title: Early Head Tremor in Essential Tremor: A Case Series and Commentary.
abstract: BACKGROUND
  Classically, the onset of head tremor in essential tremor (ET) patients follows that of hand tremor, such that there is a somatotopic spread of involved areas. Here we present a series of seven self-reportedly "unaffected" relatives of ET cases. These seven were clinically asymptomatic and had normal levels of arm tremor on examination, yet each evidenced a transient head wobble on examination. We estimate the prevalence of this phenotype within the two studies from which cases were ascertained.
  
  
  METHODS
  ET cases and their self-reportedly affected and unaffected relatives, enrolled in two family studies, underwent a medical history and videotaped neurological examination.
  
  
  RESULTS
  In seven self-reportedly "unaffected" relatives, a transient and subtle head wobble was seen, always during sustained phonation, speech, or reading aloud. Total tremor score (a measure of arm tremor) ranged from 5 to 12 (i.e., mild tremor within the range of normal). The prevalence of this phenotype of early head tremor was 3.7% in one study and 23.1% in the other.
  
  
  CONCLUSIONS
  We present a series of seven individuals who had early head tremor in an evolving transition state from normal to ET. These cases raise a number of broad clinical, phenotypic, and pathophysiological issues about ET.
authors.affiliation: Division of Movement Disorders, Department of Neurology, Yale School of Medicine, New Haven, CT, USA; Department of Chronic Disease Epidemiology, Yale School of Public Health, New Haven, CT, USA; Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, New Haven, CT, USA.
authors.forename: Elan D
authors.initials: ED
authors.lastname: Louis
authors.affiliation: Division of Movement Disorders, Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
authors.forename: Funmi M
authors.initials: FM
authors.lastname: Badejo
authors.affiliation: Division of Movement Disorders, Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
authors.forename: Ashley D
authors.initials: AD
authors.lastname: Cristal
authors.affiliation: Division of Movement Disorders, Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
authors.forename: James
authors.initials: J
authors.lastname: Meyers
authors.affiliation: Division of Movement Disorders, Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
authors.forename: Nora
authors.initials: N
authors.lastname: Hernandez
authors.affiliation: Division of Movement Disorders, Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
authors.forename: Karen P
authors.initials: KP
authors.lastname: Chen
authors.affiliation: Division of Movement Disorders, Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
authors.forename: Kelly V
authors.initials: KV
authors.lastname: Naranjo
authors.affiliation: Division of Movement Disorders, Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
authors.forename: Jemin
authors.initials: J
authors.lastname: Park
authors.affiliation: Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA.
authors.forename: Lorraine N
authors.initials: LN
authors.lastname: Clark
keywords: Essential tremor; clinical; head tremor; phenotype