An electrophysiological study of visual processing in spinocerebellar ataxia type 2 (SCA2)

Cerebellum. 2011 Mar;10(1):32-42. doi: 10.1007/s12311-010-0220-7.

Abstract

Reports of visual functional impairment in spinocerebellar ataxia type 2 (SCA2) have been studied previously using pattern reversal visually evoked potentials (VEPs) with contradictory results. To provide additional evidence to this area, visual functions were studied using VEPs and event-related potentials (ERPs) in a group of ten patients with genetically verified SCA2. The electrophysiological examination included pattern reversal and motion-onset VEPs as well as visually driven oddball ERPs with an evaluation of a target and a pre-attentive response. In six patients, we found abnormal visual/cognitive processing that differed from normal values in latency, but not in the amplitude of the dominant VEP/ERP peaks. Among the VEPs/ERPs used, the motion-onset VEPs exhibited the highest sensitivity and showed a strong Spearman correlation to SCA2 duration (from r = 0.82 to r = 0.90, p < 0.001) and clinical state assessed by Brief Ataxia Rating Scale (from r = 0.71 (p = 0.022) to r = 0.80 (p < 0.001)). None of the VEP/ERP latencies showed a correlation to the triplet repeats of the SCA2 gene. In three patients, we did not find any visual/cognitive pathology, and one subject showed only a single subtle prolongation of the VEP peak. The observed visual/cognitive deficit was related to the subjects' clinical state and the illness duration, but no relationship to the genetic marker of SCA2 was found. From the VEP/ERP types used, the motion-onset VEPs seems to be the most promising candidate for clinical state monitoring rather than a tool for early diagnostic use.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age of Onset
  • Aged
  • Aging / physiology
  • DNA / genetics
  • Electroencephalography
  • Electrophysiological Phenomena
  • Evoked Potentials / physiology
  • Evoked Potentials, Visual / physiology
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neurologic Examination
  • Pattern Recognition, Visual / physiology
  • Photic Stimulation
  • Signal Processing, Computer-Assisted
  • Spinocerebellar Ataxias / genetics
  • Spinocerebellar Ataxias / physiopathology*
  • Spinocerebellar Ataxias / psychology*
  • Trinucleotide Repeats
  • Visual Cortex / physiopathology
  • Visual Perception / physiology*
  • Young Adult

Substances

  • DNA