Abstract for presentation at The Australian and New Zealand Association of Neurologists Annual Scientific Meeting 2007

Vestibular, saccadic and fixation abnormalities in genetically confirmed Friedreich Ataxia

  • Dr Michael Fahey, Murdoch Childrens Research Institute, Australia
  • Owen White, Royal Melbourne Hospital, Australia
  • Dr Phillip Cremer, Royal North Shore Hospital, Australia
  • Ms Lynette Millist, Royal Melbourne Hospital, Australia
  • Dr Swee Aw, Royal Prince Alfred Hospital, Australia
  • Ms Louise Corben, Murdoch Childrens Research Institute, Australia
  • Dr Andrew Churchyard, Southern Health, Australia
  • A/Prof Martin Delatycki, Murdoch Childrens Research Institute, Australia

    • Aim: To assess eye movement abnormalities in Friedreich ataxia (FRDA) and compare these results to clinical measures
    Methods: We studied 21 patients with genetically determined FRDA. All patients were assessed with infared oculography. 17 of these were able to have scleral coils placed. 15 patients underwent a full paradigm of eye movement recordings. Ten patients were analysed using 2-dimensional equipment and five using 3-dimensional recording equipment. Additional information including visual quality of life (VF-14, VQ-25), low contrast letter acuity (Sloan Low Contrast Letter Chart, SLCLC) and the Friedrech Ataxia Rating Scale (FARS) was recorded.
    Results: Fixation abnormalities consisting of square wave jerks and flutter were common. The number of square wave jerks inversely correlated with age at disease onset (Pearson’s correlation= -0.56; p<0.05) but did not significantly correlate with disease duration. Saccadic latency was prolonged and correlated with clinical measures of disease severity, including the FARS examination (Spearman’s Rho= 0.66; p<0.05) and the SLCLC (Spearman’s Rho= -0.75; p= 0.001). Vestibular abnormalities were evident in the group with average latency on head thrust testing of 25ms (N= 8ms) and a mean yaw gain of 0.49 (N= 1.0).
    Conclusions: The range of eye movement abnormalites suggest that neurological dysfunction in FRDA includes brainstem, cortical and vestibular systems. The correlation of latency with FARS score raises the possibility of its use as a biomarker for FRDA clinical trials.

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