Effectiveness of acoustic reflex threshold criteria in the diagnosis of retrocochlear pathology.

This study examines the acoustic reflex threshold criteria, derived from a large group of patients with cochlear hearing loss proposed by Cohen & Prasher (1992), in order to evaluate their effectiveness in differentiating between cochlear and retro-cochlear lesions. This criterion was tested on 63 patients with surgically confirmed cerebello-pontine angle (CPA) lesions. The false results obtained with this and other criteria were compared. The best balance between the false positive and negative results in the cochlear and retrocochlear group is provided by the criterion of any two adjacent test frequencies (proposed in the companion paper) having an upper limit of 105 dB for hearing below 60 dB and 110 dB for hearing over 60 dB. This study has also singled out the interaural difference criterion as the best diagnostic indicator with the lowest false results with only 1 false negative from 63 CPA cases and 3 false positive cases from 61 cochlear lesions with hearing thresholds over 55 dB.