Molecular mechanisms involved in cochlear implantation trauma and the protection of hearing and auditory sensory cells by inhibition of c‐jun‐N‐terminal kinase signaling

Abstract

Molecular mechanisms involved in programmed cell death of HCs are different than the ones involved in programmed cell death of SCs. Local delivery of AM-111 provided a significant level of protection against EIT-induced hearing losses, HC losses, and damage to neural elements.

Application of a TNF-alpha-inhibitor into the scala tympany after cochlear electrode insertion trauma in guinea pigs: Preliminary audiologic results

“…Compared to data from similar animal models of intracochlear trauma, this is a considerable high extent of hearing loss in comparison to earlier reports that described hearing loss within a range of 0 dB to 40 dB (Eshraghi et al, 2006(Eshraghi et al, , 2007a(Eshraghi et al, , 2013James et al, 2008;Chang et al, 2009;Eastwood et al, 2010a,b;Souter et al, 2012). However, the amount of surgical trauma has been acknowledged to be unpredictable in animal models (Eastwood et al, 2010b) as well as in humans (Carlson et al, 2011) and therefore variation to some degree is explainable.…”

“…While the present study measured postoperative hearing immediately after cochlear implantation trauma, a more common approach was a fi rst measurement from one day (Eshraghi et al, 2013) to one week (Chang et al, 2009;Maini et al, 2009;Eastwood et al, 2010a;Souter et al, 2012).…”

“…During surgery, the electrode analogue was inserted for 3 mm through the cochleostomy alongside the direction of the scala tympani and then gently withdrawn. Although this insertion depth is the current paradigm employed in almost all previous animal studies (Eshraghi et al, 2006(Eshraghi et al, , 2007a(Eshraghi et al, , 2013Souter et al, 2012), it is considerably less than usually achieved in human patients. A typical example of a commercially available electrode array is implanted for 17.5 mm to 19.2 mm after cochleostomy and thereby occupies almost the whole basal turn (Manrique et al, 2014).…”

“…They include the application of n-acetyl cysteine (Eastwood et al, 2010b), glucocorticoids (Eshraghi et al, 2007a;James et al, 2008;Chang et al, 2009;Eastwood et al, 2010a;van de Water et al, 2010a) and an interference with the MAPK/ JNK signaling pathway (Eshraghi et al, 2010(Eshraghi et al, , 2013. Also there has been a prospective, double-blind controlled clinical trial performed in humans showing the effectiveness of topical application of methylprednisolone to the round window to attenuate vestibular dysfunction and reduce electrode impedances after cochlear implantation (Enticott et al, 2011).…”

Micro-CT scan, electron microscopy and optical microscopy study of insertional traumas of cochlear implants

“…Preservation of residual hearing requires an atraumatic surgical technique. Topical dexamethasone [20], hyaluronic acid [5] or intraveinous corticosteroids [3] are generally used to limit cochlear trauma. Currently, clinical imaging (scanner, cone beam) does not always explain failures to preserve residual hearing and histological analysis is important to understand microscopic cochlear damages in cases of insertion traumas.…”