Rule 3,000: a more reliable precursor to perceive vestibular schwannoma on MRI in screened asymmetric sensorineural hearing loss

Abstract

Nine different definitions of asymmetric sensorineural hearing loss (SNHL) have been reported in literature. The objectives of this study are to: (1) compare all these definitions of asymmetric SNHL; (2) measure the agreement between these definitions in detecting vestibular schwannoma (VS); and (3) determine the strongest association between an asymmetric SNHL definition and positive VS on magnetic resonance imaging (MRI). The study is a retrospective chart review in a tertiary care center. Cases were included if they were evaluated by an audiometric assessment and a posterior fossa MRI. Definitions of asymmetric SNHL reported in literature were applied to request for a further MRI investigation. The likelihood ratio (LR) for a positive test result (LR+) was the highest for the Rule 3,000 (2.91). On comparing all the other definitions with Rule 3,000, seven of the eight existing definitions have a kappa under the clinical usefulness threshold (Kappa < 0.6). When specification tests were applied, the Chi-square test identified Rule 3,000 with a highly significant P value (P < 0.0001). Rule 3,000, defined as asymmetric SNHL of 15 dB or more at the frequency 3,000 Hz, could serve as a universal referral guide for further MRI investigation. Results show that Rule 3,000 is more reliable to detect VS on MRI, a very simple rule that covers all the eight definitions of asymmetric SNHL reported in literature. This would help to reduce the number of negative MRI and to save time and money. If asymmetric SNHL is less than 15 dB, a biannual audiometry testing follow-up could be done.

Prospective Evaluation of the Clinical Profile and Referral Pattern Differences of Vestibular Schwannomas and Other Cerebellopontine Angle Tumors

“…Moreover, the mean audiogram pattern exhibited by both groups involved a loss of high tone, with no significant difference observed between the 2 groups. Recently, an asymmetric SNHL of 15 dB or more at a frequency 3,000 Hz (e.g., the rule 3,000) has been described as a universal referral guide for further MRI investigations (19). In the current study, highly significant differences ( p G 0.001) were found between affected and nonaffected ears at all frequencies for both groups.…”

Hearing disorders in brainstem lesions

“…A consensus is emerging that, for most of the cases, magnetic resonance is the imaging modality of choice for lesions of the cerebellopontine angle and internal auditory canal (Zamani, 2000;Adunka et al, 2007;Saliba et al, 2010;Sriskandan and Connor, 2011;Yoshida et al, 2011). However, when visualization of the internal auditory canal and/or of the bony cochlear nerve canal is needed, then high-resolution CT is best as it allows better evaluation of bony structures (Adunka et al, 2007).…”

Which Patients With Asymmetric Sensorineural Hearing Loss Should Undergo Imaging?

“…In a second retrospective chart review, Saliba et al compared the diagnostic efficiency of eight published definitions of asymmetry in their series of audiograms among patients referred to their tertiary center with VS versus a separate control group. Among 84 patients with VS they found that the rule 3000 ( ≥ 5 dB at 3 kHz) had the greatest diagnostic accuracy.…”

“…Among 84 patients with VS they found that the rule 3000 ( ≥ 5 dB at 3 kHz) had the greatest diagnostic accuracy. Saliba estimated that their method would detect VS in about 2% of MRI scans …”

“…Saliba et al proposed that patients would undergo imaging when the ASNHL is 15 dB or more at 3 kHz. The test–retest variability for pure‐tone audiometry at any individual frequency is generally accepted to be ±5 dB or more.…”