title: Agnosia for head tremor in essential tremor: prevalence and clinical correlates.
abstract: BACKGROUND
  Lack of awareness of involuntary movements is a curious phenomenon in patients with certain movement disorders. An interesting anecdotal observation is that patients with essential tremor (ET) often seem unaware of their own head tremor. In the current study, we asked ET patients whether they were aware of head tremor while it was occurring on examination, thereby allowing us to gauge real-time awareness of their involuntary movement.
  
  
  METHODS
  ET cases enrolled in an ongoing clinical research study at the Columbia University Medical Center (2009-2014). During a videotaped tremor examination, they were questioned about the presence of head tremor. True positives were cases who exhibited head tremor on examination and were aware of it; false negatives were cases who exhibited head tremor but were unaware of it.
  
  
  RESULTS
  The 126 ET cases had a mean age of 72.6 ± 12.4 years. Nineteen (48.7 %) of 39 cases with head tremor on examination did not report having head tremor at that moment. Even among cases with moderate or severe head tremor on examination, unawareness of head tremor was 45.5 %. We assessed the clinical correlates of unawareness of head tremor, comparing true positives to false negatives, and unawareness was correlated with older age, lower mental status test scores and several other clinical variables.
  
  
  CONCLUSIONS
  Nearly one-half of ET cases with head tremor on examination were acutely unaware of their tremor. Whether such agnosia for tremor may be leveraged as a diagnostic feature of ET is a question for future clinical studies.
authors.affiliation: Department of Neurology, Yale School of Medicine, Yale University, LCI 710, 15 York Street, PO Box 208018, New Haven, CT 06520-8018 USA.
authors.forename: Hatice N
authors.initials: HN
authors.lastname: Eken
authors.affiliation: Department of Neurology, Yale School of Medicine, Yale University, LCI 710, 15 York Street, PO Box 208018, New Haven, CT 06520-8018 USA ; Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT USA ; Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT USA.
authors.forename: Elan D
authors.initials: ED
authors.lastname: Louis
keywords: Agnosia; Clinical; Essential tremor; Head tremor