Coil embolisation of unruptured intracranial aneurysms

The Interventional Procedures Advisory Committee (IPAC) originally considered this procedure as part of coil embolisation for intracranial aneurysms. However, as a result of comments received during the initial consultation in June 2003, IPAC decided to consider the procedure separately for ruptured intracranial aneurysms and for unruptured intracranial aneurysms.

# Guidance
Current evidence suggests that coil embolisation is efficacious in obliterating unruptured intracranial aneurysms and that its safety is similar to that of surgical treatment.
The annual risk of haemorrhage from unruptured intracranial aneurysms varies widely, depending on their site and size; and the lifetime risk depends on life expectancy and other factors. The decision to treat unruptured intracranial aneurysms by coil embolisation therefore requires judgement of the risks for each patient, and recognition of the importance of patient choice. Clinicians wishing to undertake this procedure should ensure that:
normal arrangements are in place for audit and clinical governance
patients understand the relative risks of coil embolisation and surgery compared to the risk of having no treatment when giving their consent for this treatment. Use of NICE's information for the public on coil embolisation of unruptured cranial aneurysms is recommended.
The procedure should only be performed in specialist units with expertise in the endovascular treatment of intracranial aneurysms.# The procedure

# Indications
Intracranial aneurysms are small balloon-like dilated portions of blood vessels that may occasionally rupture, causing haemorrhage, stroke or death. Usually, the cause is unknown, but people with genetic causes of weak blood vessels are more likely to develop aneurysms.
The traditional treatment for ruptured or unruptured aneurysms involves open surgery to clip the abnormal blood vessels inside the skull.

# Outline of the procedure
The coil technique involves approaching the aneurysm from inside the diseased blood vessel, thereby avoiding the need to open the skull. A thin tube containing the coil on a guidewire is inserted into a large artery, usually in the groin, and passed up into the skull under radiological guidance. The coil is placed inside the aneurysm and detached from the guidewire. Once in position, it causes clotting and stops blood from entering the aneurysm. Multiple coils may be inserted into the aneurysm through the same tube until the aneurysm is filled with coils.
The coil technique is mainly carried out on ruptured aneurysms but may also be used to treat unruptured aneurysms.

# Efficacy
In a large observational study, it was reported that overall morbidity and mortality associated with endovascular repair was 9% (41/451) at 1 year after having the procedure, compared with 12% (233/1917) for surgery. Similar results were reported in smaller studies comparing the two techniques. However, these comparisons are difficult because patient characteristics differed between the two groups; for example, those who underwent endovascular repair were often older than those who had surgery.
For the patients undergoing endovascular repair by coil embolisation in the International Study of Unruptured Intracranial Aneurysms, obliteration was complete in 55% (207/379) of patients, incomplete in 24% (91/379), unsuccessful in 18% (67/379), and unknown in 3% (12/379) of patients. At 1 year after the procedure, less than 1% of patients (4/451) had a moderate or severe disability, as measured by the Rankin score. In other studies on this procedure, the rate of permanent complications ranged from 5% (6/116) to 8% (3/38). For more details, refer to the Sources of evidence section.
The Specialist Advisors considered that the main uncertainty related to the long-term durability of the procedure.

# Safety
In a retrospective study of 62 patients, the procedure-related complication rate was 23% (14/62) after coil embolisation. Major complications resulting in reduced functional status were reported in five patients (8%) and minor complications causing prolonged hospitalisation were reported in nine patients (15%). Adverse events during initial and follow-up hospitalisation included intra- or postoperative rupture (6%, 4/62 patients) and cranial neuropathy (11%, 7/62 patients). For more details, refer to the Sources of evidence section.
In the large observational study, perioperative haemorrhage was noted in 2% (10/451) and cerebral infarction in 6% (26/451) of patients who underwent endovascular repair.
The Specialist Advisors considered that this was a safe procedure. One Advisor noted that complications during the procedure include rupture of the aneurysm or thrombo-embolic occlusion of intracranial vessels, but these complications are uncommon. There is also a small risk of delayed haemorrhage from the aneurysm.# Further information
This guidance relates to unruptured aneurysms. See also published separate NICE guidance on the use of coil embolisation for ruptured intracranial aneurysms.

# Sources of evidence
The evidence considered by the Interventional Procedures Advisory Committee is described in the overview to this guidance.

# Information for patients
NICE has produced information on this procedure for patients and carers ('Understanding NICE guidance'). It explains the nature of the procedure and the guidance issued by NICE, and has been written with patient consent in mind.
ISBN: 978-1-4731-3985-5