Introduction: Posterior Reversible Leukoencephalopthy Syndrome (PRES) is linked to various etiologies, foremost systemic hypertension. Its association with intracranial hypotension (IH) is under- recognized. We review the literature and report a case of lumboperitoneal shunt induced IH resulting in PRES with the goal to raise awareness, and provide a potential biological mechanism, based on the Monro-Kellie hypothesis.

Methods: Case report and review of literature.

Results: A 26-year-old woman with AIDS and epilepsy was admitted for recurrent cryptococcal meningitis and breakthrough seizures. There was no radiologic evidence of hydrocephalus. Due to persistently elevated symptomatic intracranial pressure, a lumboperitoneal shunt was placed. Subsequently, the patient had a breakthrough seizure and became encephalopathic, in the absence of systemic hypertension. An electroencephalogram showed diffuse theta slowing. Repeat head computed tomography (CT) showed extensive white matter hypodensities in the bilateral parieto-occipital lobes. CT venogram showed engorged venous sinuses without thrombosis. Brain MRI showed tonsillar transforaminal herniation in addition to bi-posterior PRES lesions. After programmable valve placement in series with the lumboperitoneal shunt to prevent CSF overdrainage, she experienced dramatic clinical and radiological improvement.

Conclusions: IH appears to be a distinct, under-reported cause of PRES. It occurs in susceptible patients, typically 2-5 days after the IH trigger, and seems clinically and radiologically similar to the more common hypertensive cases, both in terms of initial presentation and prognosis. In accord with the Monro-Kellie doctrine stating that the sum of brain, blood, and CSF volume is constant, venous sinus engorgement associated with IH could increase the hydrostatic pressure in the brain arterioles and capillaries and result in interstitial extravasation and brain edema of PRES. Increased vigilance is required to allow for prompt recognition and management.

Patient Care: This research will result in increased vigilance for PRES caused by intracranial hypotension in neurosurgical patients undergoing shunting, and shed light on possible pathologic mechanisms. It is the first known report of this phenomenon in the neurosurgery literature.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the etiology and causes of PRES; 2) Describe a case of PRES linked to intracranial hypotension due to lumbar-peritoneal shunting; 3) Identify intracranial hypotension as an under-recognized source of PRES in the neurosurgical patient population and discuss possible mechanisms.

References: Bartynski WS, Boardman JF. Distinct imaging patterns and lesion distribution in posterior reversible encephalopathy syndrome. AJNR. American journal of neuroradiology. Aug 2007;28(7):1320-1327. Minai FN, Hasan SF, Sheerani M. Post-dural puncture posterior reversible encephalopathy syndrome. J Coll Physicians Surg Pak. Jan 2011;21(1):37-39. Mokri B. The Monro-Kellie hypothesis: applications in CSF volume depletion. Neurology. Jun 26 2001;56(12):1746-1748. Pugliese S, Finocchi V, Borgia ML, et al. Intracranial hypotension and PRES: case report. The journal of headache and pain. Oct 2010;11(5):437-440.