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

BACKGROUND: Diseases presenting with only downward gaze palsy are extremely rare particular in cerebral hemorrhage. CASE DESCRIPTION: A 63-year-old man with no medical history developed a downward-dominant vertical gaze paralysis with a convergence disorder. Computed tomography and magnetic resonance imaging showed a small hemorrhage of 13 mm in diameter in the right midbrain tegmental area. The patient was conservatively treated. His symptoms showed a gradual improvement from upward gaze paralysis and convergence disorder followed by downward gaze paralysis. All symptoms disappeared in 3 weeks after the onset. The center of vertical eye movement was thought to be the rostral interstitial nucleus of medial longitudinal fasciculus (riMLF) and posterior commissure (PC). CONCLUSION: In this case, bilateral riMLF and PC were impaired, resulting in bilateral vertical ocular motility disorder with upward gaze paralysis. Brainstem hemorrhage rarely presents with vertical gaze palsy. Most are cerebral infarctions, and few are due to cerebral hemorrhage. This case was important for better understanding the pathophysiology of an ocular motility disorder. We also summarized the characteristics of isolated vertical gaze palsy caused by cerebral hemorrhage.