Neurology · MU Sofia

62. Subarachnoid brain haemorrhage

Covers bleeding into the subarachnoid space, starting with its definition and the main causes, led by ruptured saccular aneurysms, followed by AVM, trauma and other factors. It then describes the pathogenesis, the thunderclap headache and meningeal signs, neurological and fundoscopic findings, and diagnosis by CT, lumbar puncture with xanthochromia, and angiography. The note closes with early and delayed complications, treatment including nimodipine and aneurysm clipping or coiling, and differential diagnoses.

Inside: 1 section · 2 labelled pictures · 15 flashcards · 2 min

Topic 62 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 1 section, about 240 words (2 min of reading), with 15 flashcards.

In this note

  1. Subarachnoid brain haemorrhage

Subarachnoid brain haemorrhage

Definition: Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space (between the arachnoid and pia mater), where cerebrospinal fluid circulates. It is a neurological emergency with high mortality.

Etiology

  • Most Common Cause: Rupture of a saccular (berry) aneurysm (~80%)
  • Other Causes: Arteriovenous malformation (AVM). Head trauma. Coagulation disorders. Vasculitis. Idiopathic (unknown cause)

Pathogenesis

Rupture of vessel → blood enters subarachnoid space → meningeal irritation + increased intracranial pressure (ICP) + cerebral vasospasm → cerebral ischemia.

Clinical Features

  • Classic Presentation: “Thunderclap headache”. Sudden onset. Severe ("worst headache of my life")
  • Associated Symptoms: Nausea and vomiting. Neck stiffness. Photophobia. Loss of consciousness (may be transient). Seizures
  • Meningeal Syndrome: Neck rigidity. Positive Kernig sign. Positive Brudzinski sign
  • Severe Cases: Coma. Brainstem dysfunction. Respiratory abnormalities

Examination

  • Neurological Findings: Meningeal signs. Cranial nerve palsies (especially CN III with posterior communicating artery aneurysm). Altered consciousness
  • Fundoscopy: Subhyaloid or retinal hemorrhages may occur

Diagnosis

CT Brain (First-line Investigation): Hyperdense blood in subarachnoid cisterns/sulci. Highest sensitivity within first 24 hours

Lumbar Puncture

  • If CT is negative but suspicion remains: Xanthochromia (yellow CSF). RBCs in CSF

Cerebral Angiography (CTA/MRA/DSA)

  • Used to identify: Aneurysm. AVM

Complications

Early: Rebleeding (most feared early complication). Acute hydrocephalus

Delayed: Cerebral vasospasm (most important). Delayed cerebral ischemia. Seizures

Treatment

Initial Management: ICU/stroke unit care. Blood pressure control. Analgesia and supportive care

Prevent Vasospasm: Nimodipine (standard treatment)

Definitive Treatment: Surgical clipping of aneurysm. Endovascular coiling

Differential Diagnosis: Migraine. Meningitis. Intracerebral hemorrhage. Ischemic stroke. Cerebral venous thrombosis

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