2 The procedure
2.1.1 Cerebral aneurysms are small balloon-like dilated portions of blood vessels that may occasionally rupture, causing haemorrhage, stroke or death. Therapy is designed to support recovery from the initial bleed, together with specific treatment to prevent re-bleeding.
2.1.2 The majority of cerebral aneurysms arise from the major blood vessels in the centre of the head as they cross the space between the skull and the brain (the subarachnoid space). The standard surgical approach to this area is through an incision in the scalp, just in front of the ear, and an opening in the underlying bone on the side of the head. The abnormal vessels are approached side-on in the subarachnoid space beneath the brain. The surgical treatment of cerebral aneurysms involves placing a permanent clip across the neck of the aneurysm (effectively closing the neck of the balloon) to separate it from the normal vessel while preserving blood flow to the brain. If clipping is not possible, the aneurysm may be reinforced by wrapping it with synthetic material to reduce the risk of rupture.
2.2.1 Supraorbital minicraniotomy is an alternative approach through a smaller incision made above the eyebrow and through the underlying skull. This allows a front-on approach to the abnormal vessels. The aneurysm is then clipped or wrapped using conventional microsurgical instruments.
2.3.1 No controlled studies were identified. In two studies, all the aneurysms were either successfully clipped or wrapped, but length of follow-up was not reported. In another study, 89% (33/37 patients) showed good recovery on the Glasgow Outcome Scale, but it was not clear how many of the patients were followed up for the entire duration of the study (17 months). This study also reported good cosmetic outcomes following surgery. For more details, refer to the Sources of evidence section.
2.3.2 One Specialist Advisor considered it unlikely that the efficacy of treating an aneurysm would be affected by the small exposure used in this procedure when compared with the standard surgical approach.
2.4.1 In the three case series reviewed, rupture of the aneurysm during surgery occurred in 3% (4/139), 2% (2/102) and 3% (1/37) of patients. Other adverse events were: death within 8 days of surgery (4%, 4/102); central nervous system infection (2%, 2/102); impaired cerebrospinal fluid circulation requiring shunting (7%, 7/102); supraorbital nerve damage (11%, 4/37); and wound infection (3%, 1/37). For more details, refer to the Sources of evidence section.
2.4.2 The Specialist Advisors had no major safety concerns.
2.5.1 This procedure involves a different surgical approach for performing an established procedure (craniotomy for intracranial aneurysm) and, although there may be a greater risk of per-operative rupture, this has usually been managed successfully.
2.5.2 There is an increasing trend to deal with aneurysms by endoluminal techniques.