The subependymal microvascular network revealed by endoscopic fluorescence angiography

The subependymal vascularization of the cerebral ventricles has been described in anatomical studies on human specimens. Its identification in vivo during neuroendoscopic navigation could have anatomical interest and may lead to a safer ventricular navigation, also avoiding unexpected bleeding. The traditional endoscopic visualization allows the certain identification of only the main vessels. In this study we describe the features of the subependymal vascular network (SEVN) enhanced by sodium fluorescein (SF) angiography. We compare these findings with the vascular patterns visible under white light to evaluate the sensitivity of this technique in unveiling the most distant branches of the SEVN.

We reviewed the video records of 39 fluorescein-assisted neuroendoscopic procedures. Steerable fiberscopes equipped with a dual observation mode for both white light and fluorescence were used. After preliminary inspection of the ventricular cavities, the camera was switched to the blue light fluorescent mode. Identical portion of ventricular walls observed in both modalities were compared and analyzed to enhance potential differences of the vascular features.

The main veins were positive (fluorescein enhanced) in 10 patients (25.6%), vessels of smaller diameter visible also under white light presented a detectable fluorescence in 27 patients (69.2%), the micro SEVN, not visible under with light, was revealed by SF in 21 patients (53.8%).

Fluorescein-guided neuroendoscopy deserves closer investigation since it allows detection of small vessels, not otherwise visible, in the ventricle walls. This method could be applied to ameliorate the knowledge of the environment the surgeon is working on, leading as a result to a safer navigation, also by avoiding minor bleedings.