For Patients & General Readers

Subarachnoid hemorrhage is a sudden bleeding into the space around the brain, often caused by a ruptured blood vessel like an aneurysm. It's a medical emergency that can happen to anyone, but is more common in people with certain risk factors. Prompt recognition and treatment are crucial to prevent severe brain damage and improve outcomes.

Clinical Overview

Subarachnoid hemorrhage (SAH) is defined as bleeding into the subarachnoid space, typically resulting from the rupture of a cerebral aneurysm or arteriovenous malformation (AVM). It is a catastrophic neurological event characterized by sudden onset of severe headache and requires immediate diagnostic and therapeutic intervention to mitigate secondary brain injury and improve prognosis.

Clinical Presentation

Sudden onset of the 'worst headache of life' (thunderclap headache)
Nausea and vomiting
Photophobia
Neck stiffness (nuchal rigidity)
Altered level of consciousness (ranging from confusion to coma)
Seizures

Signs & Symptoms

Symptoms (Patient-Reported)

Sudden, severe headache, often described as the worst headache of my life
Stiff neck
Sensitivity to light
Nausea or vomiting
Sudden dizziness or loss of balance
Blurred or double vision
Sudden weakness or numbness in part of the body

Signs (Clinician-Observed)

Nuchal rigidity
Photophobia
Papilledema (may be present)
Focal neurological deficits (e.g., cranial nerve palsies, hemiparesis)
Altered mental status

Differential Diagnoses

Condition	Distinguishing Feature
Migraine Headache	Migraines are typically unilateral, pulsating, and associated with photophobia and phonophobia, but usually lack the sudden, 'thunderclap' onset and nuchal rigidity of SAH.
Meningitis	Meningitis presents with fever, headache, and nuchal rigidity, but the headache is usually gradual in onset and associated with systemic signs of infection, unlike the sudden vascular event of SAH.
Cerebral Venous Sinus Thrombosis (CVST)	CVST can cause severe headache and neurological deficits, but the onset is often more insidious, and imaging will reveal thrombosis rather than free blood in the subarachnoid space.
Intracerebral Hemorrhage (ICH)	ICH involves bleeding within the brain parenchyma, causing focal deficits and headache, but typically lacks the diffuse subarachnoid blood seen on imaging.
Reversible Cerebral Vasoconstriction Syndrome (RCVS)	RCVS can cause thunderclap headaches and neurological deficits due to multifocal vasoconstriction, but imaging shows diffuse vasoconstriction rather than a focal rupture site.
Pituitary Apoplexy	Sudden onset of severe headache, visual disturbances, and ophthalmoplegia can mimic SAH, but is related to pituitary hemorrhage or infarction and has characteristic imaging findings.

Red Flags — Seek Immediate Care

Sudden, severe, 'thunderclap' headache
New onset neurological deficits (e.g., weakness, numbness, speech difficulty)
Sudden loss of consciousness or significant alteration in mental status
Seizures

Key Investigations

Non-contrast CT scan of the head (initial imaging of choice)
Lumbar puncture (if CT is negative but suspicion remains high, to rule out xanthochromia)
CT angiography (CTA) or MR angiography (MRA) of the head and neck (to identify aneurysm or vascular malformation)
Cerebral angiography (digital subtraction angiography - DSA) (gold standard for vascular lesion detection, especially if CTA/MRA is inconclusive)

Management Overview

Management of SAH is time-sensitive and focuses on immediate hemodynamic stabilization, securing the ruptured aneurysm (via endovascular coiling or surgical clipping), and preventing and managing secondary complications such as rebleeding, vasospasm, hydrocephalus, and seizures. Multidisciplinary care involving neurosurgeons, neurologists, and intensivists is essential.

Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment. TruelyserMD does not replace clinical judgement.