Destruction of auditory hair cells results in a subsequent loss of auditory neurons. In situ hybridization and neuronal cell culture studies as well as analyses of the inner ears of neurotrophin and neurotrophin receptor gene knockout mice have shown that NT-3 and BDNF mediate both the development and survival of auditory neurons. In this study guinea pigs were exposed to the ototoxic combination of an aminoglycoside antibiotic and a loop diuretic and then received 8 weeks of intracochlear infusion of either NT-3, BDNF or NT-3 + BDNF to determine whether site-specific application of these neurotrophins could prevent the loss of auditory neurons that follows a loss of auditory hair cells. Infusion of either NT-3 or NT-3 + BDNF into the scala tympani resulted in a > 90% survival of auditory neurons while BDNF infusion yielded a 78% survival rate, compared with a 14–24% neuronal survival rate in untreated ototoxin-exposed cochleae. These results show that loss of auditory neurons that occurs subsequent to a loss of auditory hair cells can be prevented by in vivo neurotrophin therapy with either NT-3 or BDNF.

To identify whether patients with diabetes have a higher incidence of sensorineural hearing loss than the general population and examine whether control of diabetes is related to severity of hearing loss. Retrospective database review; complete data mining of electronic medical record from 1989 to present. Tertiary referral center. Electronic medical records from 53,461 nondiabetic age-matched patients and 12,575 diabetic patients were reviewed. Presence or absence of diabetes and/or sensorineural hearing loss, serum creatinine, pure tone hearing (dB), speech discrimination (%), serum cholesterol, and triglycerides. Sensorineural hearing loss was more common in the diabetic patients than in age0matched nondiabetic patients from the same institutions. Poor control of diabetes, as measured by increasing serum creatinine, but not apparent in hemoglobin A1C laboratory data, correlated with worsening hearing in patients with diabetes who had sensorineural hearing loss. Sensorineural hearing loss was more common in patients with diabetes than in the control nondiabetic patients, and severity of hearing loss seemed to correlate with progression of disease as reflected in serum creatinine. This may have been due to microangiopathic disease in the inner ear.

The comprehensive Hearing Preservation classification system presented in this paper is suitable for use for all cochlear implant users with measurable pre-operative residual hearing. If adopted as a universal reporting standard, as it was designed to be, it should prove highly beneficial by enabling future studies to quickly and easily compare the results of previous studies and meta-analyze their data. To develop a comprehensive Hearing Preservation classification system suitable for use for all cochlear implant users with measurable pre-operative residual hearing. The HEARRING group discussed and reviewed a number of different propositions of a HP classification systems and reviewed critical appraisals to develop a qualitative system in accordance with the prerequisites. The Hearing Preservation Classification System proposed herein fulfills the following necessary criteria: 1) classification is independent from users' initial hearing, 2) it is appropriate for all cochlear implant users with measurable pre-operative residual hearing, 3) it covers the whole range of pure tone average from 0 to 120 dB; 4) it is easy to use and easy to understand.