Anatomy and functionality of leptomeningeal anastomoses: a review.

BACKGROUND This review seeks to provide a structured presentation of existing knowledge of leptomeningeal anastomoses from anatomic and functional points of view and to identify problems and possible research directions to foster a better understanding of the subject and of stroke mechanisms. SUMMARY OF REVIEW Available data show that leptomeningeal anastomoses may be important in understanding stroke mechanisms and that leptomeningeal anastomoses play an important role in penumbra outcome. However, the literature shows no consensus between statements on the existence of leptomeningeal anastomoses and compensatory capacity. CONCLUSIONS By analyzing the available literature and identifying the factors that contribute to this confusion, we found that variability and the functional consequences thereof are important but that quantitative data are lacking. Moreover, vascular remodeling is an issue to consider.