A 52-year-old man presents with progressive hearing loss over 6 months. Otoscopy shows a normal tympanic membrane. Weber test shows lateralization to the right ear, and Rinne test shows bone conduction better than air conduction bilaterally. Which single feature best distinguishes sensorineural hearing loss from conductive hearing loss in this patient?

Explanation

## Distinguishing Conductive from Sensorineural Hearing Loss ### Weber Test Interpretation **Key Point:** In sensorineural hearing loss, the Weber test lateralizes to the *better-hearing ear* (the unaffected side). In conductive hearing loss, it lateralizes to the *worse-hearing ear* (the affected side with conduction block). In this patient, Weber lateralizes to the right ear. This indicates the right ear has better bone conduction (sensorineural pathway intact), meaning the left ear has sensorineural loss. ### Why This Discriminates | Feature | Conductive Loss | Sensorineural Loss | |---------|-----------------|--------------------| | **Weber lateralization** | To affected ear (conduction block) | To better ear (cochlear/nerve loss) | | **Rinne test** | BC > AC (bone better) | AC > BC (air better) OR both reduced | | **Otoscopy** | Abnormal (perforation, fluid, ossicle fixation) | Normal | | **Mechanism** | Middle/outer ear obstruction | Cochlea or CN VIII damage | **High-Yield:** The Weber test is the *single most discriminating* tuning fork test because it directly reveals which ear has the sensorineural deficit via the lateralization direction. ### Clinical Pearl Weber lateralization direction is counterintuitive to students: - **Conductive loss:** Weber goes *toward* the bad ear (bone conduction is relatively better because air conduction is blocked) - **Sensorineural loss:** Weber goes *away* from the bad ear (bone conduction is absolutely worse because the cochlea/nerve is damaged) **Mnemonic:** **SWAB** — **S**ensorineural Weber goes to the *good* ear (opposite of affected); **C**onductive Weber goes to the *bad* ear (same side as affected). ### Why Other Options Are Incorrect While this patient does have bone conduction better than air conduction on Rinne testing, this is *not* the discriminating feature—it can occur in both mixed hearing loss and advanced sensorineural loss with a conductive component. The Weber lateralization pattern is pathognomonic.