[The relationship between ocular abnormalities and MRI findings in patients with spinocerebellar degeneration].

We studied the relationship between MRI findings and ocular abnormalities in 46 patients with spinocerebellar degeneration. MRI was performed for all patients. In order to evaluate the severity of atrophy in the brainstem and cerebellum, we delineated the region of the pons, mesencephalic tegmentum, medulla oblongata, cerebellar hemisphere, and vermis on a typical section of their T1 weighted image. Each area or the longest diameter of each regions were measured by using a computed graphic analyzer. The data were compared with those of 10 normal subjects and the severity of atrophy in each region was quantitatively estimated. In all of the patients, electro-oculographic tests including gaze nystagmus, positional and positioning nystagmus, smooth pursuit eye movements (smooth pursuit), optokinetic nystagmus test (OKN), horizontal saccade test, and visual suppression of the caloric nystagmus test (VS test) were examined. Eight patients with rebound nystagmus showed more severe atrophy than those of 38 patients without rebound nystagmus in the cerebellar hemisphere and vermis. Nine patients with apogeotrophic derection changing nystagmus indicates more severe atrophy than those of 35 patients without it in the cerevellar hemisphere, pons, mesencephalic tegmentum, medulla oblongata. Twenty three patients who showed severe impairments of OKN, 11 patients with a burst phenomenon on VS test and 19 patients with significantly reduced saccade velocity showed particularly severe pontine atrophy. A significant atrophic change in the pons and medulla oblongata was seen in 4 patients with severely impaired pursuit eye movements. Our finding that there is good correlation between ocular abnormalities and markedly atrophic regions on MRI support the neurophysiological findings which had been reported concerning the generation of ocular abnormalities in humans and animals.