Trend in Outcome of Cerebral Aneurysmal Rupture Since 1985: A Proposal for Future Treatment
To the Editor:
Since 1985, we have been carrying out a population-based study of cerebral aneurysms in the Yamaguchi prefecture of Japan. The population of the area is approximately 1.5 million and has changed little over the last 15 years. The crude annual incidence rate of aneurysmal rupture has gradually increased from 1985 to 1997, from 12.9/100 000 population in 1985 (95% CI, 11.2 to 14.8) to 15.5/100 000 in 1997 (95% CI, 13.5 to 17.8).1 Any patient with cerebral aneurysmal rupture in Yamaguchi was admitted to one of 28 neurosurgical centers, where surgery was performed by well-trained neurosurgeons certified by the Japanese Neurosurgical Society. Our interest has focused on whether the overall management outcome for cerebral aneurysmal rupture, which is a severe type of intracranial hemorrhage with high mortality, has improved as a result of recent advances in surgical and management techniques.2 The 3119 patients who were admitted with cerebral aneurysmal rupture between 1985 and 1997 were enrolled in the Yamaguchi Data Bank of Cerebral Aneurysm. The outcome was estimated in terms of the Glasgow Outcome Scale3 at 6 months after aneurysmal rupture. The outcome trend is shown in the Figure⇓. The proportion of patients with a favorable outcome (good recovery or moderate disability) relative to that of patients with an unfavourable outcome (severe disability, persistent vegetative state, or death) did not change significantly during these 13 years. Multivariate analysis was applied to these 3119 patients to determine which factors had the greatest influence on outcome. Among 11 possible factors—patient age, sex, neurological grade on admission, thickness of subarachnoid hemorrhage, side of aneurysmal rupture, aneurysmal location and size, number of aneurysms, rebleeding, symptomatic cerebral vasospasm, and hydrocephalus—the most important was the neurological grade on admission, which was assessed in terms of Hunt and Kosnik (H&K) grade.4 The trend for the proportion of patients with severe aneurysmal rupture (H&K grades IV and V) and that for patients with an unfavorable outcome were parallel (Figure⇓). The next most important factor was the occurrence of symptomatic cerebral vasospasm, followed by a high patient age. Among the 3 most important factors, severity of aneurysmal rupture and patient age cannot be modulated by medical intervention. With regard to cerebral vasospasm after aneurysmal rupture, no established treatment for suppression of cerebral vasospasm has yet been developed, although efforts to do so are continuing worldwide. Accordingly, we anticipate that the outcome of cerebral aneurysmal rupture will not improve dramatically in the near future. Recently, a screening system known as “Brain Check-Up,” for detection of unruptured cerebral aneurysms by use of MR angiography, has been developed in Japan.5 Cerebral aneurysms 5 mm or larger can be easily detected by MR angiography. The operative outcome of unruptured cerebral aneurysms is generally excellent1 5 and the cost of performing the treatment is much less than that for treating ruptured cerebral aneurysms. Therefore, we propose that the screening system for detecting unruptured cerebral aneurysms warrants further development and that treatment involving aneurysmal neck clipping or endovascular treatment to prevent rupture should be carried out if the patient is aged <65 years.6 However, the cumulative rate of rupture of cerebral aneurysms is less than that reported previously.7 The issues requiring most urgent evaluation are the size, shape, and location of unruptured cerebral aneurysms that should be treated aggressively.
- Copyright © 1999 by American Heart Association