Brainstem vascular syndromes

The brainstem is a heterogeneous assembly of well-organized nuclei and pathways that play a critical role in motor, sensory, arousal, and autonomic functions. Because of its extensive reciprocal connections with the cortex, basal ganglia, and cerebellum, the brainstem is involved in generating, controlling, and regulating all eye movements. Brainstem vascular supply, which is especially complex in the midbrain, comes entirely from the vertebrobasilar system. Brainstem infarcts are infrequent, and hemorrhages are even less common. The pons is the section most often affected by ischemic or hemorrhagic stroke. A wide spectrum of clinical motor, sensory, eye movement, or behavioral manifestations - some with devastating effects - may occur in brainstem infarcts and hemorrhages. Neuro-ophthalmologic signs, particularly in the vertical plane and sometimes associated with the most complex eye movement patterns observed in clinical neurology, may predominate in midbrain stroke. Pontine stroke is characterized by horizontal eye movement disorders and motor, sensory, and cerebellar manifestations, either isolated or in combination. Sensory and cerebellar deficits and eye movement disorders due to central vestibular pathway involvement are the main clinical features of medullary stroke; autonomic dysfunction may sometimes occur. Occlusive large artery disease is the leading infarct etiology in almost all brainstem vascular territories.