Long-term facial nerve outcome in surgically treated petrous bone cholesteatoma patients.

Introduction: The term petrous bone cholesteatoma (PBC) represents a slow-growing epidermal lesion arising from the petrous part of the temporal bone. It is a rare incidence accounting for only 4-9% of all petrous bone lesions. PBC represents a real surgical challenge due to its complex relationship with critical neurovascular structures.

Objective: To demonstrate our experience in using various options of facial nerve (FN) management during surgical treatment of PBC and analyze the long-term facial function outcomes.

Study design: Retrospective medical record review in a quaternary skull-base center.

Materials and methods: Medical records of 298 PBC cases operated between the years 1983 and 2024 were thoroughly evaluated. Sanna's classification scheme was used to classify cases into the appropriate class and the House-Brackmann (HB) grading system of the FN was used to assess the facial function pre- and postoperatively.

Results: A total of 298 PBC cases were surgically treated at our center. Males constitute 68% (n = 203) of total operated PBC patients while the rest 32% (95) were females, making the male-to-female ratio 2.2:1. The age in this series ranged from 9 to 85. According to updated Sanna's PBC classification, 44% were supralabyrinthine, 33% were massive, 9% were infralabyrinthine-apical, 8% were infralabyrinthine, and 5% were apical. On preoperative FN function examination, 45% (n = 133) of patients had various degrees of paresis and complete paralysis whereas 55% (n = 165) had normal FN function. The commonest degree of paresis observed was HB-III (18.5%) followed by HB-IV (5.7%). A total of 40(13.4%) patients, however, had complete facial paralysis at the initial presentation. The facial function was compromised more frequently in supralabyrinthine and massive PBCs. Among the total patients who had an abnormal facial function at presentation, 52% had paresis/paralysis for less than a year whereas 48% had FN paresis/paralysis for greater than one year. The most commonly used surgical approaches at our center were transotic (TO), modified transcochlear type A (MTCA) with rerouting of the FN, and translabyrinthine (TLAB) with external auditory canal (EAC) closure. Intraoperatively an intact fallopian canal was found only in 33% (n = 99) cases whereas the rest 67% (n = 199) had erosion of the fallopian canal either with intact (n = 24) or infiltrated FN (n = 175). The FN was maintained in the bony fallopian canal in 35% (n = 104) cases. An active form of FN management, however, was required in 65% (n = 194) of cases either intraoperatively or as a second-stage procedure. Factors affecting postoperative FN function include age, preoperative FN function (HB), duration of paralysis, class of PBC, surgical approach, and method of active FN management.

Conclusion: PBCs represent diagnostically and surgically challenging lesions of temporal bone which are usually frustrating to the treating surgeon. Preoperative anatomic classification of the lesion enables the physician to choose the appropriate surgical approach. Sanna's classification is the most widely accepted system used to classify PBC. This classification is based on the relation of the lesion to the labyrinthine block. Active FN management, including rerouting, end-to-end anastomosis, cable nerve grafting, and masseteric-to-FN anastomosis routinely come into play in the surgical management of PBCs, and the postoperative FN results after such interventions can be satisfactory in most cases.