The hearing screening activities of the Audiology Dept. at Ferrara University begun in 1983, examining in depth the neonates at risk of the NICU register, using Auditory Brainstem Responses. Within this context, the services of the department became a point reference in the state of Emilia-Romagna.

      In 1995 we ran one of the very first pilot studies in Italy and Europe on neonatal hearing screening, using the first commercially available devices of Otodynamics the ILO-88 (2-card system). The results of the pilot study were not encouraging, due to high number of false positives. It should be mentioned that this pilot study examined the well-babies with a single phase procedure (single OAE testing) and considering our lack of experience, the early hearing screening results we attained are not surprising.

      In 1996, we received a research grant from the region of Emilia-Romagna to test various technologies and clinical protocols associated with an OAE neonatal hearing screening. We used a number of hardware configurations, the ILO-92, the ILO-292, and the Virtual 330. The pilot program lasted two years (1996-1997) and during this period we tested various OAE protocols such as : (1) Linear TEOAEs ; (2) Non-Linear TEOAEs ;(3) QuickScreen TEOAEs ; (4) 65-50 dB SPL, DPOAEs ; (5) 65-55 dB SPL DPOAEs; (6) 75-65 dB SPL DPOAEs. The results from these studies have been published in a number of papers , which can be found in the Italian contribution section. The clinical protocol we have adopted for all these tests was the standard 3-phase procedure, in which the first two phases test the hearing status by OAEs and the last phase refers to ABR recordings. During this period a number of randomly selected subjects (100), who passed the OAE testing, were selected for an ABR evaluation. The high correlation of the ABR and OAE testing outcomes provided the basis for our UHNS program.

      In 1998, with the aid of additional regional grants, we started screening the population of the Ferrara region with an initial coverage of 85%. The latter increased to 92% , and 94% the next few years. In terms of hardware we used the ILO-292 and the StarKey DP-2000. Minimal testing has been done with Madsen's Echoscreen as well. The protocol we follow is the standardized, by now, three phase testing. The neonates (approximately 1500 births per year) are tested in the second day of life (approximately 48 hours) with Linear TEOAEs and 75-65 dB SPL DPOAEs. We have found out that DPOAEs are less prone to ambient noise and we prefer to use the latter protocol when noise seems to be a problem. From the data we have collected the last 4 years, certain trends have appeared.

• Despite the robustness of the DPOAE responses, very often the neonatal DP-gram reports a notch around 3.0 kHz. We believe that this notch is the result of a standing wave interaction with the cubic distortion product. There are several ways to resolve this problem, either by repositioning the probe or testing a frequency slightly higher than F₂ = 3.0 kHz.
  
  
• The Echoscreen device works as well as the ILO-292, but it seems to be more sensitive to ambient noise ( therefore the testing might take more time).
  
  
• The number of cases with unilateral hearing losses are equal or greater than the cases presenting bilateral losses. The actual values of incidence refer to a 2.12 and 1.89 per thousand respectively.
  
  
• The major cause of unilateral hearing loss is of sensorineural origin and very few cases have been identified with transmissive losses.
  
  
• The major cause of bilateral losses is of sensorineural origin and the majority of the cases have presented 30 - 40 dB HL ABR threshold elevation.
  
  
• The times necessary for an intervention (hearing aid prostheses) have been estimated as less than 6 months (median estimate 5.4 months). It should be noted than the reason of delays in our screening program is the fact that the neonates who fail the screening program undergo additional ABR and Electrocochleography testing.
  
  

      From 2000 we have extended our screening program to cover preterm neonates, using a different protocol. One of the objectives of the preterm neonatal screening is to collect evidence regarding the maturation of the cochlea and the auditory periphery. Candidates for the screening program are subject having a PCA age of at least 28 weeks. For younger subjects we have faced technical problems and the OAE testing is often not conclusive (the probe was much larger that the diameter of the acoustic meatus). The neonates are tested for a number of times (up to eight) in the NICU environment and before their release the OAE outcomes are validated with ABR testing. Usually we employ linear and high intensity DPOAE protocols. The incidence of unilateral cases is less in the NICU population than the well babies and the incidence of cases with bilateral losses is higher in the NICU population as expected. At present, the combined incidence of bilateral losses in our UHNS program is of 4.19 per thousand.

Date of the Report : October 2001
Contact: Stavros Hatzopoulos , Ph.D.
Address: Audiology Dept. , Ferrara University, 203 Corso Giovecca, 44100 FERRARA
Telephone: 0532-236341
Email:  sdh@dns.unife.it