Implications of Tumor Size on Auditory Brainstem Implant Performance

Abstract

Objectives

To better understand the implications of tumor size on auditory brainstem implant (ABI) categories of auditory performance (CAP) score to facilitate more precise patient counselling.

Design

Single-center retrospective chart review.

Setting

Tertiary referral center.

Participants

Patients > 18 years old with neurofibromatosis type 2 who underwent ABI placement between the years 2009 and 2023 were included. Patients with prior surgical resection were excluded to reduce the potential of previous cochlear nucleus trauma confounding results.

Main Outcome Measures

Ipsilateral tumor volume was measured from the preoperative MRI, and the primary endpoint was the 1-year CAP score.

Results

Fourteen patients were included for analysis, with an average age of 35.3 years. The average preoperative ipsilateral tumor volume was 22.8 cm³ (± 22.4). The average postoperative CAP score was 2.7 (± 2). A negative association was found between ipsilateral tumor size prior to treatment and CAP score (slope = − 0.058, p = 0.010) utilizing a linear regression model. The model accounted for 43.7% of the variance in outcome (R ² = 0.437, adjusted R ² = 0.390), with a significant overall model fit (F [1, 12] = 9.31, p = 0.010).

Conclusion

Increased tumor size has a negative correlation with ultimate ABI performance. There were patients in this study with larger tumor sizes who still benefited from ABI placement. While larger tumor size should not be a contraindication for ABI placement, understanding the role tumor size can have on performance variation can serve to improve tumor management strategies and preoperative counselling.

Keywords

ABI performance - vestibular Schwannoma - NF2 - CPA tumor - auditory brainstem implant

Publikationsverlauf

Eingereicht: 29. Juli 2025

Angenommen: 18. September 2025

Accepted Manuscript online:
22. September 2025

Artikel online veröffentlicht:
01. Oktober 2025

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