Comparison of Intradural, Interdural, and Extradural Pituitary Transposition Techniques for Accessing Lesions Involving the Upper Clivus, Retroinfundibular Area, and Interpeduncular Cistern

Introduction: Multiple endoscopic endonasal pituitary transposition techniques have been described to approach lesions involving the upper clivus, retroinfundibular area, and interpeduncular cistern. These described transposition techniques include: intradural (hemi- or full transposition); interdural transcavernous (uni- or bilateral), and subsellar extradural. The objective of the study was to delineate the anatomical and surgical nuances for these competing techniques and propose their surgical indications.

Methods: Ten formalin-fixed and injected human anatomical specimens (20 sides) underwent different endoscopic endonasal pituitary transposition procedures. The transposition techniques included the intradural, interdural transcavernous and the subsellar extradural approaches. The surgical access provided by each technique was noted. The surgical experience of the senior author was reviewed to evaluate indications for each technique.

Results: The subsellar extradural approach provides access to the lower aspect of the dorsum sella and does not involve sacrifice of the IHA. Further rostral exposure including access to the posterior clinoids is limited via this approach. The interdural transcavernous approach provides excellent exposure for performing posterior clinoidectomy by mobilizing the medial wall of the cavernous sinus along with the pituitary gland and provides access to the oculomotor and interpeduncular cisterns. This technique necessitates sacrifice of the IHA, which is typically transected in a proximal location (cavernous segment) as it arises from the meningohypophyseal trunk. It also requires identification and transection of parasellar ligaments; among them, the caroticoclinoid ligament can be divided to provide additional access to the suprasellar space. The intradural procedure involves the transposition of the pituitary gland by dissecting the glandular capsule off the medial wall of the cavernous sinus. Pituitary ligaments are divided and the IHA is transected in a distal location (sellar segment) closer to the gland. This approach provides an excellent rostrocaudal exposure of the retrosellar and retroinfundibular areas. For unilateral access, this approach can be modified to carry out a hemitransposition leaving the gland attached to the contralateral medial wall of the cavernous sinus, thereby preserving glandular venous drainage.

Conclusion: Interdural transcavernous and intradural pituitary transposition techniques provide optimal surgical access to the posterior clinoids, dorsum sella and retroinfundibular area. Intradural pituitary transposition is preferred for resection of midline intrinsic tumors arising from the pituitary stalk, posterior gland and optico-hypothalamic region, such as craniopharyngiomas, pituicytomas, or glioma-type lesions. Interdural transcavernous approach is suitable for accessing paramedian extrinsic lesions, such as chordomas or petroclival meningiomas where removal of the upper clivus and interruption of the blood supply via transection of meningo-hypophyseal trunk is advantageous. This approach can be performed bilaterally for large or giant lesions. Pituitary transposition techniques are based on a detailed understanding of the surgical anatomy including appreciation of the layers of dura around the pituitary gland, related ligaments and the trajectory