Middle fossa approach for vestibular schwannoma

The middle fossa approach, as popularized by William Fouts House, provides excellent exposure to the internal auditory canal (IAC) for the removal of small intracanalicular vestibular schwannomas distal in the canal with the potential for hearing preservation.

Cochlear Fibrosis

Sixty-seven patients underwent VS resection via MCF approach including 16 patients > = 60 years (mean 64.4 SD 3.3) and 51 patients < 60 years (mean 45.7 SD 10.2). Between these two groups, there were no differences in sex, tumor laterality, tumor size (10.4 mm versus 9.8 mm, p = 0.6), or other demographic characteristics. Postoperatively, there were no differences between groups in complication rates. Rates of HB 1 or 2 facial nerve function were similar (93.8% versus 88.2%, p = 0.7) as were rates of maintenance of class A or B hearing (58.3% versus 44.4%, p = 0.7).

Conclusions: Patients over 60 undergoing MCF for VS resection experienced similar rates of postoperative complications, facial nerve outcomes, and hearing preservation compared with younger patients. MCF for VS may be considered in the older population. Further research is warranted to evaluate appropriate limitations for this approach based on age 1).

A retrospective cohort study of 63 patients who underwent the MCF approach for resection of VS from 2006 to 2016. Audiometric data included pure-tone average (PTA), low-tone pure-tone average (LtPTA), word recognition score, and American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) hearing classification at presentation and follow-up. Patients with postoperative serviceable (AAO-HNS class A-B) and/or useful (AAO-HNS class A-C) hearing were compared to those without HP. Facial nerve function was assessed using the House-Brackmann scale.

Results: The mean age and duration of follow-up were 50 ± 13 yr and 21 ± 21 mo, respectively. The mean tumor size was 10 ± 4 mm. The serviceable and usable HP rates were 54% and 50%, respectively. Some residual hearing was preserved in 71% of patients. Large tumor size (P = .05), volume (P = .03), and extrameatal tumor extension (P = .03) were associated with poor audiometric outcomes. The presence of a fundal fluid cap (P = .01) was a favorable finding. At definitive testing, LtPTA was significantly better preserved than traditional PTA (P = .01). Facial nerve outcomes, tumor control rates, and durability of audiometric outcomes were excellent. 47% of patients pursued aural rehabilitation.

In our series, the MCF approach for VS provided excellent rates of tumor and facial nerve function, with durable serviceable HP 2).

Among 78 identified patients (mean age, 49 years; 53% female; mean tumor size, 7.5 mm), 78% had functional hearing preoperatively (American Academy of Otolaryngology-Head and Neck Surgery class A/B). Follow-up audiologic data were available for 60 patients overall (mean follow-up, 15.1 months). The hearing preservation rate was 75.5% (37/49) at last known follow-up for patients with functional hearing preoperatively. Other than preoperative hearing status (P < 0.001), none of the factors assessed, including demographic profile, size of tumor, and fundal fluid cap, predicted hearing preservation (P > 0.05). Good functional preservation of the facial nerve (House-Brackmann class I/II) was achieved in 90% of patients. The only operative complications were 3 wound infections (3.8%).

Conclusions: Preliminary results from this single-center retrospective study of patients undergoing MFA for resection of VS showed that good hearing preservation and facial nerve outcomes could be achieved with few complications. These results suggest that resection via the MFA is a rational alternative to watchful waiting or stereotactic radiosurgery 3).

Kohlberg GD, Lipschitz N, Raghavan AM, Breen JT, Pensak ML, Zuccarello M, Samy RN. Middle Cranial Fossa Approach to Vestibular Schwannoma Resection in the Older Patient Population. Otol Neurotol. 2021 Jan;42(1):e75-e81. doi: 10.1097/MAO.0000000000002881. PMID: 32947493.
Kosty JA, Stevens SM, Gozal YM, DiNapoli VA, Patel SK, Golub JS, Andaluz NO, Pensak M, Zuccarello M, Samy RN. Middle Fossa Approach for Resection of Vestibular Schwannomas: A Decade of Experience. Oper Neurosurg (Hagerstown). 2019 Feb 1;16(2):147-158. doi: 10.1093/ons/opy126. PMID: 29889286.
Raheja A, Bowers CA, MacDonald JD, Shelton C, Gurgel RK, Brimley C, Couldwell WT. Middle Fossa Approach for Vestibular Schwannoma: Good Hearing and Facial Nerve Outcomes with Low Morbidity. World Neurosurg. 2016 Aug;92:37-46. doi: 10.1016/j.wneu.2016.04.085. Epub 2016 May 3. PMID: 27150655.
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