Exaggerated acoustic reflex response in a patient with transient facial palsy and hyperacusis.

An unusual acoustic reflex response was documented by immittance recording in a patient with acute facial palsy. The amplitude of the stapedial response to sustained stimulation was reduced when recorded from the affected side, suggesting the facial nerve was affected proximal to the stapedius muscle. In addition, the impedance change at onset of intense acoustic stimulation of the affected side was unusually large, regardless of which stapedius response was recorded. The large change was coincident with the reported hyperacusis in the stimulated ear. This suggested the cochlear nerve as site of involvement of hyperacusis in this case of facial palsy.