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Subarachnoid Hemorrhage

VERSION: 1.0 CREATED: January 27, 2026 STATUS: Approved


DIAGNOSIS: Subarachnoid Hemorrhage (SAH)

ICD-10: I60.9 (Nontraumatic subarachnoid hemorrhage, unspecified), I60.7 (SAH from unspecified intracranial artery), I60.0-I60.6 (SAH from specific arteries)

CPT CODES: 85025 (CBC with differential), 80053 (CMP (BMP + LFTs)), 85610 (PT/INR), 85384 (Fibrinogen), 86900 (Type and crossmatch), 84484 (Troponin), 83880 (BNP or NT-proBNP), 82947 (Blood glucose), 83735 (Magnesium), 82330 (Calcium, ionized), 84100 (Phosphorus), 83605 (Lactate), 84703 (Pregnancy test (β-hCG)), 83930 (Serum osmolality), 84443 (TSH), 82533 (Cortisol (AM)), 80061 (Lipid panel), 83036 (HbA1c), 87040 (Blood cultures), 84145 (Procalcitonin), 80307 (Toxicology (cocaine, amphetamines)), 70450 (CT head without contrast), 70496 (CT angiography (CTA) head), 93000 (ECG (12-lead)), 36224 (Conventional cerebral angiography (DSA)), 93886 (Transcranial Doppler (TCD)), 93306 (Echocardiogram (TTE)), 95700 (Continuous EEG (cEEG)), 71046 (Chest X-ray), 62270 (LUMBAR PUNCTURE Indication: CT-negative suspected SAH...), 96365 (Blood pressure control: Nicardipine IV), 96374 (Blood pressure control: Labetalol IV)

SYNONYMS: Subarachnoid hemorrhage, SAH, ruptured aneurysm, aneurysmal SAH, aSAH, subarachnoid bleed, thunderclap headache, worst headache of life, brain aneurysm rupture, bleeding around brain

SCOPE: Spontaneous (non-traumatic) aneurysmal subarachnoid hemorrhage in adults. Covers thunderclap headache evaluation, CT/LP diagnosis, aneurysm identification and securing, vasospasm prevention and treatment (nimodipine, triple-H therapy), hydrocephalus management, and complications. Excludes traumatic SAH, perimesencephalic (non-aneurysmal) SAH management, and intracerebral hemorrhage (separate template).


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 ED HOSP OPD ICU Rationale Target Finding
CBC with differential (CPT 85025) STAT STAT - STAT Baseline; thrombocytopenia; leukocytosis (stress response); pre-surgical Normal
CMP (BMP + LFTs) (CPT 80053) STAT STAT - STAT Electrolytes (hyponatremia from cerebral salt wasting or SIADH is common); renal/hepatic function Normal; watch Na closely
PT/INR (CPT 85610), aPTT (CPT 85730) STAT STAT - STAT Coagulopathy assessment; pre-procedure; anticoagulant use Normal
Fibrinogen (CPT 85384) STAT STAT - STAT Coagulopathy; DIC screen >150 mg/dL
Type and crossmatch (CPT 86900) STAT STAT - STAT Surgical intervention likely; potential blood loss On file; crossmatch 2-4 units
Troponin (CPT 84484) STAT STAT - STAT Neurogenic stunned myocardium occurs in 20-30% of SAH; stress cardiomyopathy Often elevated (neurogenic — not ACS)
BNP or NT-proBNP (CPT 83880) URGENT ROUTINE - URGENT Neurogenic cardiac dysfunction; volume status assessment Elevated (neurogenic)
Blood glucose (CPT 82947) STAT STAT - STAT Hyperglycemia worsens outcomes; stress response 140-180 mg/dL target
Magnesium (CPT 83735) STAT STAT - STAT Hypomagnesemia increases vasospasm risk; maintain high-normal >2.0 mg/dL (replete aggressively)
Calcium, ionized (CPT 82330) STAT STAT - STAT Electrolyte management; nimodipine monitoring Normal
Phosphorus (CPT 84100) STAT ROUTINE - STAT Electrolyte management; refeeding risk Normal
Lactate (CPT 83605) STAT ROUTINE - STAT Perfusion status <2 mmol/L
Pregnancy test (β-hCG) (CPT 84703) STAT STAT - STAT Affects imaging, anesthesia, and treatment decisions Document result

1B. Extended Workup (Second-line)

Test ED HOSP OPD ICU Rationale Target Finding
Serum osmolality (CPT 83930) URGENT ROUTINE - ROUTINE Cerebral salt wasting vs SIADH differentiation; osmotherapy monitoring 280-295 mOsm/kg
Urine osmolality and sodium - ROUTINE - ROUTINE CSW: high urine Na, high urine osm, hypovolemic. SIADH: high urine Na, high urine osm, euvolemic Differentiate CSW vs SIADH
TSH (CPT 84443) - ROUTINE - - Thyroid dysfunction screen Normal
Cortisol (AM) (CPT 82533) - ROUTINE - ROUTINE Adrenal insufficiency (pituitary dysfunction from SAH) >18 µg/dL
Lipid panel (CPT 80061) - ROUTINE ROUTINE - Cardiovascular risk assessment Document
HbA1c (CPT 83036) - ROUTINE ROUTINE - Diabetes management <7.0%
Blood cultures (CPT 87040) URGENT ROUTINE - URGENT If febrile (differentiate central fever vs infection) No growth
Procalcitonin (CPT 84145) URGENT ROUTINE - URGENT Differentiate neurogenic fever from infection <0.5 (elevated suggests infection)

1C. Rare/Specialized

Test ED HOSP OPD ICU Rationale Target Finding
Urine catecholamines/metanephrines - EXT EXT - Pheochromocytoma as cause of hypertensive hemorrhage Normal
Toxicology (cocaine, amphetamines) (CPT 80307) STAT ROUTINE - STAT Sympathomimetic-associated SAH Negative
Sickle cell screen - EXT EXT - Sickle cell associated aneurysms and SAH (young patients, African descent) Normal
Connective tissue disorder workup (Ehlers-Danlos, Marfan) - - EXT - Familial aneurysm syndromes; young SAH with marfanoid habitus or skin hyperextensibility Clinical + genetic

2. DIAGNOSTIC IMAGING & STUDIES

2A. Essential/First-line

Study ED HOSP OPD ICU Timing Target Finding Contraindications
CT head without contrast (CPT 70450) STAT STAT - STAT IMMEDIATE (door-to-CT <25 min). Sensitivity: 98-100% within 6h; ~93% at 12h; ~85% at 24h; declines after 3-5 days Hyperdense blood in basal cisterns, Sylvian fissure, interhemispheric fissure; modified Fisher grade; hydrocephalus; intraventricular hemorrhage None significant
CT angiography (CTA) head (CPT 70496) STAT STAT - STAT Simultaneously with non-contrast CT. Identifies aneurysm (sensitivity 95-100% for aneurysms >3mm) Aneurysm location, size, morphology; multiple aneurysms (15-20% have >1); vasospasm (delayed) Contrast allergy (premedicate); renal impairment (benefit outweighs risk)
ECG (12-lead) (CPT 93000) STAT STAT - STAT Immediately Deep T-wave inversions ("cerebral T waves"), ST changes, QT prolongation, arrhythmias — all may be neurogenic; do NOT misdiagnose as primary cardiac event None

2B. Extended

Study ED HOSP OPD ICU Timing Target Finding Contraindications
Conventional cerebral angiography (DSA) (CPT 36224) - STAT - STAT Within 24h — GOLD STANDARD for aneurysm identification; also therapeutic (coiling). If CTA negative but clinical suspicion high, DSA is mandatory Aneurysm (location, neck width, dome-to-neck ratio, relationship to branches); may find aneurysm missed by CTA; vasospasm assessment Contrast allergy; renal impairment; coagulopathy (relative)
Repeat DSA (if initial negative) - ROUTINE - ROUTINE At 7-14 days if initial DSA negative and non-perimesencephalic pattern; small aneurysm may be thrombosed or compressed by hematoma Previously missed aneurysm Same as initial
MRI/MRA brain - ROUTINE ROUTINE - When stable; helpful for subacute diagnosis or if CT negative but suspicion persists Blood products (FLAIR); aneurysm (MRA); ischemia from vasospasm (DWI) Pacemaker; hemodynamic instability
Transcranial Doppler (TCD) (CPT 93886) - STAT - STAT Begin daily on post-bleed day 3; continue through day 14 (vasospasm window) Mean flow velocities: MCA >120 cm/s concerning; >200 cm/s severe vasospasm. Lindegaard ratio >3 suggests vasospasm (>6 = severe) Absent temporal bone window (~10%)
CT perfusion (CTP) (CPT 0042T) - URGENT - URGENT If vasospasm suspected clinically (new deficit days 4-14) Perfusion deficits in vascular territory of spastic vessel; mismatch (reversible ischemia) Contrast allergy; renal impairment
CTA (repeat for vasospasm) - URGENT - URGENT If clinical vasospasm suspected Arterial narrowing; correlate with TCD and clinical exam Same as initial CTA
Echocardiogram (TTE) (CPT 93306) - ROUTINE - ROUTINE Within 24-48h Takotsubo (apical ballooning); regional wall motion abnormalities; EF assessment — neurogenic stunned myocardium in 20-30% None significant
Continuous EEG (cEEG) (CPT 95700) - URGENT - STAT If altered consciousness; delayed deterioration; suspected seizures Non-convulsive seizures; electrographic vasospasm correlate; periodic discharges None
Chest X-ray (CPT 71046) URGENT ROUTINE - URGENT On admission; daily in ICU Neurogenic pulmonary edema; aspiration; ARDS None

2C. Rare/Specialized

Study ED HOSP OPD ICU Timing Target Finding Contraindications
3D rotational angiography - URGENT - URGENT During DSA for complex aneurysm anatomy Detailed aneurysm morphology for treatment planning Same as DSA
Xenon CT or CT perfusion (quantitative) - EXT - EXT Research/advanced vasospasm assessment Quantitative cerebral blood flow mapping Limited availability
MRA screening (unruptured aneurysm in family members) - - ROUTINE - Elective — for first-degree relatives of SAH patients (2 or more affected family members) Incidental unruptured aneurysm Standard MRI contraindications

LUMBAR PUNCTURE

Indication: CT-negative suspected SAH. If CT head is normal but clinical suspicion (thunderclap headache "worst of my life") remains — LP (CPT 62270) is MANDATORY. Wait ≥6h (ideally 12h) from headache onset for xanthochromia to develop.

Timing: URGENT — but ≥6h from headache onset to allow xanthochromia development.

Study ED HOSP OPD Rationale Target Finding
Opening pressure URGENT ROUTINE - Elevated in SAH Often elevated (>20 cm H2O)
Cell count (tubes 1 AND 4) URGENT ROUTINE - Distinguish SAH from traumatic tap: SAH = RBC count does NOT clear significantly between tube 1 and tube 4 RBC in tube 4 ≥ tube 1 (SAH); if tube 4 << tube 1 = traumatic tap
Xanthochromia (visual and/or spectrophotometry) URGENT ROUTINE - Yellow discoloration from RBC breakdown (bilirubin); develops >6h after SAH; spectrophotometry more sensitive than visual inspection Present = SAH (sensitivity >95% at 12h-2 weeks post-bleed). Absent = unlikely SAH
Protein URGENT ROUTINE - Elevated in SAH Elevated
Glucose URGENT ROUTINE - Usually normal in SAH Normal
Gram stain and culture URGENT ROUTINE - Exclude meningitis (meningeal signs overlap) No organisms

Special Handling: Xanthochromia sample must be protected from light (wrap tube in foil); centrifuge immediately; spectrophotometry if available (more sensitive than visual inspection).

Note: CT within 6h of ictus has near 100% sensitivity. If CT is obtained within 6h and is clearly negative, some guidelines suggest LP may not be needed if CTA is also negative. However, LP remains standard of care for CT-negative thunderclap headache in most institutions.


3. TREATMENT

⚠️ CRITICAL PRIORITIES

  1. Secure the airway (if GCS ≤8)
  2. Stabilize blood pressure (SBP <160 until aneurysm secured)
  3. Identify and secure the aneurysm (clipping or coiling) as soon as possible (<24h)
  4. Prevent and treat vasospasm (nimodipine, euvolemia)
  5. Monitor for hydrocephalus (EVD if needed)

3A. Acute/Emergent

Treatment Route Indication Dosing Contraindications Monitoring ED HOSP OPD ICU
Blood pressure control: Nicardipine IV (CPT 96365) IV - 5 mg/h :: IV :: - :: 5 mg/h IV; titrate by 2.5 mg/h q5-15min; max 15 mg/h. Target SBP <160 mmHg UNTIL aneurysm is secured (re-bleed risk highest in first 24h with uncontrolled HTN); after securing: target SBP <180 (or higher if vasospasm) Severe aortic stenosis Continuous arterial BP; neuro checks q1h STAT STAT - STAT
Blood pressure control: Labetalol IV (CPT 96374) IV - 10-20 mg :: IV :: - :: 10-20 mg IV q10-20min; max 300 mg. Alternative to nicardipine Heart block; severe bradycardia; asthma HR; BP continuous STAT STAT - STAT
Blood pressure control: Clevidipine IV (CPT 96365) IV - 1-2 mg/h :: IV :: - :: 1-2 mg/h IV; max 32 mg/h Soy/egg allergy BP continuous STAT STAT - STAT
Nimodipine (CORNERSTONE of vasospasm prevention) IV - 60 mg :: IV :: q4h :: 60 mg PO/NG q4h x 21 days. START within 96h of SAH onset. If hypotension: 30 mg q2h. This is an ORAL calcium channel blocker — do NOT give IV (severe hypotension). Proven to reduce poor outcomes from vasospasm Hypotension (SBP <90 — reduce dose); do NOT crush extended-release formulations; use oral syringe if NG BP with each dose; do NOT give IV; ensure enteral route only - STAT - STAT
External ventricular drain (EVD) - - N/A :: - :: once :: For acute hydrocephalus (GCS declining; CT showing ventriculomegaly); allows ICP monitoring and CSF drainage. Set drain height per neurosurgery (typically 15-20 cm above tragus) Coagulopathy (correct first) ICP continuous; CSF output q1h; drain position; infection surveillance (CSF culture q3 days per some protocols) STAT STAT - STAT
Seizure prophylaxis (short-term) IV - 1000 mg :: IV :: BID :: Levetiracetam 1000 mg IV/PO load, then 500-1000 mg BID. AHA 2012: short-term (3-7 days) prophylaxis is reasonable. Avoid phenytoin (associated with worse cognitive outcomes in SAH — Naidech et al.) Renal impairment (dose adjust) Seizure monitoring STAT STAT - STAT
Intubation / Airway protection - - N/A :: - :: once :: GCS ≤8; inability to protect airway; respiratory failure; impending herniation N/A Avoid hypotension during RSI; maintain SBP goal STAT STAT - STAT
Aminocaproic acid (antifibrinolytic) (CPT 96365) IV - 4g :: IV :: once :: 4g IV load then 1g/h IV infusion. ONLY use for short-term (<72h) if aneurysm securing will be delayed. Reduces re-bleeding risk but increases thrombotic risk. Discontinue once aneurysm is secured Active DIC; DVT/PE; renal impairment Coagulation; thrombotic events; discontinue when aneurysm treated STAT STAT - STAT
IV isotonic fluids (euvolemia) IV - 1-1.5 mL/kg :: - :: - :: NS at 1-1.5 mL/kg/h (80-125 mL/h); goal euvolemia. Avoid hypovolemia (worsens vasospasm) and avoid aggressive hypervolemia (no proven benefit; risk of pulmonary edema). Target CVP 5-8 or clinical euvolemia Volume overload; CHF I/O; daily weights; CVP if central line; serum Na q6-8h STAT STAT - STAT
Stress ulcer prophylaxis: Pantoprazole IV - 40 mg :: IV :: daily :: 40 mg IV/PO daily C. diff risk GI symptoms - ROUTINE - ROUTINE
DVT prophylaxis: Pneumatic compression devices - - N/A :: - :: continuous :: Apply bilaterally on admission; SAH patients are HIGH VTE risk Acute DVT Skin checks STAT STAT - STAT
DVT prophylaxis: Heparin SC (after aneurysm secured) SC - 5000 units :: SC :: q8h :: 5000 units SC q8h; start 24h after aneurysm is secured (clipping or coiling); some centers start earlier Active bleeding; within 24h of craniotomy (per surgeon) Platelets q3 days - ROUTINE - ROUTINE

3B. Aneurysm Securing (Definitive Treatment)

Treatment Route Indication Dosing Contraindications Monitoring ED HOSP OPD ICU
Endovascular coiling - - N/A :: - :: once :: Interventional neuroradiology; catheter-based platinum coil deployment into aneurysm sac. Preferred per ISAT trial for posterior circulation and many anterior circulation aneurysms Difficult vascular access; very wide neck without stent option - - - - -
Surgical clipping (craniotomy) - - N/A :: - :: once :: Neurosurgical; microsurgical clip placement across aneurysm neck Poor grade with brain swelling (relative — may clip if accessible); medically unstable - - - - -
Flow diverter (Pipeline, FRED) - - N/A :: - :: per protocol :: For large/giant or wide-necked aneurysms not amenable to standard coiling Requires dual antiplatelet therapy (may not be ideal in acute SAH) - - - - -

3C. Vasospasm Treatment (Post-Bleed Days 4-14)

Treatment Route Indication Dosing Contraindications Monitoring ED HOSP OPD ICU
Nimodipine (continued) PO - 60 mg :: PO :: q4h :: Continue 60 mg PO q4h x 21 days total Hypotension BP with each dose - STAT - STAT
Induced hypertension IV - N/A :: IV :: continuous :: If clinical vasospasm (new deficit days 4-14, aneurysm MUST be secured first): raise SBP to 180-220 mmHg using vasopressors. Phenylephrine 0.5-5 µg/kg/min or norepinephrine 0.05-0.3 µg/kg/min IV Unsecured aneurysm (NEVER induce hypertension before securing); cardiac failure; pulmonary edema Arterial line; neuro checks q1h; TCD; CT perfusion - - - STAT
IV fluid bolus (euvolemia maintenance) IV - 500-1000 mL :: - :: once :: NS bolus 500-1000 mL if hypovolemic; maintain euvolemia. Avoid prophylactic hypervolemia (no benefit per current evidence — Robertson et al.) Volume overload CVP; I/O; daily weights - - - STAT
Milrinone IV (alternative vasospasm treatment) IV - 0.25-0.75 µg/kg/min :: IV :: continuous :: 0.25-0.75 µg/kg/min IV continuous; some centers use as rescue for vasospasm not responding to induced hypertension; acts as cerebral vasodilator Severe hypotension; arrhythmia BP (may cause hypotension); HR; cardiac output - - - STAT
Intra-arterial vasodilator therapy (endovascular rescue) PO - 5-10 mg :: PO :: - :: Verapamil 5-10 mg intra-arterial or nicardipine 5-10 mg intra-arterial; via catheter into spastic vessel during angiography. For medically refractory vasospasm Hemodynamic instability during procedure Angiographic improvement; clinical response; BP - - - STAT
Angioplasty (balloon) - - N/A :: - :: per protocol :: Mechanical dilation of spastic proximal vessels during angiography. For focal proximal vasospasm refractory to medical treatment Vessel rupture risk; distal vasospasm (not amenable to balloon) Angiographic result; clinical response - - - STAT
Magnesium sulfate (supplemental) IV - 2.0 mg :: IV :: PRN :: Target serum Mg >2.0 mg/dL; replete with MgSO4 2-4 g IV over 1-2h PRN. MASH-2 trial: IV magnesium infusion did NOT improve outcomes, but maintaining normal-high Mg is standard Renal failure; hypermagnesemia Serum Mg q12-24h; deep tendon reflexes - ROUTINE - ROUTINE

3D. Complications Management

Treatment Route Indication Dosing Pre-Treatment Requirements Contraindications Monitoring ED HOSP OPD ICU
Hyponatremia management: Differentiate CSW vs SIADH PO Na <135: CSW = volume depleted (treat with NS/hypertonic saline + fludrocortisone). SIADH = euvolemic (treat with fluid restriction ± hypertonic saline) 0.1-0.2 mg :: PO :: BID :: CSW: NS or 3% saline; fludrocortisone 0.1-0.2 mg PO BID. SIADH: fluid restriction 1-1.2 L/day; 3% saline if <120 - - Na q6h during correction; avoid >8-10 mEq/L rise in 24h (central pontine myelinolysis risk) - - - -
Fludrocortisone PO Cerebral salt wasting (volume depletion + hyponatremia) 0.1-0.2 mg :: PO :: BID :: 0.1-0.2 mg PO BID - - Na; K+ (hypokalemia); volume status; BP - - - -
Hydrocortisone IV Refractory hyponatremia; cerebral salt wasting; adrenal insufficiency 50-100 mg :: IV :: q8h :: 50-100 mg IV q8h - - Na; glucose; cortisol - - - -
Ventriculoperitoneal shunt (VPS) - Chronic hydrocephalus (EVD-dependent; unable to wean) N/A :: - :: once :: Neurosurgical procedure - - Shunt function; neurologic status - - - -
Lumbar drain - CSF diversion after EVD if transitioning; mild chronic hydrocephalus N/A :: - :: per protocol :: Neurosurgical placement - - CSF output; ICP; position - - - -

4. OTHER RECOMMENDATIONS

4A. Referrals & Consults

Recommendation ED HOSP OPD ICU Indication
Neurosurgery STAT STAT - STAT ALL SAH patients; EVD placement; surgical clipping decision; hydrocephalus management
Interventional neuroradiology / Neuroendovascular STAT STAT - STAT Endovascular coiling; intra-arterial vasospasm treatment; angioplasty
Neurocritical care / Neurointensivist STAT STAT - STAT ICU management; vasospasm monitoring; medical optimization
Cardiology - ROUTINE - ROUTINE Neurogenic stunned myocardium; Takotsubo; arrhythmia management
Pulmonology - ROUTINE - ROUTINE Neurogenic pulmonary edema; ARDS; ventilator management
Endocrinology - ROUTINE ROUTINE - Pituitary dysfunction post-SAH (growth hormone, cortisol, thyroid); diabetes insipidus
Speech-language pathology (SLP) - URGENT ROUTINE URGENT Dysphagia evaluation; cognitive-linguistic assessment
Physical therapy (PT) - URGENT ROUTINE URGENT Early mobilization when stable; fall prevention; strength
Occupational therapy (OT) - URGENT ROUTINE URGENT ADL assessment; cognitive rehabilitation
Rehabilitation medicine (physiatry) - ROUTINE ROUTINE - Rehabilitation planning; disposition
Social work - ROUTINE ROUTINE - Family support; advance directives; discharge planning
Palliative care - ROUTINE - ROUTINE Poor-grade SAH (Hunt-Hess IV-V); goals of care
Genetics / Genetic counseling - - ROUTINE - Familial aneurysm screening; connective tissue disorders

4B. Patient / Family Instructions

Recommendation ED HOSP OPD
SAH is life-threatening; treatment is time-sensitive STAT ROUTINE ROUTINE
Call 911 immediately if: sudden severe headache ("worst headache of life"), loss of consciousness, seizure, new weakness, vision changes - ROUTINE ROUTINE
Blood pressure control is critical long-term — take all prescribed medications - ROUTINE ROUTINE
Smoking cessation is essential (smoking is the strongest modifiable risk factor for aneurysm formation and rupture) - ROUTINE ROUTINE
Do NOT drive until cleared by neurology/neurosurgery - ROUTINE ROUTINE
Avoid heavy lifting, straining, and Valsalva maneuvers for 4-6 weeks - ROUTINE ROUTINE
Follow-up imaging (CTA or MRA) at 6 months, then annually for several years to assess treated aneurysm and screen for new aneurysm - ROUTINE ROUTINE
First-degree relatives should discuss aneurysm screening with their physician if ≥2 family members have had SAH - ROUTINE ROUTINE
Cognitive difficulties (memory, attention, fatigue) are common after SAH — neuropsychological evaluation and rehabilitation are available - ROUTINE ROUTINE
Depression and anxiety are common; seek support early - ROUTINE ROUTINE

4C. Lifestyle & Prevention

Recommendation ED HOSP OPD
Smoking cessation (ABSOLUTE — strongest modifiable risk factor) - ROUTINE ROUTINE
Blood pressure control (<130/80 mmHg) - ROUTINE ROUTINE
Alcohol moderation/cessation (heavy drinking increases SAH risk) - ROUTINE ROUTINE
Cocaine/stimulant cessation (vasospasm and SAH risk) - ROUTINE ROUTINE
Avoid excessive straining (constipation management; stool softeners) - ROUTINE ROUTINE
Regular moderate exercise after recovery and medical clearance - - ROUTINE
Adequate hydration - ROUTINE ROUTINE
Stress management - ROUTINE ROUTINE

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

5. DIFFERENTIAL DIAGNOSIS

Alternative Diagnosis Key Distinguishing Features Tests to Differentiate
Thunderclap headache — reversible cerebral vasoconstriction syndrome (RCVS) Recurrent thunderclap headaches over days-weeks; triggered by exertion, Valsalva, sexual activity; vasospasm on CTA; may have convexity SAH; no aneurysm CTA (multifocal segmental narrowing); MRI (may show edema, infarct, cortical SAH); DSA; clinical course (resolves in weeks)
Primary intracerebral hemorrhage Parenchymal hematoma with minimal/no subarachnoid blood; hypertensive location (basal ganglia, thalamus) CT (parenchymal not cisternal); CTA (no aneurysm unless hemorrhage extends into subarachnoid space)
Bacterial meningitis Fever, meningismus, altered mental status, CSF neutrophilic pleocytosis with low glucose LP (gram stain, culture, BioFire); procalcitonin elevated; CT without blood
Migraine (severe) Prior migraine history; gradual onset of associated features; photophobia, phonophobia; no blood on CT Normal CT; normal LP; clinical history
Hypertensive emergency Severely elevated BP; headache; but no blood on CT; may have PRES features CT (no blood); MRI (PRES: posterior white matter edema)
Cervical artery dissection Neck pain, headache, Horner syndrome, stroke; may have traumatic SAH from vertebral dissection CTA neck (intimal flap, pseudoaneurysm); MRI neck (crescent sign)
Cerebral venous thrombosis (CVT) Headache, seizures; may have hemorrhagic venous infarct or cortical SAH; risk factors (OCPs, pregnancy) MRV/CT venogram (thrombosed sinus)
Pituitary apoplexy Sudden headache, visual field defect, ophthalmoplegia; known pituitary adenoma; may have subarachnoid blood from pituitary hemorrhage MRI sella (hemorrhagic pituitary mass); hormone panel
Perimesencephalic SAH (non-aneurysmal) Blood confined to perimesencephalic cisterns (anterior to brainstem); benign course; CTA/DSA negative for aneurysm CT pattern (perimesencephalic); negative CTA and DSA; excellent prognosis
Traumatic SAH History of trauma; may have other traumatic injuries (contusion, subdural, skull fracture) Clinical history; CT pattern
Spinal SAH Sudden back/leg pain with meningismus; blood on lumbar CT or MRI; rare Spinal MRI; spinal angiography

6. MONITORING PARAMETERS

Parameter ED HOSP OPD ICU Frequency Target/Threshold Action if Abnormal
Blood pressure (arterial line) STAT STAT ROUTINE STAT Continuous via arterial line in ICU. Pre-securing: target SBP <160. Post-securing: allow SBP 120-180 (higher if vasospasm treatment) SBP <160 (unsecured); SBP 120-180 (secured); SBP 180-220 if treating vasospasm Titrate antihypertensives; vasopressors for vasospasm
GCS / Neurologic exam STAT STAT ROUTINE STAT q1h x 24h; then q2h x 48h; then q4h. Hunt-Hess grade at admission Stable or improving If declining: STAT CT (rebleed, hydrocephalus, infarct); TCD; adjust treatment
ICP (if EVD in place) - - - STAT Continuous; record q1h ICP <22 mmHg; CPP 60-70 mmHg Tiered ICP management; CSF drainage; osmotherapy
Transcranial Doppler (TCD) - STAT - STAT Daily from day 3 through day 14 (vasospasm window); some continue to day 21 MCA mean velocity <120 cm/s; Lindegaard ratio <3 If MCA >120: CTA/CTP; clinical correlation. If >200: severe vasospasm — consider induced hypertension +/- endovascular rescue
Serum sodium STAT STAT - STAT q6h x 72h; then q8-12h 135-145 mEq/L If <135: differentiate CSW vs SIADH; treat accordingly. If <120: 3% saline; limit correction <10 mEq/24h
Serum magnesium STAT ROUTINE - STAT Daily; q12h if repleting >2.0 mg/dL Replete with MgSO4 2-4 g IV
Temperature STAT STAT - STAT q4h (q1h if febrile) <37.5°C (normothermia) Central fever (common): cooling; acetaminophen. If >38.3°C: infection workup (cultures, CXR, UA)
Blood glucose STAT STAT - STAT q6h (q1h if insulin drip) 140-180 mg/dL Insulin; avoid <60
Troponin / BNP STAT ROUTINE - ROUTINE Troponin daily x 3; BNP at admission and PRN Track trend If rising with new ECG changes or hemodynamic instability: echo; cardiology
Hemoglobin STAT ROUTINE - ROUTINE Daily >8 g/dL (some argue >10 in vasospasm patients) Transfuse PRBCs
Fluid balance (I/O) STAT STAT - STAT q1h in ICU; q4h shift on floor Net even to slightly positive; euvolemia Avoid dehydration (vasospasm risk); avoid overhydration (pulmonary edema)
Repeat CT head - STAT - STAT At 24h post-admission; with any neurologic change; post-procedure; if new hydrocephalus suspected Stable hemorrhage; no rebleed; no new infarct; ventricle size Adjust EVD; surgery; vasospasm treatment
Hunt-Hess / WFNS grade STAT - - - At admission (prognostic) Document grade Goals of care if poor grade

7. DISPOSITION CRITERIA

Disposition Criteria
Discharge home Never discharge from ED with confirmed SAH. Discharge from hospital when: aneurysm secured; past vasospasm window (day 14-21); stable neurologic exam; Na stable; able to take oral nimodipine; no EVD dependency; adequate follow-up
Admit to Neuro-ICU ALL confirmed aneurysmal SAH patients; minimum 14-21 days ICU-level monitoring during vasospasm window. Transfer to step-down only after vasospasm window passed
Transfer to comprehensive stroke center / Neurovascular center If no neurosurgery or interventional neuroradiology on-site — TRANSFER IMMEDIATELY. SAH requires tertiary neurovascular services
Inpatient rehabilitation Significant deficits but medically stable; past vasospasm window; able to participate in 3h/day therapy
Skilled nursing facility Cannot tolerate intensive rehab; requires ongoing skilled care
Hospice / Comfort care Devastating SAH (Hunt-Hess V with poor prognostic factors); after appropriate observation period and family discussion

8. EVIDENCE & REFERENCES

Recommendation Evidence Level Source
Nimodipine 60 mg PO q4h x 21 days Class I, Level A Pickard et al. (BMJ 1989); only proven agent to improve outcomes in SAH vasospasm
Early aneurysm securing (<24h, ideally <12h) Class I, Level B ISAT; AHA/ASA 2012 SAH Guidelines; de Gans et al. (Neurosurgery 2002)
Endovascular coiling preferred over clipping for most aneurysms Class I, Level A ISAT trial (Molyneux et al. Lancet 2002); long-term follow-up
SBP <160 until aneurysm secured Class I, Level B AHA/ASA 2012 SAH Guidelines
Euvolemia (avoid hypovolemia; avoid prophylactic hypervolemia) Class I, Level B Lennihan et al. (Stroke 2000); HIMALAIA trial
Induced hypertension for clinical vasospasm (after aneurysm secured) Class IIa, Level B AHA/ASA Guidelines; standard practice
TCD daily for vasospasm monitoring Class IIa, Level B Sloan et al. (2004); AHA/ASA Guidelines
Short-term seizure prophylaxis (3-7 days) reasonable Class IIb, Level B AHA/ASA 2012
Avoid phenytoin in SAH (worse cognitive outcomes) Class III (Harm) Naidech et al. (Stroke 2005)
CT sensitivity ~100% within 6h Class I, Level A Perry et al. (BMJ 2011); Backes et al. (Stroke 2012)
LP if CT negative but clinical suspicion Class I, Level B AHA/ASA Guidelines; standard of care
Aminocaproic acid (short-term) if aneurysm securing delayed Class IIa, Level B Hillman et al. (J Neurosurg 2002); AHA/ASA 2012
Magnesium infusion does NOT improve outcomes Class III (No Benefit) MASH-2 trial (Dorhout Mees et al. Lancet 2012)
Fludrocortisone for cerebral salt wasting Class IIa, Level B Hasan et al. (Stroke 1989)
Intra-arterial vasodilator / balloon angioplasty for refractory vasospasm Class IIa, Level B Multiple case series; AHA/ASA Guidelines
Avoid self-fulfilling prophecy in poor-grade SAH Class I, Level C AHA/ASA 2012: aggressive treatment for at least 72h in poor-grade

APPENDIX: HUNT AND HESS GRADING SCALE

Grade Description Approximate Mortality
I Asymptomatic or mild headache, slight nuchal rigidity ~1%
II Moderate-severe headache, nuchal rigidity, no neurologic deficit other than cranial nerve palsy ~5%
III Drowsiness, confusion, or mild focal deficit ~19%
IV Stupor, moderate-severe hemiparesis, possible early decerebrate rigidity ~42%
V Deep coma, decerebrate rigidity, moribund appearance ~77%

APPENDIX: MODIFIED FISHER GRADE (Vasospasm Risk)

Grade CT Findings Vasospasm Risk
0 No SAH or IVH Very low
1 Thin SAH, no IVH Low (24%)
2 Thin SAH, with IVH Moderate (33%)
3 Thick SAH, no IVH High (33%)
4 Thick SAH, with IVH Very high (40%)

APPENDIX: CEREBRAL SALT WASTING vs SIADH

Feature Cerebral Salt Wasting SIADH
Volume status Hypovolemic (dehydrated) Euvolemic
Serum Na Low (<135) Low (<135)
Urine Na High (>40) High (>40)
Urine osm High High
Treatment Volume replacement (NS, hypertonic saline); fludrocortisone Fluid restriction; hypertonic saline if severe
Key differentiator Clinical dehydration (tachycardia, dry mucous membranes, elevated BUN:Cr ratio, negative fluid balance) Clinically euvolemic