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Comprehensive Endovascular and Open Surgical Management of Cerebral Arteriovenous Malformations
Published on: October 20, 2017
Long-term outcome of unruptured cerebral aneurysms
Eiji Matsumoto1, Toshio Masuzawa, Yosikazu Nakamura
1Department of Surgical Neurology, Jichi Medical School, Tochigi 329-0498, Japan.
Insights
The annual rupture rate of unruptured cerebral aneurysms is higher than previously thought. Understanding the natural history of these aneurysms is crucial for reducing mortality.
Area of Science:
- Neurosurgery
- Neurology
- Epidemiology
Background:
- Increased detection of unruptured cerebral aneurysms due to advanced diagnostics.
- High case-fatality rate of aneurysmal subarachnoid hemorrhage despite treatment improvements.
- Need for better understanding of unruptured cerebral aneurysm natural history.
Purpose of the Study:
- To investigate the natural history of unruptured cerebral aneurysms.
- To determine the incidence and rupture rates of unruptured cerebral aneurysms.
- To compare survival rates between treated and untreated unruptured cerebral aneurysms.
Main Methods:
- Retrospective study of 156 patients with unruptured cerebral aneurysms (1989-1998).
- Classification of patients based on aneurysm detection method.
- Calculation of standardized mortality ratios using age- and sex-specific mortality rates.
Main Results:
- Standardized mortality ratios varied based on aneurysm detection.
- Incidence rate of unruptured cerebral aneurysm rupture was 1.3 per 100 person-years.
- Surgically treated unruptured cerebral aneurysms showed higher survival rates than untreated cases.
Conclusions:
- The annual rupture rate of unruptured cerebral aneurysms may be higher than previously reported.
- Further research into the natural history of unruptured cerebral aneurysms is warranted.
Background:
The frequency at which unruptured cerebral aneurysms are detected has increased due to advances in low- or non-invasive diagnostic techniques. Despite the recent improvements in surgical and medical management of aneurysmal subarachnoid hemorrhages, however, the overall case-fatality rate of this disease is still high. To reduce it, the natural history of unruptured cerebral aneurysms should be better understood.
Methods:
The subjects consisted of 156 patients with unruptured cerebral aneurysms who had been admitted to the Department of Surgical Neurology, Jichi Medical School Hospital or Jichi Medical School Ohmiya Medical Center, Japan, between January 1989 and December 1998. All of the patients were classified according to the process by which aneurysms had been detected. The expected number of deaths was calculated by using age- and sex-specific mortality rates obtained from the vital statistics. A standardized mortality ratio and 95% confidence interval were calculated by using the expected and observed numbers of deaths.
Results:
The standardized mortality ratios differed among the groups according to the process of detecting aneurysms. The incidence rate of rupture of unruptured cerebral aneurysms was 1.3 per 100 person-years. The annual rupture rate of unruptured cerebral aneurysms was higher than previously reported. The survival rate of the group that underwent surgical treatment for unruptured cerebral aneurysms was higher than that of the untreated group.
Conclusions:
The annual rupture rate of unruptured cerebral aneurysms may be higher than previously reported.
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