Bilateral Asymmetric SNHL — Schwannoma vs Sudden SNHL MCQ — NEET PG Practice Question | NEETPGAI
Bilateral Asymmetric SNHL — Schwannoma vs Sudden SNHL
medium
ear ENT
A 52-year-old man presents with progressive hearing loss in the right ear over 6 months. Audiometry shows a pure-tone average (PTA) of 35 dB in the right ear and 15 dB in the left ear, with word recognition score (WRS) of 60% on the right and 95% on the left. The difference between ears is 20 dB at 2 kHz and 18 dB at 4 kHz. This pattern corresponds to the condition marked **A** in the diagram. Which of the following is the most appropriate next diagnostic step?
A. High-dose oral prednisolone 1 mg/kg for 14 days followed by intratympanic dexamethasone
B. Observation with repeat audiometry in 3 months and counseling regarding noise avoidance
C. Auditory brainstem response (ABR) testing to assess interaural wave V latency
D. MRI of the internal auditory canal with gadolinium (T1, T2, and post-contrast sequences)
Explanation
Why MRI of the internal auditory canal with gadolinium is correct
Asymmetric sensorineural hearing loss (ASHL) is defined as a difference of ≥15 dB at any two adjacent frequencies (or ≥10 dB at two consecutive frequencies) or a difference in word recognition score ≥15% between ears. This patient meets criteria: 20 dB difference at 2 kHz, 18 dB at 4 kHz, and WRS difference of 35% (60% vs 95%). Per AAO-HNS 2019 SSNHL Guideline and Cummings Otolaryngology, asymmetric SNHL mandates evaluation for retrocochlear pathology, most commonly vestibular schwannoma (acoustic neuroma). MRI IAC with gadolinium (T1 + T2 + post-contrast) is the gold standard for diagnosis, as schwannomas enhance avidly and often show the characteristic "ice cream cone" appearance with intracanalicular and cerebellopontine angle components. The disproportionately poor word recognition score (60% for PTA of 35 dB) further suggests rollover phenomenon, a hallmark of retrocochlear pathology.
Why each distractor is wrong
High-dose oral prednisolone 1 mg/kg for 14 days: This is the appropriate management for sudden sensorineural hearing loss (SSNHL), defined as ≥30 dB drop over ≥3 adjacent frequencies within 72 hours. This patient has progressive hearing loss over 6 months, not sudden onset, and meets criteria for asymmetric SNHL rather than SSNHL. Steroids are not first-line for asymmetric SNHL workup.
Auditory brainstem response (ABR) testing: While ABR showing interaural wave V latency >0.2 ms can suggest retrocochlear pathology, it has low sensitivity (70%) and has been superseded by MRI. ABR is no longer recommended as a primary diagnostic tool for suspected vestibular schwannoma; MRI is the gold standard.
Observation with repeat audiometry in 3 months: This approach is appropriate for symmetric presbycusis or noise-induced hearing loss (conditions B and C in the diagram), not for asymmetric SNHL. Asymmetric SNHL requires urgent imaging to rule out retrocochlear pathology and vestibular schwannoma, which may progress and cause neurological complications if untreated.
High-YieldNEET PG
Asymmetric SNHL (≥15 dB difference at any two adjacent frequencies or ≥15% WRS difference) = MRI IAC with gadolinium is mandatory to exclude vestibular schwannoma and other retrocochlear lesions.
