Tailoring Endoscopic Approach to Colloid Cysts of the Third Ventricle: A Multicenter Experience

Endoscopic removal of third ventricular colloid cysts has grown in popularity. The biggest issues concern radicality, cure or at least long-term control of the disease, and endoscopic remnants. Technologic advances in instrumentation and introduction of novel tools have greatly improved endoscopic results. Deeper knowledge of surrounding anatomy and awareness that colloid cysts vary in their position (foraminal or retroforaminal) can further improve with the selection of a tailored approach for each patient.

During the last 12 years, 22 colloid cysts were treated endoscopically in our centers. Cysts were classified into 3 groups: A, foraminal (n = 6); B, foraminal with retroforaminal extension (n = 10); C, retroforaminal (n = 6). The following entry points and trajectories were selected: precoronal foraminal (n = 7), precoronal retroforaminal (n = 4), precoronal combined retroforaminal/foraminal (n = 5), supraorbital foraminal (n = 6). Navigation guidance was used in 17 cases.

Major complications resulted in permanent deficits in 1 case, and 2 other patients experienced transient memory impairment. Remnants were noted by surgeon's intraoperative assessment in 6 cases; only 2 remnants were large, whereas the others were small bits of coagulated cyst stem. In 18 cases, no remnant was found on postoperative magnetic resonance imaging.

A traditional precoronal transforaminal approach should be considered only for pure foraminal cysts (group A), as the retroforaminal component is poorly controlled. Retroforaminal cysts (groups B and C) should be resected through a retroforaminal transpellucidum interfornicialis route. A supraorbital transforaminal approach is a more versatile approach suitable for most cases.