The Stapedial Reflex in Pontine Lesions

Abstract

The stapedial reflex (StapR) is elicited by excitation of the auditory nerve. The reflex loop runs across the cochlear nucleus and the superior olivary complex to the facial nuclei on both sides (Fig. 1). From there motor nerve fibers lead directly to the stapedius muscle. Its latency is approximately 10 ms [1, 5]. Using retrograde-transported horseradish-peroxidase tracers in guinea pigs, Strutz recently suggested (1992, personal communication) that the reflex pathway passes the lateral lemniscus as well. From a clinical point of view, this seems improbable. The contraction of the stapedius muscle in conjunction with the tensor tympani muscle prevents a nonlinearity of the ossicular chain to loud signals.