myasthenic syndrome (LEMS) is a rare condition, which may mimic myopathy. A few reports have described that EMG in LEMS may show changes compatible with myopathy, and muscle biopsies have been described with type II as well as type I atrophy. The EMG results were, however, based on qualitative EMG examination and the histopathological methods were not always clear. The objective of this study was to investigate if the previous EMG findings could be confirmed with quantitative EMG (QEMG) and to describe muscle histology in LEMS.
  
  
  METHODS
  QEMG, nerve conduction studies and muscle biopsy were performed in four consecutive LEMS patients.
  
  
  RESULTS
  QEMG showed significantly decreased mean MUP duration and muscle biopsy showed marked type II fiber atrophy.
  
  
  CONCLUSIONS
  EMG and biopsy abnormalities mimicking myopathy may often be found in patients with LEMS.
  
  
  CONCLUSIONS
  LEMS is a debilitating, but treatable disease, which often precedes detection of a malignancy and it is therefore of obvious importance to diagnose these patients with speed and certainty. Hence it is important that neurophysiologists and neurologists are aware that EMG and histological abnormalities mimicking myopathy may be found in LEMS patients so that these findings do not prolong or misdirect the diagnostic process in these patients.
authors: Department of Clinical Neurophysiology, Rigshospitalet, University of Copenhagen, Denmark. clarissa.crone@rh.regionh.dk
authors: Clarissa
authors: C
authors: Crone
authors: Ingelise
authors: I
authors: Christiansen
authors: John
authors: J
authors: Vissing
mesh_terms: D000368:Aged; D001284:Atrophy / Q000473:pathology; D001707:Biopsy, Needle; D003937:Diagnosis, Differential; D004576:Electromyography; D005260:Female; D006801:Humans; D015624:Lambert-Eaton Myasthenic Syndrome / Q000150:complications / Q000175:diagnosis* / Q000473:pathology* / Q000503:physiopathology; D008175:Lung Neoplasms / Q000150:complications / Q000175:diagnosis / Q000473:pathology; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000473:pathology* / Q000502:physiology; D009135:Muscular Diseases / Q000175:diagnosis / Q000473:pathology; D009431:Neural Conduction / Q000502:physiology; D055752:Small Cell Lung Carcinoma / Q000150:complications
keywords: Lambert-Eaton myasthenic syndrome; Muscle biopsy; Myopathy; Quantitative EMG; Type II muscle fiber atrophy