Grüber's ligament as a useful landmark for the abducens nerve in the transnasal approach

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OBJECT

Extended endoscopic transnasal surgeries for skull base lesions have recently been performed. Some expert surgeons have attempted to remove tumors such as chordomas, meningiomas, and pituitary adenomas in the clival region using the transnasal approach and have reported abducens nerve injury as a common complication. There have been many microsurgical anatomical studies of the abducens nerve, but none of these studies has described an anatomical landmark of the abducens nerve in the transnasal approach. In this study the authors used cadaver dissections to describe Grüber's ligament as the most reliable landmark of the abducens nerve in the transnasal transclival view.

METHODS

The petroclival segment of the abducens nerve was dissected in the interdural space—which is also called Dorello's canal, the petroclival venous gulf, or the sphenopetroclival venous confluence—using the transnasal approach in 20 specimens obtained from 10 adult cadaveric heads.

RESULTS

The petroclival segment of the abducens nerve clearly crossed and attached to Grüber's ligament in the interdural space, as noted in the transnasal view. The average length of the dural porus to the intersection on the abducens nerve was 5.2 ± 1.0 mm. The length of the posterior clinoid process (PCP) to the intersection on Grüber's ligament was 6.4 ± 2.6 mm. The average width of Grüber's ligament at the midsection was 1.6 ± 0.5 mm.

CONCLUSIONS

Grüber's ligament is considered a useful landmark, and it is visible in most adults. Thus, surgeons can find the abducens nerve safely by visualizing inferolaterally along Grüber's ligament from the PCP.

ABBREVIATIONSICA = internal carotid artery; PCP = posterior clinoid process.

Article Information

Correspondence Ryosuke Tomio, Department of Neurosurgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan. email: tomy0807@hotmail.com.

INCLUDE WHEN CITING Published online November 7, 2014; DOI: 10.3171/2014.10.JNS132437.

DISCLOSURE The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.

Headings

Figures

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    Photographs and corresponding illustrations showing the transnasal dissection of the left side of a head with colored silicone injections. A: The clivus (CL), carotid prominence (CP), and tuberculum sellae (TS) were exposed after expanded removal of the intranasal structures and the anterior wall of the sphenoid sinus. B: The clivus and the anterior wall of the ICA were drilled out. The periosteal dura (pD) was cut and opened superolaterally to find Grüber's ligament (GL) near the PCP. This interdural space was lined with the meningeal dura (mD). C: The abducens nerve (VI) was exposed along Grüber's ligament inferolaterally. The intersection point of Grüber's ligament and the abducens nerve was also confirmed. Lt = left. Copyright Ryosuke Tomio. Published with permission. Figure is available in color online only.

  • View in gallery

    Photographs and illustrations showing the right side of a cadaver head without colored silicone injections. A: The intersection point of Grüber's ligament (GL) and the abducens nerve (VI) were clearly visualized when the ICA was retracted laterally. B: The ICA was retracted medially to show the cavernous sinus part of the abducens nerve, which runs anteriorly on the right lateral side of the ICA. BA = basilar artery; dmA = dorsal meningeal artery; en = dural entrance porus; mD = meningeal dura; Po = pons; PV = petrosal vein; Rt = right; VI = abducens nerve. Copyright Ryosuke Tomio. Published with permission. Figure is available in color online only.

  • View in gallery

    Photograph displaying dissection of the left side of a cadaver head with colored silicone injections. After Grüber's ligament (GL) and the abducens nerve (VI) were dissected in the interdural space behind the medial line of the ICA, the meningeal dura (mD) and arachnoid were opened to confirm the pons (Po) and cisternal compartment of the abducens nerve. The measurements of the length of the dural porus to the intersection on the abducens nerve were performed with a ruler (in millimeters). pD = periosteal dura; TS = tuberculum sellae. Figure is available in color online only.

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