Upbeat nystagmus at caudal brainstem lesions in four cases with multiple sclerosis and its related disorders

Abstract

Upbeat nystagmus (UBN) is relatively rare. Little is known about UBN in acute central nervous system inflammatory disorders, including multiple sclerosis (MS), neuromyelitis optica (NMO) and related disorders. We investigated two patients with MS, one with clinically isolated syndrome and one with brainstem inflammation possibly related to NMO who developed UBN because of brainstem lesions. Three of the four patients presented caudal medulla lesions and one presented a caudal pontomesencephalic lesion on magnetic resonance imaging. Caudal brainstem lesions may cause UBN in these disorders, probably by impairing the ventral tegmental tract.