Comparison Of Endovascular Coiling With Neurosurgical Clipping

Endovascular aneurysm treatment strategies are now challenging neurosur-gical clipping as the standard approach to treatment of cerebral aneurysms. In some institutions, GDC coiling is even considered the first-line treatment in

From: Minimally Invasive Neurosurgery, edited by: M.R. Proctor and P.M. Black © Humana Press Inc., Totowa, NJ

these patients (5-7). It was estimated that in August 2002, 100,000 patients with intracranial aneurysms had been treated with GDCs worldwide (8). Considering these large and increasing numbers, a comparison of the efficacy and risk of morbidity and mortality of the two treatment strategies must be made. Comparisons between surgical and endovascular series should be made with caution because of the heterogeneity in study design, patients, and aneurysms (9).

A small randomized single-institution trial compared the outcomes of surgical clipping and endovascular treatment in 109 patients with ruptured intracra-nial aneurysms. The basic characteristics of the patients in both treatment groups were similar in terms of aneurysm location and size, severity of sub-arachnoid bleeding, and clinical grade. Surgery- and coiling procedure-related mortality was similar in both groups, and there was no difference in the short-term clinical outcome. One-year clinical and neuropsychological outcomes were comparable (10,11).

The International Subarachnoid Aneurysm Trial (ISAT) is a multicenter, randomized clinical trial comparing a policy of neurosurgical clipping with a policy of endovascular treatment with detachable platinum coils in patients with ruptured intracranial aneurysms considered suitable for either treatment (12). In all, 9278 patients were evaluated for eligibility, and finally clinical equipoise was observed in 2143 patients who were enrolled in the study and randomly assigned to endovascular treatment (n = 1073) or neurosurgical clipping (n = 1070). Almost all (97.3%) lesions were located in the anterior circulation, 50.5% in the anterior cerebral artery (ACA), 32.5% in the internal cerebral artery (ICA), and 14.1% in the middle cerebral artery (MCA), with only 2.7% of lesions in the posterior circulation. The great majority of the aneurysms were 10 mm or smaller in size. At 1 yr, 23.7% of patients allocated to endovascular treatment were dead or dependent compared with 30.6% in the surgical group. The relative risk of dependence or death was reduced by 22.6% in patients treated with endovascular coiling, with an absolute risk reduction of 6.9%. Trial recruitment was stopped by the steering committee after a planned interim analysis, but follow-up will continue.

In a retrospective observational study, Johnston et al. (13) compared the risks of endovascular and surgical treatment in 130 patients with unruptured cerebral aneurysms, who were considered candidates for either procedure on blinded review, and overall anticipated procedure risk was rated as identical. Surgery was found to be associated with greater rates of early and persistent disability, more procedure-related major complications, and longer delays in return of function. Length of stay was longer, and hospital charges were greater for the surgical group.

A permanent complication rate of 7% was shown on metaanalysis of 1383 patients with intracranial aneurysms, treated with endovascular GDC emboli-zation (9).

In a recent review on surgery of unruptured aneurysms in 2460 patients, the morbidity was 11% and mortality 3% (14). The International Study of Unruptured Intracranial Aneurysms (ISUIA) showed an unexpectedly high rate of neurological deficits, cognitive impairement, and mortality after surgical clip ping of unruptured intracranial aneurysms (15). At 30 d after surgery, cognitive impairements were evident in 5.5% of patients, neurologic disabilities in 3.6%, and both in 6.1% in the subgroup of patients without previous surgery or sub-arachnoid hemorrhage (SAH). Furthermore, the cognitive deficits failed to improve during the next year.

The available studies indicate that the complications in the endovascular series are lower than in the surgical series. This difference is accentuated by the fact that aneurysm treatment by endovascular methods is usually reserved for sicker patients with more difficult aneurysms (16). The lower procedural mortality and morbidity rates of endovascular aneurysm treatment, compared with those of surgical clipping, have to be weighed against a higher rate of incomplete aneurysm obliteration and aneurysm recurrence following aneurysm coiling. Several studies attest to the protective effect of coiling in the acute phase of SAH . On metaanalysis, a rerupture rate of 0.9% per yr is estimated after coil embolization of ruptured aneurysms in various locations in an average follow-up of up to 1.8 yr (17). Vinuela et al. (18) reported a 6-mo rebleeding rate of 2.2% in 403 patients with acute SAH treated with GDCs. Rerupture after surgical clipping does also occur (11,12,19,20).

In the ISAT study, the long-term risks of further bleeding from the treated aneurysm were low with either therapy, although somewhat more frequent with endovascular coiling. Within 1 yr, 2.4% of endovascular cases (26/1048) and 1% (10/994) of surgical cases rebled (12). It is hoped that the ongoing follow-up of these patients will shed some light on the long-term efficacy of endovascular therapy.

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