title: Changes in motor cortical excitability in patients with Sydenham's chorea.
abstract: OBJECTIVE
  The neurophysiological characteristics of motor cortex have been well characterized in patients with Huntington's disease. We present the first data on cortical excitability in patients with Sydenham's chorea.
  
  
  METHODS
  Motor cortex excitability was examined using transcranial magnetic stimulation in 16 patients in the early clinical stages of Sydenham's chorea and in 17 age- and sex-matched control subjects. Investigations included resting and active motor threshold, motor evoked potential, input-output curves, contralateral silent period, and transcallosal inhibition.
  
  
  RESULTS
  Resting and active motor threshold were significantly higher and motor evoked potentials were significantly smaller in patients in comparison with controls. The input-output curves were shallower in both hemispheres of patients with chorea compared with controls. No significant differences were seen in silent period or transcallosal inhibition duration.
  
  
  CONCLUSIONS
  Sydenham's chorea is characterized by reduced excitability of corticospinal output similar to that observed in Huntington's disease.
authors.affiliation: Departments of Neuropsychiatry, Faculty of Medicine, Assiut University, Assiut, Egypt.
authors.forename: Eman M
authors.initials: EM
authors.lastname: Khedr
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Ahmed
authors.forename: Anwar M
authors.initials: AM
authors.lastname: Ali
authors.forename: Reda
authors.initials: R
authors.lastname: Badry
authors.forename: John C
authors.initials: JC
authors.lastname: Rothwell
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002819:Chorea / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D006816:Huntington Disease / Q000150:complications; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D011595:Psychomotor Agitation / Q000628:therapy; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
keywords: Sydenham's chorea; cortical excitability; cortical silent period; motor threshold; transcranial magnetic stimulation