Handheld cochlear nerve action potential mapping for real-time functional navigation in vestibular schwannoma surgery
In brief
Handheld CNAP mapping finds cochlear nerve in 83% of cases, predicts hearing preservation
In a series of 193 vestibular schwannoma operations, bipolar handheld CNAP recording identified the cochlear nerve in 83% of patients versus 46% with standard BAEPs, and a stable CNAP signal was linked to hearing preservation in over 90% of those cases. The technique offers real-time functional guidance, though outcomes still depend on nerve integrity in large tumors.
- Journal
- Journal of neurosurgery (Q1)
- Published
- 4 September 2026
- Study design
- Retrospective cohort
- Evidence level
- Level 3, Low (CEBM 3b)
- Authors
- Xiaoyu Li, Xu Gong, Penghao Liu, Hanyi Jiao, Gang Song, Jiantao Liang
- PMID
- 42696771
- DOI
- 10.3171/2026.3.JNS252763
Why clinicians should know about it
- Picked for Otorhinolaryngology (paper of the day, 6 September 2026): CNAP mapping identified cochlear nerve in 83.4% cases
Abstract
OBJECTIVE: Hearing preservation in vestibular schwannoma (VS) surgery remains challenging due to frequent cochlear nerve displacement and the limited reliability of brainstem auditory evoked potentials (BAEPs) once waveforms deteriorate. This study evaluated the feasibility and clinical utility of bipolar handheld cochlear nerve action potential (CNAP) mapping for intraoperative nerve identification and compared its prognostic performance with BAEP monitoring. METHODS: In this retrospective single-center cohort, 193 patients with histologically confirmed VS underwent intraoperative auditory mapping between September 2021 and November 2024. Two color-coded bipolar handheld probes were used: one for facial nerve stimulation and the other for near-field CNAP recording along the presumed cochlear nerve course. CNAP responses were considered favorable if waveforms remained stable or decreased by < 50% in amplitude. Functional hearing preservation (American Academy of Otolaryngology-Head and Neck Surgery class A-C) served as the primary endpoint. Logistic regression and receiver operating characteristic (ROC) analyses evaluated predictive performance. RESULTS: CNAP mapping identified the cochlear nerve in 83.4% of cases, significantly higher than intraoperative BAEP elicitation (46.1%; p < 0.001). Favorable CNAP responses were strongly associated with hearing preservation (91.4% vs 8.1%, p < 0.001; adjusted OR 37.0, 95% CI 9.28-217.8). The combined CNAP + BAEP model showed excellent discrimination (area under the ROC curve = 0.91) and good calibration (p = 0.24, Hosmer-Lemeshow test). CONCLUSIONS: CNAP mapping enabled real-time functional localization of the cochlear nerve and provided complementary intraoperative functional information. While postoperative hearing remains dependent on the structural integrity of the cochlear nerve, particularly in large tumors, CNAP mapping provides complementary functional information strongly associated with hearing preservation.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.