A Case of Cavernous Malformation in Medulla Oblongata Presenting Upbeating Nystagmus Only

Abstract

Background & Significance: Cavernous malformation is a vascular malformation that occurs throughout the central nervous system. Brainstem cavernous malformation is relatively common and induces variable neurological symptoms, such as headache, vertigo, and cranial nerve deficits. But there is no report about a case of cavernous malformation in the medulla oblongata only presenting with upbeat nystagmus without any other neurological deficit. Case: A 18-year-old woman had visited our outpatient clinic with complaints of continuous vertical oscillopsia. Her symptom was suddenly developed two days ago. In ocular motor examination, continuous conjugated upbeat nystagmus was observed in primary position of gaze. Nystagmus was slightly increased in upward gaze, decreased in downward gaze, but not modified by lateral gaze. Otherwise, there were no remarkable neurological symptoms or signs. Brain CT and MRI showed focal hemorrhagic signal in the central caudal medulla caused by cavernous malformation. The spontaneous upbeat nystagmus disappeared gradually as the hemorrhage resolved over time. Conclusions or Commentes: Upbeat nystagmus has been described in bilateral lesions of the upward vestibuloocular reflex (VOR) pathway in the medulla, ventral tegmentum, anterior vermis of cerebellum, and midbrain. Only upbeat nystagmus shown in our case suggests that focal hemorrhage in medullary cavernous malformation might injure the perihypoglossal nuclei and nucleus intercalatus which contribute to vertical oculomotor integrator without involvement of adjacent brainstem structures.