Tinnitus? Or Notched or Sloped Hearing Loss?
Tinnitus is a heterogenous phenomenon that includes a range of sound percepts, patient reactions, and patient characteristics. It is also not uncommon for patients to complain of tinnitus, but based upon further inquiry to determine their chief complaint is actually hearing loss.
Numerous studies have demonstrated the limited relationship between tinnitus reaction and psychophysical measures of tinnitus (e.g., pitch match). Yet, the identification of clinical phenotypes of tinnitus would be a meaningful starting point for clinical decision making and treatment recommendations.
Lewis et al (2020) sought to identify predictors of tinnitus as a primary complaint in a large dataset from the Massachusetts Eye and Ear Infirmary. The group examined audiometric configurations (categorized as normal, notched, sloping, flat, or asymmetrical) and if tinnitus was reported as the patient’s primary complaint. They further examined tinnitus descriptors that were ultimately labeled as tonal, broadband, and periodic.
A total of 10,532 patients indicated tinnitus as their primary complaint out of 51,989 records. Of the participants with tinnitus as primary complaint, the majority had either a notched or sloping hearing loss, but approximately 20 percent had hearing within normal limits (defined as thresholds <= 25dBHL at each test frequency in each both ears); less than 10 percent of tinnitus complaints were seen with flat losses.
In an exploratory analysis, they examined the relationship between tinnitus percept quality and audiometric shape. Tonal and broadband tinnitus were most commonly reported with few patients reporting periodic tinnitus. Further, there did not appear to be a clear relationship between tinnitus percept quality and audiometric shape.
In summary, the authors reported tinnitus as a primary complaint was more common with notched and sloping hearing loss and less common with flat losses. They also report a relatively large prevalence of persons with normal hearing, however, this is likely based on how normal hearing was defined and lack of extended high -testing. Based on these findings the authors suggest that tinnitus arises from sharp discontinuities in peripheral innervation and cochlear function, which may induce topographic restricted changes linked to the tinnitus percept.
Lewis et al (2020). Audiometric predictors of bothersome tinnitus in a large clinical cohort of adults with sensorineural hearing loss. Otol Neurotol 41 (4): e414-e421.