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Non-aneurysmal subarachnoid haemorrhage (NASAH)

Patient information A-Z

Who is this information for? What is its aim?

This page provides useful information to patients who have suffered a non-aneurysmal subarachnoid haemorrhage (NASAH).

What is non-aneurysmal subarachnoid haemorrhage (NASAH)?

NASAH is bleeding into the fluid space surrounding the brain not caused by aneurysm, vascular malformation, or head injury. The cause of NASAH is unknown.

Although there is no identifiable cause for NASAH despite extensive diagnostic investigation, it is unlikely to happen again.

What are the symptoms of non-aneurysmal subarachnoid haemorrhage (NASAH)?

The symptoms of NASAH have a similar presentation to aneurysmal subarachnoid haemorrhage (SAH). Common symptoms include sudden onset of headache, neck pain or stiffness, light sensitivity, nausea, and vomiting.

Investigations performed after subarachnoid haemorrhage includes CT angiogram and / or cerebral angiogram. A cerebral angiogram is a test involving the use of contrast dye to examine and take pictures of blood vessels in the brain.

If the CT Angiogram or cerebral angiogram does not show an aneurysm or any vascular malformation, it is called non-aneurysmal subarachnoid haemorrhage.

Occasionally, we will repeat a cerebral angiogram at around 2 weeks. This is not done in every patient and will depend on a number of factors.

What is the prognosis (patient outcome) after a Non-Aneurysmal subarachnoid haemorrhage (NASAH)?

Patients with non-aneurysmal subarachnoid haemorrhage usually recover with most patients returning to normal life and work with no need for long-term follow-up. It is associated with good clinical outcomes compared to aneurysmal subarachnoid haemorrhage. As the risk of it happening again is low, no specific treatment is necessary.

What happens after discharge?

Patients with NASAH will often have persistent headaches and a feeling of fatigue or clouded thinking for several weeks. Providing that symptoms are improving over time, this is not of concern. The best advice is to gradually increase your level of activity over time and should take things more slowly.

If you develop new neurological symptoms, such as limb weakness or numbness or loss of speech, it is important to let a medical professional know.

Although patients who have had NASAH make an excellent recovery, we strongly advise patients to follow a healthy, active lifestyle, stop smoking and maintain normal blood pressure. High blood pressure is a risk factor for bleeding on the brain and it should be treated if your blood pressure is high.

You will receive a follow-up appointment after hospital discharge.

Can I drive?

The regulations regarding driving are put in place by the DVLA. Current guidance is that you must not drive and inform the DVLA that you have had a NASAH. The DVLA will contact your consultant for information regarding your health condition.


Flaherty ML, Haverbusch M, Kissela B, et al. Perimesencephalic subarachnoid hemorrhage: incidence, risk factors, and outcome. J Stroke Cerebrovascular Disease 2005; 14:267–71.

Contacts / further information

Neurovascular clinical nurse practitioner (CNP): 01223 216 189

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Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151