Oculomotor testing in the differential diagnosis of degenerative ataxic disorders.
BACKGROUND
Oculomotor abnormalities have been reported in patients with degenerative ataxic disorders.


OBJECTIVE
To assess the diagnostic sensitivity and specificity of oculomotor deficits in patients with Friedreich ataxia (FA), cerebellar atrophy (CA), and olivopontocerebellar atrophy (OPCA).


METHODS
Neurology clinic at a university hospital in Lübeck, Germany.


METHODS
Seven patients with FA, 9 with CA, and 10 with OPCA were studied. These patients were selected from an ongoing follow-up study.


METHODS
Eye movements were recorded by electro-oculography; an extensive battery of quantitative tests was used.


RESULTS
A proven CAG repeat expansion on chromosome 6 or 14 was significantly associated with reduced saccadic eye velocity and vertical gaze palsy (P<.001, Mann-Whitney U test). All 6 patients with OPCA and slow saccades had an autosomal-dominant inheritance; 4 of them were proved to have spinocerebellar atrophy type 1. In 9 of these patients (4 with FA, 1 with CA, and 4 with OPCA), the genetic defect could not be identified. Saccadic dysmetria, impairment of smooth pursuit and optokinetic nystagmus, deficient suppression of the vestibulo-ocular reflex by either visual or otolith input, and pathological nystagmus were attributed to degenerative lesions in different parts of the cerebellum. However, these symptoms failed to clearly distinguish between the different groups of patients, whereas decreased vestibulo-ocular reflex gain, slow saccades, and vertical gaze palsy pointed to an extracerebellar manifestation of the degenerative disease, occurring only in patients with OPCA and FA.


CONCLUSIONS
In this prospective study, oculomotor disturbances were mainly related to cerebellar dysfunction. Only a few of them were caused by extracerebellar manifestations of the disease, such as slowing of saccades, which was characteristic for patients with OPCA of autosomal-dominant inheritance.
Department of Neurology, Medical University, Lübeck, Germany.
K
K
Wessel
C
C
Moschner
K P
KP
Wandinger
D
D
Kömpf
W
W
Heide
D000328:Adult; D001284:Atrophy / Q000473:pathology; D002531:Cerebellum / Q000473:pathology*; D003937:Diagnosis, Differential; D004585:Electrooculography; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D005621:Friedreich Ataxia / Q000175:diagnosis* / Q000503:physiopathology; D005799:Genes, Dominant; D006801:Humans; D008297:Male; D008875:Middle Aged; D009849:Olivopontocerebellar Atrophies / Q000235:genetics / Q000473:pathology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011930:Reaction Time / Q000502:physiology; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric