Pathology of the nervous arc of the acoustic reflexes

A short comment is made on the pathological conditions of the input and efferent arc of the stapedius reflex. The modifications of this reflex during pathological and experimental inpairment of the intermediate portion of the arc, at the brain stem level, in human subjects are analyzed in more detail. The graphic and oscilloscopic records demonstrate a modification of the latency, amplitude and particularly of the speed of onset of the reflex. A concomitant modification of the electronystagmogram and tonal tests of lateralization is also demonstrated. Some abnormal responses observed in cases of facial palsy (efferent arc) as compared with electrogustometry and the problem of eliciting an isolated reflex contraction of the tensor tympani are briefly commented upon.