Review of the Petroclinoid Ligament

An atypical anatomical variation of the petrosphenoidal ligament in a newborn cadaver

PURPOSE

To report an atypical anatomical variation of the petrosphenoidal ligament in a newborn cadaver and to discuss its clinical significance.

METHODS

During a study of ten newborn cadavers, the skull base was dissected to reveal the anatomy of the petrosphenoidal ligament and its relationship with the abducens nerve. An atypical anatomical variation was observed, and this is described. The length of the right and left ligaments to the point where it splits into two arms, the joint length of the two ligaments at the junction of the clivus, the length of the ligament proceeding to the posterior clinoid process, and the abducens nerve's diameter as it passes below the ligament were measured on ImageJ software.

RESULTS

The petrosphenoidal ligaments were y-shaped, and the attachment of the proximal ligaments was bifid. In the midline above the clivus, some ligament bundles joined the contralateral petrosphenoidal ligament, whilst another group of bundles originated at the posterior clinoid process. At the entry to Dorello's canal, the abducens nerve had a diameter of 0.59 mm on the left and 0.65 mm on the right. The part of the ligaments converging on the clivus in the midline after dividing into two arms was 10.68 mm.

CONCLUSIONS

We think that this case report will provide useful information for surgical procedures to the petroclival region, transnasal surgical approaches, and surgical interventions involving the carotid artery.

High resolution 3D magnetic resonance imaging of Gruber's ligament: a pilot study

INTRODUCTION

Gruber's ligament (GL), a surgical landmark, extends from the lateral upper clivus to the petrous apex (PA), forming the superior boundary of Dorello's canal (DC). It overlies the interdural segment of the abducens nerve (CN VI). High-resolution 3D skull base MRI (SB-MRI) demonstrates anatomic details visible to the surgeon, but not well seen on traditional cross-sectional imaging. The aim of this study was to demonstrate visualization of the GL and its relationship to CN VI utilizing contrast enhanced high-resolution SB-MRI.

METHODS

Two neuroradiologists retrospectively reviewed in consensus the SB-MRIs of 27 skull base sides, among 14 patients. GL detection rate, confidence of detection, and GL length were recorded. When GL was successfully identified, the position of the interdural segment of CN VI within DC was recorded.

RESULTS

GL was readily identified in 16 skull base sides (59%), identified with some difficulty in 2 skull base sides (7%), and failed to be identified in 9 skull base sides (33%). The mean GL length was 7.1 mm (4.5-9.3 mm). Among the 18 cases where GL was successfully identified, CN VI was readily identified in all cases (100%), coursing the lateral third of DC in 72% of sides, and middle third in the remaining 28% of sides.

CONCLUSION

GL can be identified in approximately two-thirds of cases utilizing 3D high resolution SB-MRI. CN VI passes most commonly along the lateral third of DC. This is the first report demonstrating visualization of GL and its relation to CN VI, on imaging.