EVALUATION OF FUNCTIONALITY OF COCHLEAR OUTER HAIR-CELLS IN PATIENTS WITH RETINITIS-PIGMENTOSA AND IN THEIR RELATIVES

Hearing functionality was studied in 36 patients with retinitis pigmen tosa (RP) and 29 of their relatives. These patients were defined as ha ving bilateral normal hearing on the basis of tonal-threshold audiomet ric and acoustic-immittance tests. The transiently evoked otoacoustic emissions (TEOAES) were studied in these normal hearing patients. TEOA Es represent an extremely sensitive method to study the functionality of the outer hair cells of the organ of Corti. When the values of TEOA E amplitude, intensity, and frequency in Rp patients and in their rela tives were compared with those in control subjects, they were found to be significantly reduced. The TEOAEs were clearly pathological in 52. 8% of patients with RP and in 24.I% of their relatives. During embryol ogic development, there is one transitory axoneme in the outer hair ce lls of the organ of Corti; this transitory axoneme is important for th e organization of the stereocilia. Axonemes are found in mature hair c ells, including photoreceptors. The alteration of cochlear outer hair cells in a high percentage of patients with RP and in some of their re latives corroborates the hypothesis that, in some instances, retinitis pigmentosa may be due to a structural anomaly of the ciliated cells.