Conductive Recruitment

Abstract

Twenty-four cases of unilateral pure conductive loss due to fixation of the ossicular chain have been examined by objective recruitment test (stapedius reflex measurement). In all of them the stapedius reflex was recorded on acoustic stimulation of the affected ear in spite of the absence of conditions for achieving adequate stimulation owing to the conductive loss. The diastatis between the hearing- and reflex-thresholds diminishes with the severity of the hearing loss. Such a reduction is usually considered to indicate recruitment. In a binaural balance test a similar low-grade but definite recruitment was found. That the phenomenon is dependent on the conductive defect is confirmed by comparative measurements before and after operation. In six cases of interruption or dislocation in the ossicular chain the degree of recruitment was considerably less marked if not entirely absent, and this applies also to a conductive loss produced experimentally by plugging the auditory canal.