Monitoring of cerebrospinal fluid flow by intraoperative ultrasound in patients with Chiari I malformation

Abstract

Objective: To investigate the feasibility of intraoperative ultrasound (IOUS) for monitoring cerebrospinal fluid (CSF) flow in patients with Chiari I malformation.

Methods: Twenty patients with Chiari I were scanned by IOUS with color Doppler flow imaging (CDFI). CSF flow status and flow velocity were monitored at different times during the surgery.

Results: CSF flow was detected in all 20 cases by IOUS-CDFI in real time. CSF flow was extremely slow or even ceased following bony decompression (craniectomy+laminectomy) in 19 patients; however, bi-directional flow was observed in the systolic phase and cranially directed flow in the diastolic phase. The maximum flow rate ranged from 4 to 13cm/s after duraplasty, and this varied with respiratory rhythm. Only 1 patient showed typical CSF flow after craniectomy, suggesting sufficient decompression, and without further duraplasty. All surgeries were terminated when bi-directional CSF flow was observed using IOUS-CDFI. With the exception of 1 patient, all the patients' symptoms were significantly relieved.

Conclusion: IOUS-CDFI can monitor CSF flow during posterior fossa decompression, provide information about the re-circulation of CSF flow, and objectively evaluate the efficacy of surgery.