Tohoku
J. exp.
Med.,
Distribution
1978, 126,
of
125-132
Intracranial
Aneurysm
TAKASHI YOSHIMOTO, TAKAMASA KAYAMA, NAMIO KODAMA and
JIRO
SUZUKI
Division of Neurosurgery, Institute of Brain Diseases, Tohoku University School of Medicine, Sendai 982
YOSHIMOTO,T., KAYAMMA, T., KODAMA, N. and SUZUKI, J. Distribution of Intracranial Aneurysm. Tohoku J. exp. Med., 1978, 126 (2), 125-132 The 1,080 cases of intracranial saccular aneurysms, which were seen at our clinic during the period from June 1961 to September 1975, were subjected to the analysis on the location of the aneurysms, age distribution and sex incidence. intracranial aneurysm; distribution
We reported the statistical studies on the 3548 cases of intracranial aneurysms in the neurosurgical clinics in Japan (Suzuki et al. 1971). Recently we noted that more than one thousand cases of intracranial aneurysm were seen and examined at our clinic alone. In the present study, the distribution of intracranial aneurysms, based on our 1080 saccular aneurysm cases, is investigated. MATERIALS 1,116 cases of various kinds of intracranial aneurysms were seen in our clinic during the period from June 1961 to September 1975. The 1,116 cases included 1080 saccular aneurysm
cases,
11 sclerotic,
3 traumatic,
1 mycotic,
TABLE 1.
Various types of intracranial 1961-Sept. 1975)
CVD, cerebro-vascular disease; HICH, hypertensive intracerebral Received
for publication,
January
2 anomalous,
cell
aneurysms (Tohoku Univ. June
AVM, arterio-venous hematoma.
7, 1978. 125
1 giant
malformation;
arteritis
126
T. Yoshimoto
et al.
and 18 aneurysm cases accompanied with other cerebrovascular diseases (Table 1). For the object of this study only cases of saccular aneurysms were subjected to the analysis. RESULTS
The 1,080 cases of intracranial saccular aneurysms were analyzed for the frequency of aneurysm sites. There were 366 cases of the anterior communicating artery, 286 cases of the internal carotid artery, 182 cases of the middle cerebral artery, 50 cases of the anterior cerebral artery, 30 cases of the vertebro-basilar arteries and 166 cases of multiple aneurysms (Table 2). TABLE 2.
Fig. 1.
Location
Site
distribution
of 1,307 saccular
aneurysms
in 1,080
cases.
In cases of multiple aneurysms there were 127 cases of two aneurysms, 25 cases of three, 9 of four, 4 of five and 1 case of eight. The total cases including 914 cases of a single aneurysm and 166 cases of multiple aneurysms had 1,307 aneurysms. There were 462 aneurysms (35.3%) on the anterior communicating artery, 422 aneurysms (32.2%) on the internal carotid artery , 298 aneurysms
Distribution
of Intracranial
Aneurysm
127
(22,8%) on the middle cerebral artery, 80 aneurysms (6.1%) on the anterior cerebral artery and 45 aneurysms (3.4%) on the vertebro-basilar artery (Fig. 1). The age ranged from 16-year-old male to 86-year-old female. The peak incidence occurred in the sixth decade with 32.2 percent followed by the fifth decade with 31.0 percent (Table 3). Our series revealed distinct difference of site distribution between age groups younger than 30 years and all other decennial age groups. Of the 44 cases younger than 30 years, only 1 case had an aneurysm of the middle cerebral artery. On the other hand, 17 of 44 cases showed aneurysms of the internal carotid artery. No significant differences could be seen between the group older than 60 years and the overall age group (Table 4). TABLE 3.
TABLE 4.
Site
distributions
TABLE 5.
Age distribution
in younger
Age distribution
and
older age groups
and sex incidence
128
T. Yoshimoto
et al.
TABLE 6.
Distiribution of aneurysm cases according to number of aneurysms, sex and age
The sex incidence in our series was male-predominant. There were 578 male with 54 percent and 502 female with 46 percent. Male predominance exhibited a maximum ratio of 2.5 to 1 for the ages below 20 years, but the gap diminished gradually until the fifth decade. And, female became predominant after 50 years (Table 5). No significant differences were seen between the age distribution in cases of single and multiple anerusysm. However, about a quarter of the female cases over the sixth decade were the cases of multiple aneurysms (Table 6). DISCUSSION
Ramamurthi (1969) reported that the incidence of intracranial aneurysm in South-East Asian countries including Japan is considerably lesser than that in European countries and the United States. However, we reported that 3,548 cases with 3,898 aneurysms in total had been seen in 111 Japanese neurosurgical clinics for a period of about 10 years (Suzuki et al. 1971). The number of aneurysms in our clinic had increased progressively year by year and the 1000th case was operated on intracranially in September 1975 (Fig. 2).
Fig. 2.
Saccular
aneurysm
seen each
year
in Tohoku
University.
Distribution
One
of
increased advance
the
reasons
progressively and
why from
development
of the
present, the incidence per lesser, but probably higher incidence
has remained
the
of Intracranial
aneurysm 1960's cerebral
Aneurysm
cases, in
especially
Japan
had
angiography
population of intracranial than Western countries.
low in many
South-East
129
surgical
been
for the
cerebral
aneurysms It is rather
Asian
ones,
attributed
have
to
the
stroke.
At
in Japan is not curious that the
countries.
The Japanese National Health Statistics on the cases of death reported cerebral stroke as the most popular, cancer as the second, heart attack as the third (Fig. 3). The order of these causes is different from those in the United States and European countries. Moreover, according to the statistics of mortality rate of cerebrovascular disease by World Health Statistics Annual in 1970, the
Fig. 3.
Fig. 4.
Causes of death in Japan.
Mortality rate of cerebrovascular
Japan National Health Statistics
(1972).
disease. World Health Statistics Annual (1970).
130
T. Yoshimoto
et al. TABLE 7.
* Only
single
aneurysm
cases including
56 cases with
both
aneurysm
Site
and
and side
arteriovenous
incidence of cerebral stroke in Japan was the highest among the reported countries (Fig. 4). Our statistical study covering the north-eastern districts (Tohoku) in Japan has been compared with studies of distribution of intracranial aneurysm of the United States Cooperative Study in 1966 (USA Coop) (Sahs et al. 1969), and of the Japanese neurosurgical clinics in 1969 (JNC) (Suzuki et al. 1971). The total numbers of aneurysm cases in these statistics were 2,672 cases in the USA Coop, 3,548 cases in the JNC and 1,080 cases in the Tohoku. In the USA Coop and the JNC, the internal carotid artery was most frequently involved, followed by the anterior communicating artery. In the Tohoku the anterior communicating artery was the highest and the internal carotid artery the lowest among the three investigations (Table 7). However, all studies were in agreement in that the most frequent sites were the internal carotid artery, anterior communicating
Fig.
5.
Age
of
cases; •ü-•ü, U.S.A.
aneurysm Tohoku
(1966)
2,627
cases (1970-1975) cases.
in
U.S.A. 772
and cases;•£-•£
Japan. •œ-•œ,
Tohoku Japan
(1969)
(1961-1969) 3,430
cases; •¢-•¢,
308
Distribution
distribution
of Intracranial
Aneurysm
131
of aneurysms
malformation.
Fig. 6.
Fig.
7.
Sex
ratio
(F/M)
Sex incidence
of
the
of aneurysm
incidence •œ-•œ
-,
Tohoku USA
(1975), Coop
(1966),
1,080
cases •ü-•ü 2,627
of aneurysms (1961-1969) (1970-1975)
cases.
by 308
decennial cases
772
cases
age.
cases
artery and middle cerebral artery. These three arteries altogether account for 89.1% of the total cases in the USA Coop, 87% in the JNC and 90.3% in the Tohoku.
132
T. Yoshimoto
et al.
In age distribution, more than 90 percent of the saccular aneurysms were found in the age range between 30 and 69 years with a peak at the fifth decade in the JNC and our 1960's series (Tohoku), while peaks were in the sixth decade in the USA Coop and our 1970's series (Tohoku). The cases of aneurysm were few in the first, second and eighth decades in every series (Fig. 5). The sex incidence in Japan with male predominance was contrary to that of the USA Coop. However, female cases in our clinic have increased according to our recent series (Fig. 6). Sex ratio in each decade changes with a clear-cut tendency in the USA Coop and the Tohoku. The younger the decade is, the more predo minant males are, and the older the decade is, the more predominant females are. In the USA Coop, females became predominant above 40 years and the ratio of female predominance was very distinct. On the other hand, in the Tohoku females became predominant above 50 years and the ratio was not remarkable (Fig. 7). References
1) 2) 3)
Ramamurthi, B. (1969) Incidence of intracranial aneurysms in India. J. Neurosurg., 30, 154-157. Sahs, A.L., Perret, G.E., Locksley, H.B. & Nishioka, H. (1969) Intracranial Aneurysms and Subarachnoid Hemorrhage, J.B. Lippincott Co., Philadelphia-Toronto, pp. 37-57. Suzuki, J., Hori, S. & Sakurai, Y. (1971) Intracranial aneurysms in neurosurgical clinics in Japan. J. Neurosurg., 35, 34-39.
J. exp.
Med.,
Distribution
1978, 126,
of
125-132
Intracranial
Aneurysm
TAKASHI YOSHIMOTO, TAKAMASA KAYAMA, NAMIO KODAMA and
JIRO
SUZUKI
Division of Neurosurgery, Institute of Brain Diseases, Tohoku University School of Medicine, Sendai 982
YOSHIMOTO,T., KAYAMMA, T., KODAMA, N. and SUZUKI, J. Distribution of Intracranial Aneurysm. Tohoku J. exp. Med., 1978, 126 (2), 125-132 The 1,080 cases of intracranial saccular aneurysms, which were seen at our clinic during the period from June 1961 to September 1975, were subjected to the analysis on the location of the aneurysms, age distribution and sex incidence. intracranial aneurysm; distribution
We reported the statistical studies on the 3548 cases of intracranial aneurysms in the neurosurgical clinics in Japan (Suzuki et al. 1971). Recently we noted that more than one thousand cases of intracranial aneurysm were seen and examined at our clinic alone. In the present study, the distribution of intracranial aneurysms, based on our 1080 saccular aneurysm cases, is investigated. MATERIALS 1,116 cases of various kinds of intracranial aneurysms were seen in our clinic during the period from June 1961 to September 1975. The 1,116 cases included 1080 saccular aneurysm
cases,
11 sclerotic,
3 traumatic,
1 mycotic,
TABLE 1.
Various types of intracranial 1961-Sept. 1975)
CVD, cerebro-vascular disease; HICH, hypertensive intracerebral Received
for publication,
January
2 anomalous,
cell
aneurysms (Tohoku Univ. June
AVM, arterio-venous hematoma.
7, 1978. 125
1 giant
malformation;
arteritis
126
T. Yoshimoto
et al.
and 18 aneurysm cases accompanied with other cerebrovascular diseases (Table 1). For the object of this study only cases of saccular aneurysms were subjected to the analysis. RESULTS
The 1,080 cases of intracranial saccular aneurysms were analyzed for the frequency of aneurysm sites. There were 366 cases of the anterior communicating artery, 286 cases of the internal carotid artery, 182 cases of the middle cerebral artery, 50 cases of the anterior cerebral artery, 30 cases of the vertebro-basilar arteries and 166 cases of multiple aneurysms (Table 2). TABLE 2.
Fig. 1.
Location
Site
distribution
of 1,307 saccular
aneurysms
in 1,080
cases.
In cases of multiple aneurysms there were 127 cases of two aneurysms, 25 cases of three, 9 of four, 4 of five and 1 case of eight. The total cases including 914 cases of a single aneurysm and 166 cases of multiple aneurysms had 1,307 aneurysms. There were 462 aneurysms (35.3%) on the anterior communicating artery, 422 aneurysms (32.2%) on the internal carotid artery , 298 aneurysms
Distribution
of Intracranial
Aneurysm
127
(22,8%) on the middle cerebral artery, 80 aneurysms (6.1%) on the anterior cerebral artery and 45 aneurysms (3.4%) on the vertebro-basilar artery (Fig. 1). The age ranged from 16-year-old male to 86-year-old female. The peak incidence occurred in the sixth decade with 32.2 percent followed by the fifth decade with 31.0 percent (Table 3). Our series revealed distinct difference of site distribution between age groups younger than 30 years and all other decennial age groups. Of the 44 cases younger than 30 years, only 1 case had an aneurysm of the middle cerebral artery. On the other hand, 17 of 44 cases showed aneurysms of the internal carotid artery. No significant differences could be seen between the group older than 60 years and the overall age group (Table 4). TABLE 3.
TABLE 4.
Site
distributions
TABLE 5.
Age distribution
in younger
Age distribution
and
older age groups
and sex incidence
128
T. Yoshimoto
et al.
TABLE 6.
Distiribution of aneurysm cases according to number of aneurysms, sex and age
The sex incidence in our series was male-predominant. There were 578 male with 54 percent and 502 female with 46 percent. Male predominance exhibited a maximum ratio of 2.5 to 1 for the ages below 20 years, but the gap diminished gradually until the fifth decade. And, female became predominant after 50 years (Table 5). No significant differences were seen between the age distribution in cases of single and multiple anerusysm. However, about a quarter of the female cases over the sixth decade were the cases of multiple aneurysms (Table 6). DISCUSSION
Ramamurthi (1969) reported that the incidence of intracranial aneurysm in South-East Asian countries including Japan is considerably lesser than that in European countries and the United States. However, we reported that 3,548 cases with 3,898 aneurysms in total had been seen in 111 Japanese neurosurgical clinics for a period of about 10 years (Suzuki et al. 1971). The number of aneurysms in our clinic had increased progressively year by year and the 1000th case was operated on intracranially in September 1975 (Fig. 2).
Fig. 2.
Saccular
aneurysm
seen each
year
in Tohoku
University.
Distribution
One
of
increased advance
the
reasons
progressively and
why from
development
of the
present, the incidence per lesser, but probably higher incidence
has remained
the
of Intracranial
aneurysm 1960's cerebral
Aneurysm
cases, in
especially
Japan
had
angiography
population of intracranial than Western countries.
low in many
South-East
129
surgical
been
for the
cerebral
aneurysms It is rather
Asian
ones,
attributed
have
to
the
stroke.
At
in Japan is not curious that the
countries.
The Japanese National Health Statistics on the cases of death reported cerebral stroke as the most popular, cancer as the second, heart attack as the third (Fig. 3). The order of these causes is different from those in the United States and European countries. Moreover, according to the statistics of mortality rate of cerebrovascular disease by World Health Statistics Annual in 1970, the
Fig. 3.
Fig. 4.
Causes of death in Japan.
Mortality rate of cerebrovascular
Japan National Health Statistics
(1972).
disease. World Health Statistics Annual (1970).
130
T. Yoshimoto
et al. TABLE 7.
* Only
single
aneurysm
cases including
56 cases with
both
aneurysm
Site
and
and side
arteriovenous
incidence of cerebral stroke in Japan was the highest among the reported countries (Fig. 4). Our statistical study covering the north-eastern districts (Tohoku) in Japan has been compared with studies of distribution of intracranial aneurysm of the United States Cooperative Study in 1966 (USA Coop) (Sahs et al. 1969), and of the Japanese neurosurgical clinics in 1969 (JNC) (Suzuki et al. 1971). The total numbers of aneurysm cases in these statistics were 2,672 cases in the USA Coop, 3,548 cases in the JNC and 1,080 cases in the Tohoku. In the USA Coop and the JNC, the internal carotid artery was most frequently involved, followed by the anterior communicating artery. In the Tohoku the anterior communicating artery was the highest and the internal carotid artery the lowest among the three investigations (Table 7). However, all studies were in agreement in that the most frequent sites were the internal carotid artery, anterior communicating
Fig.
5.
Age
of
cases; •ü-•ü, U.S.A.
aneurysm Tohoku
(1966)
2,627
cases (1970-1975) cases.
in
U.S.A. 772
and cases;•£-•£
Japan. •œ-•œ,
Tohoku Japan
(1969)
(1961-1969) 3,430
cases; •¢-•¢,
308
Distribution
distribution
of Intracranial
Aneurysm
131
of aneurysms
malformation.
Fig. 6.
Fig.
7.
Sex
ratio
(F/M)
Sex incidence
of
the
of aneurysm
incidence •œ-•œ
-,
Tohoku USA
(1975), Coop
(1966),
1,080
cases •ü-•ü 2,627
of aneurysms (1961-1969) (1970-1975)
cases.
by 308
decennial cases
772
cases
age.
cases
artery and middle cerebral artery. These three arteries altogether account for 89.1% of the total cases in the USA Coop, 87% in the JNC and 90.3% in the Tohoku.
132
T. Yoshimoto
et al.
In age distribution, more than 90 percent of the saccular aneurysms were found in the age range between 30 and 69 years with a peak at the fifth decade in the JNC and our 1960's series (Tohoku), while peaks were in the sixth decade in the USA Coop and our 1970's series (Tohoku). The cases of aneurysm were few in the first, second and eighth decades in every series (Fig. 5). The sex incidence in Japan with male predominance was contrary to that of the USA Coop. However, female cases in our clinic have increased according to our recent series (Fig. 6). Sex ratio in each decade changes with a clear-cut tendency in the USA Coop and the Tohoku. The younger the decade is, the more predo minant males are, and the older the decade is, the more predominant females are. In the USA Coop, females became predominant above 40 years and the ratio of female predominance was very distinct. On the other hand, in the Tohoku females became predominant above 50 years and the ratio was not remarkable (Fig. 7). References
1) 2) 3)
Ramamurthi, B. (1969) Incidence of intracranial aneurysms in India. J. Neurosurg., 30, 154-157. Sahs, A.L., Perret, G.E., Locksley, H.B. & Nishioka, H. (1969) Intracranial Aneurysms and Subarachnoid Hemorrhage, J.B. Lippincott Co., Philadelphia-Toronto, pp. 37-57. Suzuki, J., Hori, S. & Sakurai, Y. (1971) Intracranial aneurysms in neurosurgical clinics in Japan. J. Neurosurg., 35, 34-39.
