Impact of intrascalar blood on hearing.

Objective/hypothesis: The objective of this controlled animal study was to evaluate the effects of intrascalar blood on hearing.
Material and Methods: Eight guinea pigs underwent intrascalar administration of their own blood in one ear and control solution in the contralateral ear. Solutions were applied through cochleostomy to the scala tympani. Compound action potential (CAP) thresholds were determined before administration and at different intervals for 2 months thereafter.
Results: Immediate deterioration of thresholds was seen mainly in the high-frequency range, averaging 27 dB and 20 dB in the study and control groups, respectively. At day 3, threshold shifts recovered in the control group but remained in the low-frequency range in the study group. An extensive recovery was seen in both groups. However, permanent threshold shifts persisted. There was an enhanced shift of thresholds of up to 7 dB in the study group.
Conclusions: Even small amounts of intrascalar blood seem to cause transient and permanent detrimental effects on cochlear function. In procedures involving opening of the otic capsule-like stapes surgery and cochlear implantation with hearing preservation-minimizing surgical blood admixture to intracochlear compartments seems therefore fundamental.