Subarachnoid Haemorrhage (SAH)
In patients under 20 years of age, arteriovenous (AV) malformations are the commonest cause of non-traumatic cases. In older patients, rupture of a cerebral artery aneurysm is the usual cause.
Known risk factors
Known risk factors include:
- Female gender
- Hypertension
- Positive family history
- Polycystic kidney disease
Presentation
Classic presentation of a sudden severe ‘thunderclap’ headache is often described as ‘my worst ever headache’. This is associated with nausea, vomiting, photophobia or neck stiffness.
Neurological symptoms
Neurological symptoms may occur such as:
- Seizures
- Diplopia
- Brief loss of consciousness
- Reduced level of consciousness
On examination, 70% of patients have neck stiffness and 20% have a focal neurological deficit.
The commonest neurological deficit is a cranial nerve (CN) III nerve palsy.
In severe cases, retinal haemorrhage may be seen.
Hunt and Hess scale for grading SAH
| Scale | Symptom |
| 1 | Asymptomatic, or minimal headache and slight nuchal rigidity |
| 2 | Moderate to severe headache, nuchal rigidity and no neurological deficit except cranial nerve palsy |
| 3 | Drowsy, minimal neurological deficit |
| 4 | Drowsy, significant neurological deficit |
| 5 | Deep coma, decerebrate rigidity and moribund appearance |
Important: Overall, approximately 50% of patients die from the immediate haemorrhage, or as a consequence of secondary complications, and 50% of the patients who survive are rendered seriously disabled. In patients with an SAH, the outcome is directly related to the neurological status at presentation.
More information on this subject can be found in the session about subarachnoid haemorrhage.