Table 2.
Modality-level summary of intraoperative (or early postoperative) neuromonitoring constructs treated as rule-in predictors of early serviceable hearing. “Threshold (direction)” specifies the positivity rule (i.e., a finding consistent with hearing preservation), and “Index outcome(s)” prioritizes early serviceability (GR I–II or AAO-HNS A–B); where only broader hearing preservation (A–C) was reported, this is indicated in the Evidence column. “Evidence & key figures” cites representative study-level accuracy (sensitivity/specificity with likelihood ratios when available) or quantitative correlations; “Notes” provide implementation caveats (e.g., artifact susceptibility, need for persistence/repeatability, and use as a confirmatory channel). Deterioration-oriented ABR rules are included for context but were not used as rule-in endpoints in the primary analysis. Abbreviations: ABR/BAEP, auditory brainstem response/brainstem auditory evoked potentials; CNAP/DCAP, (direct) cochlear nerve compound action potential; ECochG, electrocochleography; WRS, word recognition score; PTA, pure-tone average; GR, Gardner–Robertson; AAO-HNS, American Academy of Otolaryngology–Head and Neck Surgery
| Modality | Threshold (direction) | Index outcome(s) evaluated | Evidence & key figures | Notes |
|---|---|---|---|---|
| ABR/BAEP (far-field) | Stable wave-V (no intraoperative deterioration) | Early serviceable hearing (WRS ≥ 50%/GR I–II) |
Ren 2021: Se 0.82, Sp 0.85. Li 2023 (reframed to preservation): Se 0.33, Sp 1.00. |
Rule-in screen; require persistence and stage-concordance. Susceptible to anesthesia/drilling artifacts—confirm across repeated blocks. |
| ABR/BAEP (far-field) | ROC-derived latency rule: IT5 < 1.12 ms (operated ear) | Early serviceable hearing (GR I–II) | Aihara 2013 (whole cohort): Se 0.863, Sp 0.778 (ROC-derived; no published 2 × 2). | Calibrated latency rule; good sensitivity with moderate specificity. |
| BAEP (standardized indices) | STIAS–Am‑V ≥ 0.05 µV post‑resection | 2-week hearing preservation (AAO-HNS A–C) | Jiao 2024: Se 0.789, Sp 0.920. | Standardized amplitude processing strengthens rule-in vs. conventional peaks; endpoint broader than strict A–B. |
| Near-field CNAP/DCAP | Presence at case end | Early serviceable hearing (preferred) | Directionally supportive (Colletti 1996; Zappia 1996), but A–B early 2 × 2 seldom reported. Hochet 2023: early CNAP presence predicted 6‑month A–C (not early A–B). | Biologically plausible rule-in; consider as confirmatory when stable at closure; reporting often lacks extractable denominators. |
| ECochG (TT/IME/RW), adjunct | Stable/robust near-field cochlear potentials | Early change vs. postoperative audiometry | Morawski 2007: intraop TT‑ECochG change correlated with PTA shift. Han 2010; Attias 2008: combined ABR+EcochG improves interpretability of declines. | High temporal resolution; valuable as concordant second channel alongside ABR/CNAP; artifact-aware interpretation required. |
| ABR/BAEP (far-field), deterioration rules (for context) | Sustained wave‑V loss; latency ↑ ≥ ~1 ms; amplitude ↓ ≥ 50% | Early/long-term decline (worse AAO‑HNS/GR; PTA/WRS loss) | Loss is usually highly specific but variably sensitive across cohorts. James 2005 (CPA subgroup): limited discrimination for permanent loss under mixed pathology/conditions. | Useful intraoperative ‘red‑stop’ signals when sustained and repeatable; interpret in context. Current analysis emphasizes preservation‑oriented rule‑in; deterioration rules shown for completeness. |