Object: Sinus pericranii (SP) is a rare venous varix in an extracranial location connected to the intracranial venous system. The aim of this retrospective study was to report on 16 pediatric cases of SP with consideration of the preoperative evaluation of surgical risk.
Methods: The study population consisted of 10 patients who had undergone surgery for SP and 6 patients with concomitant craniosynostosis and SP. The mean age of the patients at presentation was 3.7 years. To identify characteristics of SP with high operative risk, 8 cases in this report and 11 previously reported cases of SP with sufficient information were categorized on the basis of the number and size of SP, the number and size of transcranial channels, the venous drainage type, and the amount of blood loss. Hemorrhage amounts were classified into 3 grades based on the description of intraoperative blood loss.
Results: Sinus pericranii not associated with craniosynostosis were resected without any postoperative morbidity. Sinus pericranii associated with craniosynostosis were preserved. After craniofacial reconstruction, 2 cases of SP with craniosynostosis regressed, completely in one patient and partially in another. These 2 patients with SP were confirmed to have compromised intracranial sinus before craniofacial reconstruction. Among a total of 19 patients, multiplicity or size (> 6 cm) of SP (p = 0.036) and multiplicity (> 3) or size (> 3 mm) of transcranial channels (p = 0.004) was associated with more severe hemorrhage grade. Sinus pericranii with peripheral venous drainage (drainer type) was not associated with hemorrhage grade after classification into 3 grades (p = 0.192). However, all 3 cases of SP with massive Grade 3 hemorrhage were the drainer type. Hemorrhage grade was correlated with the number of risk factors for SP (r = 0.793, p < 0.001).
Conclusions: Three risk factors of SP and the presence of compromised intracranial sinus are markers for highrisk SP. "Squeezed-out sinus syndrome" is suggested as a concept for SP associated with compromised intracranial sinus, mainly caused by craniosynostosis. Sinus pericranii in squeezed-out sinus syndrome probably serves as a crucial alternative to venous drainage of the brain with intracranial venous compromise. Conservative treatment for such patients with SP is recommended.