Brainstem involvement in hypertensive encephalopathy: a report of two cases and literature review.

The cerebral hemispheres show prominent involvement in hypertensive encephalopathy far more frequently than the brainstem. Two patients with severe paroxysmally accelerated hypertension associated with brainstem hyperintensity in T2-weighted magnetic resonance images are presented. Both present hyperintense lesions improved dramatically in appearance after stabilization of blood pressure. Extreme acceleration of hypertension may be essential for breakdown of autoregulation in the brainstem circulation. The marked clinicoradiologic dissociation ruled out major brainstem infarction and made tumor unlikely.