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Hearing Loss Screening In Newborns And Infants In Paysandu, Uruguay
NOTE :Dr. De Monte has provided,
very generously, an additional PowerPOint presentation with extra
visual material on the same topic, which he presented to the 2003
IFOS meeting in Cairo, Egypt. Interested readers can
download the powerpoint PDF file clicking here. I. Introduction
Among sensorial sequelae, hearing loss constitutes a major factor affecting child development when not identified and treated at an early stage. The advent of new and improved techniques for assessing hearing has paved de way for new methods of early Screening of hearing loss in newborn. Screening for hearing loss by high risk registry alone overlooks the fact that fifty percent of children with congenital hearing loss are normal newborns. Although the early detection of hearing loss has been recommended by the National Institute of Health and the Joint Committee on Infant Hearing Screening since 1994 in the United States, such standard has yet to be implemented in our country, Uruguay. Screening is justified when the disorder has a substantial negative impact on those affected and, once identified, can be treated appropriately. It should in addition be reasonably prevalent, and a quick, reliable and accepted method should exist for those undergoing examination. Hearing loss unquestionably meets these criteria (ASHA 1990, 1992; JCIH 1994, 2000) This paper seeks to highlight the importance of testing all normal and problem newborn and demonstrate how this can be done as part of a Follow-up Programme for monitoring both normal newborns and those with perinatal risk. II. Materials and Methods We used a Starkey DP-2000 to measure the Distortion product of otoacoustic emissions (DPOAEs), with the 2.00a software version, and the following protocol: Test parameters:
Where F1 and F2 are stimulus tones and L1 and L2 are their respective intensity levels, in dB SPL. TA is the tone average time, MinSN the minimum signal-to-noise ratio in dB SPL and MinDP the minimum acceptable value of the resulting distortion product. In line with this, the distortion product was studied over frequencies 2-6 kHz, and a pass was required in respect of 4 o f the 6 frequencies analyzed in order for the patient to pass. The plan was to test all at-risk infants admitted to the Special Care Unit for Premature Babies and Infants (Comepa’s NICU) of the Paysandú Medical Corporation (COMEPA), together with all normal babies born between 15 January – 15 April 1999 at the COMEPA Hospital, which serves a population of about 40,000 with an average birth rate of 60 per month. We also studied all the patients discharged from the Neonatal Intensive Care Unit, especially premature infants below 1500 g., in order to assess the incidence of Sensory neural Hearing Loss in normal newborns vs. at-risk. We use the Marion Downs Protocol from Colorado. The first difficulty we encountered, following the method outlined, was that the babies born under normal conditions at the Comepa Hospital, could not be examined prior to their discharge at 48 hours, since they were discharged at 24 hours. A proposal was put forward to test between 48 and 72 hours after birth at the practice, but this was not possible: infants were brought by their grandmothers or other relatives, as their mothers were not in position to do so. We then proposed to amend the method, and bearing in mind the ideal scenario whereby a diagnosis is made before 3 month and intervention occurs before 6 month, we deemed appropriate to test within the first 15 days from birth, with the second test conducted at 30-45 days. The following work outline was adopted: Normal Newborns: DPOAE before 2 weeks. If result is a REFER, we examine the newborn again at 30 – 45 days. If result is REFER again, we perform an ABR test. If we confirm the suspected Hearing Loss, we make a Behavioral assessment and Fitting. The newborns that PASS the Screening leave. At Risk-Newborns: In addition, we test ABR on ALL at-risk newborns, and periodic reassessment of the babies with DPOAE and ABR and Treatment of associated pathology. Auditory Brainstem Response: All the DPOAE REFER babies are assessed with ABR, of short latency. We have performed studies with clicks or stimuli of very short duration (100 microseconds), with an intensity of stimulus starting at 85 db, and a frequency of 30 per sec, studying the frequencies between 2000-4000 Hz with a peak at 3000 Hz. This makes it possible to detect whether there is pathology anywhere between the distal portion of the 8th pair to the lower colliculus. Should there be a response, the central conduction time and the peripheral conduction time are analyzed. In all the cases of PASS, a “hearing threshold” test is performed. In the case of babies with a REFER ABR, the test is repeated 45 to 60 days later, expecting the maturity of the hearing pathway more so in the case of preterm babies or infants with perinatal pathology. Sedation has been used in most babies to be able to perform these tests. However, but they have also been performed under spontaneous sleep conditions whenever possible. III. Discussion As Lee and Kim have concluded, environmental noise, including a baby’s crying, is a critical factor. We found it much easier to conduct the test in the silent atmosphere of the practice than in the hospital NICU (Newborn Intensive Care Unit) that was consistently noisier. A baby’s crying is a problem of timing: one needs to wait for the right moment, and as a result the average time taken for a test is around 15 minutes. Breast-feeding a baby is a suitable way to settle it down so the test can be performed, when it is not calm, and does not relax spontaneously or with a “pacifier”. We learn just how critical is to put the probe in the External Ear Canal. There are often differences between the left and right side that require changing the size of the probe tip. It is also crucial that the tip fits perfectly on the outlets of the speakers that stimulates F1 and F2 and the microphone that picks up burst (the otoacoustic emissions). In order to ensure the permeability to the tip’s channels, a small needle is passed though them. In the event of a REFER, the child is retested immediately several times, until a PASS is obtained or we are absolutely sure of the referral. In this manner, it was possible to reduce the refer rate of the first day. The new Starkey software makes it possible to study frequencies individually, and this is very useful for reexamining only those frequencies that are not within protocol specifications. According to Rhodes et al., who compared different screening methods the most suitable methods, on account both of their sensitivity and specificity, and their usefulness, were DPOAE and A-ABR. Neither otoscopy nor the impedanciometry is particularly reliable at this age. This is why we believe it appropriate to test with DPOAE, repeated at 15-30 days, and in case of a REFER, in a normal newborn to use ABR, since we still do not have available A-ABR. Use of ABR is mandatory for infants admitted to the COMEPA’s NICU. The final results of this short series of tests showed there were 4 infants in whom otoacoustic emissions could not be detected in the second test. Of these 4 infants, three were tested using ABR, while the fourth was unable to be contacted again. Two of them have permeable auditory tracts and one has absent evoked potential in both ears and will be referred for assessment and treatment. As we stated in the introduction, this paper seeks to illustrate the importance of testing all normal neonates and at-risk neonates, and demonstrate the need to do this as part of a programme for monitoring both normal newborns ant those with perinatal risk. COMEPA, Follow-up Programme 2000. Universal Newborn Hearing Screening. From 1 January 2000, we have used a UNHS program for all babies born in Comepa Hospital and discharged from Comepa’s NICU. As of 5th December 2000, 671 bilateral tests had been carried out on normal neonates and neonates with perinatal risk; that is all newborns in Comepa’s Hospital, plus all those discharged from the NICU (Ucepyn). From the total number, we can examine 606 that are 95.73 %. 21 of them, including two that live in Montevideo did not show up to their appointment. We have a Pass rate of 94% at the first examination. Four parents did not accept to participate in the Screening Plan. The average age in days was 29, with a minimum age of 3 and a maximum of 326. At NICU, the minimum age was 48 days old. We have, in this Plan 2000, three infants suspected of Sensory Neural Hearing Loss which were evaluated with the Marion Downs Protocol. We have continued working in 2001, and at end August, we had tested a total of 1090 Newborns To finish this presentation, we would like to comment on four particular cases, to exemplify the problems and benefits of the UNHS
MA.
SMA: Born: 6/14/00 weight at birth: 3970 Grs. Date admission: 6/23/00 Weight admission: 3700 Grs. Date release: 6/26/00 Weight release: 3766gr Age:12 days Hemolytic Disease, Rh conflict, Phototherapy and 2 transfusions. Mother 0 Rh(-) , Coombs indirect + Physical examination: . Jaundice Normal Neurological tone, normal reflex TB 20.60 mg% , DB 8.30 mg% , I B 12.30 mg%. Intra Hospital Infection, Klebsiella sepsis .
DPOAE Pass ABR refer in both ears: Diagnoses : Auditory Neuropathy by Jaundice.
AINC Born: 01/11/2000 Weight at birth: 696 grs. Date admission : 01/11/2000 Weight at release 1724 gr Well controlled Pregnancy, Ecodoppler: umbilical artery pathology, oligoamnios. Admittance reason : Extreme prematurity weight: 696 grs. Intra hospital infection staphylococcus coag + Seven days of Ceftriaxona + Amikacina Hypoglycemia Anaemia Prematurity Pulmonar Bronchodisplasy no oxygen dependent.
DPOAE Pass (4 times) ABR Refer (2 times) One year later, DPOAE and ABR are normal.
Diagnoses : Auditory Neuropathy by Prematurity. Improves with maturity.
CS. 3 years old No relevant background, diagnosed with a Deep Bilateral Sensory Neural Hearing Loss when visiting for a mild earache. Had the programme been in place, this girl would have won 3 years on her fitting and auditory reeducation.
IV. Summary The advent of new and proved techniques for assessing hearing has paved the way for new methods of early Screening of hearing loss in newborns. Screening for hearing loss by high-risk registry alone overlooks the fact that fifty percent of children with congenital hearing loss are normal newborns. Although the National Institute of Health of the Unites States and the Joint Committee on Infant Hearing Screening have both recommended screening for hearing loss since 1994, testing has yet to be implemented in Uruguay.
Nowadays, we have access to instruments and methods that are suitable for effective early diagnosis and treatment of infants suffering from hearing loss. We seek to encourage their use among pediatricians, otolaryngologists, audiologists, health care Administrators and parents, in order to promote intervention in children with hearing impairments at an early stage that is beneficial in terms of the development of language. Bibliography
1. Hall, J. W. III, & Mueller, H. G. III. (1997). Audiologists' Desk Reference Volumen 1. San Diego: Singular Publishing Group. 2. Hall, J. W. III. (March 1998). Paper presented at the conference on Universal Newborn Hearing Screening and Early Intervention: The First Year, Mississippi State Department of Health, Jackson, MS. 3. Joint Committee on Infant Hearing Year 2000 Position Statement: Principles and Guidelines for Early Hearing Detection and Intervention Programs 4. McDaniel, S., Lytle, S., & Hall, J. W. III. (April 1996). Relation between sensory hearing loss and distortion product otoacoustic emissions. Paper presented at the American Academy of Audiology Convention, Salt Lake City, Utah. 5. NIH Consensus Statement (Volume 11, Number 1). Early Identification of Hearing Impairment in Infants and Young Children. March 1-3, 1993. 6. Rodhes, M.C. et al. Hearing Screening in the newborn intensive care nursery. June 1999 Otolaryngology-Head and Neck Surgery vol 120 N°6 pp 799-808 7. Mehl, A. Thomson V. Newborn Hearing Screening: The great Omission. January 1998 PEDIATRICS vol 101 N° 1 8. Otoacoustic Emissions. Basic Science and Clinical Applications. Charles Berlin editor, Singular 1998. 9. Otoacoustic Emissions. Clinical Applications . Martin S. Robinette Theodore Glattke editors, Thieme 1997 10. Handbook of Otoacoustic Emissions. Hall, J. W. III. Singular 2000 11. Clinical applications of the auditory Brainstem Response. Hood L. Singular 1998 |
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