title: Corticomuscular coherence in asymptomatic first-degree relatives of patients with essential tremor.
abstract: BACKGROUND
  Essential tremor (ET) follows an autosomal dominant type of inheritance in the majority of patients, yet its genetic basis has not been identified. Its exact origin is still elusive, but coherence measurements between electromyography tremor bursts and electroencephalography unequivocally demonstrate a correlation.
  
  
  METHODS
  We tested these measurements in 37 healthy first-degree relatives (children) of patients with essential tremor (ET) and a group of 37 age-matched and sex-matched controls. Pooled coherence spectra of the maximally coherent electroencephalogram electrodes were computed for ET relatives and controls.
  
  
  RESULTS
  The maximal coherence and its frequency were significantly higher in ET relatives than in controls during the pinch grip task and during slow hand movements. Electromyography amplitude (root-mean-square) was slightly but significantly greater in ET relatives, whereas 2-Hz to 40-Hz power and spectral peak frequency were not different.
  
  
  CONCLUSIONS
  The presymptomatic alteration in corticomuscular interaction may reflect a role of genetic factors.
authors.affiliation: Department of Neurology, University Hospital Schleswig, Holstein, Campus Kiel, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Raethjen
authors.forename: Muthuraman
authors.initials: M
authors.lastname: Muthuraman
authors.forename: Achim
authors.initials: A
authors.lastname: Kostka
authors.forename: Martin
authors.initials: M
authors.lastname: Nahrwold
authors.forename: Helge
authors.initials: H
authors.lastname: Hellriegel
authors.forename: Delia
authors.initials: D
authors.lastname: Lorenz
authors.forename: Günther
authors.initials: G
authors.lastname: Deuschl
mesh_terms: D000328:Adult; D004569:Electroencephalography; D004576:Electromyography; D020329:Essential Tremor / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D005192:Family Health; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology*