Upbeat nystagmus changing to downbeat nystagmus with convergence in a patient with a lower medullary lesion

Abstract

The authors report an 18-year-old male patient with acute onset hemiparesis on the right side, difficulties in speaking and swallowing, and upbeat nystagmus changing to downbeat nystagmus on convergence, with a circumscribed structural lesion in the lower medulla on MRI scan. Stereotactic biopsy did not disclose the diagnosis, only nonspecific edema with gliosis and siderophages was found. Accordingly, a nonspecific inflammation was suspected. Over several months most of the symptoms, except the hemiparesis, subsided despite the fact that the lesion did not change in size or enhancement on MRI scan. To our knowledge, this is the first case with a localized structural lesion that shows this unusual oculomotor syndrome. The syndrome is discussed in the light of recent results on the origin of vertical spontaneous nystagmus.

Key Words:

• upbeat nystagmus
• downbeat nystagmus
• convergence
• vestibular system
• medullary lesion