Neurosurgical management of petrous bone lesions: classification system and selection of surgical approaches

Acta Neurochirurgica (2021) 163:2895–2907

Surgery of petrous bone lesions (PBLs) is challenging for neurosurgeons. Selection of the surgical approach is an important key for success. In this study, the authors present an anatomical classification for PBLs that has been used by our group for over the past 26 years. The objective of this study is to investigate the benefits and applicability of this classification.

Methods Between 1994 and 2019, 117 patients treated for PBLs were retrospectively reviewed. Using the V3 and arcuate eminence as reference points, the petrous bone is segmented into 3 parts: petrous apex, rhomboid, and posterior. The pathological diagnoses, selection of the operative approach, and the extent of resection (EOR) were analyzed and correlated using this classification.

Results This series included 22 facial nerve schwannomas (18.8%), 22 cholesterol granulomas (18.8%), 39 chordomas/ chondrosarcomas (33.3%), 6 trigeminal schwannomas (5.1%), 13 epidermoids/dermoids (11.1%), and 15 other pathologies (12.8%). PBLs were most often involved with the petrous apex and rhomboid areas (46.2%). The extradural subtemporal approach (ESTA) was most frequently used (57.3%). Gross total resection was achieved in 58.4%. Symptomatic improvement occurred in 92 patients (78.6%). Our results demonstrated a correlation between this classification with each type of pathology (p < .001), selection of surgical approaches (p < 0.001), and EOR (p = 0.008). Chordoma/chondrosarcoma, redo operations, and lesions located medially were less likely to have total resection. Temporary complications occurred in 8 cases (6.8%), persistent morbidity in 5 cases (4.3%), and mortality in 1 case.

Conclusion In this study, we proposed a simple classification of PBLs. Using landmarks on the superior petrosal surface, the petrous bone is divided into 3 parts, apex, rhomboid, and posterior. Our results demonstrated that chordoma/chondrosarcoma, redo operations, and lesions involving the tip of the petrous apex or far medial locations were more difficult to achieve total resection. This classification could help surgeons understand surgical anatomy framework, predict possible structures at risk, and select the most appropriate approach for each patient.

Petrous bone lesions: surgical implementation and outcomes of extradural subtemporal approach

Acta Neurochirurgica (2021) 163:2881–2894

Petrous bone lesions (PBLs) are rare with few reports in the neurosurgical literature. In this study, the authors describe our current technique of extradural subtemporal approach (ESTA). The objective of this study was to evaluate the role and efficacy of ESTA for treatment of the PBLs. To our knowledge, this is the largest reported clinical series of using an ESTA-treated PBLs in which the clinical outcomes were evaluated.

Methods Between 1994 and 2019, 67 patients with PBLs treated by ESTA were retrospectively reviewed. Extent of resection, neurological outcomes, recurrence rate, and surgical complications were evaluated and compared with previous studies. The indications, advantages, limitations, and outcomes of ESTA were analyzed according to pathology.

Results This series included 7 facial nerve schwannomas (10.4%), 16 cholesterol granulomas (23.9%), 16 chordomas (23.9%), 6 chondrosarcomas (9%), 5 trigeminal schwannomas (7.5%), 9 epidermoids/dermoids (13.4%), and 8 other pathologies (11.9%). The most common location of PBLs operated with ESTA was at the petrous apex and rhomboid areas (68.7%). Gross total resection was achieved in 35 (55.6%). Symptomatic improvement occurred in 56 patients (83.6%). Complications occurred in 7 (10.4%) of cases including one mortality. Nine patients (17%) had recurrence within the mean follow-up 71 months. Compared to previous literature, our results demonstrated comparable outcomes but with higher rates of hearing and facial nerve preservation as well as minimal morbidity. From our results, ESTA is an effective therapeutic option for lesions located at the rhomboid and petrous apex, particularly when patients presented with intact facial and hearing function.

Conclusion Our series demonstrated that ESTA provided satisfactory outcomes with excellent benefits of hearing and facial function preservation for patients with petrous bone lesions. ESTA should be considered as a safe and effective therapeutic option for selected patients with PBLs.