2025 Poster Presentations
P329: A REVIEW ON THE SURGICAL INDICATIONS FOR PETROSAL FISSURE SPLITTING
Vita Olson, BA; Maria José Pachón-Londoño, MD; Maged T Ghoche, MD; Estefana Bcharah; Charbel Moussalem, MD; Devi P Patra, MD; Bernard R Bendok, MD MSCI; Mayo Clinic
Introduction: The petrosal fissure, originating at the convergence of the superior and inferior limbs of the cerebellopontine fissure at the cerebellopontine angle, extends laterally between the superior and inferior semilunar lobules to the posterior cerebellum. Petrosal fissure splitting is a critical technique in skull base surgery, providing enhanced access to the middle cerebellar peduncle and the lateral aspect of the pons. Despite its clinical utility, the precise indications for its use require further elucidation. This review aims to synthesize current knowledge on the surgical indications for petrosal fissure splitting, offering a comprehensive overview of its application in contemporary skull base surgery.
Objective: To review and identify the surgical indications for petrosal fissure splitting, highlighting its advantages, limitations, and outcomes in various clinical scenarios.
Methods: A comprehensive literature review was conducted using PubMed, Scopus, and Google Scholar, focusing on articles published up to 2024. Articles were selected based on relevance and quality, and data were extracted regarding indications, surgical outcomes, and complications.
Results: In total, 12 clinical and 9 cadaveric studies were retrieved. Several key indications for petrosal fissure splitting were identified:
Access to Middle Cerebellar Peduncle and the Posterolateral Pons: In 19 patients, splitting of the petrosal provided access to the middle cerebellar peduncle and the lateral pons. The rate of effective resection of pontine cavernomas ranged between 90-100%.
Enhancing Visualization in the Cerebellopontine Angle (CPA): In 420 patients, the suprafloccular approach via the petrosal fissure and venous corridors facilitated microvascular decompression of the trigeminal neuralgia (90%), enabling better visualization (100%).
Avoidance of Cerebellar Retraction: Traditional approaches may require cerebellar retraction, which can lead to complications such as cerebellar edema or hematoma. Splitting the petrosal fissure avoided injury to the pontine tegmentum and fibers of cranial nerves VI to VIII. This improved access reduced the need for cerebellar retraction, thereby minimizing the risk of cerebellar or superior petrosal vein injury.
Comparison to alternative approaches: In 9 cadaveric heads, 5 patients underwent the Transpetrosal Presigmoid Retrolabrynthine (TPPR) approach, and 4 underwent Retrosigmoid Horizontal Fissure (RTSH) approach. With similar efficiency, RTSH had shorter time (4.5hr Vs 7.3hr) and less extensive bone drilling.
Conclusion: Petrosal fissure splitting is a valuable technique in skull base surgery, particularly indicated for accessing the middle cerebellar peduncle and lateral pons, enhancing visualization in the CPA, performing MVD for trigeminal neuralgia, and resecting pontine cavernomas. While it offers substantial benefits in terms of less need for cerebellar retraction, sacrifice of superior petrosal vein, time and outcomes, careful consideration of potential risks is essential. Further research and standardized guidelines are needed to optimize its use and improve patient outcomes.