A 32 year old primaparaous woman was delivered of a normal male child at full term. About three hours after delivery the patient developed a severe diffuse bursting headache associated with vomiting. On the next day she had a single episode of generalised tonic-clonic convulsions, after which she became confused and was found to have right sided weakness on examination. Her blood pressure was 210/104 mm Hg. She was afebrile, there was no pedal oedema, and fundus examination was normal. She was drowsy and confused and had right hemiparesis Grade IV.
Electroencephalography showed intermittent generalised delta activity. NCT (Head) was done 24 hours after the seizure. This showed hypodensities in the white and grey matter of both Posterior Parietal and Occipital lobes. Antihypertensive treatment was immediately begun with intravenous Labetolol. Anticonvulsants were started for seizure prophylaxis using Keppra.
MRI Brain was ordered after stabilization to exclude a large number of etiologies which can masquerade as PRES. MR Images revealed the most commonly described abnormality in PRES consisting of symmetrical cortical and subcortical hyperintense signals on MRT2W and FLAIR images in the Parieto-occipital lobes of both hemispheres. These areas are frequently hypointense on corresponding MRT1W images and have a decreased attenuation on CT scans.
Two weeks following her delivery the patient was discharged with a blood pressure of 140/86 mm Hg, seizure free with recovery of right hemiparesis. Repeat NCT (Head) 3 weeks following discharge was normal.
Posterior reversible encephalopathy syndrome (PRES) is a recently recognized brain disorder that predominantly affects the cerebral white matter. PRES, also called the acute hypertensive encephalopathy and reversible posterior leukoencephalopathy syndrome (RPLS), is a neurotoxic syndrome of cerebral vasoregulation. PRES was first described by Hinchey (1996). The oedematous lesions particularly involve the Posterior Parietal and Occipital lobes, and may spread to basal ganglia, brain stem, and cerebellum. PRES has been described both in pediatric and adult age groups. A greater risk for females developing this syndrome has also been noted.
PRES presents with rapid onset of symptoms including headache, seizures, altered consciousness, and visual disturbance. It is often – but by no means always – associated with acute hypertension. If promptly recognized and treated, the clinical syndrome usually resolves within a week, and the changes seen on CT/MR Imaging resolve over days to weeks.
Complete reversibility of both clinical signs and CT/MR Imaging lesions as seen in this case is regarded as a defining feature of PRES.