The National Institute for Clinical Excellence is examining embolisation of intracranial aneurysms and will publish guidance on its safety and efficacy to the NHS in England and Wales. The Institute's Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisors, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about embolisation of intracranial aneurysms.

This document has been prepared for public consultation. It summarises the procedure and sets out the provisional recommendations made by the Advisory Committee.

Note that this document is not the Institute's formal guidance on this procedure. The recommendations are provisional and may change after consultation.

The process that the Institute will follow after the consultation period ends is as follows.

• The Advisory Committee will meet again to consider the original evidence and its provisional recommendations in the light of the comments received during consultation.
• The Advisory Committee will then prepare the Final Interventional Procedures Document (FIPD) and submit it to the Institute.
• The FIPD may be used as the basis for the Institute's guidance on the use of the procedure in the NHS in England and Wales.

For further details, see the Interim Guide to the Interventional Procedures Programme, which is available from the Institute's website (www.nice.org.uk/ip).

Closing date for comments: 24 June 2003
Target date for publication of guidance: 24 September 2003

*SERNIP was the Safety and Efficacy Register of New Interventional Procedures. NICE is reviewing procedures that SERNIP classified

Note that this document is not the Institute's guidance on this procedure. The recommendations are provisional and may change after consultation

Provisional recommendations

The Committee decided that the guidance on embolisation of intracranial aneurysms should be specific to two different indications:

• ruptured aneurysms
• unruptured aneurysms.

Ruptured aneurysms

Current evidence on the safety and efficacy of embolisation of ruptured intracranial aneurysms appears adequate to support use of the procedure, provided that normal arrangements are in place for consent, audit and clinical governance.

The Committee recommended that rapid access to appropriate specialist care is important for patients with subarachnoid haemorrhage, and that clear arrangements should be in place for the involvement of different clinical disciplines in treatment and follow up. Clinicians should follow the guidelines from the Royal College of Physicians on the management of stroke, including subarachnoid haemorrhage (www.rcplondon.ac.uk).

Current evidence on the safety and efficacy of embolisation of unruptured intracranial aneurysms does not appear adequate for this procedure to be used without special arrangements for consent, and for audit or research. Clinicians wishing to undertake embolisation of intracranial aneurysms should inform the clinical governance leads in their Trusts. They should ensure that patients offered the procedure understand the uncertainty about its safety and efficacy, and that appropriate arrangements are in place for clinical audit. Publication of safety and efficacy outcomes will be useful in reducing the current uncertainty. NICE is not undertaking further investigation at present.

The Committee recommended that this procedure should be performed only in specialist neurological centres.

The procedure

Indications

Intracranial aneurysms are dilated blood vessels within the skull. They may be present from birth, or they may develop as a result of damage to the wall of the blood vessels caused by high blood pressure or fatty deposits. People with genetic causes of weak blood vessels are more likely to develop aneurysms. Often the cause is unknown.

Rupture of intracranial aneurysms causes subarachnoid haemorrhage and has a poor prognosis. About 30% of people die within 24 hours and a further 25-30% die within 4 weeks.

Outline of the procedure

Standard treatment for ruptured and unruptured intracranial aneurysms involves open surgery to clip the abnormal blood vessels inside the skull. The Guglielmi coil technique involves approaching the aneurysm from inside the diseased blood vessel (an endovascular technique). A thin tube containing the Guglielmi coil on a guidewire is inserted into a large artery, usually in the groin, and passed up into the skull under X-ray control. The coil is placed inside the aneurysm and detached from the guidewire. Many coils are usually required.

This endovascular technique is mainly carried out on ruptured aneurysms, but may also be used to treat unruptured aneurysms. It is suitable only for people with aneurysms in which the entrance to the dilated part of the blood vessel (the aneurysm neck) is relatively narrow.

Efficacy

The procedure in ruptured aneurysms was supported by a high-quality randomised controlled trial which showed a 23% reduction in the risk of death with coils compared with surgical clipping. With unruptured aneurysms the procedure is often used as an adjunct to surgery, not an alternative, which makes the assessment of efficacy problematic.

The Specialist Advisors stated that the procedure is superior to surgical clipping in the short term. However, the long-term durability of coils has not been established.

Safety

Currently, there is inadequate evidence on the procedure's long-term results in the embolisation of ruptured aneurysms. The heterogeneity of the lesions needing treatment in unruptured aneurysms makes assessment complicated.

The Specialist Advisors considered that this procedure is safer than surgical clipping in ruptured aneurysms. They stated that procedural mortality (rates of 1-3%) and stroke (5-8%) were the main adverse events. They also stated that there is a small risk of re-bleeding, and that this should be monitored over the long term.