Incomplete Circle of Willis: A risk factor for mesial temporal sclerosis?

- Incomplete posterior circulation appears associated with the presence of ipsilateral MTS.
- Fetal posterior circulation shows a tendency toward association with ipsilateral MTS.
- Incomplete posterior circulation may facilitate development of MTS, in the watershed zones.

ObjectiveThe aim of this study was to investigate whether there may be a correlation between the anatomical variants of Circle of Willis (CoW) and presence/laterality of mesial temporal sclerosis (MTS).MethodsWe retrospectively identified the CoW variants on Wada angiograms in 71 patients with pathologically proven MTS. Angiograms were interpreted by two radiologists independently and blinded to clinical data. We divided the anterior and posterior components of the CoW into functionally complete and functionally incomplete groups. We then sought its correlation with the presence and laterality of MTS.ResultsNo statistically significant relationship was found between the functional status of the anterior circulation and the laterality of the MTS (p = 0.657). Relationship of the posterior incomplete circle to MTS was statistically significant on both sides (p = 0.023 for the left, p = 0.04 for the right), with an effect size moderate to large for the left side and moderate for the right side. Although the fetal variant appeared to be related to the ipsilateral MTS, it did not reach to a level of statistical significance (p = 0.15).SignificanceThe study demonstrates a statistically significant association of the incomplete posterior circulation of the CoW to the presence of ipsilateral MTS. Further studies in larger patient populations may be needed to seek whether an incomplete circulation may facilitate development of MTS, especially affecting the watershed zones.