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Seppo Juvela

✓ This follow-up study was designed to evaluate whether the use of aspirin either before or after aneurysm rupture affects the occurrence of delayed cerebral ischemia. Aspirin inhibits platelet function and thromboxane production and has been shown to reduce the risk of various cardiovascular and cerebrovascular ischemic diseases. Following admission, the patients in this study were interviewed regarding their use of aspirin and other medicines prior to and after hemorrhage, and their urine was screened qualitatively for salicylates. Patient outcome and the occurrence of hypodense lesions consistent with cerebral infarction on follow-up computerized tomography (CT) were studied prospectively up to 1 year after hemorrhage.

Of 291 patients, 31 (11%) died because of the initial hemorrhage and 18 (6%) died due to rebleeding within 4 days after hemorrhage. Of the remaining 242 patients, 90 (37%) had delayed cerebral ischemia, which caused a permanent neurological deficit or death in 54 patients (22%). Of 195 patients undergoing follow-up CT, 85 (44%) had cerebral infarction that was not seen on the CT scan obtained on admission. Those who had salicylates in the urine on admission had a relative risk of 0.40 (95% confidence interval (CI), 0.15 to 1.10) of delayed ischemia with fixed deficit and a risk of 0.40 (95% CI, 0.18 to 0.93) of cerebral infarction compared with patients who did not have salicylates in their urine. This reduced risk of ischemic complications with aspirin use was restricted to those patients who used aspirin before hemorrhage, when the risk of ischemia was 0.21 (95% CI, 0.03 to 1.63) and the risk of infarct was 0.18 (95% CI, 0.04 to 0.84) compared with those who had not used aspirin. The reduced risk of cerebral infarction remained significant after adjustment for several potential confounding factors (adjusted risk 0.19; 95% CI, 0.04 to 0.89).

These observations suggest that platelet function at the time of subarachnoid hemorrhage may be associated with delayed cerebral ischemia after aneurysm rupture.

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Seppo Juvela

OBJECTIVE

Risk factors for growth of unruptured intracranial aneurysms (UIAs) during a lifelong follow-up in relation to subsequent rupture are unknown. The author’s aim in this study was to investigate whether risk factors for UIA growth are different for those that lead to rupture than for those that do not.

METHODS

The series consists of 87 patients with 111 UIAs diagnosed before 1979, when UIAs were not treated. A total follow-up time of the patients was 2648 person-years for all-cause death and 2182 years when patients were monitored until the first rupture, death due to unrelated causes, or the last contact (annual incidence of aneurysm rupture, 1.2%). The follow-up time between aneurysm measurements was 1669 person-years. Risk factors for UIA growth were analyzed in relation to subsequent rupture.

RESULTS

The median follow-up time between aneurysm measurements was 21.7 years (range 1.2–51.0 years). In 40 of the 87 patients (46%), the UIAs increased in size ≥ 1 mm, and in 31 patients (36%) ≥ 3 mm. All ruptured aneurysms in 27 patients grew during the follow-up of 324 person-years (mean growth rates 6.1 mm, 0.92 mm/year, and 37%/year), while growth without rupture occurred in 13 patients during 302 follow-up years (3.9 mm, 0.18 mm/year, and 4%/year) and no growth occurred in 47 patients during 1043 follow-up years. None of the 60 patients without aneurysm rupture experienced one during the subsequent 639 follow-up years after the last aneurysm measurement. Independent risk factors for UIA growth (≥ 1 mm) in all patients were female sex (adjusted OR 3.08, 95% CI 1.04–9.13) and smoking throughout the follow-up time (adjusted OR 3.16, 95% CI 1.10–9.10), while only smoking (adjusted OR 4.36, 95% CI 1.27–14.99) was associated with growth resulting in aneurysm rupture. Smoking was the only independent risk factor for UIA growth ≥ 3 mm resulting in aneurysm rupture (adjusted OR 4.03, 95% CI 1.08–15.07). Cigarette smoking at baseline predicted subsequent UIA growth, while smoking at the end of the follow-up was associated with growth resulting in aneurysm rupture.

CONCLUSIONS

Cigarette smoking is an important risk factor for UIA growth, particularly for growth resulting in rupture. Cessation of smoking may reduce the risk of devastating aneurysm growth.

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Seppo Juvela

Object. The pathogenesis of cerebral vasospasm and delayed ischemia after subarachnoid hemorrhage (SAH) seems to be complex. An important mediator of chronic vasospasm may be endothelin (ET), with its powerful and long-lasting vasoconstricting activity. In this study the author investigated the correlation between serial plasma concentrations of ET and ischemic symptoms, angiographically demonstrated evidence of vasospasm, and computerized tomography (CT) findings after aneurysmal SAH.

Methods. Endothelin-1 immunoreactivity in plasma was studied in 70 patients with aneurysmal SAH and in 25 healthy volunteers by using a double-antibody sandwich-enzyme immunoassay (immunometric) technique.

On the whole, mean plasma ET concentrations in patients with SAH (mean ± standard error of mean, 2.1 ± 0.1 pg/ml) did not differ from those of healthy volunteers (1.9 ± 0.2 pg/ml). Endothelin concentrations were significantly higher (p < 0.05) in patients who experienced delayed cerebral ischemia with fixed neurological deficits compared with those in other patients (post-SAH Days 0–5, 3.1 ± 0.8 pg/ml compared with 2.1 ± 0.2 pg/ml; post-SAH Days 6–14, 2.5 ± 0.4 pg/ml compared with 1.9 ± 0.2 pg/ml). Patients with angiographic evidence of severe vasospasm also had significantly (p < 0.05) elevated ET concentrations (post-SAH Days 0–5, 3.2 ± 0.8 pg/ml; post-SAH Days 6–14, 2.7 ± 0.5 pg/ml) as did those with a cerebral infarction larger than a lacuna on the follow-up CT scan (post-SAH Days 0–5, 3.1 ± 0.8 pg/ml; post-SAH Days 6–14, 2.5 ± 0.4 pg/ml) compared with other patients. Patients in whom angiography revealed diffuse moderate-to-severe vasospasm had significantly (p < 0.05) higher ET levels than other patients within 24 hours before or after angiography (2.6 ± 0.3 compared with 1.9 ± 0.2 pg/ml). In addition, patients with a history of hypertension or cigarette smoking experienced cerebral infarctions significantly more often than other patients, although angiography did not demonstrate severe or diffuse vasospasm more often in these patients than in others.

Conclusions. Endothelin concentrations seem to correlate with delayed cerebral ischemia and vasospasm after SAH. The highest levels of ET are predictive of the symptoms of cerebral ischemia and vasospasm, and ET may also worsen ischemia in patients with a history of hypertension. Thus, ET may be an important causal or contributing factor to vasospasm, but its significance in the pathogenesis of vasospasm remains unknown.

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Seppo Juvela

Object. Pathogenesis of delayed ischemia after aneurysmal subarachnoid hemorrhage (SAH) seems to be complex. An important mediator of chronic vasospasm may be endothelin (ET)-1 with its powerful and long-lasting vasoconstricting activity. In this prospective study the author investigated the correlations between serial plasma concentrations of ET-1 and big ET-1 as well as the ET-1/big ET-1 molar concentration ratio and serum endothelin-converting enzyme (ECE)-1 activity, and ischemic complications after SAH.

Methods. To measure plasma ET-1 (51 patients), big ET-1 immunoreactivity (22 patients), and serum ECE-1 activity (13 patients), blood samples were obtained on admission, in the morning after aneurysm surgery, and during the 2nd week after hemorrhage in 51 consecutive patients (28 men and 23 women, with a mean age of 50.8 years) with aneurysmal SAH. Mean plasma concentrations of ET-1 in patients with SAH (mean ± standard deviation: on admission, 4.2 ± 2 pg/ml; after surgery, 4.3 ± 2.2 pg/ml; and during the 2nd week after SAH, 3.7 ± 1.9 pg/ml) differed from those in healthy volunteers (2.9 ± 1.2 pg/ml; p < 0.01). Plasma concentrations of ET-1 and big ET-1 as well as the ET-1/big ET-1 ratio did not change significantly with elapsed time following SAH; however, serum ECE-1 activity during the 2nd week after SAH was higher in patients with SAH than that in controls (162 ± 43 compared with 121 ± 56 pg/ml, respectively; p = 0.028). Plasma ET-1 concentrations (p < 0.05) and the ET-1/big ET-1 ratios (p = 0.063) were higher but plasma big ET-1 concentrations were lower (p < 0.05) in patients who experienced symptomatic delayed cerebral ischemia, compared with other patients with SAH. In addition, in cases in which follow-up computerized tomography scans or magnetic resonance images demonstrated permanent ischemic lesions attributable to vasospasm, patients had higher ET-1 concentrations than did other patients with SAH.

Conclusions. The plasma ET-1 concentration correlates with delayed cerebral ischemia after SAH, suggesting that an increased ET conversion rate in the endothelium predicts ischemic symptoms. Increased serum ECE-1 activity during the 2nd week may reflect the severity of endothelial injury to cerebral arteries.

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Editorial

Unruptured aneurysms

Seppo Juvela

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Seppo Juvela and Marrku Kaste

✓ Serial blood samples were obtained from 80 patients with subarachnoid hemorrhage (SAH) to study adenosine diphosphate-induced platelet aggregation and associated thromboxane B2 release. The goal of the investigation was to detect whether reduced platelet function is involved in rebleeds. Seventeen patients (21%) suffered a rebleed, six of those experiencing their first rebleed within 24 hours after SAH. Therefore, most platelet function studies were performed after rebleeds. Thromboxane release was lower in patients with rebleeds than in the others, both before and after rebleeding, although statistical significance was reached only in samples collected after rebleeds. Patients rebleeding within 24 hours after SAH had lower platelet aggregability (p = 0.037) than patients without a rebleed in the samples taken within 3 days after SAH. The results suggest that reduced platelet aggregability and thromboxane release are involved in rebleeds following primary SAH.

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Seppo Juvela, Matti Porras and Kristiina Poussa

Object. The authors conducted a study to investigate the long-term natural history of unruptured intracranial aneurysms and the predictive risk factors determining subsequent rupture in a patient population in which surgical selection of cases was not performed.

Methods. One hundred forty-two patients with 181 unruptured aneurysms were followed from the 1950s until death or the occurrence of subarachnoid hemorrhage or until the years 1997 to 1998. The annual and cumulative incidence of aneurysm rupture as well as several potential risk factors predictive of rupture were studied using life-table analyses and Cox's proportional hazards regression models including time-dependent covariates.

The median follow-up time was 19.7 years (range 0.8–38.9 years). During 2575 person-years of follow up, there were 33 first-time episodes of hemorrhage from previously unruptured aneurysms, for an average annual incidence of 1.3%. In 17 patients, hemorrhage led to death. The cumulative rate of bleeding was 10.5% at 10 years, 23% at 20 years, and 30.3% at 30 years after diagnosis. The diameter of the unruptured aneurysm (relative risk [RR] 1.11 per mm in diameter, 95% confidence interval [CI] 1–1.23, p = 0.05) and patient age at diagnosis inversely (RR 0.97 per year, 95% CI 0.93–1, p = 0.05) were significant independent predictors for a subsequent aneurysm rupture after adjustment for sex, hypertension, and aneurysm group. Active smoking status at the time of diagnosis was a significant risk factor for aneurysm rupture (RR 1.46, 95% CI 1.04–2.06, p = 0.033) after adjustment for size of the aneurysm, patient age, sex, presence of hypertension, and aneurysm group. Active smoking status as a time-dependent covariate was an even more significant risk factor for aneurysm rupture (adjusted RR 3.04, 95% CI 1.21–7.66, p = 0.02).

Conclusions. Cigarette smoking, size of the unruptured intracranial aneurysm, and age, inversely, are important factors determining risk for subsequent aneurysm rupture. The authors conclude that such unruptured aneurysms should be surgically treated regardless of their size and of a patient's smoking status, especially in young and middle-aged adults, if this is technically possible and if the patient's concurrent diseases are not contraindications. Cessation of smoking may also be a good alternative to surgery in older patients with small-sized aneurysms.