Vestibular impairments in episodic ataxia type 2

J Neurol. 2022 May;269(5):2687-2695. doi: 10.1007/s00415-021-10856-4. Epub 2021 Oct 28.

Abstract

Episodic ataxia type 2 (EA2) can present diverse ocular motor abnormalities, but few studies have systematically evaluated vestibular function during the interictal periods. This study aimed to determine vestibular impairments in patients with EA2 during the interictal periods. We recruited 17 patients with genetically confirmed EA2 (10 men, age range = 16-85 years, median = 32 years). We systematically evaluated the vestibular function by measuring the semicircular canals (SCCs) function with bithermal caloric tests, rotatory chair test, and video head impulse test (vHIT), and the otolith function with subjective visual vertical (SVV) tilt and variability, and cervical and ocular vestibular-evoked myogenic potentials (VEMPs). Patients with EA2 commonly showed abnormal VOR responses at least for one SCC with high-acceleration, high-frequency head impulses (14/16, 88%), and impaired visual-vestibular interaction (7/12, 58%). In response to low acceleration and frequency stimuli, the VOR gains were generally normal. The majority of EA2 patients had impairments in at least one of the otolith function tests (13/16, 81%): SVV tilt or variability (7/14, 50%), oVEMP (8/15, 53%), and cVEMP (4/16, 25%). Vestibular impairments are common in EA2 even during the interictal periods. Selective decrease in the VOR responses during higher acceleration stimuli along with impaired visual-vestibular interaction and otolith function suggests degeneration of the vestibulocerebellum or vestibular nuclei.

Keywords: Episodic ataxia; Head impulse test; Otolith function; Vestibular evoked myogenic potentials; Vestibulo-ocular reflex.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Ataxia
  • Female
  • Head Impulse Test
  • Humans
  • Male
  • Middle Aged
  • Nystagmus, Pathologic* / diagnosis
  • Nystagmus, Pathologic* / etiology
  • Reflex, Vestibulo-Ocular / physiology
  • Vestibular Evoked Myogenic Potentials* / physiology
  • Young Adult

Supplementary concepts

  • Episodic Ataxia, Type 2