Vertical gaze palsy with a unilateral vascular lesion of the midbrain. In relation to the rostral interstitial nuclei of the medial longitudinal fasciculus.

Midbrain hemorrhage presenting with isolated downward gaze palsy: A case report

“…Defective downward gaze may occur when the defect is bilaterally confined to the riMLF or when the fibers near the origin of the fascicles are bilaterally affected. [8] To satisfy these conditions, the lesion must be extremely localized toward the midline, so it is extremely rare for downward gaze paralysis to appear alone. In this case, the main locus of hemorrhage was in the right midbrain tegmentum, right riMLF, and edematous changes extended to the PC and contralateral riMLF.…”

“…The mainstream theory is that the supranuclear fiber bundles of downward gaze enter the nucleus without crossing from the riMLF. [ 1 , 2 , 4 , 7 , 10 ] On the other hand, there have been sporadic cases of bilateral vertical eye movement disorders due to unilateral midbrain lesions,[ 4 , 8 , 9 , 13 ] suggesting the possibility that some of the nerve fibers involved in downward gaze are crossed on the contralateral side. In other words, upward gaze disorders occur with bilateral riMLF disorders, PC disorders, unilateral riMLF disorders, and disorders after the crossing of the connecting fibers to the contralateral side at the PC.…”

“…Defective downward gaze may occur when the defect is bilaterally confined to the riMLF or when the fibers near the origin of the fascicles are bilaterally affected. [ 8 ]…”

“…Most of the cerebrovascular diseases that cause vertical gaze palsy are caused by cerebral infarction, and cerebral hemorrhage has so far occurred in only six cases, including this case [ Table 1 ]. [ 8 , 11 - 13 ] In all cases, small hemorrhages with about 1 cm diameter were localized in the midbrain tegmentum. The male-to-female ratio was 4:2, and the average age was 52.3 years old.…”