Re: OAE and BAER

["Daniel M. Schwartz" <schwartzd@SURGMON.COM>]

The application of BAER screening for detection of hearing loss in neonates
has proven to be a quick, reliable and valid tool for more than 25 years
since first spearheaded at San Diego Children's Hospital by Dr. Bob
Galambos.  You may not be aware that there is actually a commercially
available neonatal BAER screening device I think that it is called ALGO
which was designed expressly for this purpose and which has a proven track
record.  I disagree with Dr. Goldberg that it is not a quick screening test
and therefore not suitable for large numbers.  If performed correctly
relative to a screening test and not a diagnostic test then it is in fact
acceptable time appropriate.  The problem is that all too often people use
it as a diagnostic test by recording the BAER at many different intensity
levels in the ICN  which of course consumes allot of time.  The object of
BAER screening is quite simple, is there a wave V at a sufficiently low
intensity level to r/o marked hearing loss.  That level is 40 dB nHL.  If
there is a wave V at this level they pass, if not they fail and are then
referred for complete evaluation in the lab not the nursery.  I refer you to
a bookchapter  wrote on this topic many years ago Schwartz, D.M. and
Schwartz, J.A. Auditory evoked potentials in clinical pediatrics. In:
Rintelmann, W.F. (Ed.). Hearing Assessment 2nd Edition, ProEd Press
Publishers, Austin, TX (1990).

Otoacoustic emissions are relatively new in the past decade or so with great
interest in the auditory community for hearing screening for about five
years.  The technique provides information about the peripheral hearing
apparatus only whereas the BAER measures the peripheral and central auditory
systems, respectively.  In general the limiting factor of OAE's in the
nursery is the signal-to-noise ratio.  Because these "acoustic echoes"
require a very low noise floor to be recorded, reliable, valid data is
difficult to obtain in an electrically and acoustically hostile environment
such as the ICN.  Moreover, as I understand it from my audiology colleagues,
there are numerous technical variables that have yet to be addressed which
argue against routine clinical use.  I certainly would stick to what is
quite time-honored and of proven value, the BAER screen.

Daniel M. Schwartz
schwartzd@surgmon.com
-----Original Message-----
From: Alicia Saenz de Cabezon <asaenz@REDESTB.ES>
To: Multiple recipients of list CLIN_NEUROPHYSIOL
<CLIN_NEUROPHYSIOL@LISTSERV.UMU.SE>
Date: Friday, November 28, 1997 11:42 AM
Subject: Re: Microelectrode recordings before pallidotomy


>Thank you very much by your answer. Next Wensday I have to be in a round
>table talking about this issue together with neonatologists, and I will
>feel better after your comments.
>Alicia
>
>----------
>De:             Gary Goldberg MD[SMTP:goldberg@VM.TEMPLE.EDU]
>Enviado:        jueves 27 de noviembre de 1997 13:41
>Para:           Multiple recipients of list CLIN_NEUROPHYSIOL
>Asunto:         Re: Microelectrode recordings before pallidotomy
>
>We have been doing objective audiometry (ObjAud) with BAEP testing on
>neonates in our laboratory for several years.  The babies are screened in
>the NICU for auditory impairment and then sent to us if they fail a
>screening examination.  Otherwise we only test the most high-risk infants
>with ObjAud.  The OEA examination may be useful as a screening tool only if
>it has significantly more false positive results than false negative
>results.  We looked at this technology a few years ago and did not feel it
>offered much advantage over ObjAud or our current screening techniques
>which are BAEP-based (although not at all perfected).  We believe that
>BAEP-based objective audiometry is the most accurate test but it is fairly
>expensive and time-consuming to perform and therefore not suitable for
>screening large numbers of infants.  I think the challenge in this area is
>to create a series of examinations that begins with a determination of
>clinical risk and then goes to a suitable screening examination (relatively
>quick and inexpensive but with a relatively large number of false positive
>results but low number of false negative results) followed by a
>high-accuracy examination like ObjAud.  I would be very interested in
>hearing of others' experiences with this techology applied to this clinical
>problem.  Thanks.
>Gary Goldberg MD
>Director, Evoked Potential Lab
>MossRehab Hospital
>Albert Einstein Healthcare Network
>