title: [Clinical features of congenital myasthenic syndrome in Japan].
abstract: OBJECTIVE
  We examined the clinical and neurophysiological features of Japanese patients with congenital myasthenic syndrome (CMS).
  
  
  METHODS
  Subjects were five patients who were diagnosed with CMS on the basis of clinical course, repetitive nerve stimulation (RNS), and genetic analysis.
  
  
  RESULTS
  Four patients manifested motor retardation within one year of birth, while one manifested motor intolerance at three years of age. The most characteristic symptom observed in all the patients was fluctuating muscle weakness, which varied on a daily basis or continued for several days after the late infancy period. Only one patient manifested daily fluctuation of muscle weakness. RNS of the accessory nerve evoked a decrementing response in three patients who were examined;however, RNS of the median, ulnar, and tibial nerves (one patient each) did not evoke such responses. After the edrophonium chloride test, no improvement was seen even if the patients manifested ptosis. For judgment of this test, improvement in decrementing rate observed while performing RNS was useful. All five patients who were administered medication based on the results of genetic analysis demonstrated an improvement in their symptoms.
  
  
  CONCLUSIONS
  We suggest that CMS can be diagnosed based on careful examination and electrophysiological results. CMS is a treatable disorder, and therefore, correct diagnosis is important.
authors.affiliation: Department of Child Neurology, National Center Hospital of Neurology and Psychiatry, Kodaira, Tokyo.
authors.forename: Kaori
authors.initials: K
authors.lastname: Irahara
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Komaki
authors.forename: Ryoko
authors.initials: R
authors.lastname: Honda
authors.forename: Akihisa
authors.initials: A
authors.lastname: Okumura
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Shiraishi
authors.forename: Yuu
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Azuma
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Nakata
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ohya
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sasaki
mesh_terms: D000293:Adolescent; D002648:Child; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D018908:Muscle Weakness / Q000151:congenital / Q000175:diagnosis / Q000235:genetics / Q000628:therapy; D009154:Mutation; D020294:Myasthenic Syndromes, Congenital / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology / Q000628:therapy; D016896:Treatment Outcome; D055815:Young Adult