Anatomical meningo-orbital band evaluation and clinical implications: a cadaveric dissection study.

BACKGROUND: The meningo-orbital band (MOB) is a dural structure which runs around the superior orbital fissure (SOF) tethering the frontotemporal basal dura to the periorbita, through the SOF. MOB division is important to expose and remove the anterior clinoid process, to access to proximal carotid artery and cavernous sinus area. The goal of the study was to measure how the MOB could be safely incised without cranial nerves and cavernous sinus injuries. METHODS: Anatomical dissections and extradural exposure of the anterior clinoid process was performed on 20 cadavers (40 sides). Measurement of the MOB thickness was performed before its incision, after dura propria dissection, and retraction off the inner cavernous membrane, to expose the cranial nerves. RESULTS: We analyzed 20 cadaveric formalin-fixed heads injected with colored silicone, 11 man and 9 woman of caucasian race. The average length of a safe incision of the MOB was 10.6 ± 1.1 mm on the right side, and 10.65 ± 1.09 mm on the left side. CONCLUSIONS: In our study the average length of a safe incision of the MOB was 10.6 ± 1.1 mm. Thus, the incision length of the MOB should not exceed 9 mm; the peeling of the anterior cavernous sinus and of the SOF, dissecting the two layers of the dura throughout the incision of the MOB, is an useful technique to avoid cranial nerves and cavernous sinus lesions.