Characterizing the Venous Anatomy of Craniopagus Twins

Craniopagus deformity is a rare congenital anomaly occurring in 1 of 1 700 000 live births and represents 2%-6% of all conjoined twins. Staged surgical separation, with a focus on disconnecting shared venous anatomy, has become the mainstay of treatment for most patients in the modern era. The aim of this report was to classify the shared venous anatomy of these twins and determine implications on surgical separation.

Cases from Dr James Goodrich's library were classified and rendered according to their venous anatomy into virtual models. Data from 16 sets of twins were studied. Two were O'Connell type I, 4 were type II, and 10 were type III twins. Two patterns of venous anatomical communication and sharing emerged with twins showing a more acute angle of rotation demonstrated a common circumferential sinus pattern, and twins with a greater rotational angle (type II) demonstrated a helical sinus orientation of their sagittal sinuses.

This is the largest anatomical study of craniopagus twins, focused on shared venous anatomy. A better understanding of the anatomical patterns of these patients may result in safer surgical disconnection in the future. We observed that as axial rotation approaches 90°, the organization around a circumferential sinus slowly transitions into a continuous helical sinus, connecting the anterior superior sagittal sinus of each twin. In the future, as our understanding of the vascular anatomy matures, a vessel-specific plan for separation within these two patterns, taking into account blood flow and perfusion, will be possible before ever stepping foot into the operating room.