Isolated brainstem involvement in a patient with hypertensive encephalopathy.

Hypertensive encephalopathy (HE) is one of the acknowledged hypertensive emergencies. Isolated hypertensive brainstem encephalopathy (HBE) without concomitant typical parietooccipital lesion is unusual. Patients with HBE may or may not present with symptoms attributable to brainstem and the diagnosis is challenging in an emergency setting. The most important differential diagnosis in HBE is brainstem infarction, because the goals of blood pressure treatment are different. Evidence of vasogenic edema on magnetic resonance image, i.e. absence of high signal lesions on diffusion weighted images and increased value of apparent diffusion coefficient are diagnostic indicators of HBE, but not brainstem infarction. Prompt recognition of HBE and adequately lowering blood pressure offer the best outcomes.