160 The assessment of coilability itself is difficult because no definite criteria for coilability exist. Although a wide neck of the aneurysm or vessels originating from the aneurysm are generally factors leading to preference for surgical treatment, the choice of treatment remains subjective depending on skills and experiences of the treating neuro-interventionalist or neurosurgeon. In Chapter 3 this is demonstrated by the low interobserver agreement we found in the evaluation of the standard of reference, DSA, by two experienced neuro-interventionalists with respect to coilability (Kappa 0.41). Despite this obvious difficulty in assessing coilability of an aneurysm, the results of the study remain valid as long as no better way of evaluating the performance of imaging modalities with respect to coilability of intracranial aneurysms exists. Since MRA appears to perform equally to CTA at best, the latter must remain the preferred imaging modality for patients with SAH. This is even truer now that CT technique has considerably improved since the inclusion of our study took place, as can be read in Chapter 1, whilst technical developments in MRI during this period are limited and the same MRA at 1.5 Tesla is still widely used. Potential consequences of using different imaging strategies in choice of treatment of SAH can be identified by running a simulation which evaluates the effects of different imaging strategies on both patient treatment and diagnostic costs. Chapter 4 describes our simulation study in which, using the images from the MACCA-study, different combinations of CEMRA and DSA were tried. We found that non-invasive imaging like CEMRA as first line modality is safe and less expensive than performing diagnostic DSA in all patients, reserving additional diagnostic DSA for those patients in whom no aneurysm is found or harboring an aneurysm that is probably not suitable for endovascular treatment. In our study group of 75 patients this imaging strategy would save 46 diagnostic DSA’s translating to a total of approximately 14,500 Euro in diagnostic costs. On the other hand, it would also lead to one patient undergoing surgical clipping of an aneurysm that was coilable based on DSA, and to one patient undergoing an unsuccessful coiling attempt under general anaesthesia. In view of the small difference in outcome after coiling versus clipping, however, and the small additional risk of general anaesthesia during a DSA, this disadvantage is deemed acceptable. For the assessment of coilability one should consider the background of the centres in which the assessment is carried out: it is probable that centres where more than 90% of intracranial aneurysms are treated by endovascular means use different coilability criteria than centres treating the majority of aneurysms by surgical clipping. Chapter 5 gives an overview of our neuro-interventional practice from 2000 to 2008, elucidating the clinical background of the studies in previous chapters. In this overview we evaluated 443 ruptured aneurysms in 403 patients treated in our hospital in that time-period: 173 patients (42.9%) harbouring 199 aneurysms underwent surgical treatment, and 244 (55.1%) aneurysms were coiled in 230 patients. During an average follow-up period of 33.9 months (range 12 – 106), rebleeding occurred in 3.1% of patients after surgical treatment, and in 2.3% after endovascular treatment. Total mortality (related and unrelated to the SAH) in this follow-up period was 11.6% after surgery, and 17.4% after coiling (p=0.104), but pretreatment clinical condition according to Hunt and Hess grading scale (HH) was significantly better in surgically treated patients (p=0.018). These figures are comparable with other publications, taking into account the frequently poor clinical condition of
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