A 60-year-old man with a history of hypertension and renal insufficiency presented to the emergency department (ED) after a single generalized tonic-clonic seizure. On awakening, he complained of a headache and blurred vision. According to his family, he was lethargic and vomited that morning and had not taken his blood pressure medications for several days. In the ED, the patient's blood pressure was 220/130 mm Hg. He was arousable to voice and displayed no neurologic deficits. A computed tomographic scan revealed bilateral posterior hypodensities without mass effect (Figure 1). Magnetic resonance imaging showed increased fluid-attentuated inversion recovery signal in the same region (Figure 2).
Figure 2. Confluent and patchy areas of increased signal within the periventricular and subcortical white matter, predominantly in the parietal occipital lobes but also extending to the frontal lobes. Used with permission of Barry Hahn, MD, Department of Emergency Medicine, Staten Island University Hospital, Staten Island, NY.
Diagnosis
Posterior reversible leukoencephalopathy
Posterior reversible encephalopathy syndrome is a clinical and radiographic entity most commonly characterized by headaches, altered mental status, and vision loss. Seizures are common at the onset but can develop later. Posterior reversible encephalopathy syndrome is most commonly associated with an abrupt increase in blood pressure but can be observed with eclampsia, immunosuppressive medications, and renal failure.1 The exact pathogenesis is unclear but is thought to be related to the breakdown of cerebral autoregulation, resulting in disruption of the blood-brain barrier and also resulting in vasogenic edema.2 The most common abnormality on neuroimaging is edema of the white matter in the posterior portions of the cerebral hemispheres, especially bilaterally in the parieto-occipital regions.3 Treatment involves blood pressure control, removal of any offending medications, and seizure prevention. With prompt treatment, most patients recover completely within hours to days. Untreated, this condition may lead to posterior circulation infarction or hemorrhage.4
3. 3Lee H. Posterior reversible encephalopathy syndrome. Appl Radiol. 2007;36:42–43.
4. 4Striano P, Striano S, Tortora F, et al.Clinical spectrum and critical care management of posterior reversible encephalopathy syndrome (PRES). Med Sci Monit. 2005;11:CR549–CR553. MEDLINE
aDepartment of Emergency Trauma Medicine, Hackensack University Medical Center, Hackensack, NJ
bDepartment of Emergency Medicine, Staten Island University Hospital, Staten Island, NY
For the diagnosis and teaching points, see page 231.
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