J Neurol Surg B Skull Base 2024; 85(S 01): S1-S398
DOI: 10.1055/s-0044-1779971
Presentation Abstracts
Oral Abstracts

The Importance of Ossification of the Falciform Ligament in Decompression Procedures

Cassidy Werner
1   Tulane University, New Orleans, Louisiana, United States
,
Pate Duddleston
1   Tulane University, New Orleans, Louisiana, United States
,
Mansour Mathkour
1   Tulane University, New Orleans, Louisiana, United States
,
Aaron S. Dumont
1   Tulane University, New Orleans, Louisiana, United States
,
Joseph R. Keen
2   Ochsner Medical Center, Jefferson, Louisiana, United States
,
Blair Barton
2   Ochsner Medical Center, Jefferson, Louisiana, United States
,
Joe Iwanaga
1   Tulane University, New Orleans, Louisiana, United States
,
R. Shane Tubbs
1   Tulane University, New Orleans, Louisiana, United States
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Introduction: The falciform ligament (FL) is a dural extension forming the roof of the perceived entrance of the optic canal (i.e., preforaminal segment of the optic nerve), covering the optic nerve and ophthalmic artery. This structure is seldom studied but is clinically relevant because of its relationship to neighboring neurovascular structures such as the internal carotid artery (ICA) and ophthalmic artery. In pathological conditions such as ICA dilatation and optic nerve meningiomas, the optic nerve can be compressed against the FL, leading to visual deficits. Therefore, FL release has been used to decompress the optic nerve through transcranial and endonasal approaches. We hypothesized that the finding of a stenotic proximal optic canal could be due to ossification of the FL.

Methods: Ten cadaveric FL (20 sides) were investigated grossly and histologically. Additionally, the proximal optic canals of 300 skulls (600 sides) were observed for proximal stenosis, specifically at the location of the FL. Lastly, samples of stenotic proximal canals at the site of the FL were studied histologically following decalcification.

Results: The FL ranged in length from 1.5 to 4 mm (mean: 2.7 mm). Histologically, the soft tissue FL consisted of dura, including dural border cells and blood vessels. Stenotic proximal optic canals were identified on 35 sides (5.8%). Decalcified samples demonstrated normal bone tissue, including osteocytes. All grossly stenotic proximal optic canals appeared to be due to ossification of the FL.

Conclusions: Knowledge of the histological composition of the FL is necessary for ensuring the safety of its release during surgery. If the FL is partially ossified, pulling on this dural fold could cause tension on the optic nerve and lead to injury. If the FL becomes fully ossified, the proximal optic canal can become stenotic, leading to optic nerve compression.



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Artikel online veröffentlicht:
05. Februar 2024

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