Is human T-lymphotropic virus type 1 infection associated with hearing loss?

Objectives/hypothesis: Human T-lymphotropic virus type 1 (HTLV-1) infection is endemic in the northeast area of Iran. Although various neurological disturbances have been reported in HTLV-1 infection, possible audiovestibular involvement during this infection has not yet been studied.

Study Design: Case control study.

Methods: Sixty-eight cases in three groups including 24 HTLV-1-infected patients with HTLV-1- associated myelopathy/tropical spastic paraparesis (HAM/TSP) (group 1), 23 HTLV-1-infected cases without clinical presentation (group 2), and 21 normal individuals (group 3) entered our study. A complete history of hearing-related disorders and a profile of audiologic tests, including pure-tone audiometry (PTA) with high frequencies, speech reception threshold (SRT), and auditory brainstem response (ABR) were taken.

Results: Subjective audiovestibular complaints of participants showed a significant difference among HAM/TSP patients and the two other groups regarding hearing loss and tinnitus, but not vertigo or aural fullness. Hearing evaluation by SRT and PTA in all frequencies showed a significant difference between HAM/TSP patients (group 1) and the controls (group 3). The difference was also significant between asymptomatic cases (group 2) and the controls only in PTA frequencies above 4 kHz. Auditory brainstem-evoked potential did not show any significant differences among the groups regarding latency of I, III, and V waves and interwave differences.

Conclusions: HTLV-1 infection, particularly in those with a clinical presentation, appears to accompany hearing loss. Based on the results of PTA and ABR tests, this study may suggest a cochlear source of hearing impairment rather than neural problems.