Reversed ipsilateral acoustic reflex pattern.

Objective: To determine the characteristics and possible origin of reversed ipsilateral acoustic reflex.

Study design: Retrospective.

Setting: University hospital.

Patients: Sixty-three ears in 52 patients (mean age 37.6 years) with unilateral or bilateral sensorineural hearing loss and 45 age- and sex-matched persons as controls.

Methods: Audiometry and impedance audiometry examinations were studied retrospectively. Hearing test records were investigated, and patients with unilateral or bilateral sensorineural hearing loss were included. Forty-five age- and sex-matched persons served as controls. The ipsilateral and contralateral acoustic reflex patterns of these patients were investigated. Reflex-forming acoustic thresholds and latencies of ipsilateral reversed (positive) reflexes were compared with ipsilateral negative (upward) reflexes.

Results: The ipsilateral acoustic reflexes of 18 of 63 ears with sensorineural hearing loss were absent, and the remaining 45 were reversed (positive). A significant difference was found between ipsilateral reversed and ipsilateral negative acoustic reflex thresholds (p < .001) and latencies (p < .001). No statistically significant differences were found between ipsilateral and contralateral negative reflex latencies.

Conclusions: The reversed acoustic reflex pattern is not an artifact but a physiologic event. This reflex does not appear to be related to stapedius or tensor tympani muscle contraction. We believe that the etiology of the reversed reflex is related to the system that contains the tympanic membrane, malleus, and incus and their ligaments but not the middle ear muscles.