Hypertensive Encephalopathy / PRES

complete reference · posterior vasogenic edema · controlled BP reduction · eclampsia · reversibility · Full Card

Symptoms / Associated Sx

• Subacute (hours-days) headache, altered mental status (confusion, lethargy, agitation), visual disturbances (blurred vision, homonymous hemianopia, even cortical blindness — reflecting the posterior/occipital predilection), and seizures (often the presenting event), in the setting of an acute and marked rise in blood pressure. "PRES" = Posterior Reversible Encephalopathy Syndrome — both "posterior" and "reversible" are typical but not absolute; it can involve other regions and, if untreated, become irreversible.

Neg

• No sudden focal deficit maximal at onset in a single arterial territory — argues against ischemic stroke (PRES is usually symmetric/posterior and evolves; imaging distinguishes)

• No thunderclap headache with cisternal blood — argues against SAH (CT/clinical course)

• No fever, meningismus, or CSF pleocytosis — argues against encephalitis (consider if febrile or atypical)

• Blood pressure is markedly elevated (not normal) and edema is vasogenic/posterior — supports the diagnosis (though drug- and eclampsia-related PRES can occur at only moderately elevated BP)

Social History (SHx)

• Chronic/uncontrolled hypertension and medication adherence; recent BP-raising events; substance use (cocaine/sympathomimetics).

• Pregnancy/postpartum (preeclampsia-eclampsia); renal disease; immunosuppressant/calcineurin-inhibitor use (tacrolimus, cyclosporine), cytotoxic chemotherapy, autoimmune disease.

Main Etiology

• A rapid rise in blood pressure exceeds the upper limit of cerebral autoregulation, causing hyperperfusion, endothelial dysfunction, and breakdown of the blood-brain barrier with vasogenic edema — preferentially in the parieto-occipital regions (the posterior circulation has relatively sparse sympathetic innervation). Endothelial-toxic states (eclampsia, calcineurin inhibitors, chemotherapy, sepsis, autoimmune disease) can produce the same syndrome even without extreme hypertension.

RF

• Modifiable: uncontrolled hypertension, medication non-adherence, offending drugs (calcineurin inhibitors, chemotherapy), stimulant use.

• Non-modifiable: renal failure, pregnancy/eclampsia, autoimmune disease, solid-organ or stem-cell transplant.

Data

• MRI brain (diagnostic — symmetric vasogenic edema, T2/FLAIR hyperintensity in parieto-occipital and posterior regions, typically without restricted diffusion; usually reversible on follow-up imaging)

• Blood pressure measurement and fundoscopy (grade III–IV hypertensive retinopathy, papilledema, hemorrhages, exudates)

• CMP/renal function, urinalysis (end-organ damage, proteinuria, renal cause/effect); CBC, LDH/haptoglobin/smear if microangiopathy suspected

• β-hCG (eclampsia in any woman of childbearing age); urine toxicology (sympathomimetics)

• Non-contrast CT to exclude hemorrhage acutely; EEG if seizures/non-convulsive status suspected.

DDx

Ischemic or hemorrhagic stroke (focal, asymmetric, arterial territory) · subarachnoid hemorrhage (thunderclap, cisternal blood) · encephalitis (fever, CSF pleocytosis) · cerebral venous sinus thrombosis (prothrombotic, venous pattern) · metabolic/toxic encephalopathy (organ failure, drugs) · status epilepticus / postictal state · bilateral PCA infarction (restricted diffusion, vascular distribution)

Home Meds

• Restart and optimize antihypertensives once acute IV control is achieved; address non-adherence.

• Identify and stop offending drugs where feasible — calcineurin inhibitors (tacrolimus, cyclosporine), certain chemotherapies (in coordination with the prescribing service).

• In pregnancy, manage per eclampsia protocols (magnesium, pregnancy-safe antihypertensives).

Plan

Consults

• Neurology — diagnosis, seizure management, imaging interpretation.

• Nephrology — if renal disease/failure contributes.

• OB — emergently if pregnant/postpartum (eclampsia).

• ICU — for continuous IV antihypertensive titration, status epilepticus, or malignant hypertension with multi-organ involvement.

Controlled blood-pressure reduction

• Lower gradually — reduce MAP by ~10–15% (no more than ~25%) within the first hour, and do NOT normalize the BP acutely. Aggressive overcorrection risks cerebral, renal, and coronary watershed ischemia. Use a titratable IV agent: nicardipine (Cardene) 5 mg/h IV, titrate by 2.5 mg/h q5–15min (max 15 mg/h); labetalol (Trandate) 10–20 mg IV boluses or infusion; or clevidipine (Cleviprex). Avoid sodium nitroprusside where possible (raises ICP, cyanide accumulation in renal failure).

Eclampsia

• Magnesium sulfate for seizure prophylaxis/treatment (loading + maintenance infusion), blood-pressure control with labetalol or hydralazine (pregnancy-safe), and delivery is the definitive treatment — coordinate emergently with OB.

Seizures / trigger

• Treat seizures with levetiracetam (Keppra) 60 mg/kg IV load then maintenance; seizures usually resolve as BP and edema improve, and long-term AEDs are typically unnecessary. Remove the precipitating drug/state where possible.

Always

• PT / OT eval if functional or visual deficits during recovery.

• Trend: mental status, visual function, blood pressure (continuous during IV therapy), renal function; follow-up MRI typically shows resolution of the edema, confirming the diagnosis.

• Escalation triggers: need for continuous IV titration → ICU · status epilepticus → ICU · declining consciousness or new focal deficit (consider hemorrhage/infarction superimposed) → re-image, ICU · malignant hypertension with cardiac/renal end-organ failure → ICU.

• Discharge checklist: optimized oral antihypertensive regimen with adherence plan and home BP monitoring · removal/substitution of offending drugs documented · ophthalmology follow-up if visual symptoms persisted · neurology follow-up with planned repeat MRI to confirm reversibility · for eclampsia, postpartum BP follow-up · counseling that the syndrome is usually reversible with prompt BP control · return precautions (recurrent headache, visual change, seizure).

Red Flags — ICU / Urgent

• Status epilepticus → ICU, SE algorithm + BP control.
• Declining consciousness / new focal deficit → re-image for hemorrhage or infarction complicating PRES.
• Eclampsia → magnesium, BP control, urgent delivery.
• Malignant hypertension with other end-organ damage (acute kidney injury, pulmonary edema, MI, aortic involvement) → ICU.
• Cortical blindness or rapidly worsening vision → urgent BP control to preserve reversibility.

Senior IM Resident Pearls

• Lower the BP, but don't crash it. Reduce MAP ~10–15% (max ~25%) in the first hour — normalizing it abruptly converts hyperperfusion injury into ischemic injury. Use a titratable IV drip, not a sledgehammer.
• It's "reversible" only if you treat it. Prompt BP control and trigger removal usually reverse the syndrome and the MRI changes; delay can leave permanent deficits or hemorrhage.
• Think posterior and visual. Cortical visual symptoms (blurring, hemianopia, even cortical blindness) plus seizures and high BP is the classic combination — and the edema is parieto-occipital.
• PRES isn't always hypertensive. Eclampsia, tacrolimus/cyclosporine, and chemotherapy can cause it at only modestly elevated pressures — look for the offending drug or state.
• Always check a pregnancy test. Eclampsia is a can't-miss cause; the treatment (magnesium + delivery) is specific and different.
• Seizures rarely need chronic AEDs. They typically remit with BP control and edema resolution — treat acutely, don't commit to lifelong therapy.
• Avoid nitroprusside when you can — it can raise ICP and accumulate cyanide in renal failure; nicardipine and labetalol are cleaner.
• Common mistake: mistaking the posterior edema for bilateral PCA strokes and withholding BP treatment — the absence of restricted diffusion and the reversible vasogenic pattern point to PRES.