Electrooculography findings in Friedreichs ataxia

Introduction. Friedreich's ataxia (FA) is the most frequent of the recessive hereditary ataxias. Aims. Our aim was to analyse the findings from electrooculography studies in subjects with FA attended in our Service over a 30-year period. Patients and methods. Between the years 1970 and 1999, 51 patients with FA diagnosed in the Neurology Service of our hospital were examined. All of them were submitted to an electronystagmography study and an examination of the oculomotor system using electrooculography (EOG). In the EOG study, saccades, (square-wave) saccadic intrusions, spontaneous, triggered, positional and optokinetic nystagmus (OKN), visual suppression of the vestibulo-ocular reflex (VOR) and following were all evaluated. Results. The disorders that were found most often were ataxic following (72.5%), abnormalities in rotational testing (56.8%) and dysmetria in the saccades (52.9%). The presence of square waves was observed in just over half the traces (52.9%). Conclusions. In FA the predominant EOG findings are those suggesting a cerebellar disease.