title: Cortical silent period in essential tremor.
abstract: BACKGROUND
  Pathophysiology of essential tremor (ET) is controversial, current evidence indicating its genesis through a central oscillator and modulation by a peripheral component. Since transcranial magnetic stimulation induced silent period (SP) has been attributed mainly to intracortical inhibitory mechanisms, it has been found useful in assessing central motor disturbances.
  
  
  OBJECTIVE
  To assess if the cortically induced SP was different in ET patients as compared to age matched healthy controls.
  
  
  METHODS
  Twenty-four patients of ET (mean age 45.4 +/- 14.9 years) diagnosed according to criteria of Louis et al (1998) and an equal number of healthy controls (mean age 36.2 +/- 15.7 years) were recruited in the study. Cortically induced (magnetic) SP were recorded according to the standard methods described. Student's "t" test and Wilcoxon sign rank test were used for statistical analysis.
  
  
  RESULTS
  The mean +/- SD cortical SP in ET patients (180.75 +/- 57.11 msec) in ET patients and in controls (163.83 +/- 35.65 msec) were statistically similar (p = 0.22).
  
  
  CONCLUSIONS
  Our study shows that there is no significant difference in mean cortical SPs in patients with ET as compared to controls.
authors.affiliation: Dept. of Neurology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: G
authors.initials: G
authors.lastname: Shukla
authors.forename: M
authors.initials: M
authors.lastname: Bhatia
authors.forename: R M
authors.initials: RM
authors.lastname: Pandey
authors.forename: M
authors.initials: M
authors.lastname: Behari
mesh_terms: D000328:Adult; D000368:Aged; D002540:Cerebral Cortex / Q000473:pathology / Q000502:physiology*; D004576:Electromyography; D020329:Essential Tremor / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged