title: Long-term course of orthostatic tremor in serial posturographic measurement.
abstract: OBJECTIVE
  Primary orthostatic tremor (OT) is a rare neurological disease of unknown pathophysiology characterized by a high-frequency tremor mainly of the legs when standing. The aim of this study was to examine its long-term course by subjective estimation and objective recording by serial posturography and to obtain further standardized epidemiological and clinical data on patients with OT.
  
  
  METHODS
  A clinical cohort of 37 patients with the diagnosis of primary OT was screened for this longitudinal follow-up study. Eighteen patients consented to participate. During study visit all patients underwent a standardized neurological examination and completed subjective scales and scores. Posturographic recordings at follow-up were compared to prior clinical posturographic measurements in 15 cases.
  
  
  RESULTS
  In our cohort the mean duration of symptoms was 14.1 ± 6.8 years. Subjectively, 78% of patients reported progression of the disease. Posturographic data (5.4 ± 4.0 years) revealed a significant increase of the total sway path (standing on firm ground with eyes open) from 2.4 ± 1.3 to 3.4 ± 1.4 m/min (p = 0.022) and of the total root mean square values from 9.8 ± 4.3 to 12.4 ± 4.8 mm (p = 0.028). None of these observations are explained by aging of the patients. Mean frequency of the tremor did not change over time (14.7 ± 1.9 Hz vs. 14.9 ± 2.0 Hz at follow-up). Clinically, most patients had signs of cerebellar dysfunction and a substantial portion also showed proprioceptive deficits in the long-term course.
  
  
  CONCLUSIONS
  This long-term follow-up study indicates, that primary OT is a progressive disorder. Furthermore, the clinical observation of cerebellar dysfunction in most OT patients in the long-term course might indicate an important role of the cerebellum in its pathophysiology.
authors.affiliation: Department of Neurology, University Hospital Munich, Campus Grosshadern, Munich, Germany; German Center for Vertigo and Balance Disorders, University Hospital Munich, Campus Grosshadern, Munich, Germany. Electronic address: katharina.feil@med.uni-muenchen.de.
authors.forename: K
authors.initials: K
authors.lastname: Feil
authors.affiliation: Department of Neurology, University Hospital Munich, Campus Grosshadern, Munich, Germany; German Center for Vertigo and Balance Disorders, University Hospital Munich, Campus Grosshadern, Munich, Germany. Electronic address: Nicolina.boettcher@med.uni-muenchen.de.
authors.forename: N
authors.initials: N
authors.lastname: Böttcher
authors.affiliation: Department of Neurology, University Hospital Munich, Campus Grosshadern, Munich, Germany. Electronic address: Flavia.guri@med.uni-muenchen.de.
authors.forename: F
authors.initials: F
authors.lastname: Guri
authors.affiliation: Department of Neurology, University Hospital Munich, Campus Grosshadern, Munich, Germany; German Center for Vertigo and Balance Disorders, University Hospital Munich, Campus Grosshadern, Munich, Germany. Electronic address: Siegbert.krafczyk@med.uni-muenchen.de.
authors.forename: S
authors.initials: S
authors.lastname: Krafczyk
authors.affiliation: Department of Neurology, University Hospital Munich, Campus Grosshadern, Munich, Germany; German Center for Vertigo and Balance Disorders, University Hospital Munich, Campus Grosshadern, Munich, Germany. Electronic address: Florian.schoeberl@med.uni-muenchen.de.
authors.forename: F
authors.initials: F
authors.lastname: Schöberl
authors.affiliation: Department of Neurology, University Hospital Munich, Campus Grosshadern, Munich, Germany; German Center for Vertigo and Balance Disorders, University Hospital Munich, Campus Grosshadern, Munich, Germany. Electronic address: Andreas.zwergal@med.uni-muenchen.de.
authors.forename: A
authors.initials: A
authors.lastname: Zwergal
authors.affiliation: Department of Neurology, University Hospital Munich, Campus Grosshadern, Munich, Germany; German Center for Vertigo and Balance Disorders, University Hospital Munich, Campus Grosshadern, Munich, Germany. Electronic address: Michael.strupp@med.uni-muenchen.de.
authors.forename: M
authors.initials: M
authors.lastname: Strupp
mesh_terms: D000368:Aged; D002531:Cerebellum / Q000503:physiopathology*; D018450:Disease Progression; D004244:Dizziness / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D004856:Postural Balance / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*; D014202:Tremor / Q000503:physiopathology*
keywords: Clinical neurology; EMG; Long-term course; Orthostatic tremor