Stem Cell Treatment Hearing Loss

Stem Cell Treatment Hearing Loss at SIRM

Two Types:

1. Conductive hearing loss

A conductive hearing impairment is present when the sound is not reaching the inner ear, the cochlea. This can be due to external ear canal malformation, dysfunction of the eardrum or malfunction of the bones of the middle ear. The ear drum may show defects from small to total resulting in hearing loss of different degree. Scar tissue after ear infections may also make the ear drum dysfunction as well as when it is retracted and adherent to the medial part of the middle ear.

Dysfunction of the three small bones of the middle ear; hammer, anvil and stapes may result in conductive hearing loss. The mobility of the ossicles may be impaired of different reasons and disruption of the ossicular chain due to trauma, infection or anchylosis may also result in hearing loss.

2. Sensorineural hearing loss

A sensorineural hearing loss is one resulting from dysfunction of the inner ear, the cochlea, the nerve that transmits the impulses from the cochlea to the hearing centre in the brain or damage in the brain. The most common reason for sensorineural hearing impairment is damage to the hair cells in the cochlea. As we grow older the hair cells degenerate and lose their function, and our hearing deteriorates. Depending on the definition it could be estimated that more than 50% of the population over the age of 70 has an impaired hearing. Impaired hearing is the most common physical handicap in the industrialized world.

Another common reason for hearing loss due to hair cell damage is noise-induced hearing loss. These types of hearing loss are often most pronounced in the high frequency range. This will often interfere with speech understanding, as it is in the high frequency range that we find the consonant sounds that are most important especially in noisy surroundings. Head trauma, ear infections, tumours and ototoxic drugs such as gentamyacin are other reasons for sensorineural hearing loss.

Mixed hearing loss

Mixed hearing loss is a combination of the two types discussed above. Chronic ear infection that is a fairly common diagnosis could result in a defect ear drum and/or middle ear ossicle damages.

Stem Cell Treatment for Hearing Loss

Streaming NIH Database:

Related Articles Preservation of Neural Sensitivity after Noise-Induced Suppression of Sensory Function. J Am Acad Audiol. 2016 Jan;27(1):49-61 Authors: Guthrie OW Abstract BACKGROUND: Permanent loss of outer hair cell (OHC) amplification may occur within days of acoustic overexposure. This loss of sensory function typically results in an immediate loss of neural sensitivity although neurodegeneration occurs months or years after damage to OHCs. This delay in neurodegeneration might provide an opportunity to preserve neural sensitivity although OHC amplification is permanently lost. PURPOSE: To test the hypothesis that neural functions can be preserved after permanent and severe loss of OHC amplification. To begin to address this possibility, an animal model of severe permanent loss of both OHC and neural functions was established. RESEARCH DESIGN: This research employed a 4 × 4 split-plot factorial design, with four levels of the within-subject factor (time: baseline, 1-day, 1-week, and 1-mo postnoise exposure) and four levels of the between-subject factor (experimental groups: control, noise exposed, therapy, and noise exposed + therapy). STUDY SAMPLE: Twenty-six hooded male Long-Evans rats (263 ± 63 g) served as subjects for this experiment. All animals exhibited baseline auditory function that approximated normative values for rats of the same strain. DATA COLLECTION AND ANALYSIS: Distortion product otoacoustic emissions and auditory brainstem responses were used to assay and differentiate OHC versus neural functions. Factorial analysis of variances was computed to identify statistically significant main effects and Dunnett testing was employed in post hoc computations. INTERVENTION: To rescue neural function after permanent loss of OHC amplification, small molecular weight carboxy alkyl esters were employed after noise injury. RESULTS: The results revealed that in the presence of permanent loss of OHC amplification, the loss of neural sensitivity could be rescued. In addition, auditory brainstem response wave I amplitudes at suprathreshold levels were rescued from noise-induced depletion into the biologic noise floor. CONCLUSION: Since mammalian OHCs do not regenerate after damage, these results encourage further experiments aimed at preserving neural functions following noise injury. PMID: 26809326 [PubMed - indexed for MEDLINE]
Related Articles Hearing Loss after Round Window Surgery in Mice Is due to Middle Ear Effusion. Audiol Neurootol. 2016;21(6):356-364 Authors: Zhu BZ, Saleh J, Isgrig KT, Cunningham LL, Chien WW Abstract BACKGROUND: Delivery of therapeutic agents directly through the round window (RW) offers promise for treating sensorineural hearing loss. However, hearing loss can result from the surgical approach itself, and the reasons for this are poorly understood. We examined the hearing loss following the 3 major steps involved with the RW approach to access the mouse cochlea: bullostomy, RW puncture, and RW injection. METHODS: Twenty-one adult CBA/J mice underwent bullostomy alone, 10 underwent RW puncture, and 8 underwent RW injection with PBS with 5% glycerol. Auditory brainstem responses (ABR) and otoscopy were performed preoperatively and up to 6 weeks postoperatively. Hair cells were stained, and survival was assessed using immunofluorescence. RESULTS: One week postoperatively, mice in all groups showed significant threshold shifts. Otoscopy revealed approximately half of all mice had middle ear effusion (MEE), with a higher incidence of effusion in the RW puncture and RW injection groups. Those with MEE had significant ABR threshold shifts, whereas those without MEE had minimal hearing loss. MEE persisted through 6 weeks in a majority of cases, but in those mice with MEE resolution, there was at least partial improvement in hearing. Immunohistochemistry showed minimal loss of hair cells in all animals. CONCLUSION: MEE is highly correlated with hearing loss in mice undergoing RW surgery. Otoscopy is an important adjunct to consider after ear surgery in mice, as MEE may contribute to postsurgical hearing loss. PMID: 28068659 [PubMed - indexed for MEDLINE]

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