2025 Poster Presentations
P023: THE TWO-MODULE ENDOSCOPIC ENDONASAL OPTIC CANAL DECOMPRESSION. A CADAVERIC STUDY AND ILLUSTRATIVE CASE PRESENTATION.
Maria Karampouga, MD1; Gregory J Varga, MS1; Kyle Affolter, BS1; Gabrielle R Bonhomme, MD2; Tonya S Stefko, MD2; Garret W Choby, MD3; Eric Wang, MD3; Carl H Snyderman, MD3; Paul A Gardner, MD1; Georgios A Zenonos, MD1; 1Department of Neurological Surgery, Center for Cranial Base Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA; 2Department of Ophthalmology, Center for Cranial Base Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA; 3Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
Objective: Clinical and anatomical studies indicate that decompression of the optic canal (OC) from an endoscopic endonasal perspective is l primarily limited superiorly and laterally. In this study, we describe in a stepwise manner in two separate modules the standard endoscopic endonasal OC decompression and its extended transplanum modification that maximizes the degree of the bony removal and allows for expanded superolateral optic nerve decompression.
Methods: Anatomical dissections were performed on both sides of two cadaveric heads to comprehensively describe both modules and to identify relevant anatomical landmarks. Validation of the degree of OC decompression relied on image guidance and the superolateral limit was then confirmed through a trans-cranial approach on each side. An illustrative clinical scenario is also presented.
Results: In the first module a standard OC decompression is performed consisting of two phases: 1) Sinonasal- orbital phase: Unilateral access allows for complete ipsilateral spheno-ethmoidectomy, 2) OC phase: The inferomedial aspect of the OC is drilled usually from a lateral to medial direction. This module yielded a 198-degree of OC decompression. The extended OC decompression is divided in the following 5 phases: 1) Sinonasal- orbital phase: middle turbinectomy, wide posterior septosphenoethmoidectomy and ipsilateral medial antrostomy facilitate higher endoscope position and medial orbital wall resection, 2) Sella- tuberculum- planum phase: The bone overlying the sella, tuberculum, and ipsilateral planum sphenoidale is removed, 3) OC- carotid- medial opticocarotid recess (MOCR) phase: The OC is egg-shelled under copious irrigation and the carotid is exposed. The MOCR is removed after disconnection from its four attachments, known to be the optic, tuberculum, carotid and sella, 4), Lateral opticocarotid recess (LOCR)- optic roof (OR) phase (FIG.1): The LOCR corresponding to the optic strut is hollowed out and outfractured, maximizing the OC decompression. Mobilization of the planum dura facilitates OR decompression utilizing drilling and Kerrison rongeurs, 5) Anterior clinoid process (ACP) phase: ACP removal is attainable only when sufficient OR hyperostosis enables access to the ACP. With this module a 275-degree of OC decompression was evident. In a representative case a 58-year-old woman underwent extended OC decompression through EEA due to a RT ON lesion most consistent with a nerve sheath meningioma. Postoperative imaging revealed a 277-degree decompression of the ON, and the patient was discharged on post-op day 2 with improved visual symptoms.
Conclusion: The extended endoscopic extradural OC decompression is an effective and applicable technique that should be incorporated into the contemporary surgeon's arsenal. Implementing the previously analyzed five-phase technique in our clinical practice has significantly enhanced clinical outcomes.
FIG.1:A-C: Cadaveric dissection photographs demonstrating the lateral opticocarotid recess (LOCR)- optic roof (OR) phase (or phase no. 4) of the extended endoscopic endonasal optic canal (OC) decompression, D-F: Anterior clinoid process (ACP) phase (or phase no. 5) of the same procedure depicted in A-C, G-I: Calculations of the degree of OC decompression, following the procedure described in A-F, using image guidance.