Subarachnoid Hemorrhage

Overview

Subarachnoid hemorrhage (SAH) is a type of bleeding stroke that occurs when blood leaks into the space between the brain and the thin tissues that cover the brain (the subarachnoid space). This condition most commonly results from a ruptured cerebral aneurysm and represents a medical emergency requiring immediate intervention.

The subarachnoid space normally contains cerebrospinal fluid, which cushions and protects the brain. When bleeding occurs in this space, it can cause a sudden increase in intracranial pressure, potentially leading to brain damage, coma, or death if not treated promptly.

Subarachnoid hemorrhage accounts for approximately 5% of all strokes but has a much higher mortality rate than other stroke types. The condition affects about 6-10 people per 100,000 annually, with peak incidence occurring between ages 40-60. Women are slightly more affected than men, particularly due to higher rates of aneurysmal bleeding.

Symptoms

The symptoms of subarachnoid hemorrhage typically develop suddenly and can be severe. The most characteristic symptom is an extremely intense headache that patients often describe as "the worst headache of my life." Key symptoms include:

Primary Symptoms

• Sudden, severe headache - Often described as thunderclap headache
• Neck stiffness and pain
• Nausea and vomiting
• Altered consciousness or loss of consciousness
• Confusion and disorientation

Additional Symptoms

• Sensitivity to light (photophobia)
• Seizures
• Weakness on one side of the body
• Speech difficulties
• Drooping eyelid
• Double vision
• Rapid heart rate
• High blood pressure

Causes

Subarachnoid hemorrhage can result from several different causes, with ruptured aneurysms being the most common:

Aneurysmal Causes (85% of cases)

• Ruptured cerebral aneurysm: Weakened areas in blood vessel walls that balloon out and eventually burst
• Saccular aneurysms: Most common type, occurring at branch points of arteries
• Fusiform aneurysms: Less common, involving the entire circumference of the vessel

Non-aneurysmal Causes (15% of cases)

• Arteriovenous malformations (AVMs): Abnormal tangles of blood vessels
• Traumatic brain injury: Severe head trauma can cause bleeding
• Blood disorders: Conditions affecting blood clotting
• Tumors: Brain tumors that bleed
• Drug use: Particularly cocaine and amphetamines
• Vasculitis: Inflammation of blood vessels
• Moyamoya disease: Progressive narrowing of brain arteries

Risk Factors

Several factors can increase the likelihood of developing conditions that lead to subarachnoid hemorrhage:

Modifiable Risk Factors

• High blood pressure: The most significant modifiable risk factor
• Smoking: Significantly increases aneurysm formation and rupture risk
• Excessive alcohol consumption: Particularly binge drinking
• Drug use: Cocaine, amphetamines, and other stimulants
• Oral contraceptive use: Slightly increased risk, especially when combined with smoking

Non-modifiable Risk Factors

• Age: Risk increases with age, peak between 40-60 years
• Gender: Women have slightly higher risk, especially post-menopause
• Family history: Genetic predisposition to aneurysm formation
• Certain genetic conditions:
  • Polycystic kidney disease
  • Ehlers-Danlos syndrome
  • Marfan syndrome
  • Neurofibromatosis
• Previous aneurysm: History of aneurysm increases risk of developing new ones

Diagnosis

Rapid and accurate diagnosis of subarachnoid hemorrhage is crucial for optimal outcomes. The diagnostic process typically involves:

Initial Assessment

• Clinical history: Detailed account of symptom onset and characteristics
• Neurological examination: Assessment of consciousness, reflexes, and neurological function
• Vital signs monitoring: Blood pressure, heart rate, and respiratory status

Imaging Studies

• Non-contrast CT scan: First-line imaging; can detect blood in 95% of cases within 24 hours
• CT angiography (CTA): Identifies aneurysms and vascular abnormalities
• MRI/MRA: More sensitive for small bleeds and vascular lesions
• Digital subtraction angiography (DSA): Gold standard for detailed vascular imaging

Laboratory Tests

• Lumbar puncture: May be performed if imaging is negative but clinical suspicion remains high
• Complete blood count: Assess for bleeding disorders
• Coagulation studies: PT/PTT, INR
• Comprehensive metabolic panel: Electrolytes, kidney function

Treatment Options

Treatment of subarachnoid hemorrhage requires immediate intensive care management and often surgical intervention:

Emergency Management

• Airway protection: Intubation if consciousness is impaired
• Blood pressure control: Careful management to prevent rebleeding
• Seizure prevention: Anticonvulsant medications
• Pain management: Adequate analgesia for severe headache
• Fluid management: Prevent dehydration and maintain cerebral perfusion

Definitive Treatment

• Surgical clipping: Metal clip placed across aneurysm neck to prevent rebleeding
• Endovascular coiling: Platinum coils inserted into aneurysm via catheter
• Flow diverters: Newer devices for complex aneurysms
• Bypass surgery: For certain complex cases

Complication Management

• Vasospasm prevention: Calcium channel blockers (nimodipine)
• Hydrocephalus treatment: Ventricular drainage if needed
• Cerebral edema management: Osmotic agents, positioning
• Infection prevention: Antibiotics for invasive procedures

Rehabilitation

• Physical therapy: Recovery of motor function
• Occupational therapy: Activities of daily living
• Speech therapy: Communication and swallowing difficulties
• Neuropsychological support: Cognitive and emotional recovery

Prevention

While not all subarachnoid hemorrhages can be prevented, several strategies can reduce risk:

Lifestyle Modifications

• Blood pressure control: Regular monitoring and medication compliance
• Smoking cessation: Most important modifiable risk factor
• Limit alcohol consumption: Avoid binge drinking
• Avoid recreational drugs: Particularly stimulants
• Regular exercise: Maintain cardiovascular health
• Healthy diet: Low sodium, heart-healthy nutrition

Medical Management

• Regular check-ups: Monitor for hypertension and other risk factors
• Genetic counseling: For those with family history
• Screening programs: For high-risk individuals with family history
• Medication review: Avoid drugs that increase bleeding risk when possible

High-Risk Population Management

• Imaging surveillance: Regular monitoring of known unruptured aneurysms
• Prophylactic treatment: Consider treatment of high-risk unruptured aneurysms
• Family screening: Imaging for family members when indicated

When to See a Doctor

Regular Medical Consultation

Schedule routine appointments for:

• Hypertension management: Regular blood pressure monitoring
• Risk factor assessment: Annual physical examinations
• Family history discussion: Genetic counseling referral if needed
• Follow-up care: After treatment for aneurysms or previous SAH

Related Conditions

• Cerebral Aneurysm
• Stroke
• Arteriovenous Malformation
• Hydrocephalus
• Cerebral Vasospasm
• Traumatic Brain Injury
• Hypertension

References

1. Connolly ES Jr, Rabinstein AA, Carhuapoma JR, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2012;43(6):1711-1737.
2. van Gijn J, Kerr RS, Rinkel GJ. Subarachnoid haemorrhage. Lancet. 2007;369(9558):306-318.
3. Steiner T, Juvela S, Unterberg A, et al. European Stroke Organisation guidelines for the management of intracranial aneurysms and subarachnoid haemorrhage. Cerebrovasc Dis. 2013;35(2):93-112.
4. Lawton MT, Vates GE. Subarachnoid hemorrhage. N Engl J Med. 2017;377(3):257-266.
5. Macdonald RL, Schweizer TA. Spontaneous subarachnoid haemorrhage. Lancet. 2017;389(10069):655-666.