Pilot study of intracranial venous physiology in craniosynostosis

OBJECTIVE In addition to craniocerebral disproportion, other factors, such as Chiari malformation type I, obstructive sleep apnea, and venous outflow obstruction, are considered to have a role in the occurrence of intracranial hypertension in craniosynostosis. This pilot study examined cerebral venous flow velocity to better characterize the complex intracranial venous physiology of craniosynostosis. METHODS The authors performed a prospective cohort study of craniosynostosis patients (n = 34) referred to a single national (tertiary) craniofacial unit. Controls (n = 28) consisted of children who were referred to the unit's outpatient clinic and did not have craniosynostosis. Transfontanelle ultrasound scans with venous Doppler flow velocity assessment were performed at the first outpatient clinic visit and after each surgery, if applicable. Mean venous blood flow velocities of the internal cerebral vein (ICV_v) and the superior sagittal sinus (SSS_v) were recorded and blood flow waveform was scored. RESULTS Preoperatively, SSS_v was decreased in craniosynostosis patients compared with controls (7.57 vs 11.31 cm/sec, p = 0.009). ICV_v did not differ significantly between patients and controls. Postoperatively, SSS_v increased significantly (7.99 vs 10.66 cm/sec, p = 0.023). Blood flow waveform analyses did not differ significantly between patients and controls. CONCLUSIONS Premature closure of cranial sutures was associated with decreased SSS_v but not ICV_v; indicating an effect on the superficial rather than deep venous drainage. Further Doppler ultrasound studies are needed to test the hypothesis that at an early stage of craniosynostosis pathology SSS_v, but not pulsatility, is abnormal, and that abnormality in both SSS_v and the superficial venous waveform reflect a more advanced stage of evolution in suture closure.