Visually Induced Eye Movements in Wallenberg's Syndrome

Abstract

Eighteen patients with Wallenberg's syndrome were investigated concerning visually induced eye movements. All results were analysed quantitatively using a computer. In 16 out of 18 patients, OKN slow-phase velocities were impaired, in the remaining 2 patients they were normal. Patients who showed impaired OKN were classified into two groups according to directional asymmetry of OKN impairment. In 7 out of the 16 patients, slow-phases toward the lesion side were predominantly impaired in contrast to the slow-phases toward the intact side (group A). In the remaining 9 patients, slow-phases toward the intact side were predominantly impaired (group B). The smooth pursuit showed the same asymmetry as the OKN slow-phase, except, in 4 patients who showed normal smooth pursuit. All patients showed reduced visual suppression of caloric nystagmus during the slow-phase of nystagmus toward the lesion side, except 3 patients who showed normal visual suppression in both directions. CT scan failed to detect either the brainstem or the cerebellar lesions in any cases, but MRI performed on the most recent cases demonstrated the infarctions clearly. These findings suggest that infarctions are localized in the medulla in the patients of group A, but extend to the cerebellum as well as to the medulla in patients of group B.

Key Words:

• Wallenberg's syndrome
• visually induced eye movements
• quantitative analysis
• MRI