Etiologic and diagnostic evaluation: Algorithm for severe to profound sensorineural hearing loss in Brazil

Abstract

Objective: Evaluation of the effectiveness of imaging and genetic testing, and establishment of a cost-effective diagnostic protocol for the etiologic diagnosis of sensorineural hearing loss (SNHL) in Brazil. Design: Prospective cohort study. Study sample: Analysis of 100 unrelated Brazilian patients with severe to profound bilateral SNHL submitted to cochlear implant (CI) between 2002 and 2010 at the University of Campinas hospital. The study was based upon three groups: individuals with congenital, progressive, and sudden SNHL. Results: After the diagnostic investigation, the number of cases with unknown etiology was reduced from 72 to 42 (a 42% reduction); 25% of cases were due to environmental factors, 19% to genetic causes, and 14% to inner-ear abnormalities or other clinical features. The genetic and imaging findings contributed to the diagnosis of SNHL in 19% and 20% of the cases analysed, respectively. Molecular testing mainly contributed to the diagnosis of patients with congenital SNHL, while the contribution of radiologic examination was higher for individuals with progressive or sudden SNHL. A sequential diagnostic protocol was proposed based on these data. Conclusions: The proposed diagnostic workup algorithm could provide better optimization of etiologic diagnosis, as well as reduced costs, compared to a simultaneous testing approach.

Key Words::

• Deafness
• cochlear implant
• genetic testing
• diagnostic protocol

Acknowledgements

We would like to thank the collaboration of all the hearing-impaired patients and their relatives. We also thank the students and professionals who participated in this work. The study was supported by the Brazilian agencies FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo), CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior), and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico).

Declaration of interest: The authors report no conflicts of interest. Presented at the 12th International Congress of Human Genetics and the 61st Annual Meeting of the American Society of Human Genetics, Montreal, Canada, October 11–15, 2011.