Grading brainstem involvement in multiple sclerosis - by means of electro-oculography

One of the most frequent disorders of the brainstem in multiple sclerosis (MS) is internuclear opthalmoplegia (INO). The aim of this study is to show how it is possible to monitor the course of MS grading INO on the basis of electro-oculographic findings. We selected 130 patients with a diagnosis of clinically defined multiple sclerosis (78 males and 52 females, mean age 43.5 years) from a population of 354 MS patients. Both saccadic eye movements and spontaneous, vestibular (VOR), visuo-vestibular (VVOR) and optokinetich nystagmus (OKN) were assessed. Slowing of the adducting eye was considered as a sign of lesion of the interocular pathways. Statistical analyses showed that the most sensitive test was VVOR, the least sensitive being randomised saccades. An impairment of random saccades was always associated with abnormal results on all other tests. It seems thus possible to grade the involvement of the medial longitudinal fasciculi (MLF) in MS from an abnormality limited to the VVOR test up to an impairment of randomised saccadic movements. Grading brainstem involvement in MS is particularly important in therapeutic trials and during rehabilitation.