Hypertensive brainstem encephalopathy: a diagnosis often overlooked.

Hypertensive encephalopathy (HE) is a subset of posterior reversible encephalopathy syndrome. It typically involves the posterior supratentorial structures, but variations do occur. However, isolated brainstem involvement in HE is rare, with a few cases reported in the literature. Herein, we report a case of acute hypertensive brainstem encephalopathy in which the patient had mild symptoms with very high blood pressure and normal neurological examination. The computed tomography of the brain showed diffuse hypodensity at brainstem. The patient's symptoms improved drastically after hypertension had been controlled. Marked clinical-radiologic dissociation in this particular case was highly suggestive of hypertensive brainstem encephalopathy. Prompt recognition of the condition and aggressive treatment of hypertension in such patients is crucial to relieve oedema and to prevent life-threatening progression. Nevertheless, there is still a lack of awareness among physicians and radiologists regarding this rare clinical entity.