title: A positron emission tomography study of cerebral activation associated with essential and writing tremor.
abstract: OBJECTIVE
  To compare the abnormal patterns of cerebral activation associated with essential and writing tremors.
  
  
  METHODS
  Positron emission tomography using oxygen 15-labeled water was utilized to determine regional cerebral blood flow. Positron emission tomography images that were taken of the brain in individual patients were coregistered with magnetic resonance images of the same brain to ascertain accurate localization of cerebral activation in single patients. Patients with essential tremor underwent scanning at rest, during involuntary postural tremor, and during passive wrist oscillation. Normal control subjects underwent scanning at rest and during voluntary and passive wrist oscillation. Patients with writing tremor underwent scanning while they were holding a pen to paper with consequent involuntary tremor and again while they were holding a pen in the same supinated arm without tremor.
  
  
  METHODS
  Research hospital.
  
  
  METHODS
  Seven patients with essential tremor, six patients with writing tremor, and six matched control subjects.
  
  
  METHODS
  None.
  
  
  METHODS
  Regional cerebral blood flow.
  
  
  RESULTS
  Essential tremor was associated with abnormal bilateral cerebellar, red nuclear, and thalamic activation. Writing tremor was also associated with abnormal bilateral cerebellar activation. Voluntary wrist oscillation in control subjects caused only ipsilateral cerebellar activation. These findings were evident in single patients, when positron emission tomography images were coregistered with magnetic resonance images and on group analysis of the pooled positron emission tomography data after transformation into stereotaxic space.
  
  
  CONCLUSIONS
  These results indicate that both essential and writing tremors are associated with abnormal bilateral overactivity of cerebellar connections.
authors.affiliation: MRC Cyclotron Unit, Hammersmith Hospital, London, England.
authors.forename: A J
authors.initials: AJ
authors.lastname: Wills
authors.forename: I H
authors.initials: IH
authors.lastname: Jenkins
authors.forename: P D
authors.initials: PD
authors.lastname: Thompson
authors.forename: L J
authors.initials: LJ
authors.lastname: Findley
authors.forename: D J
authors.initials: DJ
authors.lastname: Brooks
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001931:Brain Mapping; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D005260:Female; D006225:Hand / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013788:Thalamus / Q000000981:diagnostic imaging / Q000503:physiopathology; D014055:Tomography, Emission-Computed; D014202:Tremor / Q000503:physiopathology*; D014953:Wrist / Q000503:physiopathology; D014956:Writing