Electroencephalography in Orthostatic Tremor: A Prospective Study of 30 Patients

Tremor Other Hyperkinet Mov (N Y). 2021 May 21:11:18. doi: 10.5334/tohm.596.

Abstract

Background: Orthostatic tremor (OT) is characterized by a sensation of instability while standing, associated with high frequency (1318 Hz) tremor in the legs. Small retrospective series have reported electroencephalography (EEG) findings in OT with discordant results.

Methods: We prospectively enrolled 30 OT subjects. Mean age = 68.3 (range 5487) with mean disease duration 16.3 years (range 444). A modified 1020 system EEG recording with additional midline electrodes was obtained. EMG electrodes were placed on quadricep muscles. EEG recording was performed at rest, during sleep and while standing unassisted.

Results: In all subjects, EEG showed normal background, normal drowsiness and/or stage 2 sleep, and normal responses to hyperventilation and photic stimulation. These normal results persisted during stance. EEG abnormalities were found in 3 subjects (anterior-mid temporal slow activity), but were not position-dependent and were judged unlikely to be related to OT. Tremor artifact while standing was noted in all subjects, however it was measurable in 26 with frequency in the OT range in 25. When compared with EMG, the average difference in frequency was small at 1.2 Hz (range 0.52.5, p 0.46). Visual EEG analysis in OT patients did not reveal electrographic abnormalities even upon standing unassisted.

Discussion: EEG was normal on this prospective, relatively large OT series. Clinicians interpreting video-EEGs should be aware of the OT artifact that can be seen in EEG and EKG leads mostly while standing.

Keywords: EEG; Movement Disorders; OT Pathophysiology; Orthostatic tremor; Tremor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Dizziness*
  • Electroencephalography
  • Electromyography
  • Humans
  • Prospective Studies
  • Retrospective Studies
  • Tremor* / diagnosis

Grants and funding

This work was supported by the UNMC/Nebraska Medicine Center for Clinical and Translational Research [Pilot Grant # MXH/99-925-1409]; and by University of Nebraska Medical Center Department of Neurological Sciences [internal funds]. Funding sources had no role in study design; collection, analysis, or interpretation of data; writing of the manuscript, or decision to submit for publication. Amy Hellman has been a speaker for Teva Neurosciences. Danish Bhatti has done speaking/consulting (including paid and unpaid) for Teva neurosciences, Abbvie, Adamas, Accadia, Allergan Pakistan (Barret Hodgson), Merz, Medtronic, Boston Scientific, Abbott, PharmEvo Pakistan, Amneal, and Accorda in the past. Danish Bhatti has done research funded by Abbvie, Michael J Fox Foundation, NIH, Ipsen, Revance, Prilenia, and global kinetics. Diego Torres-Russotto has been a consultant or speaker for AbbVie, Allergan, Ipsen, Merz Lundbeck, Sunovion, GKC and Teva. John Bertoni and Najib Murr have no declarations.