Subarachnoid Hemorrhage

Spontaneous subarachnoid haemorrhage has an incidence of 6 to 9 per 100,000 per year, a mean age around 55 and a female predominance. About 85% result from ruptured saccular aneurysms. About 10% are non-aneurysmal perimesencephalic bleeds with a benign course. The rest are AVMs, dissections, mycotic aneurysms, reversible cerebral vasoconstriction syndrome, vasculitis and sympathomimetic use.

• Risk factors: smoking, hypertension, heavy alcohol use, first-degree relative with aneurysm (3 to 5 fold risk), ADPKD, vascular Ehlers-Danlos syndrome, coarctation.
• Aneurysm sites: anterior communicating artery (about 30%), posterior communicating artery (about 25%), MCA bifurcation (about 20%), basilar tip.
• Rupture risk: rises with size above 7 mm, posterior circulation location, irregular shape and prior rupture.
• Mortality: 10 to 15% die before reaching hospital, with an overall mortality of about 35 to 45%.

Complications that dominate management

• Rebleeding: highest in the first 24 hours (4 to 14%), with about 70% mortality.
• Acute hydrocephalus: 20 to 30%.
• Delayed cerebral ischaemia: onset days 4 to 14, peak around days 7 to 10. Angiographic vasospasm occurs in about 70%, symptomatic in about 30%.
• Hyponatraemia from cerebral salt wasting or SIADH.
• Seizures.
• Neurogenic stunned myocardium and pulmonary oedema.

Severity grading

• Hunt and Hess I to V: from asymptomatic or mild headache to deep coma.
• WFNS I to V: GCS 15; GCS 13 to 14 without deficit; GCS 13 to 14 with deficit; GCS 7 to 12; GCS 3 to 6.
• Modified Fisher grade: predicts vasospasm risk from clot burden and intraventricular blood.

The classic presentation is thunderclap headache reaching maximum intensity within seconds to a minute, often with:

• Vomiting.
• Transient loss of consciousness.
• Neck stiffness, which may take 6 to 24 hours to develop.
• Photophobia.
• Seizure in 6 to 16%.

Focal and associated findings

• A sentinel headache in the preceding weeks occurs in 10 to 40%.
• Pupil-involving CN III palsy suggests a posterior communicating artery aneurysm.
• CN VI palsy can be a false localising sign of raised ICP.
• Terson syndrome (vitreous or subhyaloid haemorrhage) signals sudden ICP rise.
• ECG changes (ST-T abnormalities, QT prolongation, arrhythmia) and troponin elevation are common.

Red flags for high-risk headache in alert patients

• Age 40 or above.
• Neck pain or stiffness.
• Witnessed loss of consciousness.
• Onset during exertion.
• Instantly peaking headache.
• Limited neck flexion on examination.

Differential diagnosis: reversible cerebral vasoconstriction syndrome, cerebral venous thrombosis, cervical artery dissection, pituitary apoplexy, meningitis and hypertensive crisis. About 1 in 8 cases is initially misdiagnosed, often as migraine.

Non-contrast CT head is the first test. Sensitivity approaches 100% within 6 hours of onset on modern scanners with expert reading. It falls to about 85 to 93% beyond 6 hours and to about 50% at one week.

If CT is negative and onset was more than 6 hours ago, perform lumbar puncture, ideally at least 12 hours after onset:

• Spectrophotometric xanthochromia.
• Red cell count that fails to fall between the first and last tubes.

Vascular imaging

• CT angiography of head and neck detects aneurysms above 3 mm with 95 to 98% sensitivity and is the usual first study.
• Digital subtraction angiography is the reference standard, with a neurological complication rate of 1 to 2%.
• If initial studies are negative with an aneurysmal pattern of bleeding, repeat DSA at 7 to 14 days.
• Perimesencephalic bleeding with a negative CTA is usually benign, but still warrants a confirmatory DSA in most centres.

Supporting tests

• ECG, troponin, echocardiography, electrolytes, coagulation screen, CBC, glucose.
• For vasospasm surveillance, transcranial Doppler with MCA mean velocity above 120 cm/s and Lindegaard ratio above 3 suggests vasospasm. Velocity above 200 cm/s with ratio above 6 is severe.
• CT perfusion or angiography for suspected delayed ischaemia.

Resuscitation and pre-securing care

• Airway protection and intubation for GCS 8 or below.
• Keep SBP below 160 mmHg until the aneurysm is secured, avoiding hypotension. Use nicardipine 5 mg/h titrated by 2.5 mg/h every 5 to 15 minutes to a maximum 15 mg/h, or labetalol 10 to 20 mg IV then 0.5 to 2 mg/min infusion.
• Analgesia with paracetamol 1 g and titrated opioids. Ondansetron 4 mg for nausea. Avoid NSAIDs.
• Reverse anticoagulation: protamine 1 mg per 100 units of recent heparin; vitamin K 10 mg IV with 4-factor PCC 25 to 50 units/kg for warfarin.
• Antifibrinolytics are not routinely used.
• Acute hydrocephalus with depressed consciousness: external ventricular drain.

Securing the aneurysm (ideally within 24 hours)

• Endovascular coiling, with balloon or stent assistance where needed, is preferred for most suitable aneurysms and gives better one-year functional outcomes than clipping in suitable cases, especially posterior circulation and elderly patients.
• Surgical clipping is preferred for many MCA aneurysms, large intraparenchymal haematomas, wide-necked aneurysms with branch vessels arising from the sac, and when coiling is unsuitable.

Preventing delayed cerebral ischaemia

• Nimodipine 60 mg orally or via NG tube every 4 hours for 21 days. If hypotension develops, give 30 mg every 2 hours. Never give IV, as the oral preparation given intravenously has caused fatal collapse.
• Maintain euvolaemia with isotonic saline at about 1 to 1.5 mL/kg/h. Avoid hypovolaemia, and do not use prophylactic hypervolaemia or fluid restriction.
• Keep sodium at or above 135 mmol/L. Use hypertonic saline for hyponatraemia and fludrocortisone 0.1 mg twice daily for cerebral salt wasting.
• Hemoglobin above 8 to 9 g/dL, normothermia, glucose 140 to 180 mg/dL.

Treating established delayed ischaemia

• Induced hypertension with norepinephrine or phenylephrine, raising SBP to 160 to 200 mmHg, if cardiac function allows.
• Rescue endovascular therapy: intra-arterial verapamil 10 to 20 mg or nicardipine 5 to 15 mg per vessel, or milrinone, and balloon angioplasty for proximal focal narrowing.
• Magnesium, statins and clazosentan do not improve functional outcome.

Other care

• Seizure prophylaxis is not routine. Treat seizures with levetiracetam 500 to 1000 mg every 12 hours.
• Intermittent pneumatic compression from admission. Start enoxaparin 40 mg SC daily about 24 hours after aneurysm securing.
• Cardiac stunning is supportive. Neurogenic pulmonary oedema needs lung-protective ventilation.
• Follow-up vascular imaging at 6 to 12 months after coiling; smoking cessation and BP control.
• Offer MRA screening to those with two or more affected first-degree relatives.