MRI referral criteria for asymmetric hearing loss are audiogram rules that set how large a difference between the ears must be before an MRI scan is offered to look for a vestibular schwannoma, a benign nerve tumour. More than a dozen exist; looser ones miss fewer tumours but send more people to scans that find none.

Why it matters for tinnitus

Asymmetric hearing loss is a recognised trigger for a scan in tinnitus. The US tinnitus guideline's strong recommendation against imaging does not apply when it is present, and the European Society of Head and Neck Radiology's 2025 recommendations list it among the indications for MRI when tinnitus does not pulse.

Rules also differ on tinnitus: Oxford's 1996 protocol accepted, in people up to 70, an average 15 dB gap or one-sided tinnitus with normal hearing, though a 2026 retrospective UK cohort of 1,814 scans found one-sided tinnitus a poor predictor of a tumour. Tinnitus in one ear gives the yield when hearing is symmetric.

What the evidence says

Four published rules:

  • NICE NG98 (UK guideline, 2018): consider MRI for 15 dB or more at any two adjacent test frequencies (0.5, 1, 2, 4 and 8 kHz); offer it regardless of the audiogram with localising signs such as facial nerve weakness.
  • Rule 3000 (Montreal, 2009): 15 dB or more at 3000 Hz, from a retrospective chart review of 122 patients, 74 with a tumour; below that, its authors proposed repeat hearing tests.
  • Charing Cross protocol (London, 2004): 15 dB at two adjacent frequencies if only one ear has hearing loss, 20 dB if both do. Applied retrospectively to one year's scans, it would have cut them from 392 to 168, missing one tumour in a patient whose altered facial sensation justified a scan anyway.
  • US Congress of Neurological Surgeons (guideline, 2018): 10 dB or more at two or more neighbouring frequencies, or 15 dB at one, to minimise missed tumours; 15 dB at 3000 Hz alone may mean fewer scans that find none.

A 2017 meta-analysis of 12 studies (4,969 patients) of poor to moderate quality found five pure-tone rules caught 88% to 91% of tumours (sensitivity) but cleared only 31% to 58% of people without one (specificity); it judged none accurate. A 2026 systematic review of 20 mostly retrospective studies (9,119 patients) found looser thresholds neared 100% sensitivity at markedly lower specificity, and stricter ones often fell below the 90% considered acceptable for screening, yet still rated audiometric rules the best first step.

Yield is low: the systematic review behind the US neurosurgeons' 2026 update found a vestibular schwannoma on 1.68% of MRIs for asymmetric hearing loss. In the UK cohort, nobody with only mild asymmetry (under 15 dB at two consecutive frequencies) had a tumour, while severe asymmetry (odds ratio 5.26) and vertigo (4.03) were independently associated with one. Asymmetry is also common: in a 2026 analysis of US national survey audiograms, even the most specific of five criteria flagged 8.9% of adults aged 60 to 69, and the authors argue against audiogram screening of the general population.

What this means for you

  • Ask for a copy of your audiogram; how to read your audiogram explains how to compare the two ears.
  • Whether a gap leads to a scan depends on the rule a service follows; ask which, and what follow-up is planned.
  • Symptoms can outweigh the numbers: in a retrospective Finnish series of 246 people with a tumour, the 6 with no asymmetry all had tinnitus, vertigo or facial weakness.
  • Sudden hearing loss, a drop over three days or less, needs same-day assessment; NICE says within 24 hours.
  • Sudden weakness or drooping in the face or an arm, trouble speaking or seeing, or severe vertigo that will not settle mean calling your local emergency number or going to an emergency department; NICE's tinnitus guideline advises immediate referral.

How it connects