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Published on: December 28, 2014
Pretemporal and Posterior Petrosal Approaches to the Retroinfundibular Region: A Quantitative and Comparative
Amine Mellal1, Daniele Starnoni1,2,3, Jordan Squair1
1Department of Neurosurgery, Lausanne University Hospital, Lausanne, Switzerland.
Background And Objectives:
Although the endoscopic endonasal approach is currently favored for retroinfundibular lesions, transcranial approaches remain essential in selected cases. Among these, the pretemporal transcavernous approach (PTA) and the posterior petrosal approach (PPA) may be considered. This cadaveric study quantitatively compared the surgical corridors provided by PTA and PPA using a standardized tumor simulation model.
Methods:
Anatomic dissections were performed on 5 latex-injected human cadaveric heads (10 sides). A retroinfundibular tumor was simulated using a water-balloon model progressively inflated to volumes of 5, 10, 15, and 20 mL. Bilateral dissections were performed using PTA and PPA in a randomized order. Stereotactic measurements were obtained for predefined working corridors.
Results:
With PTA, exposure increased primarily within the carotid-oculomotor corridor, which showed a modest but significant enlargement with increasing tumor volume (P = .046), whereas the other corridors showed no significant change across simulated tumor sizes. PPA demonstrated a more pronounced size-dependent response. Exposure through the infraoculomotor corridor increased significantly with tumor volume (P = .02). The supraoculomotor corridor showed the greatest enlargement, progressively expanding up to a simulated tumor volume of 15 mL (P < .001), with no additional gain beyond this threshold. Direct comparison revealed a clear size-related shift in exposure advantage. PTA provided significantly greater exposure for smaller simulated tumors (5 and 10 mL; P < .05). At the intermediate tumor size (15 mL), no significant difference was observed between approaches. For larger simulated tumors (20 mL), PPA offered significantly greater exposure (P < .05).
Conclusion:
PTA and PPA provide distinct and complementary exposure profiles for retroinfundibular tumors. PTA is more favorable for smaller lesions, whereas PPA becomes advantageous for larger tumors (approximately ≥3 cm), benefiting moreover from a unique posterior-to-anterior and inferior-to-superior trajectory that allows improved control of the inferior surface of the optic chiasm and hypothalamus.
