Conjugate eye deviation: a disorder of the frontal eye fields?

Abstract

Conjugate eye deviation (CED) is a well-known sign occurring rather frequently in patients with a hemispheral stroke. Generally, the eyes were deviated towards the side of the affected cerebral hemisphere. Based upon experimental studies it is supposed that CED is caused by a lesion of the frontal eye fields (FEF), leading to a contralateral saccadic paresis. However, this theory is not quite supported by the findings of few clinical studies. Therefore we performed a prospective study of 82 patients with CED in order to establish the location of the responsible lesion and to see whether the eye movement disturbances were indicative for an FEF lesion. This was investigated by computerized tomography and eye movement recordings. The results indicate that: 1. CED occurs more frequently after right hemispheral lesions with a ratio of 2:l compared to the left; 2. the lesions of the right hemisphere are predominantly located in the subcortical fronto-parietal region and in the ventral and dorsal limb of the internal capsule; 3. on the left the entire fronto-temporo-parietal cortical and subcortical area is usually involved; 4. the eye movement disorders are not in accordance with direct damage to the FEF region. In conclusion, one exclusive location of the lesion responsible for CED seems less plausible. Probably an interruption at different sites within the circuit formed bij the inferior parietal lobule, FEF, superior colliculus and paramedian pontine reticular formation can lead to the occurrence of this sign.