Subarachnoid Haemorrhage (SAH)

SAH Summary

Definition

Bleeding into subarachnoid space
80% from intracranial aneurysm
Medical emergency

Key Symptoms

Thunderclap headache (peaks in 1-5 min)
Neck pain/stiffness
Photophobia, nausea/vomiting
Reduced consciousness

Diagnostics

Non-contrast CT head (within 6h)
LP if CT >6h (wait 12h after onset)
CT angiography to find cause
DSA/MRA if needed

Initial Management

ABC approach if GCS ≤8
Nimodipine 60mg 4-hourly
Continuous monitoring
Secure aneurysm within 48h

Monitoring

Neurological status hourly
Continuous BP, ECG, temp
Watch for rebleed, hydrocephalus
Monitor for vasospasm (days 3-14)

Complications

Rebleeding (highest risk 24h)
Acute hydrocephalus
Vasospasm/DCI (days 3-14)
Seizures, hyponatremia

Overview

The most common cause of non-traumatic subarachnoid haemorrhage (SAH) is intracranial aneurysm, accounting for approximately 80% of cases. The remaining 20% are attributed to non-aneurysmal perimesencephalic SAH, arteriovenous malformations, arterial dissections, use of anticoagulants, and other rare conditions.

Pathophysiology

Cerebral aneurysms arise at the bifurcation of major arteries that form the circle of Willis
Common locations:
- Anterior communicating/anterior cerebral artery junction (Acom/ACA)
- Internal carotid artery/posterior communicating artery junction (ICA/Pcom)
- Middle cerebral artery bifurcation (MCA)
Rupture risk depends on size, location, symptoms, multiple aneurysms, and previous rupture history
Blood flows into subarachnoid space, sometimes into brain parenchyma and/or ventricles
Sudden increase in intracranial pressure plus toxic effects of blood cause most complications

Risk Factors

Common

Hypertension
Smoking
Family history
Alcohol use
Cocaine use

Genetic Disorders

Autosomal dominant polycystic kidney disease
Marfan syndrome
Ehlers-Danlos syndrome
Pseudoxanthoma elasticum
Neurofibromatosis type I

Clinical Features

High Index of Suspicion

Have a high index of suspicion for SAH in patients with unexplained acute severe headache. Take careful history to establish rate of onset and time to peak intensity.

Key Presentation

Thunderclap headache: Sudden severe headache, typically peaking in intensity within 1 to 5 minutes (red-flag symptom)
Note: Most people with thunderclap headache do not have SAH, but this should not deter investigation if SAH is suspected

Other Symptoms and Signs

Common

Neck pain or stiffness
Photophobia
Nausea and vomiting
Limited or painful neck flexion

Neurological

Reduced consciousness
Seizure
Focal neurological deficit
Altered brain function

Diagnosis

Non-contrast CT Head

Urgent CT head if unexplained thunderclap headache or symptoms suggest SAH
Diagnostic accuracy highest within 6 hours of symptom onset
SAH confirmed by hyperdense appearance of blood in subarachnoid space/basal cisterns
If CT within 6h shows no SAH:
- Do not routinely offer lumbar puncture
- Consider alternative diagnoses
- Seek specialist advice

Lumbar Puncture

Consider if CT head >6 hours after symptom onset shows no SAH
Wait at least 12 hours after symptom onset to allow hemoglobin degradation
Diagnose SAH if elevated bilirubin (xanthochromia) on spectrophotometry
Consider alternative diagnoses if no elevated bilirubin

CT Angiography

Offer without delay to identify cause of bleeding and guide treatment
Diagnose aneurysmal SAH if:
- CT angiography shows intracranial arterial aneurysm
- Pattern of subarachnoid blood compatible with aneurysm rupture
If no cause identified but aneurysm suspected, consider DSA or MRA

Initial Management

Medical Emergency

SAH is an acute life-threatening condition. Securing the aneurysm within 48 hours is associated with lower risk of rebleeding and lower disability rates.

ABC Approach (GCS ≤8 or falling)

Protect airway with simple maneuvers and adjuncts
Give oxygen to maintain saturations >94% (88-92% if risk of hypercapnic respiratory failure)
Call anaesthetist for intubation, deep sedation, paralysis
Use isotonic saline for fluid resuscitation (3 L/day initially)
Check pupils for size, shape, and reactivity
Monitor for arrhythmias causing hemodynamic instability

Nimodipine

Consider enteral nimodipine (60 mg orally every 4 hours) for confirmed SAH
Prevents delayed cerebral ischemia and improves outcomes
Give for 14 to 21 days
Seek specialist advice if potentially contraindicated

Continuous Monitoring

Neurological

Neurological status and examination at least every hour
High suspicion for rebleed or acute hydrocephalus if acute deterioration
Arrange urgent rescan and consult neurosurgeon if deteriorating
Consult neurologist/neurosurgeon for seizures

Vital Signs

BP via arterial line continuously
ECG continuously
Temperature continuously
Investigate fever (20% have no infection found)

Initial Supportive Care

Bed rest
Analgesia: Start with paracetamol, avoid aspirin/NSAIDs before aneurysm occlusion
For severe pain: codeine, tramadol, then morphine or oxycodone
Consider stool softener and anti-emetic
Stop and reverse all anticoagulation
Maintain normovolemia, avoid hypovolemia
Avoid hypotension and hyponatremia
VTE prophylaxis with compression stockings/pneumatic devices
Avoid hyperglycemia

Referral and Further Management

Specialist Referral

Urgently discuss with specialist neurosurgical centre
When referring, specify:
- Time from onset of symptoms
- Age
- Comorbidities
- Conscious level
- Any neurological deficit

Aneurysm Management

Interventional neuroradiologist and neurosurgeon should discuss options
Consider person's condition, aneurysm characteristics, blood location/amount
Treatment options:
- Endovascular coiling
- Neurosurgical clipping
- No intervention with monitoring
Perform interventional treatment at earliest opportunity
Risk of rebleeding highest within 24 hours of symptom onset

Management of Complications

Rebleeding

May substantially alter prognosis
Consult neurosurgeon and arrange urgent rescan
Do not give antifibrinolytic agents

Acute Hydrocephalus

Consult neurosurgeon and arrange urgent rescan
Neurosurgeon may perform ventriculostomy

Seizures

Consult neurologist/neurosurgeon
Levetiracetam and sodium valproate commonly used

Vasospasm/DCI

Delayed narrowing of vessels (days 3-14)
Accounts for 23% of SAH-related deaths
Develops in up to 70% of patients, 30% have clinical symptoms
Check for new neurological symptoms/signs
Consult neurosurgeon immediately

Prognosis and Follow-up

Outcomes

Mortality rate approximately 40-50%
About 30% of survivors require long-term care
20-30% make good recovery
Early aneurysm securing improves outcomes

Long-term Complications

Cognitive impairment
Emotional and behavioral changes
Fatigue
Headaches
Epilepsy (5-10% of patients)
Endocrine dysfunction

Follow-up Care

Regular neurological assessments
Imaging follow-up for treated aneurysms
Rehabilitation services as needed
Screening for new aneurysms in high-risk patients
Management of risk factors (hypertension, smoking)