A Method of Auditory Brainstem Response Testing of Infants Using Bone-Conducted Clicks Methode d'evaluation de la reponse evoquee du tronc cerebral d'enfants a I'aide de clics par conduction osseuse

The auditory brains tern response (ABR) to bone-conducted stimuli appears to be capable of providing information about the cochlear reserve in neonates. It may be used to assist ABR testing using air-conducted stimuli in the identification of sensorineural hearing loss in at-risk infants. This paper describes a method of ABR testing of infants using bone-conducted clicks. Specifically, the control and maintenance of the delivery of bone-conducted signals is presented. ABRs to air and bone-conducted stimuli were collected from normal control and at-risk infants during the postnatal period and at four months. Sample ABR waveforms from a normal infant and from two at-risk infants, one with a conductive deficit and one with a sensorineural hearing loss, are illustrated. It is postulated that the described method may have implications for clinical practice. The auditory brainstem response (ABR) has been widely accepted as a clinical tool for testing infants, particularly in audiological screening of newborns at risk for hearing loss (Durieux-Smith, Picton, Edwards, Goodman, & MacMurray, 1985; Jacobson & Morehouse, 1984; Galambos, Hicks, & Wilson, 1984; Stein, Ozdamar, Kraus, & Paton, 1983). ABR JSLPAIROA Vol. 14, No. 4, December 1990 testing using air-conducted stimulation with at-risk infants, however, does not differentiate sensorineural hearing losses from conductive deficits (Stockard & Curran, 1990). ABR to bone-conducted stimuli appears to be capable of providing information about the cochlear reserve (Hall, Kripal, & Hepp, 1988; Hooks & Weber, 1984; Stapells, 1989; Stapells & Ruben, 1989; Yang, Rupert, & Moushegian, 1987) and hence may be used to identify sensorineural hearing losses in infants. Concerns regarding the technical problems in obtaining ABR to bone-conducted stimuli in infants have been raised (Boezeman, Kapteyn, Visser, & Snel, 1983; Cornacchia, Martin, & Morra, 1983; Gorga & Thomton, 1989; Hall et aI., 1988; Kavanagh & Beardsley, 1979; Schwartz, Larson, & De Chicchis, 1985; Stockard & Curran, 1990; Stuart, Yang, & Stenstrom, 1990; Yang, Stuart, Stenstrom, & Hollett, in press). These concerns include: (1) the lack of a standard procedure for the calibration of transient bone-conducted signals; (2) the relatively narrow dynamic range of transient bone-conducted stimuli; (3) the presence of stimulus artifact emanating from the bone vibrator during ABR recording; and (4) difficulties in controlling and maintaining the delivery of bone-conducted signals when testing infants. The present paper is a preliminary report of an ongoing study investigating the use of ABR testing using bone-conducted clicks in the audiological screening of at-risk infants. The purpose of this paper is to describe the method which we currently employ for obtaining ABRs to bone-conducted clicks with infants. Herein, we specifically focus on the control and maintenance of the delivery of the bone-conducted signal.