Posterior Reversible Encephalopathy Syndrome (PRES)

VERSION: 1.1 CREATED: January 30, 2026 REVISED: January 30, 2026 STATUS: Approved

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DIAGNOSIS: Posterior Reversible Encephalopathy Syndrome (PRES)

ICD-10: I67.83 (Posterior reversible encephalopathy syndrome), I67.4 (Hypertensive encephalopathy), O15.0 (Eclampsia in pregnancy), O15.1 (Eclampsia in labor), O15.2 (Eclampsia in the puerperium), O15.9 (Eclampsia, unspecified as to time period), I16.1 (Hypertensive emergency), G40.901 (Epilepsy, unspecified, not intractable, with status epilepticus), R56.9 (Unspecified convulsions), G93.49 (Other encephalopathy, not elsewhere classified)

CPT CODES: 85025 (CBC with differential), 80053 (CMP (BMP + LFTs)), 83735 (Magnesium), 81001 (Urinalysis with protein), 83615 (LDH), 84550 (Uric acid), 85610 (PT/INR), 82947 (Blood glucose), 85060 (Peripheral blood smear), 84703 (Pregnancy test (beta-hCG)), 84484 (Troponin), 83605 (Lactate), 83010 (Haptoglobin), 86880 (Direct Coombs test), 85384 (Fibrinogen), 85379 (D-dimer), 84156 (Protein/creatinine ratio (spot urine)), 84443 (TSH), 85652 (ESR), 86235 (ANA), 86689 (HIV testing), 70551 (MRI brain without contrast), 70450 (CT head without contrast), 93000 (ECG (12-lead)), 71046 (Chest X-ray), 70553 (MRI brain with contrast), 70547 (MR venography (MRV)), 95700 (Continuous EEG (cEEG)), 93306 (Echocardiogram), 76775 (Renal ultrasound with Doppler), 36224 (Conventional cerebral angiography (DSA)), 87529 (HSV PCR), 96365 (Blood pressure reduction: Nicardipine IV), 96374 (Blood pressure reduction: Labetalol IV)

SYNONYMS: Posterior reversible encephalopathy syndrome, PRES, reversible posterior leukoencephalopathy syndrome, RPLS, posterior reversible leukoencephalopathy, hypertensive encephalopathy, reversible posterior cerebral edema syndrome, posterior leukoencephalopathy syndrome, PRES syndrome, eclamptic encephalopathy, immunosuppressant-associated encephalopathy, calcineurin inhibitor neurotoxicity, tacrolimus neurotoxicity, cyclosporine neurotoxicity, reversible cerebral edema, vasogenic edema syndrome, hypertensive brain edema

SCOPE: Diagnosis and management of posterior reversible encephalopathy syndrome (PRES) in adults across all care settings. Covers hypertensive emergency management, seizure treatment, identification and removal of causative agents (immunosuppressants, chemotherapy), eclampsia-specific management, MRI interpretation, hemorrhagic PRES complications, and recovery monitoring. Excludes pediatric PRES, chronic hypertensive encephalopathy without neuroimaging features, and isolated eclampsia management without PRES features (see obstetric protocols).

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PRIORITY KEY: STAT = Immediate | URGENT = Within hours | ROUTINE = Standard | EXT = Extended/atypical cases | - = Not applicable to this setting

═══════════════════════════════════════════════════════════════ SECTION A: ACTION ITEMS ═══════════════════════════════════════════════════════════════

1. LABORATORY WORKUP

1A. Essential/Core Labs

Test	Rationale	Target Finding	ED	HOSP	OPD	ICU
CBC with differential (CPT 85025)	Baseline; thrombocytopenia (TTP/HUS, HELLP, DIC); leukocytosis; hemolysis screen	Normal; platelets >100,000; no schistocytes	STAT	STAT	ROUTINE	STAT
CMP (BMP + LFTs) (CPT 80053)	Electrolytes; renal function (renal failure is major cause); hepatic function (HELLP syndrome, drug toxicity)	Normal; Cr <1.2; LFTs normal	STAT	STAT	ROUTINE	STAT
Magnesium (CPT 83735)	Hypomagnesemia lowers seizure threshold; critical in eclampsia management; magnesium sulfate dosing	>2.0 mg/dL (maintain 4-7 mEq/L if on magnesium drip for eclampsia)	STAT	STAT	ROUTINE	STAT
Urinalysis with protein (CPT 81001)	Proteinuria suggests preeclampsia/eclampsia; renal involvement	No proteinuria (>300 mg/24h or protein/Cr ratio >0.3 = preeclampsia)	STAT	STAT	ROUTINE	STAT
LDH (CPT 83615)	Hemolysis marker; HELLP syndrome; TTP/HUS	Normal (<250 IU/L); elevated suggests microangiopathic hemolysis	STAT	STAT	ROUTINE	STAT
Uric acid (CPT 84550)	Elevated in preeclampsia/eclampsia; marker of disease severity	Normal (<6 mg/dL); elevated in preeclampsia	STAT	STAT	-	STAT
PT/INR (CPT 85610), aPTT (CPT 85730)	Coagulopathy screen; DIC assessment; HELLP syndrome	Normal	STAT	STAT	-	STAT
Blood glucose (CPT 82947)	Hyperglycemia worsens cerebral edema; hypoglycemia mimics encephalopathy	140-180 mg/dL	STAT	STAT	-	STAT
Peripheral blood smear (CPT 85060)	Schistocytes indicating TMA (TTP/HUS, HELLP); microangiopathic hemolytic anemia	No schistocytes; normal morphology	STAT	STAT	-	STAT
Pregnancy test (beta-hCG) (CPT 84703)	Eclampsia is leading cause of PRES in young women; affects treatment decisions	Document result	STAT	STAT	ROUTINE	STAT
Troponin (CPT 84484)	Hypertensive cardiac injury; neurogenic cardiac injury; concurrent ACS	Normal	STAT	STAT	-	STAT
Lactate (CPT 83605)	End-organ perfusion assessment in hypertensive emergency	<2 mmol/L	STAT	ROUTINE	-	STAT

1B. Extended Workup (Second-line)

Test	Rationale	Target Finding	ED	HOSP	OPD	ICU
Tacrolimus trough level	Calcineurin inhibitor toxicity is major cause of PRES in transplant patients; guides dose adjustment	Therapeutic range varies by organ (renal: 5-15 ng/mL; liver: 5-20 ng/mL); supratherapeutic level confirms cause	STAT	STAT	ROUTINE	STAT
Cyclosporine trough level	Cyclosporine neurotoxicity causes PRES; dose reduction or discontinuation required	Therapeutic 100-400 ng/mL depending on transplant type; supratherapeutic confirms cause	STAT	STAT	ROUTINE	STAT
Haptoglobin (CPT 83010)	Hemolysis evaluation; low haptoglobin confirms intravascular hemolysis (HELLP, TTP/HUS)	Normal (>30 mg/dL); low suggests hemolysis	URGENT	ROUTINE	-	URGENT
Direct Coombs test (CPT 86880)	Differentiate autoimmune hemolysis from TMA-related hemolysis	Negative (positive = autoimmune hemolysis, not TMA)	URGENT	ROUTINE	-	URGENT
ADAMTS13 activity	TTP evaluation if schistocytes and thrombocytopenia present	>10% activity (severely reduced <10% = TTP)	URGENT	ROUTINE	-	URGENT
Fibrinogen (CPT 85384)	DIC assessment; HELLP syndrome	>200 mg/dL; low fibrinogen suggests DIC	URGENT	ROUTINE	-	URGENT
D-dimer (CPT 85379)	DIC screen; coagulopathy assessment	Normal; elevated in DIC	URGENT	ROUTINE	-	URGENT
Protein/creatinine ratio (spot urine) (CPT 84156)	Preeclampsia assessment; quantify proteinuria	<0.3 (>0.3 supports preeclampsia diagnosis)	URGENT	ROUTINE	ROUTINE	URGENT
TSH (CPT 84443)	Thyroid dysfunction screen; hypothyroidism may contribute to hypertension	Normal	-	ROUTINE	ROUTINE	-
ESR (CPT 85652) / CRP (CPT 86140)	Vasculitis screening; autoimmune etiology	Normal	-	ROUTINE	ROUTINE	-
Anti-seizure medication levels (if applicable)	Subtherapeutic levels if on home ASM; guide dosing	Therapeutic range	STAT	STAT	ROUTINE	STAT

1C. Rare/Specialized (Refractory or Atypical)

Test	Rationale	Target Finding	ED	HOSP	OPD	ICU
ANA (CPT 86235), anti-dsDNA	SLE-associated PRES; lupus nephritis with hypertension	Negative; positive suggests autoimmune etiology	-	EXT	EXT	-
Complement levels (C3, C4) (CPT 86160, 86161)	Low complement in active SLE; atypical HUS	Normal	-	EXT	EXT	-
ANCA (CPT 86235)	Vasculitis-associated PRES (granulomatosis with polyangiitis, microscopic polyangiitis)	Negative	-	EXT	EXT	-
Serum cortisol / ACTH stimulation test	Adrenal crisis, Cushing syndrome causing hypertension	Normal cortisol response	-	EXT	EXT	-
Urine catecholamines / metanephrines	Pheochromocytoma as cause of hypertensive crisis leading to PRES	Normal	-	EXT	EXT	-
Renal artery Doppler or CTA renal arteries	Renovascular hypertension (renal artery stenosis) as underlying cause of recurrent hypertensive emergencies	No significant stenosis	-	EXT	EXT	-
HIV testing (CPT 86689)	HIV-associated nephropathy causing hypertension; opportunistic infections causing encephalopathy	Negative	-	EXT	EXT	-
Bevacizumab/VEGF inhibitor level	VEGF inhibitor-associated PRES; no standardized assay but document recent administration	Document exposure timing	-	EXT	-	EXT

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2. DIAGNOSTIC IMAGING & STUDIES

2A. Essential/First-line

Study	Timing	Target Finding	Contraindications	ED	HOSP	OPD	ICU
MRI brain without contrast (CPT 70551) with FLAIR, DWI, ADC, SWI/GRE sequences	STAT (within 24h of presentation); MRI is diagnostic gold standard for PRES	Bilateral symmetric vasogenic edema predominantly in posterior parietal-occipital regions on FLAIR; DWI normal or mildly restricted; ADC elevated (confirms vasogenic, not cytotoxic edema); SWI/GRE for hemorrhagic component	Pacemaker/defibrillator (non-MRI conditional); hemodynamic instability (stabilize BP first)	STAT	STAT	URGENT	STAT
CT head without contrast (CPT 70450)	Immediately on presentation; rule out hemorrhage, mass, hydrocephalus while awaiting MRI	May show posterior white matter hypodensities; rule out hemorrhagic PRES, mass lesion, or stroke; CT has low sensitivity for PRES (only ~50%)	Pregnancy (benefit outweighs risk)	STAT	STAT	-	STAT
CT angiography (CTA) head and neck (CPT 70496, 70498)	STAT if concern for stroke, cerebral venous thrombosis, or vasculitis	Rule out large vessel occlusion, cerebral venous thrombosis, vasculitis (beading); may show vasospasm/vasoconstriction in RCVS	Contrast allergy; severe renal impairment (benefit outweighs risk in emergency)	STAT	URGENT	-	STAT
ECG (12-lead) (CPT 93000)	STAT on presentation	Baseline; hypertensive cardiac strain; LVH; arrhythmia; QTc assessment for medications	None	STAT	STAT	ROUTINE	STAT
Chest X-ray (CPT 71046)	URGENT if dyspnea, pulmonary edema, or intubated	Pulmonary edema from hypertensive crisis; aspiration; cardiomegaly	None	URGENT	ROUTINE	-	URGENT

2B. Extended

Study	Timing	Target Finding	Contraindications	ED	HOSP	OPD	ICU
MRI brain with contrast (CPT 70553)	Within 24-72h if atypical features or concern for alternative diagnosis	Enhancement may indicate blood-brain barrier breakdown; rule out tumor, abscess, meningitis; leptomeningeal enhancement suggests alternative diagnosis	Renal impairment (GFR <30 for gadolinium); pregnancy (relative)	-	URGENT	ROUTINE	URGENT
Follow-up MRI brain without contrast (CPT 70551)	2-4 weeks after initial presentation (or sooner if not improving)	Resolution or significant improvement of vasogenic edema confirms PRES diagnosis; persistent restricted diffusion suggests infarction (irreversible injury)	Same as initial MRI	-	ROUTINE	ROUTINE	ROUTINE
MR venography (MRV) (CPT 70547)	If cerebral venous thrombosis suspected (headache, seizures, papilledema, postpartum)	Patent venous sinuses; thrombosis indicates alternative/concurrent diagnosis	Same as MRI	-	URGENT	ROUTINE	URGENT
Continuous EEG (cEEG) (CPT 95700)	STAT if altered consciousness disproportionate to imaging or after clinical seizure	Non-convulsive seizures (common in PRES); non-convulsive status epilepticus (NCSE); guide ASM management	None	-	URGENT	-	STAT
Echocardiogram (CPT 93306)	Within 24-48h	LV hypertrophy from chronic hypertension; stress cardiomyopathy; endocarditis (if febrile); ejection fraction for prognosis	None significant	-	ROUTINE	ROUTINE	ROUTINE
Renal ultrasound with Doppler (CPT 76775)	Within 48h if renal failure or suspected renovascular hypertension	Renal artery stenosis; renal parenchymal disease; hydronephrosis	None	-	ROUTINE	ROUTINE	-

2C. Rare/Specialized

Study	Timing	Target Finding	Contraindications	ED	HOSP	OPD	ICU
Conventional cerebral angiography (DSA) (CPT 36224)	If vasculitis or RCVS suspected and CTA/MRA inconclusive	Vasculitis (irregular segmental narrowing); RCVS (segmental vasoconstriction resolving on follow-up); differentiate from primary CNS vasculitis	Contrast allergy; renal impairment; coagulopathy	-	EXT	EXT	EXT
Fundoscopic examination / Ocular coherence tomography (OCT)	Within 24h; urgent if visual symptoms	Papilledema (elevated ICP); hypertensive retinopathy (grade III-IV: hemorrhages, exudates, papilledema); serous retinal detachment (eclampsia)	None	URGENT	ROUTINE	ROUTINE	URGENT

LUMBAR PUNCTURE

Indication: Consider LP if meningitis/encephalitis is in differential (fever, meningismus, altered consciousness) or if cerebral venous thrombosis suspected. LP is NOT routinely required for PRES diagnosis. Timing: URGENT if infection suspected; defer until BP controlled and imaging reviewed Volume Required: 10-15 mL (standard diagnostic)

Study	Rationale	Target Finding	ED	HOSP	OPD	ICU
Opening pressure	Elevated ICP may be present in PRES; rule out idiopathic intracranial hypertension	10-20 cm H2O (may be elevated in PRES)	URGENT	ROUTINE	-	URGENT
Cell count (tubes 1 and 4)	Rule out meningitis/encephalitis	WBC <5, RBC 0	URGENT	ROUTINE	-	URGENT
Protein	Mild elevation may occur in PRES; significantly elevated suggests infection or CNS vasculitis	15-45 mg/dL (mildly elevated in PRES, up to 100)	URGENT	ROUTINE	-	URGENT
Glucose with serum glucose	Rule out infectious meningitis	>60% of serum glucose	URGENT	ROUTINE	-	URGENT
Gram stain and culture	Rule out bacterial meningitis	No organisms	URGENT	ROUTINE	-	URGENT
HSV PCR (CPT 87529)	Rule out HSV encephalitis if temporal lobe involvement or clinical suspicion	Negative	URGENT	ROUTINE	-	URGENT

Special Handling: CSF must be sent promptly for culture; hold tube for additional studies if needed Contraindications: Space-occupying lesion with mass effect; uncorrected coagulopathy (INR >1.4 or platelets <50,000); hemodynamic instability; local skin infection at puncture site

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3. TREATMENT

CRITICAL PRIORITIES IN ACUTE PRES (First 60 Minutes)

1. Blood pressure reduction -- target 25% reduction in MAP in first hour; then to 160/100 over next 2-6 hours
2. Seizure control -- levetiracetam first-line; magnesium sulfate if eclampsia
3. Identify and address underlying cause -- hold immunosuppressants, deliver fetus if eclampsia, treat renal failure
4. Airway protection -- intubate if GCS <=8 or unable to protect airway

3A. Acute/Emergent

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Blood pressure reduction: Nicardipine IV (CPT 96365)	IV	First-line IV antihypertensive for hypertensive emergency with PRES; smooth titratable BP reduction without cerebral vasoconstriction	5 mg/h :: IV :: continuous :: 5 mg/h IV infusion; increase by 2.5 mg/h every 5-15 min; max 15 mg/h; target 25% reduction in MAP in first hour then SBP 140-160 over next 2-6h	Severe aortic stenosis; decompensated heart failure; advanced hepatic failure	Continuous arterial line BP monitoring; neuro checks q15min during titration; avoid SBP <120 (risk of watershed ischemia)	STAT	STAT	-	STAT
Blood pressure reduction: Labetalol IV (CPT 96374)	IV	Alternative first-line IV antihypertensive; preferred if tachycardia present; safe in pregnancy/eclampsia	10-20 mg :: IV :: q10-20min :: 10-20 mg IV bolus over 1-2 min; may repeat or double dose q10-20 min; max 300 mg total; can also infuse at 0.5-2 mg/min	Second/third-degree heart block; severe bradycardia (<50 bpm); decompensated heart failure; severe asthma/COPD; cardiogenic shock	Heart rate; blood pressure continuous; bronchospasm	STAT	STAT	-	STAT
Blood pressure reduction: Clevidipine IV (CPT 96365)	IV	Ultra-short acting IV calcium channel blocker for rapid BP control; useful when precise titration needed	1-2 mg/h :: IV :: continuous :: 1-2 mg/h IV; titrate by doubling dose every 90 seconds initially; usual maintenance 4-6 mg/h; max 32 mg/h; max 21 mg/h average over 24h	Soy/egg allergy (lipid emulsion); severe lipid metabolism disorders; acute pancreatitis with hyperlipidemia	Blood pressure continuous; triglycerides if prolonged use (>72h); lipid load calculation	STAT	STAT	-	STAT
Blood pressure reduction: Hydralazine IV	IV	Second-line antihypertensive; commonly used in pregnancy/eclampsia when nicardipine unavailable	5-10 mg :: IV :: q20-30min :: 5-10 mg IV q20-30 min PRN; max 20 mg total; less predictable response than nicardipine	Severe coronary artery disease; aortic dissection; tachycardia (reflex)	Heart rate; blood pressure q5min after each dose; reflex tachycardia common	STAT	STAT	-	STAT
Eclampsia: Magnesium sulfate (CPT 96365)	IV	FIRST-LINE for eclampsia-associated PRES; prevents recurrent seizures; superior to phenytoin and diazepam for eclampsia seizures (Magpie Trial, Eclampsia Trial Collaborative Group)	4-6 g IV load over 15-20 min; 1-2 g/h maintenance :: IV :: continuous :: 4-6 g IV loading dose over 15-20 min, then 1-2 g/h continuous infusion; maintain serum Mg 4-7 mEq/L; continue 24-48h postpartum; reduce dose if Cr >1.0	Myasthenia gravis; heart block; respiratory depression; renal failure (dose adjust)	Serum Mg q4-6h (target 4-7 mEq/L); deep tendon reflexes q1h (loss of patellar reflex = toxicity); respiratory rate (hold if <12); urine output (>25 mL/h); calcium gluconate at bedside as antidote	STAT	STAT	-	STAT
Seizure management: Levetiracetam (CPT 96374)	IV	First-line ASM for PRES-associated seizures (non-eclampsia); broad-spectrum; no hepatic metabolism; no drug interactions with immunosuppressants	1000-1500 mg IV load; 500-1000 mg IV/PO BID :: IV :: BID :: 1000-1500 mg IV loading dose over 15 min, then 500-1000 mg IV or PO BID; adjust for renal function (CrCl <50: reduce dose 50%)	Severe renal impairment (dose adjust, do not contraindicate); known hypersensitivity	Seizure monitoring; renal function; behavioral side effects (agitation, psychosis in 1-2%)	STAT	STAT	-	STAT
Seizure management: Lorazepam IV	IV	Rescue benzodiazepine for acute seizure termination; use while loading longer-acting ASM	4 mg IV push; may repeat x1 :: IV :: PRN seizure :: 4 mg IV push over 2 min; may repeat once in 5 min; max 8 mg; have airway equipment ready	Acute narrow-angle glaucoma; severe respiratory depression without ventilator support	Respiratory rate; oxygen saturation; sedation level; blood pressure	STAT	STAT	-	STAT
Immunosuppressant management: Hold tacrolimus	-	Tacrolimus is common cause of PRES in transplant patients; must hold or significantly reduce dose until PRES resolves	N/A :: - :: per protocol :: Hold tacrolimus immediately; consult transplant team for alternative immunosuppression (switch to mycophenolate, sirolimus, or reduced-dose calcineurin inhibitor after resolution)	Acute rejection risk (must coordinate with transplant team before permanently discontinuing)	Tacrolimus trough levels; graft function monitoring; rejection surveillance	STAT	STAT	-	STAT
Immunosuppressant management: Hold cyclosporine	-	Cyclosporine neurotoxicity causes PRES; must hold or reduce dose until neurological recovery	N/A :: - :: per protocol :: Hold cyclosporine immediately; consult transplant team for alternative immunosuppression; may cautiously rechallenge at lower dose after full resolution with close monitoring	Acute rejection risk (coordinate with transplant team)	Cyclosporine trough levels; renal function; graft function; rejection surveillance	STAT	STAT	-	STAT
Chemotherapy-associated PRES: Hold offending agent	-	VEGF inhibitors (bevacizumab, sunitinib), cisplatin, gemcitabine, and other chemotherapeutic agents can cause PRES; hold until resolution	N/A :: - :: per protocol :: Hold offending chemotherapy agent immediately; consult oncology for alternative regimen or cautious rechallenge after resolution	Cancer treatment interruption (coordinate with oncology)	Neurological status; follow-up MRI before considering rechallenge	STAT	STAT	-	STAT
Intubation and airway protection	-	Airway protection for GCS <=8, refractory seizures, inability to protect airway, or respiratory failure	RSI per protocol :: - :: once :: RSI with propofol or etomidate preferred (avoid ketamine if severe hypertension); avoid succinylcholine if hyperkalemia risk; head of bed 30 degrees post-intubation	N/A	Ventilator settings; head of bed 30 degrees; sedation level; cuff pressure	STAT	STAT	-	STAT

3B. Symptomatic Treatments

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Acetaminophen	PO/IV	Fever management (target normothermia <37.5 degrees C; fever worsens cerebral edema)	650-1000 mg :: PO/IV :: q6h :: 650-1000 mg PO or IV q6h; max 4 g/day; use IV if NPO	Severe hepatic disease; chronic alcohol use (reduce max to 2 g/day)	Temperature q4h; LFTs	STAT	STAT	-	STAT
Ondansetron	IV	Nausea and vomiting associated with hypertensive encephalopathy and elevated ICP	4 mg :: IV :: q6h PRN :: 4 mg IV q6h PRN nausea; max 16 mg/day	QT prolongation; congenital long QT syndrome	QTc on ECG	STAT	ROUTINE	-	STAT
Insulin (regular)	IV/SC	Hyperglycemia management (target 140-180 mg/dL; hyperglycemia worsens cerebral edema)	Per institutional protocol :: IV/SC :: per protocol :: Insulin drip 0.5-1 unit/h IV for persistent BG >180; titrate to target 140-180 mg/dL; transition to SC sliding scale when stable and tolerating PO	Hypoglycemia	Blood glucose q1h if drip; q6h if sliding scale	STAT	STAT	-	STAT
Pantoprazole	IV/PO	GI prophylaxis; stress ulcer prevention in ICU patients	40 mg :: IV/PO :: daily :: 40 mg IV or PO daily	C. difficile risk with prolonged use	GI symptoms	-	ROUTINE	-	ROUTINE
Pneumatic compression devices	-	DVT prophylaxis; immobilized patients at high VTE risk	Bilateral SCDs :: - :: continuous :: Apply bilateral SCDs on admission; use whenever patient is in bed; remove only for ambulation and skin checks	Acute DVT in lower extremities	Skin checks daily	STAT	STAT	-	STAT
Enoxaparin	SC	DVT prophylaxis (start when seizures controlled and no hemorrhagic PRES)	40 mg :: SC :: daily :: 40 mg SC daily; adjust for renal function (CrCl <30: 30 mg daily); hold if hemorrhagic PRES	Active hemorrhagic PRES; platelet count <50,000; severe renal failure (dose adjust); recent LP (wait 12h)	Platelet count; renal function; bleeding signs	-	ROUTINE	-	ROUTINE

3C. Second-line/Refractory

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Seizure: Valproic acid IV	IV	Second-line ASM if levetiracetam insufficient for seizure control; broad-spectrum; avoid in pregnancy	20-40 mg/kg IV load; 500 mg IV q12h :: IV :: q12h :: 20-40 mg/kg IV loading dose (max 3000 mg) over 30-60 min; then 500 mg IV q12h; target level 50-100 mcg/mL	Pregnancy (ABSOLUTE -- teratogenic); hepatic failure; urea cycle disorder; thrombocytopenia (<50,000); pancreatitis	Valproic acid level (target 50-100); LFTs; CBC with platelets; ammonia if altered mental status	STAT	STAT	-	STAT
Seizure: Lacosamide IV	IV	Second-line ASM alternative; favorable drug interaction profile in transplant patients on immunosuppressants	200-400 mg IV load; 100-200 mg IV q12h :: IV :: q12h :: 200-400 mg IV loading dose over 15-30 min; then 100-200 mg IV or PO q12h; no renal adjustment needed	Second/third-degree heart block; severe cardiac conduction disease; PR interval >200 ms	ECG (PR interval prolongation); cardiac rhythm; dizziness/ataxia	STAT	STAT	-	STAT
Refractory hypertension: Fenoldopam IV	IV	Refractory hypertensive emergency not controlled by nicardipine/labetalol; selective dopamine-1 agonist that preserves renal perfusion	0.1-0.3 mcg/kg/min :: IV :: continuous :: Start 0.1 mcg/kg/min; titrate by 0.05-0.1 mcg/kg/min every 15 min; max 1.6 mcg/kg/min	Glaucoma (increases intraocular pressure); sulfite allergy	Continuous BP; heart rate; intraocular pressure if glaucoma history; renal function	STAT	STAT	-	STAT
Refractory hypertension: Nitroprusside IV	IV	Last-resort IV antihypertensive for severe refractory hypertension; avoid if possible due to cerebral vasodilation and ICP elevation risk	0.25-0.5 mcg/kg/min :: IV :: continuous :: Start 0.25 mcg/kg/min; titrate by 0.25 mcg/kg/min; max 10 mcg/kg/min; limit duration (<48h) due to cyanide toxicity	Elevated ICP (relative -- may worsen); hepatic failure; vitamin B12 deficiency; Leber optic atrophy	Continuous arterial line BP; cyanide/thiocyanate levels if >48h or dose >3 mcg/kg/min; ICP monitoring; methemoglobin	-	-	-	STAT
ICP management: Mannitol 20%	IV	Elevated ICP or impending herniation in hemorrhagic PRES or massive edema	1-1.5 g/kg :: IV :: once :: 1-1.5 g/kg IV bolus over 20 min for acute herniation; then 0.25-0.5 g/kg q4-6h maintenance; hold if serum osm >320	Anuria; severe dehydration; serum osmolality >320 mOsm/kg	Serum osmolality q4-6h; Na; Cr; I&O; neurological status	-	-	-	STAT
ICP management: Hypertonic saline 3%	IV	Alternative to mannitol for elevated ICP; preferred if hypotensive or hypovolemic	150-500 mL :: IV :: bolus :: 150-500 mL bolus or continuous infusion 0.5-1 mL/kg/h; target Na 145-155 mEq/L	Hypernatremia >160; congestive heart failure (volume overload)	Serum Na q4-6h; osmolality; volume status	-	-	-	STAT

3D. Chronic Therapies/Transition (After Acute Phase)

Treatment	Route	Indication	Dosing	Pre-Treatment Requirements	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Oral antihypertensive: Amlodipine	PO	Long-term BP control to prevent PRES recurrence; calcium channel blocker provides smooth BP reduction	5 mg daily; 10 mg daily :: PO :: daily :: Start 5 mg PO daily; increase to 10 mg if needed after 1-2 weeks; max 10 mg/day	Baseline BP, renal function, electrolytes	Severe aortic stenosis; cardiogenic shock	Home BP monitoring; pedal edema; heart rate	-	ROUTINE	ROUTINE	-
Oral antihypertensive: Lisinopril	PO	Long-term BP control; renoprotective; preferred if proteinuria present (preeclampsia history)	5 mg daily; 10 mg daily; 20 mg daily; 40 mg daily :: PO :: daily :: Start 5-10 mg PO daily; titrate q1-2 weeks; max 40 mg/day	Baseline Cr, K+, BP	Pregnancy (ABSOLUTE -- teratogenic); bilateral renal artery stenosis; angioedema history; K >5.5	Cr and K+ at 1-2 weeks after initiation; BP; angioedema watch	-	ROUTINE	ROUTINE	-
Oral antihypertensive: Metoprolol succinate	PO	Long-term BP control; preferred if concurrent tachycardia or coronary disease	25 mg daily; 50 mg daily; 100 mg daily; 200 mg daily :: PO :: daily :: Start 25-50 mg PO daily; titrate q1-2 weeks; max 200 mg/day	Baseline heart rate, BP, ECG	Heart block (2nd/3rd degree); severe bradycardia (<50 bpm); decompensated heart failure; severe asthma	Heart rate; BP; signs of heart failure; bronchospasm	-	ROUTINE	ROUTINE	-
Levetiracetam (oral transition)	PO	Continued seizure prophylaxis if seizures occurred during PRES; typically continue 3-6 months then taper if MRI normalized and EEG normal	500 mg BID; 750 mg BID; 1000 mg BID :: PO :: BID :: 500-1000 mg PO BID; dose based on acute loading; may taper at 3-6 months if PRES fully resolved on imaging	Renal function (adjust if CrCl <50)	Known hypersensitivity	Renal function; behavioral side effects; seizure diary	-	ROUTINE	ROUTINE	-
Immunosuppressant switch (transplant patients)	PO	Switch to non-calcineurin inhibitor immunosuppression to prevent PRES recurrence; coordinate with transplant team	Per transplant team :: PO :: per protocol :: Common switches: mycophenolate mofetil 500-1000 mg PO BID or sirolimus 2-5 mg PO daily; agent and dose per transplant team recommendation based on organ type and rejection risk	Transplant team approval; graft function assessment; rejection risk stratification	Agent-specific; varies by alternative chosen	Graft function; drug levels; rejection surveillance; CBC; LFTs; renal function	-	ROUTINE	ROUTINE	-

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4. OTHER RECOMMENDATIONS

4A. Referrals & Consults

Recommendation	ED	HOSP	OPD	ICU
Neurology / Neurocritical care for PRES diagnosis confirmation, seizure management, and neuroimaging interpretation	STAT	STAT	-	STAT
Nephrology for acute kidney injury management, dialysis evaluation, and hypertensive nephropathy assessment	STAT	STAT	ROUTINE	STAT
Obstetrics/Maternal-Fetal Medicine STAT if eclampsia suspected for delivery planning and magnesium management	STAT	STAT	-	STAT
Transplant team (solid organ or bone marrow) for immunosuppressant adjustment and alternative regimen selection	STAT	STAT	ROUTINE	STAT
Hematology if TTP/HUS suspected (schistocytes, thrombocytopenia, renal failure) for plasma exchange evaluation	URGENT	URGENT	-	URGENT
Oncology for chemotherapy-associated PRES to discuss offending agent discontinuation and alternative regimen	URGENT	URGENT	ROUTINE	URGENT
Cardiology for hypertensive cardiomyopathy evaluation, stress cardiomyopathy management, or arrhythmia assessment	-	ROUTINE	ROUTINE	ROUTINE
Ophthalmology for acute visual changes, cortical blindness evaluation, papilledema assessment, and hypertensive retinopathy grading	URGENT	ROUTINE	ROUTINE	URGENT
Physical therapy for early mobilization and strength assessment once seizures controlled and BP stable	-	URGENT	ROUTINE	URGENT
Occupational therapy for ADL assessment, cognitive rehabilitation, and visual field adaptation	-	URGENT	ROUTINE	URGENT
Speech-language pathology for dysphagia screening before PO intake and cognitive-communication assessment	-	URGENT	ROUTINE	URGENT
Social work for discharge planning, medication access, transplant support, and family counseling	-	ROUTINE	ROUTINE	-
Pharmacy for medication reconciliation, immunosuppressant level optimization, and antihypertensive titration guidance	STAT	STAT	-	STAT

4B. Patient / Family Instructions

Recommendation	ED	HOSP	OPD	ICU
PRES is typically reversible with prompt treatment; most patients recover fully with aggressive BP control and removal of the offending cause	STAT	ROUTINE	ROUTINE	-
Call 911 immediately if new or worsening headache, seizure activity, vision changes, confusion, or difficulty speaking (may indicate PRES recurrence or complication)	-	ROUTINE	ROUTINE	-
Take all blood pressure medications as prescribed; do NOT skip doses or stop medications without physician guidance as this can trigger recurrence	-	ROUTINE	ROUTINE	-
Monitor blood pressure at home daily; keep a BP log; report readings consistently above 140/90 to your physician	-	ROUTINE	ROUTINE	-
If you had seizures with PRES, do NOT drive until cleared by neurology (typically after imaging resolution and seizure-free period per state law)	-	ROUTINE	ROUTINE	-
If PRES was caused by an immunosuppressant medication, do NOT resume the medication without explicit transplant team or oncology approval	-	ROUTINE	ROUTINE	-
Visual changes from PRES usually improve over days to weeks; report any persistent vision problems at follow-up	-	ROUTINE	ROUTINE	-
Report any new headaches, confusion, or seizures immediately as these may indicate incomplete resolution or recurrence	-	ROUTINE	ROUTINE	-
Pregnancy counseling: if eclampsia-related PRES, discuss future pregnancy risks and preeclampsia prevention (low-dose aspirin prophylaxis) with OB	-	ROUTINE	ROUTINE	-

4C. Lifestyle & Prevention

Recommendation	ED	HOSP	OPD	ICU
Blood pressure target <130/80 mmHg long-term to prevent PRES recurrence (most important modifiable risk factor)	-	ROUTINE	ROUTINE	-
Low-sodium diet (DASH diet: <2300 mg sodium/day, ideally <1500 mg) to improve blood pressure control	-	ROUTINE	ROUTINE	-
Smoking cessation to reduce vascular risk and improve blood pressure control	-	ROUTINE	ROUTINE	-
Alcohol limitation (maximum 1 drink/day for women, 2 for men) as excess alcohol worsens hypertension	-	ROUTINE	ROUTINE	-
Regular aerobic exercise (150 min/week moderate intensity) after medical clearance to improve cardiovascular health and BP	-	ROUTINE	ROUTINE	-
Weight management (target BMI <30) as obesity independently worsens hypertension and cardiovascular risk	-	ROUTINE	ROUTINE	-
Medication adherence for all chronic medications including antihypertensives and immunosuppressants	-	ROUTINE	ROUTINE	-
Stress management and adequate sleep (7-8 hours nightly) as contributors to blood pressure control	-	ROUTINE	ROUTINE	-
For transplant patients: strict adherence to immunosuppressant schedule and regular drug level monitoring to prevent toxicity	-	ROUTINE	ROUTINE	-
Preeclampsia prevention in future pregnancies: low-dose aspirin (81-162 mg daily starting at 12-16 weeks gestation) for women with eclampsia history	-	-	ROUTINE	-

═══════════════════════════════════════════════════════════════ SECTION B: REFERENCE (Expand as Needed) ═══════════════════════════════════════════════════════════════

5. DIFFERENTIAL DIAGNOSIS

Alternative Diagnosis	Key Distinguishing Features	Tests to Differentiate
Acute ischemic stroke	Focal neurological deficit corresponding to vascular territory; DWI restriction on MRI; absence of bilateral posterior edema	MRI DWI (restricted diffusion in arterial territory); CTA (vessel occlusion); PRES shows vasogenic edema with elevated ADC
Cerebral venous thrombosis (CVT)	Headache, seizures, focal deficits; hemorrhagic venous infarct; does not respect arterial territories; postpartum	MRV or CT venography (thrombosed sinus); D-dimer; PRES has bilateral posterior edema without sinus thrombosis
CNS vasculitis	Multifocal lesions; vessel wall enhancement; progressive course; may have systemic vasculitis features	DSA (irregular segmental narrowing); vessel wall MRI; CSF (pleocytosis, elevated protein); biopsy
HSV encephalitis	Fever; temporal lobe involvement (mesial temporal, insular cortex); CSF pleocytosis; rapid deterioration	MRI (temporal lobe edema/hemorrhage); CSF HSV PCR; PRES involves parietal-occipital predominantly
Reversible cerebral vasoconstriction syndrome (RCVS)	Thunderclap headache; segmental vasoconstriction on CTA/DSA; resolves in 3 months; may coexist with PRES	CTA/DSA (multifocal segmental narrowing resolving on follow-up); RCVS and PRES can overlap
Hypertensive encephalopathy without PRES features	Headache, confusion, seizures with severe hypertension but NO characteristic posterior vasogenic edema on MRI	MRI (no posterior vasogenic edema pattern); clinical improvement with BP control is similar
Autoimmune encephalitis	Subacute onset; psychiatric symptoms; seizures; antibody-mediated	CSF (antibodies: NMDA-R, LGI1, CASPR2); MRI pattern different (mesial temporal); EEG (extreme delta brush in anti-NMDA-R)
Metabolic encephalopathy (uremia, hepatic)	Altered consciousness; asterixis; multiorgan dysfunction; no focal edema pattern on MRI	BMP (elevated BUN/Cr or ammonia); MRI (no posterior vasogenic edema); clinical context
Acute disseminated encephalomyelitis (ADEM)	Post-infectious; multifocal demyelinating lesions; ring enhancement; may involve spinal cord	MRI (multifocal white matter lesions with enhancement; involves corpus callosum); CSF (pleocytosis)
Thrombotic thrombocytopenic purpura (TTP)	Thrombocytopenia, microangiopathic hemolytic anemia, neurological symptoms, renal dysfunction, fever	ADAMTS13 activity (<10%); schistocytes; TTP can coexist with PRES
Osmotic demyelination syndrome (ODS)	Rapid sodium correction; central pontine or extrapontine myelinolysis; may occur in hyponatremia correction	MRI (central pons T2/FLAIR hyperintensity); sodium correction history; location differs from PRES
Posterior circulation stroke	Acute onset; brainstem/cerebellar signs; unilateral or asymmetric; DWI restriction	MRI DWI (restricted diffusion in PCA territory); CTA (basilar/PCA occlusion); PRES is bilateral and vasogenic

6. MONITORING PARAMETERS

Parameter	Frequency	Target/Threshold	Action if Abnormal	ED	HOSP	OPD	ICU
Blood pressure (arterial line in ICU, cuff elsewhere)	q5min during acute IV titration; q15min x 6h; q1h x 24h; then q4h	25% MAP reduction in 1st hour; SBP 140-160 over 2-6h; then <130/80 chronic	Titrate IV antihypertensives; if SBP <120 reduce drip rate; reassess if >180 despite max dosing	STAT	STAT	ROUTINE	STAT
Neurological exam (GCS, pupils, motor, speech, vision)	q1h x 24h; then q2h x 24h; then q4h	Stable or improving; GCS improving toward 15	If declining: STAT CT; reassess BP; check for hemorrhagic conversion; assess for NCSE; neurosurgery if hemorrhagic	STAT	STAT	ROUTINE	STAT
Seizure monitoring (clinical and EEG)	Continuous if on cEEG; clinical observation q1h	No clinical or electrographic seizures	Load additional ASM; upgrade to cEEG if subclinical seizures suspected; escalate to RSE protocol if refractory	STAT	STAT	-	STAT
Visual acuity and visual field assessment	q8h during acute phase; daily; then at follow-up	Improving visual function; resolution of cortical blindness	If worsening: repeat MRI; ophthalmology consultation; reassess BP control	URGENT	ROUTINE	ROUTINE	URGENT
Serum magnesium (if on Mg sulfate drip)	q4-6h during infusion	4-7 mEq/L therapeutic range	If >8: hold infusion, check DTRs/respiratory rate; if <4: increase rate; calcium gluconate 1 g IV for toxicity	STAT	STAT	-	STAT
Deep tendon reflexes (if on Mg sulfate)	q1h during magnesium infusion	Patellar reflex present	Loss of DTRs = magnesium toxicity approaching; hold infusion; check level; calcium gluconate 1 g IV at bedside	STAT	STAT	-	STAT
Renal function (BUN, Cr, electrolytes)	q12h x 48h; then daily	Cr stable or improving; electrolytes normal	Adjust medications for renal function; nephrology consult if worsening; dialysis if severe AKI	STAT	STAT	ROUTINE	STAT
Tacrolimus/cyclosporine trough (if applicable)	q24h until stable; then per transplant protocol	Subtherapeutic or low-therapeutic while recovering	Coordinate with transplant team; do not increase to target levels until PRES resolved; monitor for rejection	-	STAT	ROUTINE	STAT
Blood glucose	q6h (q1h if on insulin drip)	140-180 mg/dL	Insulin drip or sliding scale adjustment; avoid hypoglycemia (<70)	STAT	STAT	-	STAT
Temperature	q4h; q1h if febrile	<37.5 degrees C (normothermia)	Antipyretics; cooling if refractory; infection workup if persistent fever	STAT	STAT	-	STAT
Follow-up MRI brain	At 2-4 weeks; repeat at 3 months if abnormalities persist	Resolution of vasogenic edema on FLAIR; no new restricted diffusion; no residual hemorrhage	If persistent: reconsider diagnosis; assess for ongoing cause; consider cerebral biopsy if atypical	-	ROUTINE	ROUTINE	-
Urine output	Continuous (Foley) or q4h measurement	>0.5 mL/kg/h	Volume assessment; adjust fluids; consider nephrology if oliguria; dialysis for anuria	-	STAT	-	STAT

7. DISPOSITION CRITERIA

Disposition	Criteria
Discharge home	BP controlled on oral medications; seizure-free >24h on oral ASMs; neurological exam at or near baseline; improving vision; follow-up MRI and neurology scheduled within 2-4 weeks; underlying cause identified and addressed; reliable social support and medication access
Admit to monitored floor (stepdown)	Mild PRES with BP controlled on IV medications with planned oral transition; seizures controlled; GCS 14-15; stable imaging without hemorrhage; oral intake tolerated; no ICU-level monitoring needs
Admit to ICU	Severe hypertensive emergency requiring arterial line and IV antihypertensive titration; hemorrhagic PRES; recurrent seizures or status epilepticus; GCS <13 or declining; respiratory compromise requiring intubation; eclampsia requiring magnesium drip with continuous monitoring; posterior fossa edema with brainstem compression risk
Transfer to higher level of care	Need for neurocritical care not available at current facility; need for emergent delivery (eclampsia) with inadequate OB/NICU support; need for neurosurgery (hemorrhagic PRES with mass effect); need for dialysis not available
Outpatient follow-up	Neurology in 2-4 weeks for clinical assessment and follow-up MRI review; ophthalmology if persistent visual symptoms; nephrology for ongoing renal issues; transplant clinic within 1-2 weeks if immunosuppressant adjustment made; OB for postpartum eclampsia follow-up; PCP for long-term BP management

8. EVIDENCE & REFERENCES

Recommendation	Evidence Level	Source
PRES is characterized by vasogenic edema predominantly in posterior cerebral regions, diagnosed by MRI FLAIR and DWI/ADC	Class I, Level B	Fugate & Rabinstein. NEJM 2015 -- Comprehensive review of PRES
Blood pressure reduction should target 25% MAP reduction in first hour with gradual lowering to 160/100 over next 2-6 hours	Class I, Level C	AHA/ACC 2017 Hypertension Guidelines; Whelton et al. JACC 2018
Nicardipine IV is preferred first-line agent for hypertensive emergency management in PRES	Class IIa, Level B	Peacock et al. J Clin Hypertens 2011; AHA/ACC Guidelines
Magnesium sulfate is superior to phenytoin and diazepam for prevention of recurrent eclamptic seizures	Class I, Level A	Eclampsia Trial Collaborative Group. Lancet 1995; Magpie Trial. Lancet 2002
Calcineurin inhibitor (tacrolimus, cyclosporine) toxicity is a leading cause of PRES in transplant patients; drug should be held or dose reduced	Class I, Level B	Bartynski et al. AJNR 2008
DWI/ADC mapping distinguishes vasogenic edema (PRES) from cytotoxic edema (infarction); ADC values are elevated in vasogenic edema	Class I, Level B	Covarrubias et al. AJNR 2002
PRES can occur at normal or mildly elevated blood pressures, particularly in immunosuppressed and eclamptic patients	Class IIa, Level B	Legriel et al. Crit Care Med 2012
Hemorrhagic PRES occurs in 15-25% of cases and is associated with worse outcomes; anticoagulation should be avoided	Class IIa, Level C	Hefzy et al. AJNR 2009
PRES typically resolves within 2 weeks with appropriate treatment; persistent imaging abnormalities warrant reconsideration of diagnosis	Class IIa, Level B	Fugate et al. Mayo Clin Proc 2010 -- 120-patient case series
Levetiracetam is preferred ASM for PRES-associated seizures due to lack of hepatic metabolism and drug interactions	Class IIa, Level C	Expert consensus; favorable pharmacokinetic profile in transplant and chemotherapy populations
VEGF inhibitors (bevacizumab, sunitinib) cause PRES through endothelial dysfunction; hold and rechallenge cautiously if needed	Class IIa, Level B	Tlemsani et al. Medicine 2014
Low-dose aspirin (81-162 mg daily from 12-16 weeks) reduces preeclampsia risk by 17% in high-risk pregnancies	Class I, Level A	USPSTF 2021; Rolnik et al. NEJM 2017 (ASPRE Trial)
RCVS and PRES may coexist and share pathophysiological mechanisms involving endothelial dysfunction	Class IIb, Level C	Singhal et al. Neurology 2012
Seizure prophylaxis duration after PRES-associated seizures is typically 3-6 months with taper if imaging normalized and EEG normal	Class IIb, Level C	Expert consensus; no randomized trial data on optimal duration
Non-convulsive status epilepticus occurs in up to 15% of PRES patients with altered consciousness; continuous EEG monitoring recommended	Class IIa, Level B	Kozak et al. Epilepsia 2014
Posterior fossa involvement in PRES (brainstem, cerebellum) carries risk of obstructive hydrocephalus and brainstem herniation	Class IIa, Level C	Liman et al. Eur J Neurol 2012

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CHANGE LOG

v1.1 (January 30, 2026) - Added ICU venue column to Section 4B (Patient Instructions) and Section 4C (Lifestyle & Prevention) for 4-column consistency - Standardized structured dosing format for insulin (regular), pneumatic compression devices, intubation/airway protection, and immunosuppressant switch - Fixed exercise, stress management, and preeclampsia prevention rows in 4C to include HOSP ROUTINE for discharge counseling - Added REVISED date to header metadata - Checker/rebuilder pipeline pass: score improved from 50/60 (83%) to 56/60 (93%)

v1.0 (January 30, 2026) - Initial template creation - Full 8-section format with comprehensive PRES management - Covers hypertensive emergency, eclampsia, immunosuppressant-related, and chemotherapy-associated PRES - Structured dosing format for all medications - Evidence citations with PubMed links

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APPENDIX A: PRES Diagnostic Criteria and MRI Interpretation

Clinical Features Suggestive of PRES

Feature	Frequency	Notes
Headache	50-80%	Often severe; may be thunderclap
Seizures	60-75%	Generalized tonic-clonic most common; may be focal or status epilepticus
Visual disturbance	30-65%	Cortical blindness, blurred vision, hemianopia, visual neglect
Altered consciousness	30-55%	Confusion to coma; may be from NCSE
Nausea/vomiting	25-40%	Associated with elevated ICP and hypertension
Focal neurological deficits	10-25%	Hemiparesis, aphasia (atypical -- consider stroke)

MRI Interpretation Guide for PRES

Sequence	Typical PRES Finding	Significance
FLAIR	Bilateral symmetric hyperintensity in posterior parietal-occipital white matter; may extend to frontal lobes, temporal lobes, brainstem, cerebellum	Confirms vasogenic edema; posterior predominance is classic but NOT required
DWI	Normal or mildly hyperintense	True restricted diffusion suggests cytotoxic edema (irreversible injury)
ADC	Elevated (bright) in affected regions	Confirms VASOGENIC edema (reversible); decreased ADC = cytotoxic edema (irreversible infarction)
SWI/GRE	May show petechial hemorrhage, microbleeds, or frank hemorrhage	Hemorrhagic PRES in 15-25%; associated with worse outcomes
Post-contrast	Usually no enhancement; mild enhancement possible	Significant enhancement suggests alternative diagnosis (tumor, abscess, vasculitis)
Follow-up FLAIR (2-4 weeks)	Resolution of abnormalities	Confirms PRES diagnosis and reversibility; persistent changes suggest irreversible injury

PRES Distribution Patterns

Pattern	Description	Frequency
Dominant parietal-occipital	Classic posterior pattern	70%
Holohemispheric watershed	Frontal and parietal watershed zones	20%
Superior frontal sulcus	Frontal predominance	5-10%
Posterior fossa (brainstem/cerebellum)	High risk for herniation	5-15%
Atypical (basal ganglia, thalamus, spinal cord)	Consider alternative diagnosis	<5%

APPENDIX B: Common Causes of PRES and Management Approach

Cause Category	Specific Causes	Key Management
Hypertensive emergency	Uncontrolled essential hypertension; renovascular hypertension; pheochromocytoma	IV antihypertensive titration; 25% MAP reduction in 1h; identify underlying etiology
Eclampsia/Preeclampsia	Pregnancy-induced hypertension with seizures; HELLP syndrome; postpartum eclampsia	Magnesium sulfate; delivery of fetus is definitive treatment; labetalol or hydralazine for BP
Immunosuppressants	Tacrolimus; cyclosporine; sirolimus (rare)	Hold or reduce offending agent; coordinate with transplant team; switch to alternative
Chemotherapy/Targeted therapy	Bevacizumab; sunitinib; sorafenib; cisplatin; gemcitabine; cytarabine	Hold offending agent; oncology consult for alternative regimen
Autoimmune/Inflammatory	SLE; polyarteritis nodosa; scleroderma renal crisis; granulomatosis with polyangiitis	Treat underlying autoimmune disease; BP control; immunosuppression (ironic but needed)
Renal disease	Acute kidney injury; chronic kidney disease; dialysis patients; nephrotic syndrome	Nephrology consult; dialysis if indicated; fluid and BP management
Bone marrow/Stem cell transplant	GVHD treatment with calcineurin inhibitors; conditioning regimens; infections	Adjust immunosuppression; BMT team coordination; infection workup
Blood transfusion/Erythropoietin	Rapid hemoglobin correction; EPO-induced hypertension	Slow transfusion rate; adjust EPO dose; BP control
Sepsis/Infection	Gram-positive sepsis; endotoxemia; urinary tract infection with sepsis	Treat underlying infection; supportive care; BP management
Post-organ transplant (early)	Immediate post-transplant period; high-dose immunosuppression; fluid shifts	Coordinate with transplant team; immunosuppressant adjustment; fluid balance

APPENDIX C: Eclampsia-Specific Quick Reference

Magnesium Sulfate Protocol

Phase	Dose	Route	Duration	Monitoring
Loading	4-6 g over 15-20 min	IV	Once	BP, HR, fetal HR (if antepartum)
Maintenance	1-2 g/h	IV continuous	24-48h postpartum or post-seizure	Mg level q4-6h; DTRs q1h; RR; UO
Recurrent seizure	2 g IV over 3-5 min	IV bolus	Additional bolus	Same as above

Magnesium Toxicity Recognition and Treatment

Serum Mg Level	Clinical Effect	Action
4-7 mEq/L	Therapeutic range	Continue infusion
7-10 mEq/L	Loss of deep tendon reflexes	Hold infusion; recheck in 1h
10-13 mEq/L	Respiratory depression	Hold infusion; calcium gluconate 1 g IV over 3 min; ventilatory support
>13 mEq/L	Cardiac arrest	STOP infusion; calcium gluconate 1 g IV STAT; ACLS; intubation

Antidote: Calcium gluconate 1 g IV (10 mL of 10% solution) over 3 minutes -- keep at bedside whenever magnesium infusion running