Posterior Reversible Encephalopathy Syndrome (PRES)

Known as Posterior Reversible Encephalopathy Syndrome (PRES), Reversible Posterior Leukoencephalopathy Syndrome (RPLS) and other names
Syndrome that results from acute hypertension and endothelial damage in the brain, leading to vasogenic edema most commonly involving the white matter in the posterior brain (hence, PRES). Unclear pathogenesis, but thought to involve autoregulatory failure and endothelial dysfunction.
Most commonly associated with 1) Severe acute hypertension (Hypertensive encephalopathy), and 2) Immunosuppressants and Cytotoxic drugs – especially Calcineurin inhibitors, also chemotherapy such as Cisplatin.
Of note, it is not necessary to have toxic levels of immunosuppressants, as PRES can occur with therapeutic levels of Prograf for example.

Clinical Manifestations:

Headaches, Altered mental status, visual disturbances (as the occipital cortex is often involved), Seizures (often the presenting symptom), in the setting of the extreme hypertension.
Of note, PRES is considered to be somewhat of a misnomer, as the syndrome is not always reversible, does not always affect the posterior brain, and often have clear mental status without encephalopathy.

Diagnosis:

CT scan – can sometimes see suggestive signs, but MRI is superior
MRI – classic finding is symmetrical white matter edema in the posterior cerebral hemispheres, especially the parieto-occipital regions. However, can have many variations on this classic finding.

Treatment:
1) Blood pressure control – similar to treatment of hypertensive emergencies, goal is to decrease MAP by ~25% over a few hours, typically using IV meds/drips. Nitroprusside is standard drug for hypertensive emergencies but caution with PRES due to theoretical concern of increased intracranial pressure (due to cerebral vasodilation). First-line is often Nicardipine or Labetalol.
2) Reduction of immunosuppressant doses, or changing the drug if possible
3) If seizures – often give antiepileptics such as Phenytoin or Keppra.
Prognosis: Generally a fairly benign entity as most patients will recover, but uncommonly can have permanent neurologic disability and death.

(Chanu Rhee MD, 1/14/11)