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P-035 completion of the circle of willis is gender, age, and indication relative
  1. O Zaninovich1,
  2. W Ramey2,
  3. C Walter2,
  4. T Dumont2
  1. 1University of Arizona College of Medicine Tucson, Tucson, Az
  2. 2Division of Neurosurgery, Banner University Medical Center Tucson, Tucson, Az


Introduction The circle of willis (cow) is the foremost anastomosis and blood distribution center of the brain. Its effectiveness in collateral circulation, redirection of blood flow, and perfusion pressure maintenance is dependent on its completion and the size and patency of its vessels. Gender- and age-related anatomical variations in the cow may play an important role in the pathogenesis of gender- and age-related differences in the rates and distribution patterns of cerebrovascular diseases. In this study, we analyzed ct angiograms to assess for gender-, age-, and indication- related differences in cow completion.

Methods CT angiograms performed at our hospital between years 2014–2016 (907 ctas) were assessed for completion of cow by the senior and first authors. CTAS were excluded, if vessels could not be visualized, slices were >1 mm thickness, or patient was pediatric. The remaining 833 cases were used to compare the incidence of complete cow and variation frequency based on gender, age, and indication. All tests were chi-squared.

Results The incidence of complete cow was 37.6% overall. Cow completion exhibited a statistically significant decrease with increasing age for all age groups in both men (47.1%, 29.4%, 18.8%) and women (60.4%, 44.7%, 32.1). Completion was greater in women (44.8%) than men (31.3%) overall and for all age groups. These gender differences were all statistically significant except for in the 18–39 age group. The most frequent of the 29 cow variations were absent bil-pcom (16.8%), r-pcom (15.4%), and l-pcom (11.0%). With respect to indications, ischemic stroke and the 18–39 age group of hemorrhagic stroke showed a statistically significant reduction in completion relative to trauma.

Conclusion The incidence of complete cow is greater in women for all age groups and decreases with age in both genders. the most frequently absent vessel is pcom, either unilaterally or bilaterally. completion was significantly reduced in ischemic stroke and a subset of hemorrhagic stroke patients, suggesting that an incomplete cow is a risk factor for these indications.

Disclosures O. Zaninovich: None. W. Ramey: None. C. Walter: None. T. Dumont: None.

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