Kim Gray

Department of Anaesthetics, Royal Prince Alfred Hospital, Sydney

Since the early 1990's, when Guglielmi detachable coils became readily available, endovascular management of cerebral aneurysms has been an accepted treatment option for the obliteration of intact and ruptured aneurysms. Radical improvements in the types of coils and catheters available for the "coiling" of cerebral aneurysms, coupled with the judicious placement of stents across some aneurysm necks and mastery of liquid polymer (ONYX) aneurysm embolisation, have made an increased number of cerebral aneurysms suitable for endovascular treatment and altered the profile of associated complications. Despite their criticisms, studies such as the International Subarachnoid Aneurysm Trial (ISAT) have fuelled the interest in this form of aneurysm treatment, largely because of the perceived lesser impact this therapy has on patients compared to the surgical alternative. This can mean that patients judged to be medically unfit for surgical clipping are referred for endovascular treatment.

The majority of endovascular procedures for cerebral aneurysms are still undertaken outside the operating theatre. For the anaesthetist this entails all the challenges of safely providing anaesthesia in a remote location and has the additional challenge of having to be prepared to manage intracranial bleeding and/or ischaemia that can occur in up to 4% of cases. Fortunately, intracranial haemorrhage is surprisingly well tolerated by the larger number of patients and the complication is now most likely to be managed by further endovascular interventions. In order to create a suitable anaesthetic plan it is important that anaesthetists involved with these procedures are familiar with the nature of the various endovascular treatment options, including the proceduralist's requirements and the risks specific to each treatment option. There are no good comparative studies looking at different anaesthetic techniques. Sedation is reported to have a fairly high failure rate in some retrospective audits, and general anaesthesia, not unlike that provided in the operating theatre for major intracranial surgery, is strongly advocated by some, but as yet, no differences in outcome have been demonstrated. Reviews of anaesthetic techniques utilized at various institutions highlight that patients undergoing endovascular aneurysm treatment have significantly less monitoring than patients having their aneurysm surgically occluded, despite the potential for significant periprocedural complications.

Knowing the patient, understanding the procedure and being prepared to deal with an acute alteration in the patient's physiological status whilst continued endovascular therapy is undertaken are all part of the art of tailoring anaesthesia for endovascular treatment of cerebral aneurysms.

References

1. Guglielmi G, Vinuela F, Sepetka I. Electrothrombosis of saccular aneurysms via endovascular approach: electrochemical basis, technique and experimental results. J Neurosurg 1991; 75: 1-7
2. Molyneux A, Kerr R, Yu L. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with intracranial aneurysms: a randomised comparison of the effects on survival, dependency, seizures, rebleeding, subgroups and aneurysm occlusion. Lancet 2005; 366: 809-817
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5. Bruder N, Levrier O. Anaesthesia for interventional neuroradiology. European Society of Anaesthesiology - Euroanesthesia 2005.
6. Jones M, Leslie K, Mitchell P. Anaesthesia for endovascular treatment of cerebral aneurysms. J Clin Neurosci 2004; 11(5): 468-470