Objective:

To discuss acute hydrocephalus as an unusual complication of Posterior Reversible Encephalopathy Syndrome.  

Background:

Posterior Reversible Encephalopathy Syndrome (PRES) is a well-recognized clinical and radiologic syndrome typically characterized by parieto-occipital vasogenic edema along with neurological symptoms, that improves after management or withdrawal of offending factor, in most cases being acute uncontrolled hypertension. However, clinical presentation and radiological findings are variable and may encompass different cerebral structures. Although pathophysiology is not well established, failure of sympathetic autoregulation in the vertebrobasilar system is thought to be related. This failure leads to breakdown of the blood-brain barrier, hence the vasogenic-type edema appreciated on imaging. Acute obstructive hydrocephalus is a rare and potentially fatal complication of PRES. 

Design/Methods:

A 56-year-old Caucasian female who presented due to encephalopathy, headache and falls in the setting of hypertensive emergency. CT (Computed Tomography) head showed hypodense pons, midbrain, cerebellum, and bilateral thalami with effacement of the fourth ventricle, ventriculomegaly in the lateral and 3rd ventricles with associated trans-ependymal edema. Due to initial concern of posterior fossa mass leading to acute hydrocephalus, neurosurgery was consulted, and extra ventricular drain (EVD) was placed for emergent CSF diversion. 

Results:

MRI Brain with and without contrast showed no evidence of acute ischemia or enhancing lesions. Severe edema was redemonstrated within the pons, midbrain, bilateral thalami, and cerebellum. Susceptibility weighted imaging showed microhemorrhages confined to the brainstem. The patient’s clinical exam improved after blood pressure management and EVD placement. Repeat head CT showed decreased cerebral edema and improvement of fourth ventricle obstruction. Based on presentation of hypertensive encephalopathy with posterior circulation vasogenic edema that improved with blood pressure management, PRES diagnosis was made. 

Conclusions:

Posterior fossa predominant PRES is an uncommon presentation that if overlooked may lead to life threatening complications. Early recognition of clinical manifestations and radiological findings may lead to favorable outcomes.