title: Electrophysiological study of neuromuscular system involvement in mitochondrial cytopathy.
abstract: OBJECTIVE
  To define the neuromuscular involvement in 'mitochondrial' patients with clinical evidence of a neuromuscular disorder, and to evaluate if the proposed electrophysiological protocol was suitable to reveal a subclinical neuropathy or myopathy in 'mitochondrial' patients with no clinical sign of a neuromuscular disturbance.
  
  
  METHODS
  Quantitative concentric needle electromyography (CNEMG), single fiber electromyography (SFEMG) and nerve conduction studies (NCS) were performed in 33 patients with mitochondrial cytopathies. Lastly, we studied 9 clinically unaffected relatives.
  
  
  RESULTS
  NCS were abnormal in 18% of patients, with CNEMG and SFEMG in 58% of cases, but there was not a complete overlapping of the positivity of the different techniques. No asymptomatic relatives showed abnormalities of the electrophysiological studies.
  
  
  CONCLUSIONS
  Electrophysiological findings did not correlate with any specific biochemical or genetic defect, but were consistent with clinical diagnosis in almost all of the patients with clinical signs of myopathy and/or neuropathy. Increase of both SFEMG jitter and fiber density was significantly tied to a neuropathic process. CNEMG and SFEMG were altered in about 30% of subjects without clinical signs of myopathy or neuropathy and were therefore able to reveal a subclinical involvement of neuromuscular system in some patients who had external ophthalmoplegia or retinitis only.
authors.affiliation: Institute of Neurological and Neurosurgical Sciences, University of Messina, Italy. girlandp@imeuniv.unime.it
authors.forename: P
authors.initials: P
authors.lastname: Girlanda
authors.forename: A
authors.initials: A
authors.lastname: Toscano
authors.forename: C
authors.initials: C
authors.lastname: Nicolosi
authors.forename: S
authors.initials: S
authors.lastname: Sinicropi
authors.forename: G
authors.initials: G
authors.lastname: Picciolo
authors.forename: V
authors.initials: V
authors.lastname: Macaione
authors.forename: A
authors.initials: A
authors.lastname: Quartarone
authors.forename: C
authors.initials: C
authors.lastname: Messina
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017240:Mitochondrial Myopathies / Q000503:physiopathology*; D009132:Muscles / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology*