Tetsuji Inagawa

Trends in Incidence and Case Fatality Rates of Aneurysmal Subarachnoid Hemorrhage in Izumo City, Japan, Between 1980–1989 and 1990–1998

Background and Purpose— With aging of the population, the profile of subarachnoid hemorrhage (SAH) is likely to change; however, evaluation of long-term trends for incidence and case fatality rates of SAH is still limited. Methods— We compared the incidence and case fatality rates of aneurysmal SAH during the 9-year period 1990–1998 with those during the 10-year period 1980–1989 in Izumo City, Japan. Results— During 1980–1989 and 1990–1998, we diagnosed 170 and 188 patients as having aneurysmal SAH, respectively. The percentage of very elderly patients aged ≥80 years increased from 5% (8 patients) during 1980– 1989 to 18% (33 patients) during 1990–1998 (P <0.001). The age-specific incidence rate of SAH has a tendency to increase with increasing age. The crude and the age- and sex-adjusted incidence rates using the 1995 population statistics for Japan were 21 and 23 per 100 000/y for all ages during 1980– 1989 and 25 and 23 per 100 000/y during 1990–1998, respectively. The 3-month case fatality rate of patients aged ≤79 years decreased from 38% during 1980–1989 to 26% during 1990–1998 (P =0.021), whereas the case fatality rates in patients aged ≥80 years were very high (63% and 79%, respectively) regardless of study periods. Consequently, the overall case fatality rates for patients with SAH were similar for the 2 study periods (39% and 36%). Conclusions— The age- and sex-adjusted incidence rates of aneurysmal SAH were stable over the 19-year period since 1980 and, despite improvement of outcome in patients aged ≤79 years, the overall case fatality rate was not lower because the improvements were counterbalanced by increasing numbers of very elderly patients.

Aneurysmal subarachnoid hemorrhage in Izumo City and Shimane Prefecture of Japan. Incidence.

During the 5-year period from 1980 to 1984, the incidence of subarachnoid hemorrhage due only to rupture of aneurysms was investigated in Izumo City, a small city with a population of 79,026. Additionally, to ascertain the relation of incidence to the size of the geographic area and/or population, a similar analysis was made on a larger area of Shimane Prefecture, including Izumo City, with a total population of 789,712. During this 5-year period, a total of 83 patients with aneurysmal subarachnoid hemorrhage were hospitalized in Izumo City, 548 patients in Shimane Prefecture. Ruptured aneurysms were confirmed in 77 cases (93%) in Izumo City and 466 cases (85%) in Shimane Prefecture. The crude annual incidences of aneurysmal subarachnoid hemorrhage for Izumo City and Shimane Prefecture were 21.0 and 13.9 per 100,000 population for all ages, and the age-adjusted annual incidences (adjusted to the 1980 population of Japan) were 18.3 and 11.0 per 100,000 for all ages, respectively. For both Izumo City and Shimane Prefecture, the age-specific annual incidences peaked at the ages of 50-69 years, and the highest incidence was 92.3 per 100,000 men from Izumo City in the eighth decade of life. The annual incidence of subarachnoid hemorrhage for Izumo City is the highest reported to date. If a wider area, such as Shimane Prefecture, were studied many patients in poor condition, particularly elderly patients, would be missed. To determine accurately the incidence of aneurysmal subarachnoid hemorrhage, it thus might be better to conduct the study in a small city such as Izumo City.

Study of Aneurysmal Subarachnoid Hemorrhage in Izumo City, Japan

BACKGROUND AND PURPOSE Estimation of the actual incidence rate of subarachnoid hemorrhage and evaluation of the treatment require the inclusion of all patients in a defined geographic area. METHODS During 1987 through 1992 in Izumo City, Japan, we estimated the incidence rate of subarachnoid hemorrhage by including dead-on-arrival patients and by further adding the results obtained after reviewing all death certificates registered in this city in the corresponding period. In addition, we compared the management and surgical outcomes in hospitalized patients from 1987 through 1992 with outcomes from 1980 through 1986. RESULTS During 1987 through 1992, we diagnosed 123 patients as having subarachnoid hemorrhage. The crude and the age- and sex-adjusted incidence rates using the 1990 population statistics for Japan were 25 (95% confidence interval, 21 to 30) per 100,000/y and 23 (95% confidence interval, 19 to 28) per 100,000/y for all ages, respectively; these occurrences are the highest among those reported to date. Of these patients, 8% died before receiving medical attention, 27% in the first week, and 39% at 1 month. The survival curve for 2 years improved significantly from 1980-1986 to 1987-1992 in patients with admission grades 4 and 5 (P = .035) and in operated patients with preoperative grades 1 through 3 (P = .036). However, there was little improvement in the overall management results (P = .168), possibly because patients with high risk and/or old age were admitted and/or diagnosed more often in the latter period. CONCLUSIONS The incidence rate of subarachnoid hemorrhage is much higher than that reported so far in the literature, and despite improvement of management and surgical therapy, the actual case-fatality rate is still high, mainly because of the high mortality rate directly associated with the primary bleeding.

Intracerebral hematoma in patients with ruptured cerebral aneurysms

BACKGROUND Intracerebral hematoma from ruptured aneurysms is one of the unfavorable factors for outcome in patients with subarachnoid hemorrhage. In this study, the clinical characteristics of intracerebral hematoma in patients with ruptured aneurysms were examined. METHODS The subjects were 512 patients who had been admitted by day 3 after aneurysmal rupture without episodes of rebleeding before the initial computed tomography (CT) scan. They were divided into two groups according to the findings of initial CT; groups 1 and 2 comprised patients with and without intracerebral hematoma, respectively. RESULTS Of the 512 patients, intracerebral hematoma was observed in 98 (19%). The incidence of intracerebral hematoma was higher in patients with distal anterior cerebral and middle cerebral artery aneurysms, compared with those at other sites (both, p < 0.01). Interhemispheric, callosal, and temporal lobe/sylvian hematomas were observed more frequently in patients with anterior communicating, distal anterior cerebral, and middle cerebral artery aneurysms, respectively, than in those with aneurysms at other sites. The incidence of rebleeding was 22% in group 1 and 14% in group 2 (p < 0.05). Clinical grades on admission were higher and outcome at 6 months after onset was less favorable in group 1 than in group 2 (both, p < 0.01). The larger the intracerebral hematoma, the higher was the clinical grade and the less favorable the outcome. However, when comparing management and surgical outcome under the same clinical grades, there was no significant difference between the two groups. CONCLUSIONS There was a close correlation between the site of hematoma and that of the ruptured aneurysm. Poor outcome in patients with intracerebral hematoma seems to be related to severity of clinical grade on admission.

Chronic hydrocephalus in elderly patients following subarachnoid hemorrhage

BACKGROUND With the aging of the population, surgery for ruptured intracranial aneurysms is increasing among the elderly. We sought to clarify the characteristics of chronic hydrocephalus following aneurysmal subarachnoid hemorrhage (SAH) in elderly patients. METHODS Of the 576 surgically treated patients, 289 were aged 59 years or younger, 169 were 60 to 69, and 118 were 70 years or older. The relationship between chronic hydrocephalus and the causative factors was analyzed for each age group. RESULTS Of the 576 patients, chronic hydrocephalus was observed in 215 (37%), with the incidence increasing significantly with age (p < 0.001) and being the highest in the oldest age group. In elderly patients, the incidence of chronic hydrocephalus was relatively high, even after mild SAH. The incidence of chronic hydrocephalus was high regardless of age in patients with severe SAH, such as in those with H&H grades III-IV, SAH grades III-IV, acute hydrocephalus, symptomatic vasospasm, and intraventricular hemorrhage, and in those with vertebro-basilar artery aneurysms. CONCLUSION In the elderly, the incidence of chronic hydrocephalus following SAH was significantly higher than in younger patients, even after mild SAH. In elderly patients, careful observation and individualized treatment are necessary even if SAH is mild.

Primary intracerebral hemorrhage in Izumo City, Japan: incidence rates and outcome in relation to the site of hemorrhage.

OBJECTIVEThe aim of this community-based study was to investigate the incidence rates and outcome of primary intracerebral hemorrhage (ICH) in relation to the site of hemorrhage. METHODSThe subjects were 350 patients with primary first-ever ICH who were treated during the 8-year period 1991 to 1998 in Izumo City, Japan. RESULTSThe crude and age- and sex-adjusted incidence rates for all types of ICH were 52 and 47 per 100,000 population, respectively, for all ages. The most common site of ICH was the putamen (120 patients, 34%), followed by the thalamus (115, 33%), lobar areas (53, 15%), brainstem (30, 9%), cerebellum (25, 7%), and caudate nucleus (7, 2%). The crude and age- and sex-adjusted annual incidence rates per 100,000 population were 18 and 16 for putaminal, 17 and 15 for thalamic, 8 and 7 for lobar, 4 and 3 for cerebellar, 4 and 4 for brainstem, and 1 and 1 for caudate hemorrhages, respectively. The Glasgow Coma Scale scores on admission were best in patients with cerebellar hemorrhage and worst in those with brainstem hemorrhage. Surgery was performed for 34% of putaminal, 9% of thalamic, 14% of caudate, 21% of lobar, and 32% of cerebellar hemorrhages but not for brainstem hemorrhages. The 30-day case fatality rate was 11% for putaminal, 9% for thalamic, 14% for caudate, 11% for lobar, 0% for cerebellar, and 53% for brainstem hemorrhages. When patients with ICH were analyzed as a whole, the overall survival rates at 30 days, 3 months, and 3 years were 87, 83, and 73%, respectively. Both the short-term and long-term outcomes after ICH were directly related to the site of hemorrhage and the severity of bleeding, which was assessed by the hematoma volume and Glasgow Coma Scale score. Overall, 190 (54%) of 350 patients had a favorable outcome, and 55 (16%) had died at discharge. CONCLUSIONMarked differences were observed in the incidence rates and outcome of primary ICH in relation to the site of hemorrhage. The differences in outcome were primarily a result of differences in the severity of bleeding for each ICH subtype.

What are the actual incidence and mortality rates of subarachnoid hemorrhage

BACKGROUND From 1987-92 in Izumo City, Japan, we diagnosed 123 patients as having subarachnoid hemorrhage (SAH) by computed tomography, autopsy, or surgery (proven SAH); the crude incidence rate was 25/100,000/year for all ages. However, to estimate the actual incidence and mortality rates, we should take into account the decedents who died without confirmation by these methods but were presumed to have died of SAH. METHODS From 1987-92, we reviewed all of 3562 death certificates for the city of Izumo (population 82,679), and calculated the incidence and mortality rates of SAH by combining proven and possible SAH. RESULTS We diagnosed 36 patients as having possible SAH on death certificates. When adding these 36 patients to the 123 with proven SAH, the crude and the age-adjusted and sex-adjusted incidence rates for all ages became 32/ 100,000/year and 29/100,000/year, respectively. Of these, 40% (64) died by day 3 (day 0 defined as the day of hemorrhage), 43% (69) within 1 week, and 53% (84) within 1-6 months, respectively. CONCLUSIONS When including the patients who may have died of SAH, the actual incidence rate of SAH is much higher than that which has been reported to date, and the actual mortality rate is still very high.

Risk factors for the formation and rupture of intracranial saccular aneurysms in Shimane, Japan

BACKGROUND Prevention of aneurysmal subarachnoid hemorrhage (SAH) can be achieved by reducing risk factors, which include those for aneurysm formation and aneurysm rupture. However, neither of these 2 factors has been discussed separately so far. A case control study was undertaken in Shimane, Japan, to identify modifiable risk factors for the formation and rupture of aneurysms. METHODS This study included 858 patients with ruptured aneurysms, 285 patients with unruptured aneurysms without a history of SAH, and 798 control subjects. Hypertension, diabetes mellitus, heart disease, hypercholesterolemia, cigarette smoking, and alcohol consumption were assessed as risk factors by using conditional logistic regression. RESULTS After adjustment for other risk factors, hypertension was the most powerful risk factor for aneurysm formation, regardless of age and sex, followed by hypercholesterolemia, heart disease, and cigarette smoking, whereas diabetes mellitus and daily drinking were insignificant for aneurysm formation. Hypertension and daily drinking were not related to the risk of aneurysm rupture, regardless of age and sex, whereas cigarette smoking was associated with an increased risk of aneurysm rupture in patients 60 years or older and in men. In contrast, hypercholesterolemia was strongly associated with a decreased risk of rupture, regardless of age and sex, and in patients with small aneurysms (<5 mm). Diabetes mellitus and heart disease were also related to a decreased risk of rupture in patients 60 years or older and in women. CONCLUSION Identification of risk factors for aneurysm formation and rupture separately seems to be pivotal for reducing the incidence of SAH.

Malignant intraventricular meningioma with spinal metastasis through the cerebrospinal fluid

A 67-year-old man developed a malignant meningioma of the right lateral ventricle at the trigone, for which he underwent total removal of the tumor and local irradiation. Six months after the operation, a spinal tumor developed and subtotal removal of the tumor was made. The spinal tumor was considered to be a metastasis via the cerebrospinal fluid in view of its histologic identity with the primary tumor, histologic findings of malignancy, absence of von Recklinghausens disease, and lack of tumor attachment to the dura.

Cerebral vasospasm in elderly patients with ruptured intracranial aneurysms

Cerebral vasospasm in elderly patients who were operated on the acute stage after subarachnoid hemorrhage was studied under strict criteria. The 138 patients were classified into three age groups: 59 years or younger (group A: 73 cases), 60 to 69 years (group B: 37 cases), and 70 years or older (group C: 28 cases). Severity of both the subarachnoid hemorrhages on computed tomography scan and the angiographic vasospasms was graded. The angiographic vasospasms were analyzed at the internal carotid artery, M1 segments of the middle cerebral artery, and A2 segments of the anterior cerebral. In all the relationships among the subarachnoid hemorrhage grades, the Hounsfield numbers, and the operative approaches to the angiographic vasospasm grade, there was a tendency for the angiographic vasospasm grades to be lower with increasing age in both the internal carotid artery and the M1 segment of the middle cerebral artery. This tendency was more apparent in the larger vessels, that is, the internal carotid arteries. Close correlations of the angiographic vasospasm grades to the incidences of symptomatic vasospasm and to low-density area on computed tomography scan were found in both the M1 and A2 territories in the three groups. However, there were no significant differences among the three groups in the incidences of symptomatic vasospasm and low-density area on computed tomography scan. Regarding the surgical outcome, the older the patients, the higher were the mortality rates: 8% in group A, 11% in group B, and 25% in group C.(ABSTRACT TRUNCATED AT 250 WORDS)