Hearing Loss After Activation of Hearing Preservation Cochlear Implants Might Be Related to Afferent Cochlear Innervation Injury

Risk Factors for Loss of Ipsilateral Residual Hearing After Hybrid Cochlear Implantation

“…In an in vitro model, high levels of electrical stimulation primarily damaged the afferent neural processes innervating the organ of Corti 3 . Significantly, noise trauma results in a similar type of damage to the afferent cochlear innervation 11 .…”

“…This hearing loss is generally mild ~12dB and coincident with implantation. Recently our group described a subset of these patients for whom hearing loss accelerates after activation, hypothesizing that high amplitude electric-acoustic stimulation (EAS) may cause excitotoxic damage to the peripheral afferent auditory system 3 . Here we analyze the same cohort of 85 patients from the FDA hearing preservation array multicenter trial and correlate ipsilateral post-implantation hearing loss with patient-specific medical risk factors known to be associated with presbycusia, such as age and the use of prescription medications.…”

Assessment of Cochlear Trauma During Cochlear Implantation Using Electrocochleography and Cone Beam Computed Tomography

“…Besides acute cochlear trauma during surgery, postoperative mechanisms seem to influence hearing preservation. Early inflammatory responses (33) or endolymphatic hydrops (34) could lead to hearing loss during the early postoperative phase, whereas tissue responses (8,35) and excitotoxicity because of electrical stimulation (36) could, among other factors, lead to delayed loss of residual hearing within months. Therefore, to further explore the correlation between trauma during surgery and postoperative hearing loss and gain more insight regarding the incidence of postoperative mechanisms, a tool to assess cochlear trauma during surgery is needed.…”

Delayed loss of hearing after hearing preservation cochlear implantation: Human temporal bone pathology and implications for etiology

“…Possible etiologies include (1) inflammatory cascade(O’Leary et al 2013) and immunogenic response(Nadol et al 2008), (2) excitotoxicity from electrical stimulation (Kopelovich et al in press 2015), (3)delayed degeneration of hair cells (Eshraghi et al 2007), spiral ganglion neurons, or their synapses, (4) delayed effects of trauma to intracochlear structures such as the stria vascularis or spiral ligament, (5) progressive alterations in cochlear mechanics due to intracochlear fibrosis and/or new bone formation, or other disease processes such as intracochlear otosclerosis, and (6) post-implantation conductive hearing loss (Chole et al 2014). Understanding the etiology of delayed post implantation hearing loss is critical for guiding both clinical management of cochlear implant patients with significant residual hearing and future research directed toward improving hearing preservation with cochlear implantation.…”