L4.3 Subarachnoid Hemorrhage -2024

Subarachnoid Hemorrhage Overview

• Department: Neurology at Shanghai Tongji Hospital, Tongji University School of Medicine.

Stroke Definition

• Stroke: Syndrome of acute, focal neurological deficit attributed to vascular injury.

  • Types of Stroke:

    • Intracerebral hemorrhage

    • Ischemic Stroke

    • Hemorrhagic Stroke

      • Subarachnoid hemorrhage (SAH)

      • Rupture leads to leakage of blood.

Key Teaching Points

• Main Topics:

  • Epidemiology

  • Clinical Findings

  • Etiology

  • Diagnosis

  • Pathogenesis

  • Treatment

  • Pathology

  • Prognosis

Epidemiology of Subarachnoid Hemorrhage

• Incidence: 5% of all strokes.

• Aneurysmal Subarachnoid Hemorrhage (aSAH) ranges from 2 to 16 per 100,000 person-years.

• Definition: Bleeding within the subarachnoid space (between arachnoid and pia mater) filled with cerebrospinal fluid.

Etiology

• Causes of SAH:

  • Saccular Aneurysms: Most common at the circle of Willis or major branches at bifurcations.

    • Ruptured Aneurysms: Account for 80-85% of cases.

    • Nonaneurysmal SAH: Accounts for 15-20%.

• Risk Factors for Rupture:

  • Increasing size of aneurysm

  • Prior SAH from another aneurysm

  • Location of posterior communicating artery

  • Cigarette smoking

  • Aneurysm-related headache

  • Hypertension

  • Releases blood into cerebrospinal fluid.

  • Increased intracranial pressure and rebleeding are common.

Clinical Findings

• Symptoms:

  • Sudden-onset severe headache, often described as the "worst headache of my life".

  • Isolated headache can occur with prodromal symptoms (sentinel headache).

  • Other manifestations include vomiting, neck stiffness, seizures, and loss of consciousness, potentially leading to sudden death.

Physical Examination

• Assess for:

  • Meningismus (meningeal irritation)

  • Kernig's sign and Brudzinski's sign (indicators of meningeal irritation)

  • Hypertension

  • Terson syndrome: Presence of preretinal hemorrhages.

  • Pupil involvement indicating third nerve palsy, which may depend on hemorrhage location.

Classification of SAH

• Hunt and Hess Scale:

  • Grade I: Asymptomatic/mild headache (70% survival)

  • Grade II: Moderate/severe headache, nuchal rigidity without neurological deficits (60% survival)

  • Grade III: Drowsiness or mild focal deficits (50% survival)

  • Grade IV: Stupor and hemiparesis (20% survival)

  • Grade V: Deep coma, decerebrate rigidity (10% survival)

• Glasgow Coma Scale and Modified Fisher scale also used for assessment.

Diagnosis

• Investigation Tools:

  • Noncontrast head CT: Initial imaging to identify SAH.

  • Lumbar puncture: CSF analysis for blood content.

  • CTA/MRA/DSA: Definitive procedures to define aneurysm anatomy.

  • Digital Subtraction Angiography (DSA): Gold standard for detecting intracranial aneurysms, facilitates endovascular treatment.

Complications of SAH

• Common complications:

  • Vasospasm (delayed cerebral ischemia)

  • Rebleeding

  • Hydrocephalus

Prognosis and Management

• Aneurysmal rebleeding risk highest within 24 hours; poor prognosis for patients who experience rebleeding.

• Delayed cerebral ischemia due to vasospasm occurs 3 to 5 days post-hemorrhage.

• Management:

  • Prevent rebleeding

  • Treat complications based on guidelines from the Chinese Stroke Association.

Mortality & Long-term Effects

• Mortality Rate: Approximately 20%.

• Neuropsychological Impacts: Long-term issues in memory, concentration, psychomotor speed, and executive function in 60-80% of patients.

• Risk factors for mortality:

  • Poor clinical grade

  • Advanced age

  • Large aneurysm size

  • Aneurysm rebleeding

  • Cerebral infarction from vasospasm

  • Global cerebral edema.

Differential Diagnosis

• Differentiate between:

  • Ischemic Stroke: Associated with gradual onset, often in quiet states.

  • Hemorrhagic Stroke: Rapid onset with severe headaches, may involve high blood pressure and CT indicating high-density lesions.