(Stroke. 1997;28:1926-1931.)
© 1997 American Heart Association, Inc.
Articles |
Cerebral Aneurysms in the Elderly in Yamaguchi, Japan
Analysis of the Yamaguchi Data Bank of Cerebral Aneurysm From 1985 to 1995
From the Department of Neurosurgery, Yamaguchi University School of Medicine (Japan).
Correspondence to Katsuhiro Yamashita, Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Yamaguchi, 755 Japan. E-mail yamasita-ygc{at}umin.u-tokyo.ac.jp
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Abstract |
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Background and Purpose The number of elderly people is markedly increasing in Japan. We have investigated the epidemiology and management outcome of cerebral aneurysms in elderly patients aged
70 years.
Methods A total of 3100 patients were enrolled in the
Yamaguchi Data Bank of Cerebral Aneurysm between 1985 and 1995.
Of these, 598 with ruptured cerebral aneurysms and 120 with
unruptured cerebral aneurysms were elderly (ie, aged 70
years).
Results The number of elderly patients with cerebral aneurysms has markedly increased since 1991, and in 1995 approximately 30% of all patients with cerebral aneurysms were elderly. In cases of ruptured cerebral aneurysms, the proportion of patients with severe neurological grade did not change and that with an unfavorable outcome did not decrease throughout the 11 years. The proportion of patients with severe neurological grade in the elderly group was higher than in the younger group (<70 years), and the management outcome of elderly patients for each neurological grade on admission was worse than that of younger patients (P<.01). However, the incidence rate of symptomatic cerebral vasospasm and rebleeding was the same for the two age groups. Eventually, 60.4% of all elderly patients with ruptured cerebral aneurysms had an unfavorable outcome. In cases of unruptured cerebral aneurysms, 63.3% of the selected elderly patients were surgically treated, and the surgical morbidity and mortality rates were 26.3% and 4.0%, respectively. These rates were nonsignificantly higher than those for younger patients.
Conclusions The number of elderly patients with cerebral aneurysms has markedly increased in Yamaguchi. Because of the unsatisfactory management outcome of ruptured cerebral aneurysms and surgical outcome of unruptured cerebral aneurysms in elderly patients during the 11-year period, we propose the treatment of unruptured cerebral aneurysms at a younger age and the use of a screening system to detect these subjects.
Key Words: cerebral aneurysm • elderly • incidence • Japan • stroke outcome
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Introduction |
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In Japan the number of elderly people is markedly increasing, and the average life spans of 76.36 years for men and 82.84 year for women are the longest in the world. According to the census of Japan, the elderly ratio, which is the ratio of people aged
65 years to all people, has
increased since 1991 (12.0% in 1990 and 14.5% in 1995). Yamaguchi
prefecture is located in the western part of Japan. With an area of
6100 km2, it has a population of approximately 1.5 million,
which has changed little during the past 11 years. This aging trend is
also seen in Yamaguchi prefecture, where the elderly ratio was 15.9%
in 1990 and 19.3% in 1995 and is expected to increase further. A
comprehensive investigation into the
epidemiology of both ruptured and unruptured
cerebral aneurysms in elderly people has not been reported thus
far, although numerous studies of cerebral aneurysms have been
published.1 2 3 4 5 In addition, it is not evident whether the
overall management outcome for ruptured cerebral aneurysms has
improved as a result of recent advances in surgical and management
techniques.4 5 6 7 It is therefore of interest to investigate
changes in overall management outcome for ruptured cerebral
aneurysms in elderly patients over a long observation
period.
The study of cerebral aneurysms in Yamaguchi has been performed
by members of the Yamaguchi Danwa-kai for Neurosurgeons society since
1985, and the data for each patient have been saved in the Yamaguchi
Data Bank of Cerebral Aneurysm. Here we report the annual
incidence and the management outcome for ruptured and unruptured
cerebral aneurysms in patients aged 70 years in Yamaguchi and
consider how we should treat cerebral aneurysms in the elderly
in the future.
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Subjects and Methods |
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Patient Selection
The 3100 patients with a mean age of 59.9 years enrolled in the Yamaguchi Data Bank of Cerebral Aneurysm between 1985 and 1995 were recruited from all patients with cerebral aneurysms admitted to 26 neurosurgical centers in Yamaguchi prefecture, Japan. Any patient with cerebral aneurysms in Yamaguchi was admitted to one of these 26 centers, and well-trained neurosurgeons certified by the Japanese Neurosurgical Society operated on cerebral aneurysms at each center. SAH was confirmed by CT scan or lumbar puncture, and the presence of a saccular cerebral aneurysm was confirmed by cerebral angiography. In some cases unruptured cerebral aneurysms were confirmed by MR angiography. Patients were excluded if they had traumatic or mycotic aneurysms and if cerebral aneurysms were not verified by cerebral angiography. H&K grade was used to represent neurological grade on admission.8 According to this scale, neurological grade of patients with aneurysmal rupture is divided into six categories from I to V (plus grade Ia) based on the level of consciousness and neurological symptoms. Decisions on the aneurysm surgery and adjunctive therapies for ruptured aneurysms and cerebral vasospasm were determined by the neurosurgeons at each center. In principle, patients with SAH whose H&K grade was categorized as I to III were surgically treated early by aneurysmal neck clipping within 3 days after SAH. The same strategy was used for elderly patients, as supported by a previous study.9 The patients treated with early surgery were kept hypervolemic to prevent a reduction in cerebral blood flow due to cerebral vasospasm between 3 and 14 days after SAH.
Trained investigators at the 26 neurosurgical centers collected the following information of the individual patient in the May after the year of admission: age, sex, neurological grade, distribution of SAH, size and location of cerebral aneurysms, surgery, rebleeding, symptomatic cerebral vasospasm, adjunctive treatments, major medical and surgical complications, and outcome. Neurological outcome was assessed 6 months after the SAH with the use of the GOS.10 According to this scale, outcome is divided into five categories: good recovery (GR), moderate disability (MD), severe disability (SD), persistent vegetative state (VS), and death (D).
The patients were divided into two age groups—<70 and 70
years—according to the criteria of the Japan Geriatric Neurosurgery
Society. In the younger and elderly groups the number of patients with
ruptured cerebral aneurysms was 1995 and 598, respectively
(Tables 3
and 4), and with unruptured cerebral aneurysms, 387
and 120, respectively (Table 5). The mean ages of these four groups of
patients were 54.3, 75.3, 57.4, and 73.3 years, respectively. We
referred to the national census of Japan to determine the population of
Yamaguchi in each year and the age distribution every 5 years. The
age-adjusted annual incidence rates of aneurysmal rupture in
1990 and 1995 were calculated by adjustment to 1985 Yamaguchi census
population. The data analysis was performed by five
neurosurgeons in Yamaguchi University School of Medicine.
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Statistical Analysis
The CIs of the incidence rate were calculated according to the
method of Schoenberg.11 The 
2 test
was used to compare the neurological grade on admission after SAH and
the outcome between two age groups. The change of the severity of SAH
and outcome during the 11 years in each age group was investigated by
the 2 test following the method of moving average
and factor analysis. The relationship of H&K grade to the GOS
in each age group was also investigated by the 2
test. A value of P<.05 was considered to indicate
statistical significance.
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Results |
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Ruptured Cerebral Aneurysms
The crude annual incidence rate of aneurysmal rupture gradually increased from 1985 to 1995, being 12.9/100 000 population in 1985 (95% CI, 11.2 to 14.8) and 16.8/100 000 in 1995 (95% CI, 14.8 to 19.1) (Fig 1
). The age-adjusted
annual incidence rates of aneurysmal rupture were 13.8/100 000
in 1990 (95% CI, 12.0 to 15.9) and 13.9/100 000 in 1995 (95% CI,
12.3 to 15.8). The absolute number of elderly patients aged 70 years
with aneurysmal rupture also increased from 1985 onward. The
number of such elderly patients in 1995 was 77, which was approximately
three times higher than in 1985. In line with this increase in absolute
number, the ratio of elderly patients relative to all patients with
aneurysmal rupture increased. The elderly patients accounted
for 13.2% of all patients in 1985 and for 29.6% in 1995 (Fig 2). The annual incidence rates of
aneurysmal rupture in the elderly aged 70 years were 22.4,
31.7, and 38.9/100 000 in 1985, 1990, and 1995, respectively (Table 1).
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The proportion of severe SAH (H&K grades IV and V) in the elderly group
did not change throughout the 11 years from 1985 to 1995, as was the
case in the younger group (Table 2), but
was significantly higher in the elderly group (ie, 31.4% versus
22.3%; 2=30.59, P<.01; Tables 3
and 4).
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In patients with ruptured cerebral aneurysms, 93.8% and 87.6% of the patients in the younger and elderly groups, respectively, were surgically treated during the 11-year period. The proportion of patients with a favorable outcome (GR and MD) in the elderly group significantly decreased between 1989 and 1995 (P<.05), whereas that in the younger group did not change throughout the 11 years.
The management outcome significantly correlated to the neurological
grade on admission in both the younger and elderly groups
(2=556.7 and 2=133.4,
respectively; P<.01; Tables 3 and 4). The proportion of
patients with a favorable outcome (GR and MD) in the elderly group was
39.6%, which was significantly lower than the 65.5% in the younger
group (2=172.1, P<.01). Eventually,
60.4% of all elderly patients with ruptured cerebral aneurysms
had an unfavorable outcome (SD, VS, and D). The management outcome for
each neurological grade on admission was then compared between the two
age groups. (H&K grade Ia was included in grade I in this statistical
analysis.) For all neurological grades except H&K grade V, the
proportion of patients with a favorable outcome in the elderly group
was significantly lower than in the younger group (P<.01;
Tables 3 and 4). There was no significant difference in the incidence
of symptomatic cerebral vasospasm (37.7% in the younger
group and 41.0% in the elderly group) and rebleeding (14.6% in the
younger group and 16.3% in the elderly group) between the two
groups.
Unruptured Cerebral Aneurysms
Since 1991 the crude annual incidence rate of patients with
unruptured cerebral aneurysms has steadily increased, being
1.89/100 000 population in 1985 (95% CI, 1.28 to 2.70), 2.96/100 000
in 1991 (95% CI, 2.17 to 3.94), and 6.70/100 000 in 1995 (95% CI,
5.49 to 8.16) (Fig 3). The annual number
of elderly patients aged 70 years with unruptured cerebral
aneurysms has also increased markedly during the 11 years
studied. It was 5 in 1985 and 34, accounting for 33% of all patients,
in 1995. Most of the unruptured cerebral aneurysms were found
incidentally by MR angiography or conventional cerebral angiography in
patients with other cerebral diseases such as cerebral infarction. In
the younger group, 70.5% of all patients were treated aggressively
with surgery, which was associated with a 20.2% surgical morbidity
rate and a 1.8% mortality rate. In the elderly group, 63.3% of all
patients were treated surgically, and cerebral aneurysms of the
internal carotid or middle cerebral artery accounted for 79% of these
cases. Cerebral aneurysms in the posterior circulation were not
surgically treated in the elderly group. The surgical morbidity rate
was 26.3% and the mortality rate was 4.0%, which were
nonsignificantly higher than those in the younger group (Table 5). The major causes of unfavorable
outcome (MD, SD, VS, and D) in the surgically treated elderly patients
were cerebral infarction due to application of a temporary clip to the
parent arteries and venous infarction.
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Discussion |
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TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
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Recently, the number and the proportion of elderly people in Japan have markedly increased and will continue to increase. The prominent aging of the population is evident in Yamaguchi as well as other rural regions of Japan, except in large cities. This increase in the elderly population is undoubtedly due to good medical care. In fact, according to an investigation of public health and welfare in Japan, the number of elderly outpatients is increasing, and the life expectancy of the elderly has increased. Reflecting this age change in the population, the number of elderly patients with ruptured and unruptured cerebral aneurysms in Yamaguchi has markedly increased, and approximately 30% of all such patients in 1995 were aged
70 years.
The increase in the crude annual incidence rate of aneurysmal
rupture since 1990 may be explained by the increase in the number of
elderly patients, because there has been little increase in the
age-adjusted annual incidence rates of aneurysmal rupture in
1990 and 1995 compared with the incidence rate in 1985. Another reason
for the increase in the number of elderly patients with
aneurysmal rupture is the increase in the incidence rate of
aneurysmal rupture, as shown in Table 1. This increase in the
incidence rate may be due to a change in the frequency of detection in
elderly patients in remote places through improvements in the emergency
medical service and an increase in the number of doctors, including
physicians. The management of cerebral aneurysms in elderly
patients is thus becoming an increasingly important issue. Between 1985 and 1995 the overall management outcome for ruptured cerebral aneurysms did not improve for either elderly or younger patients, and 60.4% of all elderly patients had an unfavorable outcome, although the surgical and management techniques for ruptured cerebral aneurysms have improved.12 13 14 15 16 17 18 19 Thus, an increase in the number of elderly patients with ruptured cerebral aneurysms and unsatisfactory management outcome will result in an increase in the absolute number of elderly patients with an unfavorable outcome.
Certain clinical factors that contribute to an unfavorable outcome after aneurysmal rupture in elderly patients have been proposed20 21 22 and include poor neurological grade on admission, symptomatic cerebral vasospasm, rebleeding, and preexisting medical conditions such as diabetes mellitus, hypertension, cardiopulmonary disease, and cerebrovascular disease.
Among these factors, poor neurological grade on admission, cerebral vasospasm, and rebleeding have been proposed to critically influence the outcome of elderly patients with aneurysmal rupture.21 23 24 25 26 In the present study the proportion of patients with severe SAH in the elderly group was actually higher than in the younger group. However, the proportion of patients with an unfavorable outcome in the elderly group was significantly higher than in the younger group for each neurological grade on admission except H&K grade V. In addition, the incidence of symptomatic cerebral vasospasm and rebleeding in the elderly group did not differ significantly from that in the younger group. Therefore, factors other than poor neurological grade on admission, cerebral vasospasm, and rebleeding should be considered to account for why elderly patients fare worse after aneurysmal rupture. The preexisting medical conditions and compromised cerebral circulation and neural plasticity with advancing age may contribute more to an unfavorable outcome of elderly patients after aneurysmal rupture.27 28 29 30 31 32
The annual number of elderly patients with unruptured cerebral aneurysms markedly increased since 1991. This increase may be explained by an increase in the number of elderly people and improved methods to detect unruptured cerebral aneurysms, such as MR angiography. Details of the management or surgical outcome of unruptured cerebral aneurysms in elderly patients thus far have not been reported. However, in view of the actual increase in the number of elderly patients with unruptured cerebral aneurysms, neurosurgeons must decide how to manage these patients. The surgical outcome of elderly patients with unruptured cerebral aneurysms for whom surgery was chosen as the treatment method after careful consideration did not differ significantly from that of younger patients in the present study. However, we should take into account the unfavorable outcome of 30.3% after surgical treatment of elderly patients with unruptured cerebral aneurysms and the annual rate of bleeding of unruptured cerebral aneurysms, which is generally estimated at 1% to 2% per year.33 34 35 Although we should also know the annual rate of bleeding of unruptured cerebral aneurysms in the elderly and investigate the surgically treated elderly cases with an unfavorable outcome, the unfavorable outcome of 30.3% in the present study would not justify aggressive surgical treatment of unruptured cerebral aneurysms in elderly patients other than for those few patients who need aneurysmal obliteration to resolve undesirable neurological symptoms.36 37
In conclusion, the number of elderly patients with cerebral aneurysms is increasing and will increase further in Yamaguchi as well as in other regions in Japan. In conservatively managed elderly patients with ruptured cerebral aneurysms, the mortality and morbidity rates are very high,38 and surgical treatment of ruptured cerebral aneurysms should not be refused to an elderly patient solely on the basis of advanced age. However, the proportion of unfavorable outcomes for elderly patients was very high and did not improve over the 11-year study period, although the surgical and management techniques for ruptured cerebral aneurysms had improved. On the other hand, surgery for unruptured cerebral aneurysms in elderly patients results in a morbidity and mortality rate >30%, which does not justify aggressive surgical treatment for such patients. The data in the present study suggest that we should treat unruptured cerebral aneurysms at a younger age and that the newly developed screening system for early detection of unruptured cerebral aneurysms in Japan would be useful,39 40 since the surgical outcome of unruptured cerebral aneurysms detected by such a screening system is good.39 41
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Selected Abbreviations and Acronyms |
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Acknowledgments |
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We thank members of the Yamaguchi Danwa-kai for Neurosurgeons society for providing data on each patient and Dr Okuda in the Department of Public Health, Yamaguchi University School of Medicine, for helpful discussions on epidemiology.
Received March 31, 1997; revision received July 11, 1997; accepted July 11, 1997.
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