C. Stapf

The New York Islands AVM Study Design, Study Progress, and Initial Results

Background and Purpose— Prospective population-based data on the incidence of brain arteriovenous malformation (AVM) hemorrhage are scarce. We studied lifetime detection rates of brain AVM and incident AVM hemorrhage in a defined population. Methods— The New York islands (ie, Manhattan Island, Staten Island, and Long Island) comprise a 9 429 541 population according to the 2000 census. Since March 15, 2000, all major New York islands hospitals have prospectively reported data on consecutive patients living in the study area with a diagnosis of brain AVM and whether the patient had suffered AVM hemorrhage. Patients living outside the ZIP code–defined study area were excluded from the study population. Results— As of June 14, 2002, 284 prospective AVM patients (mean±SD age, 35±18 years; 49% women) were encountered during 21 216 467 person-years of observation, leading to an average annual AVM detection rate of 1.34 per 100 000 person-years (95% CI, 1.18 to 1.49). The incidence of first-ever AVM hemorrhage (n=108; mean age, 31±19 years; 45% women) was 0.51 per 100 000 person-years (95% CI, 0.41 to 0.61). The estimated prevalence of AVM hemorrhage among detected cases (n=144; mean age, 33±19 years; 50% women) was 0.68 per 100 000 (95% CI, 0.57 to 0.79). Conclusions— Our prospective data, spanning 27 months, suggest stable rates for AVM detection and incident AVM hemorrhage. Approximately half of AVM patients may suffer intracranial hemorrhage.

Risk of Endovascular Treatment of Brain Arteriovenous Malformations

Background and Purpose— Independently assessed data on frequency, severity, and determinants of neurological deficits after endovascular treatment of brain arteriovenous malformations (AVMs) are scarce. Methods— From the prospective Columbia AVM Study Project, 233 consecutive patients with brain AVM receiving ≥1 endovascular treatments were analyzed. Neurological impairment was assessed by a neurologist using the Rankin Scale before and after completed endovascular therapy. Multivariate logistic regression models were used to identify demographic, clinical, and morphological predictors of treatment-related neurological deficits. The analysis included the components used in the Spetzler-Martin risk score for AVM surgery (AVM size, venous drainage pattern, and eloquence of AVM location). Results— The 233 patients were treated with 545 endovascular procedures. Mean follow-up time was 9.6 months (SD, 18.1 months). Two hundred patients (86%) experienced no change in neurological status after treatment, and 33 patients (14%) showed treatment-related neurological deficits. Of the latter, 5 (2%) had persistent disabling deficits (Rankin score >2), and 2 (1%) died. Increasing patient age [odds ratio (OR), 1.04; 95% confidence interval (CI), 1.01 to 1.08], number of embolizations (OR, 1.41; 95% CI, 1.16 to 1.70), and absence of a pretreatment neurological deficit (OR, 4.55; 95% CI, 1.03 to 20.0) were associated with new neurological deficits. None of the morphological AVM characteristics tested predicted treatment complications. Conclusions— From independent neurological assessment and prospective data collection, our findings suggest a low rate of disabling treatment complications in this center for endovascular brain AVM treatment. Risk predictors for endovascular treatment differ from those for AVM surgery.

Determinants of Neurological Outcome After Surgery for Brain Arteriovenous Malformation

Background and Purpose We sought to define determinants of neurological deficit after surgery for brain arteriovenous malformation (AVM). Methods One hundred twenty-four prospective patients (48% women, mean age 33 years) underwent microsurgical brain AVM resection. Patients were examined by 3 study neurologists immediately before surgery, postoperatively in-hospital, by in-person long-term follow-up, and with a structured telephone follow-up. They were classified according to the 5-point Spetzler-Martin grading system, with its 3 elements: size, venous drainage pattern, and location. The functional neurological status was classified with the modified Rankin scale. Multivariate logistic regression models were applied to test the effect of patient age, gender, and the 3 Spetzler-Martin elements on early and long-term postoperative neurological complications. Results Twelve patients (10%) were classified as Spetzler-Martin grade 1; 36 (29%) as grade 2; 47 (38%) as grade 3; 26 (21%) as grade 4; and 3 (2%) as grade 5. Postoperatively, in-hospital, 51 patients (41%) showed new neurological deficits (15% disabling [ie, Rankin scale score >2] and 26% nondisabling [ie, Rankin 1 or 2]). At long-term follow-up (mean follow-up time 12 months), 47 patients (38%) revealed surgery-related neurological deficits (6% disabling; 32% nondisabling). The rate of neurological complications increased by Spetzler-Martin grade. Female gender, AVM size, and deep venous drainage were significantly associated with neurological deficits at in-hospital and long-term evaluation. For patient age and AVM location, no significant association was found. Conclusions The findings suggest that female gender, AVM size, and AVM drainage into the deep venous system may be determinants of neurological deficit after microsurgical AVM resection.

Association of Infratentorial Brain Arteriovenous Malformations With Hemorrhage at Initial Presentation

Background and Purpose— The goal of this study was to analyze the association of hemorrhagic presentation with infratentorial brain arteriovenous malformations (AVMs). Methods— The 623 consecutive, prospectively enrolled patients from the Columbia AVM Databank were analyzed in a cross-sectional study. Clinical presentation (diagnostic event) was categorized as intracranial hemorrhage or nonhemorrhagic presentation. From brain imaging and cerebral angiography, AVM location was classified as either infratentorial or supratentorial. Univariate and multivariate statistical models were applied to test the effect of age, sex, AVM size and location, venous drainage pattern, and associated (ie, feeding artery or intranidal) arterial aneurysms on the likelihood of hemorrhage at initial AVM presentation. Results— Of the 623 patients, 72 (12%) had an infratentorial and 551 (88%) had a supratentorial AVM. Intracranial hemorrhage was the presenting symptom in 283 patients (45%), and infratentorial AVM location was significantly more frequent (18%) among patients who bled initially (6%; odds ratio [OR], 3.60; 95% confidence interval [CI], 2.09 to 6.20). This difference remained significant (OR, 1.99; 95% CI, 1.07 to 3.69) in the multivariate logistic regression model controlling for age, sex, AVM size, deep venous drainage, and associated arterial aneurysms. In the same model, the effect of other established determinants for AVM hemorrhage—ie, AVM size (in 1-mm increments; OR, 0.95; 95% CI, 0.94 to 0.96), deep venous drainage (OR, 3.09; 95% CI, 1.87 to 5.12), and associated aneurysms (OR, 2.78; 95% CI, 1.76 to 4.40)—remained significant. Conclusions— Our findings suggest that infratentorial AVM location is independently associated with hemorrhagic AVM presentation.

Effect of Age on Clinical and Morphological Characteristics in Patients With Brain Arteriovenous Malformation

Background and Purpose— The goal of this work was to determine the effect of age at initial presentation on clinical and morphological characteristics in patients with brain arteriovenous malformation (AVM). Methods— The 542 consecutive patients from the prospective Columbia AVM database (mean±SD age, 34±15 years) were analyzed. Univariate statistical models were used to test the effect of age at initial presentation on clinical (AVM hemorrhage, seizures, headaches, neurological deficit, other/asymptomatic) and morphological (AVM size, venous drainage pattern, AVM brain location, concurrent arterial aneurysms) characteristics. Results— Hemorrhage was the presenting symptom in 46% (n=247); 29% (n=155) presented with seizures, 13% (n=71) with headaches, 7% (n=36) with a neurological deficit, and 6% (n=33) without AVM-related symptoms. Increasing age correlated positively with intracranial hemorrhage (P =0.001), focal neurological deficits (P =0.007), infratentorial AVMs (P <0.001), and concurrent arterial aneurysms (P <0.001); an inverse correlation was found with seizures (P <0.001), AVM size (P =0.001), and lobar (P <0.001), deep (P =0.008), and borderzone (P =0.014) location. No age differences were found for sex, headache, asymptomatic presentation, and venous drainage pattern. Conclusions— Our data suggest a significant interaction of patient age and clinical and morphological AVM features and argue against uniform AVM characteristics across different age classes at initial presentation. In particular, AVM patients diagnosed at a higher age show a higher fraction of AVM hemorrhage and are more likely to harbor additional risk factors such as concurrent arterial aneurysms and small AVM diameter. Longitudinal population-based AVM data are necessary to confirm these findings.

Incidence of adult brain arteriovenous malformation hemorrhage in a prospective population-based stroke survey

Background: Brain arteriovenous malformations (AVMs) represent a potential source of intracranial hemorrhage, especially in young adults, but prospective population-based incidence data on AVM hemorrhage are lacking. We investigated the incidence of first-ever AVM hemorrhage in adults based on population data from the Northern Manhattan Stroke Study (NOMASS). Methods: NOMASS is a prospective, population-based, stroke incidence survey collecting all hospitalized and nonhospitalized cases with first-ever (incident) stroke over the age of 20 in a ZIP code-defined area. All patients undergo CT and/or MR brain imaging and clinical data are systematically collected from the medical records. For this study, data on all cases with incident intracranial hemorrhage, i.e. any intracerebral, intraventricular and/or subarachnoid hemorrhage, occurring between July 1, 1993 and June 30, 1997 were used. Patients with intracranial hemorrhage due to trauma, tumor or intracranial vascular malformations other than a previously unknown AVM were excluded from the study. Results: Of the 207 patients diagnosed with a first-ever intracranial hemorrhage, 3 cases (1.4%) with an underlying brain AVM were identified. The crude incidence rate for first-ever AVM hemorrhage in our adult population was 0.55 per 100,000 person-years (95% confidence interval 0.11–1.61). Conclusions: Our results support prior findings from retrospective surveys. Population-based studies providing a prospective design for AVM detection and diagnosis are needed to confirm the data.

Incident Hemorrhage Risk of Brain Arteriovenous Malformations Located in the Arterial Borderzones

Background and Purpose We sought to assess the relative risk of hemorrhagic presentation of brain arteriovenous malformations (AVMs) located in the arterial borderzone territories. Methods The 464 consecutive, prospectively enrolled patients from the New York AVM Databank were analyzed. AVM borderzone location was coded positive when the malformation was supplied by branches of at least 2 of the major circle of Willis arteries (anterior, middle, and/or posterior cerebral arteries). AVMs fed by branches of only 1 major pial or any other single artery served as a comparison group. Clinical presentation (diagnostic event) was categorized as (1) intracranial hemorrhage, proven by brain imaging, or (2) seizure, focal neurological deficit, headache, or other event with no signs of AVM hemorrhage on brain imaging. Results In 48% (n=222) of the patients, AVMs were located in the arterial borderzone territories; in 52% (n=242) a non-borderzone location was found. Hemorrhage was the presenting symptom in 44% (n=205); 28% (n=132) presented with seizures, 11% (n=52) with headaches, 7% (n=34) with a neurological deficit, and 9% (n=41) with other or no AVM-related symptoms. The frequency of incident AVM hemorrhage was significantly lower in borderzone AVMs (27%, n=61) than in non-borderzone malformations (60%, n=144;P <0.001). This difference remained significant in a multivariate model controlling for age, sex, AVM size, deep venous drainage, and presence of aneurysms (odds ratio, 0.4; 95% CI, 0.25 to 0.66). Conclusions Our findings suggest that borderzone location is an independent determinant for a lower risk of AVM hemorrhage at initial presentation.