Subarachnoid haemorrhage

Subarachnoid haemorrhage (SAH) presents as a sudden, severe headache that peaks within 1 to 5 minutes (thunderclap headache) and lasts more than an hour; typically alongside vomiting, photophobia, and non-focal neurological signs.

Examination may be normal or may reveal altered consciousness, meningismus, ocular findings (e.g., intraocular haemorrhages), or focal findings (e.g., unilateral loss of motor function, loss of visual field, aphasia).

Order an urgent non-contrast computed tomography (CT) head scan for all patients with suspected SAH. The CT scan should ideally be within 6 hours of symptom onset. SAH is confirmed by the hyperdense appearance of blood in the subarachnoid space/basal cisterns. Consider a lumbar puncture only if a CT head scan performed more than 6 hours after ictus is negative or inconclusive.

In patients with a Glasgow Coma Scale score of ≤8 or falling, stabilise and investigate at the same time.

As soon as the diagnosis of SAH is confirmed, urgently discuss with a specialist neurosurgical centre the need for transfer of care of the patient to the specialist centre.

Consider enteral nimodipine for all patients with confirmed SAH.

An interventional neuroradiologist and a neurosurgeon should decide the best mode of intervention to manage the culprit aneurysm, taking into account the patient's clinical condition, the characteristics of the aneurysm, and the amount and location of subarachnoid blood. If interventional treatment is planned, this should be carried out at the earliest opportunity to prevent rebleeding. The risk of rebleeding is highest within 24 hours of the onset of symptoms.

Observe patients continuously for signs of acute deterioration (e.g., new focal neurological deficit, seizure, or sudden drop in the patient's level of consciousness) or cardiac complications (e.g., arrhythmias). Neurological complications such as rebleeding, acute hydrocephalus, vasospasm, and delayed cerebral ischaemia are common and should be treated urgently.

SAH is bleeding into the subarachnoid space and is an emergency. The most common cause of non-traumatic SAH is rupture of an intracranial aneurysm.[1]Suarez JI, Tarr RW, Selman WR. Aneurysmal subarachnoid hemorrhage. N Engl J Med. 2006 Jan 26;354(4):387-96. http://www.ncbi.nlm.nih.gov/pubmed/16436770?tool=bestpractice.com Aneurysmal SAH causes substantial morbidity and mortality. When a cerebral aneurysm ruptures, blood flows into the subarachnoid space, sometimes seeping into brain parenchyma and/or ventricles. The sudden increase in intracranial pressure, as well as the destructive and toxic effects of blood on brain parenchyma and cerebral vessels, accounts for most complications. This topic focuses on aneurysmal SAH. SAH may also result from arteriovenous malformations or traumatic head injury. See Assessment of traumatic brain injury, acute.