title: Postural and Intention Tremors: A Detailed Clinical Study of Essential Tremor vs. Parkinson's Disease.
abstract: BACKGROUND
  An estimated 30-50% of essential tremor (ET) diagnoses are incorrect, and the true diagnosis in those patients is often Parkinson's disease (PD) or other tremor disorders. There are general statements about the tremor in these ET and PD, but published data on the more subtle characteristics of tremor are surprisingly limited. Postural tremor may occur in both disorders, adding to the difficulty. There are several anecdotal impressions regarding specific features of postural tremor in ET vs. PD, including joint distribution (e.g., phalanges, metacarpal-phalangeal joints, wrist), tremor directionality (e.g., flexion-extension vs. pronation-supination), and presence of intention tremor. However, there is little data to support these impressions.
  
  
  METHODS
  In this cross-sectional study, 100 patients (ET, 50 PD) underwent detailed videotaped neurological examinations. Arm tremor was rated by a movement disorder neurologist who assessed severity and directionality across multiple joints.
  
  
  RESULTS
  During sustained arm extension, ET patients exhibited more wrist than metacarpal-phalangeal and phalangeal joint tremor than did PD patients (p < 0.001), and more wrist flexion-extension tremor than wrist pronation-supination tremor (p < 0.001). During the finger-nose-finger maneuver, intention tremor was present in approximately one in four (28%) ET patients vs. virtually none (4%) of the Parkinson's patients (p < 0.001).
  
  
  CONCLUSIONS
  We evaluated the location, severity, and directionality of postural tremor in ET and PD, and the presence of intention tremor, observing several clinical differences. We hope that detailed phenomenological data on tremor in ET and PD will help practicing physicians delineate the two diseases.
authors.affiliation: Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University New York, NY, USA ; Tufts University School of Medicine Boston, MA, USA.
authors.forename: Eliezer J
authors.initials: EJ
authors.lastname: Sternberg
authors.forename: Roy N
authors.initials: RN
authors.lastname: Alcalay
authors.forename: Oren A
authors.initials: OA
authors.lastname: Levy
authors.forename: Elan D
authors.initials: ED
authors.lastname: Louis
keywords: Parkinson’s disease; clinical diagnosis; essential tremor; intention tremor; postural tremor; tremor