ECochG Atlas · Compare

Compare diseases

One table, all the disease entities covered in the atlas, set side-by-side on the diagnostic axes that matter for ECochG interpretation: SP/AP behaviour, CM / polarity findings, ABR features, the imaging gold-standard, and the role of ECochG itself. Each disease links back to its full module. See also /cases, /quiz, and /practice.

Disease	SP/AP	CM / polarity	ABR	Imaging gold-standard	Role of ECochG
Ménière's diseaseModule 05	Elevated. Ferraro ≥ 0.40, Gibson ≥ 0.30. Misses 30–50% of definite cases.	Normal CM, normal polarity behaviour.	Normal wave I–V if hearing is preserved; may shrink with severe SNHL.	MRI to exclude schwannoma; gadolinium hydrops MRI investigational.	Supportive. Adds objective marker of hydrops when clinical picture is consistent.
Superior canal dehiscenceModule 06	Elevated. Adams 0.34 cutoff: 92.3% sens, 94% spec. Reversible after plugging.	Normal CM. May show enhanced low-frequency response.	Normal; SCD does not affect the retrocochlear path.	High-resolution temporal-bone CT in the Pöschl plane — gold standard.	Adjunct. SP/AP elevation can mimic Ménière's; cVEMP threshold is the functional marker.
Auditory neuropathyModule 07	AP absent or severely diminished. SP often preserved → ratio meaningless.	CM present and inverts cleanly with polarity reversal (Berlin protocol authenticity).	Absent or grossly abnormal despite present CM/OAEs.	MRI to exclude cochlear-nerve aplasia/hypoplasia, especially in children.	Diagnostic. The polarity-reversal protocol is the definitional test for ANSD.
Sudden SNHLModule 08	Variable; no specific signature.	Variable; depends on outer-hair-cell status.	Threshold elevation tracking the audiogram.	MRI within 1–6 months per 2019 AAO-HNSF — excludes schwannoma in 1–7%.	Minimal. Not in the modern workup. ABR/MRI carry the diagnostic load.
Perilymph fistulaModule 09	May change with intra-test postural manoeuvre (Gibson 1992 protocol).	Normal CM/polarity behaviour.	Usually normal.	CT temporal bone; CTP biochemical assay (where available).	Functional test for an active fistula; controversial. Modern alternatives often preferred.
Vestibular schwannomaModule 10	Typically normal. A reassuringly normal ECochG never excludes a tumour.	Normal CM/polarity.	Wave V latency delay, IT5 asymmetry, sometimes wave-V absence — but insensitive.	Gadolinium-enhanced MRI — gold standard. No substitute.	None as a screening test. AP generator sits peripheral to most schwannomas.
Cochlear synaptopathyModule 11	Group-level elevation in the 0.35–0.60 range (Liberman); not an individual diagnostic.	Normal CM.	Reduced wave-I amplitude at suprathreshold levels — the proposed signature.	Not applicable; diagnosis is electrophysiological / behavioural.	Research metric. No validated individual clinical use yet.
Intraoperative CIModule 12	Not the measure of interest. CM amplitude vs insertion depth is the primary trace.	CM recorded via the implant's own electrodes; pattern (stable / drop-recover / progressive drop) is diagnostic.	Not used intraoperatively.	Postoperative CT for electrode position.	Real-time RCT-validated monitoring (Campbell 2022); ≥ 30% drop triggers withdrawal-and-reinsertion.

How to use this table. The table is a quick differential aid, not a substitute for the full modules. Each claim has its evidence base in the parent module; click the disease name to jump there. A few cross-cutting points:

An elevated SP/AP ratio is not specific to Ménière's. SCD, ANSD (when measurable), late-stage hydrops, and AP shrinkage from severe SNHL all elevate the ratio. Interpret alongside the audiogram and clinical picture.
An apparently normal ECochG never excludes a schwannoma. The AP generator sits peripheral to where most tumours arise. Gadolinium-enhanced MRI is the only screening test.
The polarity-reversal test is the definitional ECochG test for ANSD. CM present and clean polarity inversion + absent CAP/ABR is the signature; the Berlin protocol distinguishes biology from stimulus artifact.