Tone burst stimulus for auditory brainstem responses: Prediction of hearing threshold at 1 kHz

Authors

• Federico Dagna^, ,
• Andrea Canale,
• Michelangelo Lacilla,
• Roberto Albera

• ENT Division, University of Turin, Italy

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Abstract

Objective

To assess differences in hearing threshold estimation of four different ABR tone-bursts at 1 kHz.

Methods

Twenty-one (21) ears from 11 subjects were tested with pure-tone audiometry (PTA): 

5 ears (24%) were normal hearing, 

5 (24%) affected by mild hearing loss, 

7 (33%) showed moderate hearing loss and 

4 (19%) severe hearing loss. 

After PTA each subject underwent tone-burst ABR test at 1 kHz using 

• a linear gated (L_ABR) 

• or Blackman windowed (B_ABR) stimuli with (nn_ABR) and without ipsilateral notched noise. 

Stimulation rate and filters settings were unchanged.

Results

Overall correlation between PTA and all ABRs thresholds was high, ranging from 0.84 to 0.94.

In normal hearing ears none of the differences was significant, except for those measured with B_nn_ABR, which showed a mean 16 dB overestimation of the pure-tone threshold (p < 0.05). 

In mild hearing loss group none of the differences between thresholds were significant. 

In moderate and severe hearing loss groups significant differences were measured with L_nn_ABR (p < 0.05) with a mean 7.5 dB underestimation of PTA.

Conclusions

Although very similar, some significant differences were found when considering specific group of patients with different degrees of hearing loss.

Fuente:  Auris Nasus Larynx

Etiology of unilateral hearing loss in a national hereditary deafness repository

F:uente de la imagen: digitalhearingaid-s.com

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Abstract

Purpose

The aim of this study was to characterize the genetic, audiologic, and epidemiologic characteristics of unilateral hearing loss (HL) in a national hereditary deafness repository.

Materials and Methods

This is a prospective clinical study involving 34 subjects identified in a national hereditary deafness repository. 

Clinical data and family history of HL were obtained on enrollment. Candidate deafness genes were screened by single-stranded conformation polymorphism, and mutations were confirmed with sequencing.

Results

Thirty-four subjects (19 males, 15 females) with unilateral HL were identified, ranging in age from 2 months to 36 years. 

The mean age at diagnosis was 7 years, and the left ear was affected in 62% of the cases. 

The racial distribution of our sample was 62% white, 23% African American, and 15% Hispanic. 

Imaging results were available in 47%, and most (69%) were considered normal. 

Nineteen percent had enlarged vestibular aqueducts, 2 had ipsilateral Mondini dysplasia, and 1 had a common cavity deformity. 

Twenty subjects (59%) had a family history of HL, with 26% specifically reporting familial unilateral HL. 

Mutational screening revealed sequence variants in the GJB2 (connexin 26), GJB3 (connexin 31), TECTA, and COCH genes. Two novel mutations were detected in COCH and TECTA.

Conclusions

Sequence variants in known deafness genes were detected in more than one-third of our study population, suggesting that gene/gene or gene/environmental interactions may indeed play a role in the etiology of some cases of unilateral deafness. 

Further prospective studies including congenital cytomegalovirus screening at birth and molecular screening of deafness genes in children with congenital unilateral HL will be required to establish the etiology of unilateral deafness with certainty.

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Authors

Corresponding author. Department of Otolaryngology/Head and Neck Surgery, Virginia Commonwealth University, PO Box 980146, Richmond, VA 23298, USA. Tel.: +1 804 828 3965.

• Kelley M. Dodson, MD^{a, b, ,} ,
• Alexandros Georgolios, MD^a,
• Noelle Barr, BS^a,
• Bich Nguyen, MD^c,
• Aristides Sismanis, MD^a,
• Kathleen S. Arnos, PhD^d,
• Virginia W. Norris, MS^d,
• Derek Chapman, PhD^e,
• Walter E. Nance, MD PhD^b,
• Arti Pandya, MD^b

• ^a Department of Otolaryngology, Virginia Commonwealth University, Richmond, VA, USA
• ^b Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, USA
• ^c Department of Otolaryngology/Head and Neck Surgery, University of Missouri, Columbia, MO, USA
• ^d Department of Biology, Gallaudet University, Washington, DC, USA
• ^e Department of Epidemiology, Virginia Commonwealth University, Richmond, VA, USA

• Fuente: 
• http://dx.doi.org/10.1016/j.amjoto.2012.03.005,