An unusual case of hypertensive encephalopathy

Summary

This case report describes a 59-year-old male who presented with headaches, seizures and hypertension followed by coma. Initial magnetic resonance imaging showed T2 hyperintensities typical of Hypertensive Encephalopathy (HE), the follow up scans showed diffusion-weighted imaging (DWI) hyperintensities which is a rare finding in HE. DWI hyperintensities are typically suggestive of areas of cytotoxic damage, and the presence of these changes makes this case unusual, since the pathogenesis of HE is usually due to vasogenic oedema rather than cytotoxic damage of the brain tissue.

Introduction

The radiological findings in Hypertensive Encephalopathy (HE) are variable. Magnetic resonance neuroimaging shows a characteristic posterior leukoencephalopathy that predominantly affects the white matter of the parieto-occipital regions.[1], [2] These changes are best seen in the T2 weighted images. Studies with DWI imaging show that the leukoencephalopathy is primarily due to vasogenic rather than cytotoxic oedema.[3], [4] The likely pathogenesis of vasogenic oedema is thought to be hypertensive cerebrovascular endothelial dysfunction, disruption of the blood–brain barrier with increased permeability, cerebral oedema and microhaemorrhage formation.³ There have been case reports of patients with HE who had hyperintensities in DWI images.[5], [6] It is not clear as to the underlying pathogenesis of these changes, but autoregulatory vasoconstriction leading to hypoperfusion could be a possible mechanism.⁷ It is not clear whether HE patients with DWI changes have a poorer prognosis.⁵ We report a patient with HE due to renal artery stenosis who had DWI changes in addition to typical MRI changes of HE, who went on to have complete clinical recovery.