History: A 64-year-old woman presents to the ED via EMS after a witnessed seizure lasting less than 1 minute. The patient appeared post-ictal for EMS but is currently alert and oriented. She does not recall what happened. She has no history of seizures or syncope. She has a past medical history that includes hypertension.

Physical Exam

BP 201/106   HR 126   T 97.7   RR 20   SpO2 97%

• Patient appears slightly confused with absent recent memory, but she is alert to person, place, and time
• Her cranial nerves are intact, her reflexes are 2+, sensation and strength are intact
• Finger-to-nose and heel-to-shin are within normal limits

Differential diagnosis

• Hypertensive emergency
• Intracranial mass
• Stroke
• Syncope
• Migraine
• Drug use
• Head injury
• Metabolic
• Idiopathic

 Management:

• CTH without contrast
• Blood pressure control with IV antihypertensives-reduce SBP by 25% in the first hour
• Neurology consult
• Patients with sequala including status epilepticus, stroke, or intracranial hemorrhage often require ICU for invasive BP monitoring

Imaging:

Radiology read this as: “Ill-defined hypoattenuation involving the bilateral cerebellar hemispheres, right side greater left, nonspecific but may be secondary to acute to subacute ischemia. No acute intracranial hemorrhage.”

Discussion

• PRES has a variety of vague neurologic symptoms from headache to encephalopathy to seizure
• There are multiple theories regarding the etiology and pathophysiology
• One theory is that a rapid increase in arterial blood pressure leads to vascular leakage and vasogenic edema
• Another theory is that cytotoxic agents or immunosuppressants can cause PRES (mechanism unknown)
• CT or MRI (more sensitive) may show bihemispheric distribution of vasogenic edema in the posterior portion of the brain
• There is no established diagnostic criteria for PRES but acute onset of neurologic findings, vasogenic edema on radiologic imaging, and reversibility have been suggested as criteria
• Treatment is geared towards eliminating the trigger
• Consider starting antiepileptics in consultation with neurology

Bottom line

• PRES can often be a diagnosis of exclusion, consider it in patient with new and acute onset of neurologic findings with high blood pressure
• Get a CT and consider MRI for further evaluation 

Sources

Fischer M, Schmutzhard E. Posterior reversible encephalopathy syndrome. J Neurol. 2017;264(8):1608-1616. doi:10.1007/s00415-016-8377-8