Raised ABR threshold after suction aspiration of glue from the middle ear: three case studies

Abstract

Between 1991 and 1993, 13 children (25 hearing ears) underwent recordings of the auditory brain stem response (ABR) under a general anaesthetic. The anaesthetic technique was similar for each child. Fourteen of these ears had fluid aspirated after myringotomy with insertion of grommets prior to the auditory brain stem response investigation. On subsequent hearing assessment six of these 14 ears (43 per cent) showed clear evidence of a threshold shift of 15 dB or greater. Eleven ears had either dry myringotomies or did not have a myringotomy prior to ABR and none of these showed evidence of a temporary threshold shift. Using Fisher's Exact probability test this difference is significant (p = 0.034). We feel it is important to report these observations so that unexpected high ABR thresholds following aspiration of glue are interpreted with caution.

Should we aspirate middle-ear effusions prior to insertion of ventilation tubes?

“…Noise of this intensity is considered a potential hazard to hearing. Mason et al, 4 in a retrospective study, concluded that intense noise, such as that induced by suction, could produce a temporary shift in hearing threshold; however, more studies are needed to exclude other confounding factors.…”

Measurement of the sound intensity during suction of middle-ear fluid following myringotomy

“…SEM = standard error of the mean as measured by auditory brainstem response (ABR) testing after aural suctioning. 10 Impulse noise has been linked to noise-induced hearing loss and acoustic trauma. Impulses in the range of 0.2 ms in duration have peak energy at 2 to 3 kHz and are extremely detrimental to human hearing.…”

Pediatric hearing assessment by auditory brainstem response in the operating room

“…Early studies reported improved hearing immediately after tube placement by ABR testing and justified the use of ABR testing in the OR [10,11]. Clinical studies in recent years have revealed significant discrepancies between ABR results obtained in the OR and those obtained in the follow-up period, raising a concern regarding the validity of ABR outcomes obtained in the OR [7][8][9]. It is argued that OR-ABR results may not reflect patients' real hearing thresholds, therefore, follow-up audiological evaluations should be performed when OR-ABR indicates a hearing loss.…”

“…Our audiologists at times need to replace the fluidsoaked tips of the insert earphones during ABR testing. Another factor that may be contributing is the high intensity noises created by suction, which could cause a noise-induced temporary threshold shift in hearing [7,12]. One can imagine that mucoid fluid would need stronger or longer suction than serous effusion due to a viscosity difference, potentially inducing greater temporary threshold shifts in hearing.…”

“…1995, Mason et al observed unexpected high ABR thresholds following aspiration of middle ear fluid in 13 children (25 ears) under a general anesthesia [7]. In their study, 14 of these ears had fluid aspirated after myringotomy with insertion of grommet (tympanostomy tube) prior to ABR test.…”