The risk of subarachnoid and intracerebral hemorrhages in blacks as compared with whites

Natural history and general management of unruptured intracranial aneurysms

After an aneurysmal subarachnoid hemorrhage, nearly half of the patients die and the half who survive suffer from irreversible cerebral damage. With increasing use of noninvasive neuroimaging techniques (for example, magnetic resonance and computerized tomography angiography), more unruptured cerebral aneurysms are found. To understand the prevalence of unruptured aneurysms in the general population, along with the risks of aneurysm formation, data on growth and rupture rates are crucial. The risk of rupture in aneurysms smaller than 10 mm is still not quite clear without a population-based prospective study. Nevertheless, a 0.5 to 2% annual risk may be a reasonable estimate. Growing aneurysms and those larger than 10 mm carry a higher rate of rupture. The management of an unruptured intracranial aneurysm should be based on a thorough understanding of the natural history of these lesions and careful evaluation of the morbidity and mortality levels associated with each treatment option.

Aneurysmal subarachnoid haemorrhage in pregnancy

Although uncommon, aneurysmal subarachnoid haemorrhage (SAH) in pregnancy can be devastating for both mother and baby. It is the leading cause of other indirect maternal death in England and Wales accounting for 60 deaths in the decade 1988-1999. No single obstetric or neurosurgical unit has sufficiently large database or experience in managing this condition in pregnancy. With significant improvements in antenatal care and management of deliveries, non-obstetric causes of maternal death such as aneurysmal subarachnoid haemorrhage are likely to become increasingly significant. The clinical features of aneurysmal subarachnoid haemorrhage closely resemble those of other commoner conditions seen in pregnancy. It is therefore imperative that awareness by obstetricians and other frontline staff is increased so that a high index of suspicion is maintained when pregnant women present with unique headaches. Prompt neurosurgical referral is vital and early involvement of an experienced neuroradiologist essential. It is only when an early diagnosis is made and an aggressive treatment instituted that the bleak case-fatality figure associated with aneurysmal subarachnoid haemorrhage in pregnancy can be improved. This review, by a multidisciplinary and multicenter team, provides a comprehensive update on the epidemiology, aetiology, clinical presentation, diagnosis and the complexities of the multidisciplinary management of this serious and potentially fatal condition when it occurs in pregnancy.

Epidemiology of transient ischemic attack and ischemic stroke in patients with underlying cardiovascular disease

It is estimated that 15 to 30% of ischemic strokes are cardioembolic in origin, and that atrial fibrillation, valvular heart disease, coronary artery disease, congestive heart failure, and myocardial infarction are significant risk factors for stroke, which underscores the importance for cardiologists to understand this condition. The high incidence and substantial cost of stroke justify aggressive treatment of stroke risk factors, especially in the elderly, diabetic, and black populations, and in patients who have had an initial stroke. Antiplatelet therapy and administration of oral anticoagulants have both been shown to have a substantial impact on stroke in specified populations at risk.

Racial Disparities in Subarachnoid Hemorrhage Mortality: Los Angeles County, California, 1985–1998

We examined the racial distribution of subarachnoid hemorrhage (SAH) mortality in a unique multiracial community. Mortality rates for SAH among the residents of Los Angeles County were calculated from death certificate data (1985-1998). Residential postal zones were classified into three strata as a measure of socioeconomic status. The number of SAH deaths was 2,897. The age-adjusted SAH mortality rate was 1.9 in whites, 2.7 in Hispanics, 3.0 in Asians and 3.7 in blacks. In those younger than 70 years of age, the SAH mortality rate among blacks was 2.2 times that of whites and 1.8 times that of Hispanics and Asians. The SAH mortality rate declines after age 70 in blacks. The SAH mortality rate was higher in women than in men in all races and it was highest in elderly Asian women (23.5 per 100,000). An inverse relationship was observed between income and SAH mortality rates in all racial groups except whites.

Hemorragia intraparenquimatosa encefálica espontânea: achados à tomografia computadorizada

Foram analisados os exames de tomografia computadorizada de crânio de 250 pacientes com hematoma intraparenquimatoso encefálico espontâneo em três diferentes hospitais na cidade do Rio de Janeiro, com o objetivo de se levantar os aspectos mais freqüentes desta doença. O hematoma intraparenquimatoso cerebral profundo foi o de maior incidência, seguido do lobar. Mais raramente foi observado sangramento cerebelar e do tronco cerebral. A faixa etária de acometimento mais freqüente foi entre 61 e 70 anos de idade. Não houve diferença expressiva quanto ao sexo predominante ou ao lado mais acometido, porém verificou-se que os homens são mais acometidos em uma faixa etária mais precoce do que as mulheres. A cefaléia foi o sintoma de maior freqüência e a hipertensão arterial esteve presente na maioria dos casos. A drenagem da hemorragia para o sistema ventricular ocorreu mais comumente nos hematomas profundos.

Subarachnoid hemorrhage

The medical and surgical management of aneurysmal SAH has changed dramatically in the past few decades. Surgical management emphasizes early triage and repair of the responsible aneurysm. Medical management focuses on maintenance of adequate volume, monitoring cerebral vasospasm, and initiation of medical maneuvers or interventional procedures designed to improve vessel patency and CBF. The results of these techniques have not been studied in randomized controlled trials; however, several large retrospective analyses reveal a significant decrease in mortality and morbidity with the institution of these measures. Future improvements will continue to develop with increased understanding of cerebral vasospasm and in neurologic monitoring.

Ischemic stroke subtypes: a population-based study of incidence rates among blacks and whites

BACKGROUND AND PURPOSE

Blacks have an excess burden of stroke compared with whites; however, data comparing ischemic stroke subtypes among the 2 groups are limited and typically involve relative frequencies. The objective of this study is to compare the incidence rates of ischemic stroke subtypes between blacks and whites within a large, representative, biracial population.

METHODS

The Greater Cincinnati/Northern Kentucky Stroke Study is designed to measure incidence rates and trends of all strokes within a well-defined, large, biracial population. Hospitalized cases were ascertained by International Classification of Disease (9th revision; ICD-9) discharge codes. Out-of-hospital events were ascertained by prospective screening of emergency department admission logs, review of coroners' cases, and monitoring all public health and hospital-based primary care clinics. A sampling scheme was used to ascertain events from nursing homes and all other primary care physician offices. All potential cases underwent detailed chart abstraction and confirmed by physician review. Based on all available clinical, laboratory, and radiographic information, ischemic stroke cases were subtyped into the following categories: cardioembolic, large-vessel, small-vessel, other, and stroke of undetermined cause. Race-specific incidence rates were calculated and compared after adjusting for age and gender, and standardizing to the 1990 US population.

RESULTS

Between July 1, 1993, and June 30, 1994, 1956 first-ever ischemic strokes occurred among blacks and whites in the study population. Small-vessel strokes and strokes of undetermined cause were nearly twice as common among blacks. Large-vessel strokes were 40% more common among blacks than whites, and there was a trend toward cardioembolic strokes being more common among blacks.

CONCLUSIONS

The excess burden of ischemic strokes among blacks compared with whites is not uniformly spread across the different subtypes. Large-vessel strokes are more common and cardioembolic stroke are as common among blacks, traditionally thought to be more common among whites.

Effect of untreated hypertension on hemorrhagic stroke

BACKGROUND AND PURPOSE

Stroke is the third leading cause of death and the leading cause of disability in the United States. Intracerebral hemorrhage and subarachnoid hemorrhage represent approximately 20% of all stroke cases and have a mortality rate of 40% to 50%. Hypertension is an important risk factor for these subtypes of stroke. We sought to determine whether untreated hypertension carries a different risk from treated hypertension for hemorrhagic stroke.

METHODS

Cases of hemorrhagic stroke in the greater Cincinnati region were identified by screening all area hospital emergency rooms, radiology reports, and International Classification of Diseases 9 codes. Medical records were reviewed for risk factors and medication use. Cases of hemorrhagic stroke were approached for enrollment into the genetic sampling and interview arm. If subjects agreed, the case was matched by age, race, and gender to population-based controls.

RESULTS

Between May 1997 and December 2002, we recruited 549 cases of hemorrhagic stroke, of which 322 were intracerebral hemorrhage and 227 were subarachnoid hemorrhage. Untreated hypertension was found to be a significant risk factor for hemorrhagic stroke (odds ratio [OR]=3.5 [2.3 to 5.2]; P<0.0001) as was treated hypertension (OR=1.4 [1.0 to 1.9]; P=0.03). Insurance status of "self-pay" or Medicaid was a significant risk factor for untreated hypertension (OR=2.7 [1.6 to 4.4]). We estimate that 17% to 28% of hemorrhagic strokes among hypertensive patients would have been prevented if they had been on hypertension treatment.

CONCLUSIONS

Untreated hypertension is highly prevalent and an important risk factor for hemorrhagic stroke. We estimate that among hypertensive subjects, approximately one fourth of hemorrhagic strokes would be prevented if all hypertensive subjects received treatment.

Hypercholesterolemia, HMG-CoA reductase inhibitors, and risk of intracerebral hemorrhage: a case-control study

BACKGROUND AND PURPOSE

Several studies have demonstrated an association between hypocholesterolemia and intracerebral hemorrhage (ICH). We tested the hypothesis that hypercholesterolemia or use of HMG-CoA reductase inhibitors (statin) agents, or both, are associated with ICH.

METHODS

This study was part of the preplanned midway analysis of an ongoing, population-based, case-control study of the genetic and environmental risk factors of hemorrhagic stroke. Conditional stepwise logistic regression modeling was used to determine if self-reported hypercholesterolemia or statin use, or both, were independent risk factors for ICH.

RESULTS

Between December 1, 1997, and June 30, 2000, 188 cases of ICH and 366 age-, race-, and gender-matched controls were enrolled. Hypercholesterolemia and statin use were less common among cases than controls: 25% versus 38% (P=0.003) and 9% versus 17% (P=0.03), respectively. Hypercholesterolemia with statin use was associated with less risk of ICH (OR=0.30; P=0.0008) in multivariable analysis after controlling for alcohol use, hypertension, previous stroke, first-degree relative with ICH, education level, and apolipoprotein E alleles.

CONCLUSIONS

Hypercholesterolemia was associated with a lower risk of ICH. We have not found an increased risk of ICH with the widespread use of statins in our population. Given the lack of cholesterol levels in the current study, further studies are needed to determine if lower cholesterol levels secondary to statin use bear the same risk as low cholesterol levels for ICH.

An overview of new pharmacological treatments for cerebrovascular dysfunction after experimental subarachnoid hemorrhage

Cerebral vasospasm and the resulting cerebral ischemia occurring after subarachnoid hemorrhage (SAH) are still responsible for the considerable morbidity and mortality in patients affected by cerebral aneurysms. Mechanisms contributing to the development of vasospasm, abnormal reactivity of cerebral arteries and cerebral ischemia after SAH have been intensively investigated in recent years. It has been suggested that the pathogenesis of vasospasm is related to a number of pathological processes, including endothelial damage, smooth muscle cell contraction resulting from spasmogenic substances generated during lyses of subarachnoid blood clots, changes in vascular responsiveness and inflammatory or immunological reactions of the vascular wall. A great deal of experimental and clinical research has been conducted in an effort to find ways to prevent these complications. However, to date, the main therapeutic interventions remain elusive and are limited to the manipulation of systemic blood pressure, alteration of blood volume or viscosity, and control of arterial dioxide tension. Even though no single pharmacological agent or treatment protocol has been identified which could prevent or reverse these deadly complications, a number of promising drugs have been investigated. Among these is the hormone erythropoietin (EPO), the main regulator of erythropoiesis. It has recently been found that EPO produces a neuroprotective action during experimental SAH when its recombinant form (rHuEPO) is systemically administered. This topic review collects the relevant literature on the main investigative therapies for cerebrovascular dysfunction after aneurysmal SAH. In addition, it points out rHuEPO, which may hold promise in future clinical trials to prevent the occurrence of vasospasm and cerebral ischemia after SAH.

Accident vasculaire cérébral chez le jeune Afro-Caribéen en Martinique : étude prospective épidémiologique et étiologique

Few data are available regarding stroke among young black patients. We have conducted, in Martinique, a prospective study among young Afro-Caribbeans aged 15 to 45 Years, from June 1994 through May 1999. We identified 60 cerebral infarcts (CI) and 20 cases of intracerebral hemorrhage (ICH). Annual incidence and case fatality rate at 30 days were 7.6/100000/Year (95p.cent confidence interval, 3.13 to 11.35) and 8.3p.cent respectively for CI, and 2.42/100000/Year (95p.cent confidence interval, 0.06 to 4.7) and 25p.cent for ICH. Hypertension was the most prevalent stroke risk factor: 35p.cent in CI and 68p.cent in ICH. According to the TOAST criteria, a probable cause of ischemic stroke was identified in 61.3p.cent. Atherosclerosis, lacunar infarcts and cardioembolism were the main causes of CI (13.3p.cent for each etiology). Spontaneous cervical arterial dissection was found in only 6.7p.cent. Hypertensive ICH (60p.cent) was the most common subtype of ICH. In Martinique, high frequencies of ICH and lacunar infarcts are characteristic of stroke in young Afro-Carribeans. These suggest the role of the high prevalence of hypertension in the black population. We confirm the heterogeneity of stroke etiologies and the low prevalence of cervical arterial dissection in black people.

Stroke in a biracial population: the excess burden of stroke among blacks

BACKGROUND AND PURPOSE

Excess mortality resulting from stroke is an important reason why blacks have higher age-adjusted mortality rates than whites. This observation has 2 possible explanations: Strokes occur more commonly among blacks or blacks have higher mortality rates after stroke. Our population-based epidemiological study is set in the Greater Cincinnati/Northern Kentucky region of 1.31 million people, which is representative of the US white and black populations with regard to many demographic and socioeconomic characteristics.

METHODS

Hospitalized cases were ascertained by International Classification of Diseases (ninth revision) discharge codes, prospective screening of emergency department admission logs, and review of coroner's cases. A sampling scheme was used to ascertain cases in the out-of-hospital setting. All potential cases underwent detailed chart abstraction by study nurses, followed by physician review. Race-specific incidence and case fatality rates were calculated.

RESULTS

We identified 3136 strokes during the study period (January 1, 1993, to June 30, 1994). Stroke incidence rates were higher for blacks at every age, with the greatest risk (2- to 5-fold) seen in young and middle-aged blacks (<65 years of age). Case fatality rates did not differ significantly in blacks compared with whites. Applying the resulting age- and race-specific rates to the US population in 2002, we estimate that 705,000 to 740,000 strokes have occurred in the United States, with a minimum of 616,000 cerebral infarctions, 67,000 intracerebral hemorrhages, and 22,000 subarachnoid hemorrhages.

CONCLUSIONS

Excess stroke-related mortality in blacks is due to higher stroke incidence rates, particularly in the young and middle-aged. This excess burden of stroke incidence among blacks represents one of the most serious public health problems facing the United States.

Update on management of intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a lingering cause of significant mortality and morbidity rates in contemporary society. Despite its established burden, considerably less investigative attention has been devoted to the study of ICH than other forms of stroke. Only a limited number of clinical studies have been performed to examine the surgical (both craniotomy and minimally invasive) and medical management of patients with ICH. No consistently efficacious strategies have been identified through such investigations. Limitations in study design and execution have universally impaired the interpretation and impact of available data. Management of ICH unfortunately remains heterogeneous across institutions, and it continues to suffer from the lack of proven medical and surgical effectiveness. Urgently needed are further prospective randomized controlled trials in which investigators consider the shortcomings of previous endeavors in the management of ICH. In the present article the authors review the current management practices of ICH, discuss the controlled trials, and highlight recent trials and future avenues of further study.

Spontaneous intracerebral hemorrhage due to coagulation disorders

Although intracranial hemorrhage accounts for approximately 10 to 15% of all cases of stroke, it is associated with a high mortality rate. Bleeding disorders account for a small but significant risk factor associated with intracranial hemorrhage. In conditions such as hemophilia and acute leukemia associated with thrombocytopenia, massive intracranial hemorrhage is often the cause of death. The authors present a comprehensive review of both the physiology of hemostasis and the pathophysiology underlying spontaneous ICH due to coagulation disorders. These disorders are divided into acquired conditions, including iatrogenic and neoplastic coagulopathies, and congenital problems, including hemophilia and rarer diseases. The authors also discuss clinical features, diagnosis, and management of intracranial hemorrhage resulting from these bleeding disorders.

Racial disparities in receipt of secondary stroke prevention agents among US nursing home residents

BACKGROUND AND PURPOSE

Although medications can significantly reduce the risk of recurrent stroke, little is known about the extent to which such therapies are given to nursing home residents. We sought to evaluate the extent to which people of color were less likely to receive pharmacological agents in the treatment of recurrent stroke while living in US nursing homes.

METHODS

We identified 19 051 residents with a recent hospitalization and primary discharge diagnosis of 434 or 436 in 5 states from 1992 to 1996; of these, 7053 had concomitant conditions indicating anticoagulant therapy. We considered aspirin, dipyridamole, ticlopidine, or warfarin alone or in combination as secondary drug prevention. Generalized linear models provided estimates of the absolute difference in prevalence estimates of the receipt of agents used for the prevention of recurrent stroke between each race-ethnicity group adjusted for potential confounders.

RESULTS

Variability in use of any treatment was observed by race-ethnicity ranging from 58% of American Indians receiving therapy to only 39% of Asian/Pacific Islanders. Among residents with an indication for anticoagulant therapy, the absolute estimated crude differences indicated that residents of color were less likely than non-Hispanic whites to receive warfarin. After controlling for confounding, Asian/Pacific Islanders, blacks, and Hispanics eligible for anticoagulant therapy received warfarin less often than non-Hispanic white residents.

CONCLUSIONS

Overall, only half of our elderly population received any pharmacological agent for secondary prevention of stroke. Interventions designed to improve the pharmacological management of recurrent stroke regardless of race are needed in the nursing home setting.

Spontaneous intracerebral hemorrhage: a review

Spontaneous intracerebral hemorrhage (SICH) is a blood clot that arises in the brain parenchyma in the absence of trauma or surgery. This entity accounts for 10 to 15% of all strokes and is associated with a higher mortality rate than either ischemic stroke or subarachnoid hemorrhage. Common causes include hypertension, amyloid angiopathy, coagulopathy, vascular anomalies, tumors, and various drugs. Hypertension, however, remains the single greatest modifiable risk factor for SICH. Computerized tomography scanning is the initial diagnostic modality of choice in SICH, and angiography should be considered in all cases except those involving older patients with preexisting hypertension in thalamic, putaminal, or cerebellar hemorrhage. Medical management includes venous thrombosis prophylaxis, gastric cytoprotection, and aggressive rehabilitation. Anticonvulsant agents should be prescribed in supratentorial SICH, whereas the management of hypertension is controversial.

To date, nine prospective randomized controlled studies have been conducted to compare surgical and medical management of SICH. Although definitive evidence favoring surgical intervention is lacking, there is good theoretical rationale for early surgical intervention. Surgery should be considered in patients with moderate to large lobar or basal ganglia hemorrhages and those suffering progressive neurological deterioration. Elderly patients in whom the Glasgow Coma Scale score is less than 5, those with brainstem hemorrhages, and those with small hemorrhages do not typically benefit from surgery. Patients with cerebellar hemorrhages larger than 3 cm, those with brainstem compression and hydrocephalus, or those exhibiting neurological deterioration should undergo surgical evacuation of the clot. It is hoped that the forthcoming results of the International Surgical Trial in IntraCerebral Hemorrhage will help formulate evidence-based recommendations regarding the role of surgery in SICH.

Risk Factors for Incident Stroke among Patients with End-Stage Renal Disease

ABSTRACT. Although patients with ESRD experience markedly higher rates of stroke, no studies in the US have identified risk factors associated with stroke in this population. It was hypothesized that black race, malnutrition, and elevated BP would be associated with the risk of stroke among patients with ESRD. Data from the United States Renal Data Systems were used. Adult Medicare-insured hemodialysis and peritoneal dialysis patients without a history of stroke or transient ischemic attack (TIA) were considered for analysis. The primary outcome was hospitalized or fatal stroke. Cox proportional hazards models were used to determine the associations between the primary predictor variables and stroke. The rate of incident stroke was 33/1,000 person-years in the study sample. After adjustment for age and other patient characteristics, three markers of malnutrition were associated with the risk of stroke—serum albumin (per 1 g/dl decrease, hazard ratio [HR] = 1.43), height-adjusted body weight (per 25% decrease, HR = 1.09), and a subjective assessment of undernourishment (HR = 1.27)—as was higher mean BP (per 10 mmHg, HR = 1.11). The association between black race varied by cardiac disease status, with blacks estimated to be at lower risk than whites among individuals with cardiac disease (HR = 0.74), but at higher risk among individuals without cardiac disease (HR = 1.24). This study confirms the extraordinarily high rates of stroke in ESRD patients on dialysis and identifies high mean BP and malnutrition as potentially modifiable risk factors. The association between black race and stroke differs by cardiac disease status; the reasons for this differing effect of race deserve further investigation. E-mail: seliger@u.washington.edu

Major risk factors for aneurysmal subarachnoid hemorrhage in the young are modifiable

BACKGROUND AND PURPOSE

To identify risk factors for subarachnoid hemorrhage (SAH) and intracerebral hemorrhage, we designed a case-control study of men and women 18 to 49 years of age (the Hemorrhagic Stroke Project [HSP]). This report focuses on SAH.

METHODS

Patients were recruited from 44 hospitals in the United States. Cases with SAH must have had a ruptured aneurysm documented by angiography or surgery. Two controls, identified by random digit dialing and matched to each patient for age, sex, race, and telephone exchange, were sought for each case subject.

RESULTS

Between 1994 and 1999, 425 patients with SAH were enrolled in HSP, and 312 cases met the criteria for aneurysmal SAH. The present analyses also included 618 matched controls. Of the 312 cases, 66% were current cigarette smokers compared with 30% of controls (adjusted odds ratio [OR], 3.73; 95% CI, 2.67 to 5.21). Cocaine use within the previous 3-day period was reported by 3% of cases and no controls (bivariate exact OR, 24.97; 95% exact CI, 3.95 to infinity; adjusted estimate not calculable). Other independent risk factors in the multivariable model included hypertension (adjusted OR, 2.21; 95% CI, 1.48 to 3.29), low body mass index (OR, 1.59; 95% CI, 1.08 to 2.35), primary family history of hemorrhagic stroke (OR, 3.83; 95% CI, 1.73 to 8.46), caffeine in pharmaceutical products (OR, 2.48; 95% CI, 1.19 to 5.20), lower educational achievement (OR, 2.36; 95% CI, 1.44 to 3.87), and nicotine in pharmaceutical products (adjusted estimate not calculable).

CONCLUSIONS

Aneurysmal SAH may be largely a preventable disease among the young and middle-aged because several prevalent risk factors can be modified by medication (eg, hypertension) or behavioral change (eg, cigarette smoking, cocaine use). The association of caffeine and nicotine in pharmaceutical products and aneurysmal SAH warrants further study.

Prognostic use of circulating plasma nucleic acid concentrations in patients with acute stroke

BACKGROUND

At present there is no simple, accurate blood test that may be used to determine the severity of stroke or to predict mortality and morbidity in stroke patients presenting to emergency departments.

METHODS

Patients with stroke-like symptoms who presented to an emergency department of a university hospital in Hong Kong were recruited for the study. DNA extracted from patients' plasma was analyzed for the beta-globin gene with a fluorescent-based PCR test. The primary outcome measures were in-hospital and 6-month mortality and morbidity using the post-stroke modified Rankin Score.

RESULTS

Among the 88 consecutive patients recruited to the study, 70 (80%) had ischemic stroke, 11 (13%) had intracerebral hemorrhage, and 7 (8%) had transient ischemic attacks. Median plasma DNA concentrations taken within 3 h of symptom onset were higher in patients who died compared with those who survived at discharge (6205 vs 1334 kilogenome-equivalents/L; P = 0.03). Among patients with NIH Stroke Scale scores >8, median plasma DNA concentrations were higher in patients who died compared with those who survived to 6 months (2273 vs 968 kilogenome-equivalents/L; P = 0.002). Plasma DNA concentrations correlated with the volume of cerebral hematoma (r = 0.66; P = 0.03). Plasma DNA concentrations >1400 kilogenome-equivalents/L had a sensitivity of 100% and a specificity of 74.4% for predicting hospital mortality after stroke, and the area under the ROC curve was 0.89 (95% confidence interval, 0.80-0.94). The adjusted odds ratio for plasma DNA concentrations predicting 6-month mortality was 1.6 (1.1-2.4; P = 0.03) and for predicting 6-month post-Rankin Score >2 was 1.8 (1.0-3.3; P = 0.05).

CONCLUSION

Plasma DNA concentrations correlate with stroke severity and may be used to predict mortality and morbidity in the emergency room.

Current intracerebral haemorrhage management

Primary intracerebral haemorrhage (ICH) refers to spontaneous bleeding from intraparenchymal vessels. It accounts for 10-20% of all strokes, with higher incidence rates amongst African and Asian populations. The major risk factors are hypertension and age. In addition to focal neurological findings, patients may present with symptoms of elevated intracranial pressure. The diagnosis of ICH can only be made through neuro-imaging. A CT scan is presently standard, although MRI is increasingly important in the evaluation of acute cerebrovascular disease. A significant proportion of intracerebral haematomas expand in the first hours post-ictus and this is often associated with clinical worsening. There is evidence that the peri-haematomal region is compromised in ICH. This tissue is oedematous, although the precise pathogenesis is controversial. An association between elevated arterial pressure and haematoma expansion has been reported. Although current guidelines recommend conservative management of arterial pressure in ICH, an acute blood pressure lowering trial is overdue. ICH is associated with a high early mortality rate, although a significant number of survivors make a functional recovery. Current medical management is primarily aimed at prevention of complications including pneumonia and peripheral venous thromboembolism. Elevated intracranial pressure may be treated medically or surgically. Although the latter definitively lowers elevated intracranial pressure, the optimal patient selection criteria are not clear. Aggressive treatment of hypertension is essential in the primary and secondary prevention of ICH.

Vertebral artery atherosclerosis: a risk factor in the use of manipulative therapy?

BACKGROUND AND PURPOSE

Vertebrobasilar insufficiency, a direct result of compromised blood flow in the vertebrobasilar circulation, may be caused by stretching and/or compression of the vertebral arteries, particularly if superimposed on underlying atherosclerosis of the vessels. This is an important consideration when using manipulative therapy techniques. The aim of the present study was to investigate the incidence of atherosclerosis and to calculate the relative associated decrease in blood flow in the third and fourth parts of the vertebral artery, in a sample of the adult population.

METHOD

A laboratory-based experimental investigation was used to study 362 vertebral arteries from embalmed adult cadavers that were routinely processed for light microscopic study. The incidence of each grade of atherosclerosis in the vessels was recorded. Atherosclerosis was classified as grades 0-5, where Grade 0 represented no atherosclerosis and Grade 5 a fully developed plaque occluding more than 75% of the vessel lumen. From mean measurements of 188 of these arteries, the estimated decrease in luminal cross-sectional area and the relative decrease in blood flow in the atherosclerotic vessels were calculated.

RESULTS

The highest incidence of atherosclerosis found was Grade 3 (third part of the vertebral artery (VA3): 42.0%; fourth part of the vertebral artery (VA4): 35.2%). An estimated decrease in artery luminal cross-sectional area to 6.2% of normal in Grade 5 atherosclerosis was found. Because blood flow is proportional to the fourth power of the vessel radius, relative decreases in blood flow in grades 1-5 atherosclerosis from 100% to 0% (with critical closing pressure in vessels), respectively, are likely to occur.

CONCLUSIONS

These data suggest that, as significant numbers of the sample showed marked (Grade 3+) atherosclerosis, concomitant with decreased blood flow in the vertebral arteries, this population is at risk for developing vertebrobasilar insufficiency. Because other Western populations may be similarly at risk, particular care should be taken when considering the use of rotational manipulative therapy techniques in treatments of the cervical spine.

Familial aggregation of intracranial aneurysms in an Inuit patient population in Kalaallit Nunaat (Greenland)

OBJECTIVE

The incidence of subarachnoid hemorrhage (SAH) and intracranial aneurysm (IA) has been reported to be higher in Greenlandic Inuits than in Caucasian Danes, but the rate of familial aggregation in Inuits is unknown.

METHODS

This study retrospectively compared the rate of familial aggregation of SAH and IA (at least one first- or second-degree relative with presumed SAH and/or IA) in 120 Inuit patients from Greenland admitted to the Copenhagen University Hospital in Copenhagen, Denmark, from 1978 to 1998 with a diagnosis of ruptured IA with that in 1,037 Caucasian Danes admitted from 1978 to 1983.

RESULTS

Inuit patients had a much higher rate of familial history of SAH (23.1%) and of IA (9.6%) than Danish patients (4.3 and 1.6%, respectively). In both populations, familial SAH was associated with lower age at the time of aneurysm rupture. Danish patients with familial SAH showed a higher rate of middle cerebral artery aneurysms (40 versus 26% in sporadic SAH). In Inuit patients with familial and nonfamilial SAH, 42 and 38% of the aneurysms originated from the middle cerebral artery. The overall rate of multiple aneurysms was highest among Inuits, and in both populations, it was increased in the presence of a positive family history.

CONCLUSION

The rate of a positive family history of presumed SAH and IA is high among Inuits who present with SAH compared with Caucasian Danes who present with SAH. This finding, coupled with a higher rate of multiple aneurysms and younger age at presentation, suggests a potential genetic influence among Inuit families.

Outcome following intracerebral hemorrhage and subarachnoid hemorrhage

Intracerebral hemorrhage and subarachnoid hemorrhage account for almost 20% of all stroke cases. Both forms of stroke are associated with a high morbidity and mortality rate. The incidence of intracerebral hemorrhage increases with the age and certain ethnical groups are more affected. Subarachnoid hemorrhage tends to occur in a much younger population than other types of strokes. Outcome predictors for intracerebral and subarachnoid hemorrhage have been extensively discussed in the literature. Based on the current literature, we review the morbidity and mortality rates and predictors of outcome for these two life-threatening diseases. Initial Glasgow Coma Scale (GCS) score, hematoma volume, and presence of ventricular blood are the most prominent predictors of outcome following intracerebral hemorrhage. Age and initial severity of neurologic deficits on presentation, measured by GCS, Hunt and Hess Scale or the World Federation of Neurological Surgeons Scale, are the most important predictors of outcome following subarachnoid hemorrhage.

Natural history of perihematomal edema in patients with hyperacute spontaneous intracerebral hemorrhage

BACKGROUND AND PURPOSE

The natural history of perihematomal edema in human hyperacute spontaneous intracerebral hemorrhage (ICH) has not been well described.

METHODS

This study was a secondary analysis of a previously reported prospective, population-based study of hematoma growth in 142 patients with spontaneous ICH. Patients were first imaged within 3 hours of onset, then 1 and 20 hours later. We excluded patients with anticoagulant use (n=7), underlying aneurysm/vascular malformation (n=9), trauma (n=1), incomplete data (n=20), infratentorial ICH (n=17), and no consent (n=2), leaving an overall study population of 86 patients. From this overall group we further excluded patients with intraventricular extension (n=38), subsequent surgery (n=5), or death (n=2) before 20-hour postbaseline CT. This second, "restricted" analysis group of 41 patients was relatively devoid of clinical or radiological variables likely to confound edema measurement. Absolute and relative edema volumes (edema volume divided by hematoma volume) were descriptively summarized. Correlations between baseline edema volumes and relevant clinical and radiological variables were then performed.

RESULTS

Overall, median absolute edema volume increased from 6.93 to 14.4 cm(3) during the first 24 hours after ICH, and median relative edema volume increased from 0.47 to 0.81. In the restricted group, median absolute edema volume was 7.4 cm(3) at baseline and 11.0 cm(3) at 24 hours after ICH, and median relative edema volume increased from 0.55 to 0.81. Baseline relative edema volume was significantly negatively correlated with subsequent change in relative edema volume from baseline to 20-hour CT (r=0.57, P=0.0002) but was not significantly correlated with other clinical and radiological variables, including hematoma volume or change in hematoma volume.

CONCLUSIONS

Perihematomal edema volume increases by approximately 75% during the first 24 hours after hyperacute spontaneous ICH. Patients with the least amounts of baseline relative edema volume were most likely to develop significant additional amounts of edema during the first 24 hours after spontaneous ICH.

Genetics of intracranial aneurysm

Subarachnoid hemorrhage (SAH) secondary to ruptured saccular intracranial aneurysm (IA) is a complex trait, with both genetic and environmental risk factors playing an important part. The 30-day mortality rate of patients with SAH is 40% to 44%, with many survivors suffering from major disability. Because most of the mortality after SAH is caused by rapid and massive brain injury from the initial bleeding, primary prevention of aneurysm formation and rupture is of paramount importance. This article reviews the evidence supporting a genetic predisposition to SAH from saccular IA, the conditions commonly associated with saccular IA, and the search for genetic risk factors.

Intracerebral hemorrhage

There is a significant variation in the management of ICH by neurologists, neurosurgeons, and emergency physicians. Most of the randomized clinical therapeutic trials have focused on subarachnoid hemorrhage (SAH) and acute ischemic stroke (AIS). Well-organized practice guidelines are now available for the management of ICH. Exciting research areas are being aggressively explored. Medical and surgical interventions for SAH, AIS, and ICH are always time-dependent, which places additional responsibility on the EP to correctly and promptly recognize these conditions to prevent further injury. The time-dependent care of these patients places the EP on the front lines of future stroke care. Special thanks to Dr. Daniel Woo and Dr. Stewart Wright for their assistance in reviewing the manuscript and Amy Hess for preparation of the manuscript.

Spontaneous intracerebral hemorrhage: epidemiology and clinical presentation

The advent of widespread CT availability has dramatically changed our understanding of the incidence and risk factors regarding intracerebral hemorrhage (ICH). In the pre-CT era, many patients with a small ICH were misclassified having had ischemic strokes and patients with massive ICH or subarachnoid hemorrhage (SAH) were often difficult to classify correctly. The fact that the precise mechanism of spontaneous ICH is often difficult to ascertain without pathologic evidence continues to hamper epidemiologic studies. This article reviews the incidence rates, natural history, epidemiology, and clinical presentations of nontraumatic ICH.

Spontaneous intracerebral hemorrhage: epidemiology, pathophysiology, and medical management

This article introduces the basic epidemiology of intracerebral hemorrhage (ICH) and discusses the current available literature on the pathophysiology of primary ICH, hematoma enlargement, and cerebral edema. The article also includes a brief presentation of the basic steps regarding initial ICH management is presented as a framework for patient care.

Minimally invasive therapy for intracerebral hematomas

The efficacy of surgical treatment of ICH remains unproven and controversial [40]. Although open surgery does not appear to improve the patient's outcome [2], less invasive methods of hematoma evacuation seem to show promising results in improving patient outcome and survival. To date, the only two clinical trials that have demonstrated benefit from surgical treatment over medical therapy for ICH have used minimally invasive techniques [27,38]. Randomized controlled clinical trials comparing minimally invasive surgical techniques versus best medical treatment are needed to determine the best management of ICH.

Stroke: a review with an African perspective

The frequency of stroke and stroke-associated mortality are higher in Blacks than in other races. Several of the known risk factors for stroke, such as hypertension, diabetes and obesity, are more common in Blacks than Whites, and sickle-cell disease and HIV infection are stroke risk factors with particular relevance to Africans. Although the facilities for accurate stroke diagnosis and classification are unavailable in most parts of Africa, careful analysis of the clinical features can minimize the rates of misdiagnosis and misclassification. The high levels of stroke-attributable morbidity and mortality observed in Africans could be markedly reduced by instituting primary and secondary preventive measures and by educating health-care professionals on stroke-management strategies.

Genetic and environmental risk factors for intracerebral hemorrhage: preliminary results of a population-based study

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) has a 30-day mortality rate of 40% to 50% and lacks a proven treatment. We report a preplanned, midpoint analysis of the first population-based, case-control study that examines both genetic and environmental risk factors of ICH.

METHODS

We prospectively identified cases of hemorrhagic stroke at all 16 hospitals in the Greater Cincinnati/Northern Kentucky region. All cases underwent medical record and neuroimaging review. Cases enrolled in the direct interview and genetic sampling arm of the study were matched to population-based control subjects by age, race, and sex. Multivariable logistic regression was performed to identify significant independent risk factors.

RESULTS

We enrolled 188 cases of ICH (67 lobar, 121 nonlobar) and 366 control subjects in the direct interview arm of the study. Significant independent risk factors for lobar ICH included the presence of an apolipoprotein E2 or E4 allele, frequent alcohol use, prior stroke, and first-degree relative with ICH. Significant independent risk factors for nonlobar ICH were hypertension, prior stroke, and first-degree relative with ICH. An increasing level of education was associated with a decreased risk of nonlobar ICH. The attributable risk of apolipoprotein E2 or E4 for lobar ICH was 29%, and the attributable risk of hypertension for nonlobar ICH was 54%.

CONCLUSIONS

There is significant epidemiological evidence that the pathophysiology of ICH varies by location. We estimate that a third of all cases of lobar ICH are attributable to possession of an apolipoprotein E4 or E2 allele and that half of all cases of nonlobar ICH are attributable to hypertension.

Subarachnoid hemorrhage: a preventable disease with a heritable component

BACKGROUND AND PURPOSE

Subarachnoid hemorrhage (SAH) caused by ruptured intracranial aneurysm affects approximately 16 000 Americans annually, and almost 40% of affected patients die within 30 days despite the best current therapy. Prevention of SAH is therefore of paramount importance. We present a preliminary analysis of risk factors for SAH from our population-based, case-control study.

METHODS

Cases were prospectively collected and matched 2:1 by age, race, and gender to controls using random digit dialing. Personal risk factor history, family history, neuroimaging data, and genetic samples were obtained. Univariate and bivariate analyses were performed and population-attributable risks estimated. Multivariable analysis was performed using conditional logistic regression.

RESULTS

Between June 1997 and February 2000, 107 cases and 197 controls were enrolled. In bivariate analyses, a large proportion of population-attributable risk for SAH could be explained by modifiable risk factors: smoking, hypertension, and heavy alcohol use. In multivariable analysis, current cigarette smoking, history of hypertension, frequent alcohol use, lower body mass index, and a family history of a relative with SAH or intracranial aneurysm were found to be significant, independent risk factors for SAH.

CONCLUSION

Our data confirm previous reports that SAH clusters within some families independent of environmental risk factors, suggesting that SAH has a significant genetic component. Yet, even among families at increased risk of SAH, smoking cessation, treatment of hypertension, and reduced alcohol intake may substantially decrease SAH risk. The independent associations with heavy alcohol use and low body mass index with SAH may be confounded by smoking and require further study.

The emergence of cardiovascular disease during urbanisation of Africans

OBJECTIVE

To review the available data on risk factors for cardiovascular disease (CVD), the influence of urbanisation of Africans on these risk factors, and to examine why stroke emerges as a higher risk than ischaemic heart disease (IHD) in the health transition of black South Africans.

DESIGN

A review of published data on mortality from and risk factors of CVD in South Africans.

SETTING

South Africa.

SUBJECTS

South African population groups and communities.

METHODS

The available data on the contribution of stroke and IHD to CVD mortality in South Africa are briefly reviewed, followed by a comparison of published data on the prevalence and/or levels of CVD risk factors in the different South African population groups. The impact of urbanisation of black South Africans on these risk factors is assessed by comparing rural and urban Africans who participated in the Transition and Health during Urbanisation of South Africans (THUSA) study.

RESULTS AND CONCLUSIONS

The mortality rates from CVD confirmed that stroke is a major public health problem amongst black South Africans, possibly because of an increase in hypertension, obesity, smoking habit and hyperfibrinogenaemia during various stages of urbanisation. The available data further suggest that black South Africans may be protected against IHD because of favourable serum lipid profiles (low cholesterol and high ratios of high-density lipoprotein cholesterol) and low homocysteine values. However, increases in total fat and animal protein intake of affluent black South Africans, who can afford Western diets, are associated with increases in body mass indices of men and women and in total serum cholesterol. These exposures may increase IHD risk in the future.

Unruptured intracranial aneurysms: a review

OBJECT

In this article, pathological, radiological, and clinical information regarding unruptured intracranial aneurysms is reviewed.

METHODS

Treatment decisions require that surgeons and interventionists take into account information obtained in pathological, radiological, and clinical studies of unruptured aneurysms. The author has performed a detailed review of the literature and has compared, contrasted, and summarized his findings. Unruptured aneurysms may be classified as truly incidental, part of a multiple aneurysm constellation, or symptomatic by virtue of their mass, irritative, or embolic effects. Unruptured aneurysms with clinical pathological profiles resembling those of ruptured lesions should be considered for treatment at a smaller size than unruptured lesions with profiles typical of intact aneurysms, as has been determined at autopsy in patients who have died of other causes. The track record of the surgeon or interventionist and the institution in which treatment is to be performed should be considered while debating treatment options. In cases in which treatment is not performed immediately, ongoing periodic radiological assessment may be wise. Radiological investigations to detect unruptured aneurysms in asymptomatic patients should be restricted to high-prevalence groups such as adults with a strong family history of aneurysms or patients with autosomal dominant polycystic kidney disease. All patients with intact lesions should be strongly advised to discontinue cigarette smoking if they are addicted.

CONCLUSIONS

The current state of knowledge about unruptured aneurysms does not support the use of the largest diameter of the lesion as the sole criterion on which to base treatment decisions, although it is of undoubted importance.

Risk factors for subarachnoid hemorrhage

OBJECTIVE

Cigarette smoking has been demonstrated to increase the risk of subarachnoid hemorrhage (SAH). Whether cessation of smoking decreases this risk remains unclear. We performed a case-control study to examine the effect of smoking and other known risk factors for cerebrovascular disease on the risk of SAH.

METHODS

We reviewed the medical records of all patients with a diagnosis of SAH (n = 323) admitted to Johns Hopkins Hospital between January 1990 and June 1997. Controls matched for age, sex, and ethnicity (n = 969) were selected from a nationally representative sample of the Third National Health and Nutrition Examination Survey. We determined the independent association between smoking (current and previous) and various cerebrovascular risk factors and SAH by use of multivariate logistic regression analysis. A separate analysis was performed to determine associated risk factors for aneurysmal SAH.

RESULTS

Of 323 patients admitted with SAH (mean age, 52.7+/-14 yr; 93 were men), 173 (54%) were hypertensive, 149 (46%) were currently smoking, and 125 (39%) were previous smokers. In the multivariate analysis, both previous smoking (odds ratio [OR], 4.5; 95% confidence interval [CI], 3.1-6.5) and current smoking (OR, 5.2; 95% CI, 3.6-7.5) were significantly associated with SAH. Hypertension was also significantly associated with SAH (OR, 2.4; 95% CI, 1.8-3.1). The risk factors for 290 patients with aneurysmal SAH were similar and included hypertension (OR, 2.4; 95% CI, 1.8-3.2), previous smoking (OR, 4.1; 95% CI, 2.7-6.0), and current smoking (OR, 5.4; 95% CI, 3.7-7.8).

CONCLUSION

Hypertension and cigarette smoking increase the risk for development of SAH, as found in previous studies. However, the increased risk persists even after cessation of cigarette smoking, which suggests the importance of early abstinence from smoking.

Treatment of aneurysmal subarachnoid haemorrhage in elderly patients

Spontaneous subarachnoid haemorrhage (SAH) due to ruptured saccular aneurysm is the fourth most frequent cerebrovascular disorder following atherosclerosis, embolism, and primary intracerebral haemorrhage (1). SAH is a common and often devastating condition, which is a significant cause of world-wide morbidity and mortality (2). The aim of this article is to review the epidemiology, pathophysiology and current management of SAH.

The benefit of an acute stroke unit in patients with intracranial haemorrhage: a controlled trial

OBJECTIVES

Patients with stroke receiving organised inpatient (stroke unit) care after stroke are more likely to be alive and independent compared with patients offered conventional care. The objective was to determine the effect of an acute stroke unit on patients with primary intracranial haemorrhage.

METHODS

In a prospective controlled study, the effect of an acute stroke unit was examined on 30 day and 1 year mortality in patients with primary intracranial haemorrhage. Patients treated in general medical wards served as controls.

RESULTS

Of 121 patients included, 56 were allocated to an acute stroke unit and 65 to a general medical ward. The 30 day mortality rate was 39% in the acute stroke unit compared with 63% in the general medical wards, and the 1 year mortality rates were 52% and 69%, respectively. There was a difference between the 30 day and 1 year survival curves between the groups (p=0.007 and 0.013, respectively); however, there was no difference in survival between 30 and 365 days. There was no difference in risks of being discharged home or to long term care between the groups.

CONCLUSIONS

In this study admission to an acute stroke unit reduced mortality 30 days and 1 year after primary intracranial haemorrhage, which could be attributed to a large difference in survival during the first 30 days.

Subarachnoid haemorrhage: diagnosis, causes and management

The incidence of subarachnoid haemorrhage (SAH) is stable, at around six cases per 100 000 patient years. Any apparent decrease is attributable to a higher rate of CT scanning, by which other haemorrhagic conditions are excluded. Most patients are <60 years of age. Risk factors are the same as for stroke in general; genetic factors operate in only a minority. Case fatality is approximately 50% overall (including pre-hospital deaths) and one-third of survivors remain dependent. Sudden, explosive headache is a cardinal but non-specific feature in the diagnosis of SAH: in general practice, the cause is innocuous in nine out of 10 patients in whom this is the only symptom. CT scanning is mandatory in all, to be followed by (delayed) lumbar puncture if CT is negative. The cause of SAH is a ruptured aneurysm in 85% of cases, non-aneurysmal perimesencephalic haemorrhage (with excellent prognosis) in 10%, and a variety of rare conditions in 5%. Catheter angiography for detecting aneurysms is gradually being replaced by CT angiography. A poor clinical condition on admission may be caused by a remediable complication of the initial bleed or a recurrent haemorrhage in the form of intracranial haematoma, acute hydrocephalus or global brain ischaemia. Occlusion of the aneurysm effectively prevents rebleeding, but there is a dearth of controlled trials assessing the relative benefits of early operation (within 3 days) versus late operation (day 10-12), or that of endovascular treatment versus any operation. Antifibrinolytic drugs reduce the risk of rebleeding, but do not improve overall outcome. Measures of proven value in decreasing the risk of delayed cerebral ischaemia are a liberal supply of fluids, avoidance of antihypertensive drugs and administration of nimodipine. Once ischaemia has occurred, treatment regimens such as a combination of induced hypertension and hypervolaemia, or transluminal angioplasty, are plausible, but of unproven benefit.

Intracerebral hemorrhage: update

The present review focuses on evolving concepts in the pathogenesis and management of deep and lobar intracerebral hemorrhage subtypes, with particular focus on the relationship between lobar intracerebral hemorrhage, apolipoprotein E subtypes and cerebral amyloid angiopathy; deep intracerebral hemorrhage and the potential interaction between hypertension and low cholesterol; and new concepts in medical and surgical therapy for acute intracerebral hemorrhage.

Phenylpropanolamine and the risk of hemorrhagic stroke

BACKGROUND

Phenylpropanolamine is commonly found in appetite suppressants and cough or cold remedies. Case reports have linked the use of products containing phenylpropanolamine to hemorrhagic stroke, often after the first use of these products. To study the association, we designed a case-control study.

METHODS

Men and women 18 to 49 years of age were recruited from 43 U.S. hospitals. Eligibility criteria included the occurrence of a subarachnoid or intracerebral hemorrhage within 30 days before enrollment and the absence of a previously diagnosed brain lesion. Random-digit dialing identified two matched control subjects per patient.

RESULTS

There were 702 patients and 1376 control subjects. For women, the adjusted odds ratio was 16.58 (95 percent confidence interval, 1.51 to 182.21; P=0.02) for the association between the use of appetite suppressants containing phenylpropanolamine and the risk of a hemorrhagic stroke and 3.13 (95 percent confidence interval, 0.86 to 11.46; P=0.08) for the association with the first use of a product containing phenylpropanolamine. All first uses of phenylpropanolamine involved cough or cold remedies. For men and women combined, the adjusted odds ratio was 1.49 (95 percent confidence interval, 0.84 to 2.64; P=0.17) for the association between the use of a product containing phenylpropanolamine and the risk of a hemorrhagic stroke, 1.23 (95 percent confidence interval, 0.68 to 2.24; P=0.49) for the association with the use of cough or cold remedies that contained phenylpropanolamine, and 15.92 (95 percent confidence interval, 1.38 to 184.13; P=0.03) for the association with the use of appetite suppressants that contained phenylpropanolamine. An analysis in men showed no increased risk of a hemorrhagic stroke in association with the use of cough or cold remedies containing phenylpropanolamine. No men reported the use of appetite suppressants.

CONCLUSIONS

The results suggest that phenylpropanolamine in appetite suppressants, and possibly in cough and cold remedies, is an independent risk factor for hemorrhagic stroke in women.

Estimate of the maximum time interval between formation of cerebral aneurysm and rupture

The recent publication of the results of the international study on unruptured intracranial aneurysms highlighted a paradox: there do not seem to be enough unruptured aneurysms in the population to account for the observed incidence of subarachnoid haemorrhage. Some authors have suggested that the answer to this paradox is that most aneurysms that bleed do so shortly after formation. This would mean that the bulk of subarachnoid haemorrhages come from recently formed rather than long standing aneurysms. This paradox and proposed answer are examined. The available statistics on the incidence of subarachnoid haemorrhage, the prevalence of unruptured aneurysms, and the risk of bleeding from unruptured aneurysms are used to place a maximum on the time interval between aneurysm formation and rupture. For aneurysms less than 10 mm in diameter in persons with no history of subarachnoid haemorrhage, an estimate of less than 42 weeks was made. The null hypothesis that such aneurysms pose a constant risk with time is rejected with p <10(-9). In larger aneurysms the risk seems to be constant with time.