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Treatment of patients with aneurysmal subarachnoid haemorrhage
Reflection & Reaction Treatment of patients with aneurysmal subarachnoid haemorrhage
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could include any complications from control angiographies, retreatment, and early rebleeding. Most of the ISAT investigators preferred coiling for the treatment of posterior circulation aneurysms but many aneurysms of the middle cerebral artery are not suitable for coiling. Therefore, patients with
Courtesy of Gabriël JE Rinkel
The main aim of treatment for aneurysmal subarachnoid haemorrhage is prevention of rebleeding while preventing secondary ischaemia. This often poses a dilemma for the treatment team: for example, tranexamic acid reduces rebleeding risk but increases ischaemia risk so there is no net improvement of functional outcome. Quantification of the effect of treatment on the risk of rebleeding should therefore be based on functional outcome, not the frequency of rebleeding, as the primary outcome measure. Until recently, the standard method of rebleeding prevention was neurosurgical clipping of the aneurysm. However, in the past decade endovascular occlusion of the aneurysm with a detachable coil has been introduced and has since become widespread. However, the risks of this method include perforation of the aneurysm and thromboembolic complications. In a meta-analysis of 17 retrospective studies, the risk of an intraprocedural perforation of a previously ruptured aneurysm was 4% resulting in poor outcome in one-third of cases.1 In a recent study of patients with good clinical condition before the coiling procedure, stroke occurred in 4% of patients.2 The widespread use of endovascular coiling has necessitated a proper comparison of neurosurgical clipping with endovascular coiling. The investigators of the International Subarachnoid Aneurysm Trial (ISAT) have now done such a comparison and found a clear benefit of coiling.3 Patients were randomly assigned to have either neurosurgical clipping (n=1070) or endovascular treatment with coils (n=1073). The proportion of patients dead or dependent 1 year after the haemorrhage (the primary outcome measure) was 23·7% of patients in the coiling group versus 30·6% of those in the clipping group. The relative risk reduction was 22·6% (95% CI 8·9–34·2) with an absolute risk reduction of 6·9% (95% confidence interval 2·5–11·3). Because the assessment of functional outcome was done after 1 year, the investigators
An aneurysm before coling (left) and after coiling (right)
aneurysms at these sites are underrepresented in the study. Patients with a poor clinical condition are also under-represented, perhaps because informed consent is more difficult to obtain in these patients and representatives are not always at hand. The results of the trial, therefore, mainly apply to patients in a good clinical condition with ruptured aneurysms of the carotid artery and the anterior communicating artery. Fortunately, a considerable proportion of patients with aneurysmal subarachnoid haemorrhage admitted to hospital conform to these criteria. How should we treat patients with aneurysms of the middle cerebral artery, patients with posterior circulation aneurysm, and patients in a poor clinical condition? Since most aneurysms of the middle cerebral artery are not suitable for coiling, there is a case for clipping in these patients, as there is for coiling in aneurysms at other sites. Many aneurysms of the posterior circulation are suitable for both clipping and for coiling, but it is unlikely that we will have evidence from a randomised trial on this subset of patients in the foreseeable future. For the time being, decisions have to be based on less than optimal evidence. A recent retrospective study on ruptured basilar-artery aneurysms
compared 44 patients treated with coiling with 44 patients treated with clipping.4 After adjustment for age, clinical condition, and aneurysm size, the odds ratio for poor outcome after coiling was 0·28 (95% CI 0·08–0·99), which suggests that coiling is the preferred treatment for these patients. We do not have good evidence for patients in a poor clinical condition; because poor condition on admission is an important prognostic factor for outcome, the results of the ISAT study cannot be extrapolated directly to this group of patients. Given the absence of good evidence on the effectiveness of the standard treatment (clipping), there is also no convincing reason to support clipping in patients with a poor clinical condition. However, keeping all these uncertainties in mind, most treatment teams will prefer coiling in patients with a poor clinical condition. The ISAT trial has provided sound evidence supporting coiling in patients with ruptured intracranial aneurysms. However, clipping will still be used for aneurysms that are not suitable for coiling and neurosurgeons will still be involved if a bypass is needed or if an intraparenchymal haematoma needs to be drained. Thus, radiologists and neurosurgeons must continue to cooperate in the treatment of patients with aneurysmal subarachnoid haemorrhage for the benefit of the patient. Gabriël JE Rinkel Rudolf Magnus Institute of Neuroscience, Department of Neurology, Universtity Medical Centre Utrecht, PO Box 85500, 3508 GA Utrecht, Netherlands. Email [email protected] Conflict of interest GJER receives a clinical established investigator grant of the Netherlands Heartfoundation (grant D98.014) and was a coauthor on the study by Lusseveld.4
References 1
2
3
4
Cloft HJ, Kallmes DF. Cerebral aneurysm perforations complicating therapy with guglielmi detachable coils: a meta-analysis. AJNR Am J Neuroradiol 2002; 23: 1706–09. Derdeyn CP, Cross DT, Moran CJ, et al. Postprocedure ischemic events after treatment of intracranial aneurysms with Guglielmi detachable coils. J Neurosurg 2002; 96: 837–43. Molyneux A. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 2002; 360: 1267–74. Lusseveld E, Brilstra EH, Nijssen PC, et al. Endovascular coiling versus neurosurgical clipping in patients with a ruptured basilar tip aneurysm. J Neurol Neurosurg Psychiatry 2002; 73: 591–93.
THE LANCET Neurology Vol 2 January 2003
http://neurology.thelancet.com
For personal use. Only reproduce with permission from The Lancet Publishing Group.
12
could include any complications from control angiographies, retreatment, and early rebleeding. Most of the ISAT investigators preferred coiling for the treatment of posterior circulation aneurysms but many aneurysms of the middle cerebral artery are not suitable for coiling. Therefore, patients with
Courtesy of Gabriël JE Rinkel
The main aim of treatment for aneurysmal subarachnoid haemorrhage is prevention of rebleeding while preventing secondary ischaemia. This often poses a dilemma for the treatment team: for example, tranexamic acid reduces rebleeding risk but increases ischaemia risk so there is no net improvement of functional outcome. Quantification of the effect of treatment on the risk of rebleeding should therefore be based on functional outcome, not the frequency of rebleeding, as the primary outcome measure. Until recently, the standard method of rebleeding prevention was neurosurgical clipping of the aneurysm. However, in the past decade endovascular occlusion of the aneurysm with a detachable coil has been introduced and has since become widespread. However, the risks of this method include perforation of the aneurysm and thromboembolic complications. In a meta-analysis of 17 retrospective studies, the risk of an intraprocedural perforation of a previously ruptured aneurysm was 4% resulting in poor outcome in one-third of cases.1 In a recent study of patients with good clinical condition before the coiling procedure, stroke occurred in 4% of patients.2 The widespread use of endovascular coiling has necessitated a proper comparison of neurosurgical clipping with endovascular coiling. The investigators of the International Subarachnoid Aneurysm Trial (ISAT) have now done such a comparison and found a clear benefit of coiling.3 Patients were randomly assigned to have either neurosurgical clipping (n=1070) or endovascular treatment with coils (n=1073). The proportion of patients dead or dependent 1 year after the haemorrhage (the primary outcome measure) was 23·7% of patients in the coiling group versus 30·6% of those in the clipping group. The relative risk reduction was 22·6% (95% CI 8·9–34·2) with an absolute risk reduction of 6·9% (95% confidence interval 2·5–11·3). Because the assessment of functional outcome was done after 1 year, the investigators
An aneurysm before coling (left) and after coiling (right)
aneurysms at these sites are underrepresented in the study. Patients with a poor clinical condition are also under-represented, perhaps because informed consent is more difficult to obtain in these patients and representatives are not always at hand. The results of the trial, therefore, mainly apply to patients in a good clinical condition with ruptured aneurysms of the carotid artery and the anterior communicating artery. Fortunately, a considerable proportion of patients with aneurysmal subarachnoid haemorrhage admitted to hospital conform to these criteria. How should we treat patients with aneurysms of the middle cerebral artery, patients with posterior circulation aneurysm, and patients in a poor clinical condition? Since most aneurysms of the middle cerebral artery are not suitable for coiling, there is a case for clipping in these patients, as there is for coiling in aneurysms at other sites. Many aneurysms of the posterior circulation are suitable for both clipping and for coiling, but it is unlikely that we will have evidence from a randomised trial on this subset of patients in the foreseeable future. For the time being, decisions have to be based on less than optimal evidence. A recent retrospective study on ruptured basilar-artery aneurysms
compared 44 patients treated with coiling with 44 patients treated with clipping.4 After adjustment for age, clinical condition, and aneurysm size, the odds ratio for poor outcome after coiling was 0·28 (95% CI 0·08–0·99), which suggests that coiling is the preferred treatment for these patients. We do not have good evidence for patients in a poor clinical condition; because poor condition on admission is an important prognostic factor for outcome, the results of the ISAT study cannot be extrapolated directly to this group of patients. Given the absence of good evidence on the effectiveness of the standard treatment (clipping), there is also no convincing reason to support clipping in patients with a poor clinical condition. However, keeping all these uncertainties in mind, most treatment teams will prefer coiling in patients with a poor clinical condition. The ISAT trial has provided sound evidence supporting coiling in patients with ruptured intracranial aneurysms. However, clipping will still be used for aneurysms that are not suitable for coiling and neurosurgeons will still be involved if a bypass is needed or if an intraparenchymal haematoma needs to be drained. Thus, radiologists and neurosurgeons must continue to cooperate in the treatment of patients with aneurysmal subarachnoid haemorrhage for the benefit of the patient. Gabriël JE Rinkel Rudolf Magnus Institute of Neuroscience, Department of Neurology, Universtity Medical Centre Utrecht, PO Box 85500, 3508 GA Utrecht, Netherlands. Email [email protected] Conflict of interest GJER receives a clinical established investigator grant of the Netherlands Heartfoundation (grant D98.014) and was a coauthor on the study by Lusseveld.4
References 1
2
3
4
Cloft HJ, Kallmes DF. Cerebral aneurysm perforations complicating therapy with guglielmi detachable coils: a meta-analysis. AJNR Am J Neuroradiol 2002; 23: 1706–09. Derdeyn CP, Cross DT, Moran CJ, et al. Postprocedure ischemic events after treatment of intracranial aneurysms with Guglielmi detachable coils. J Neurosurg 2002; 96: 837–43. Molyneux A. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 2002; 360: 1267–74. Lusseveld E, Brilstra EH, Nijssen PC, et al. Endovascular coiling versus neurosurgical clipping in patients with a ruptured basilar tip aneurysm. J Neurol Neurosurg Psychiatry 2002; 73: 591–93.
THE LANCET Neurology Vol 2 January 2003
http://neurology.thelancet.com
For personal use. Only reproduce with permission from The Lancet Publishing Group.