Brain stem Posterior reversible encephalopathy-A study of four cases

INTRODUCTION Posterior reversible encephalopathy syndrome is characterized by clinical feature of headache, visual disturbance, altered sensorium, seizure and focal neurological signs with typical neuroimaging feature of involvement of bilateral parieto-occipital lobe and subcortical white matter. However atypical involvement of other regions like frontal lobe, basal ganglia, thalamus and brain stem are less frequently reported. We report here four cases of atypical Posterior reversible encephalopathy with predominant brain stem involvement.Methods Four patients of brain stem posterior reversible encephalopathy from institute of neurology, madras medical college during the year 2010-2011 were studied.Diagnosis was based on history, clinical examination and neuroimaging findings.Other basic investigation including renal function were done.Results The patients were between 34-54years of age.Three were males and one was female.The onset was acute in two and subacute in two patients. All of them presented with hypertension, altered sensorium, and blurring of vision.Two were know hypertensives. Unsteadiness was noted in two patients and one had lower motor neuron facial palsy.None of them had seizure. Two patients had renal failure in whom hypertensive retinopathy changes was noted in one patient.Neuroimaging of all four patients showed predominant involvement of brain stem.Two patients in addition had thalamic and parieto-occipital region involvement.Antihypertensives were administered for hypertension control. Complete resolution of clinical symptoms and radiological lesions occurred in all four patients within few days to two weeks.ConclusionThis paper is presented to highlight atypical clinical and neuroimaging findings of posterior reversible encephalopathy. Posterior reversible encephalopathy should be considered in the differential diagnosis of brain stem lesions with background history of hypertension in addition to other causes.