Relationship of A1segment hypoplasia to anterior communicating artery aneurysm morphology and risk factors for aneurysm formation.
OBJECTIVE Hypoplasia of the A1segment of the anterior cerebral artery is frequently observed in patients with anterior communicating artery (ACoA) aneurysms. The effect of this anatomical variant on ACoA aneurysm morphology is not well understood. METHODS Digital subtraction angiography images were reviewed for 204 patients presenting to the authors' institution with either a ruptured or an unruptured ACoA aneurysm. The ratio of the width of the larger A1segment to the smaller A1segment was calculated. Patients with an A1ratio greater than 2 were categorized as having A1segment hypoplasia. The relationship of A1segment hypoplasia to both patient and aneurysm characteristics was then assessed. RESULTS Of 204 patients that presented with an ACoA aneurysm, 34 (16.7%) were found to have a hypoplastic A1. Patients with A1segment hypoplasia were less likely to have a history of smoking (44.1% vs 62.9%, p = 0.0410). ACoA aneurysms occurring in the setting of a hypoplastic A1were also found to have a larger maximum diameter (mean 7.7 vs 6.0 mm, p = 0.0084). When considered as a continuous variable, increasing A1ratio was associated with decreasing aneurysm dome-to-neck ratio (p = 0.0289). There was no significant difference in the prevalence of A1segment hypoplasia between ruptured and unruptured aneurysms (18.9% vs 10.7%; p = 0.1605). CONCLUSIONS Our results suggest that a hypoplastic A1may affect the morphology of ACoA aneurysms. In addition, the relative lack of traditional risk factors for aneurysm formation in patients with A1segment hypoplasia argues for the importance of hemodynamic factors in the formation of ACoA aneurysms in this anatomical setting.
Departments of 1 Neurosurgery.
Lorenzo
L
Rinaldo
Departments of 1 Neurosurgery.
Brandon A
BA
McCutcheon
Departments of 1 Neurosurgery.
Meghan E
ME
Murphy
Departments of 1 Neurosurgery.
Mohamad
M
Bydon
Neurocritical Care, and.
Alejandro A
AA
Rabinstein
Departments of 1 Neurosurgery.|Neurointerventional Radiology, Mayo Clinic, Rochester, Minnesota.
Giuseppe
G
Lanzino
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017542:Aneurysm, Ruptured / Q000453:epidemiology / Q000209:etiology; D015901:Angiography, Digital Subtraction; D020771:Anterior Cerebral Artery / Q000002:abnormalities* / Q000000981:diagnostic imaging; D015331:Cohort Studies; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors
A1 hypoplasia; ACA = anterior cerebral artery; ACoA = anterior communicating artery; DSA = digital subtraction angiography; WFNS = World Federation of Neurosurgical Societies; aneurysm morphology; anterior communicating artery aneurysms; dome-to-neck ratio; mFS = modified Fisher scale; vascular disorders