A study of the cerebral venous drainage patterns in craniosynostosis: nonsyndromic cases and the induction effect of Virchow's law on venous sinuses.

Objective: Surgical intervention is commonly necessary for craniosynostosis. One of the preoperative concerns revolves around the cerebral venous drainage pattern and its potential involvement during surgery. Although there have been reports regarding venous drainage patterns in syndromic craniosynostosis, studies of nonsyndromic cases have been rare. In the present study, the aim was to study venous drainage patterns in nonsyndromic craniosynostosis.

Methods: Nonsyndromic cases at a single institute were retrospectively reviewed, and cerebral venous drainage in the posterior (transverse sinus [TS]) and anterior (cavernous sinus [CS] and para-CS [ParaCS]) venous routes was systematically investigated. The occipital sinus (OS) and emissary veins were also evaluated.

Results: A total of 89 nonsyndromic cases were evaluated, including 12 right coronal synostosis (RCS), 14 left coronal synostosis (LCS), 15 bilateral coronal synostosis (BCS), 36 sagittal synostosis, 6 metopic synostosis, and 6 combined metopic-sagittal synostosis cases. All venous studies were performed using MR venography. There was a significant difference among all six groups in TS dominance (p = 0.0108). In unilateral coronal synostosis (UCS; including RCS and LCS) cases, 76.9% had TS dominance on the opposite side of the synostotic suture (20 of 26 UCS, including 10 of 12 RCS and 10 of 14 LCS). There was a significant difference in the incidence of OS, with the highest incidence observed in the BCS group (33.3%, p = 0.027). CS/ParaCS venous drainage was observed in 94.4% of cases on the right side and 95.5% on the left side, showing no significant difference among the groups on both sides. No visible emissary vein was observed in any of the groups.

Conclusions: A significantly higher predominance of left TS was found in RCS cases, in contrast with the typical right-side predominance seen in the normal population. In addition, the majority of UCS cases exhibited TS dominance on the opposite side of the synostotic suture. Furthermore, the present results showed a significant difference in the prevalence of OS, which was predominantly observed in BCS cases. These findings could be explained by the induction effect on venous sinuses by the compensatory growth of the skull according to Virchow's law, suggesting that synostotic sutures induce compensatory skull expansion in regions farthest (diagonally) from the affected sutures, thereby enlarging nearby venous sinuses.