![]() In the cochlea, acoustic stimuli are detected by the HCs in the organ of Corti, which transduce the acoustic signals to the primary auditory SGNs through the ribbon synapses (see Fig. Therefore, based on the anatomical morphology and according to the affected site, HL can be conductive, sensorineural, central, or psychogenic. Normal hearing requires anatomical integrity and functional compliance of all parts of the auditory system: the outer, middle, and inner ear, the cochlear nerve as well as the central auditory pathways. In addition, a variety of nervous neoplasms can cause HL, including the vestibular schwannoma (VS), described below. Similarly, age-related HL (i.e., presbycusis) is the most frequent type of SNHL affecting 40–50% of the population by age 75, although also traumatic injuries, for instance, following a fierce noise exposure, or the exposure to ototoxic drugs (e.g., gentamicin, streptomycin or kanamycin) can lead to HL. Congenital cytomegalovirus infection, instead, is the most common non-genetic cause of sensorineural HL (SNHL) among children. Overall, the causative genes are classified as presynaptic, synaptic, and postsynaptic. Many factors have been indicated to cause HL, among which can be considered the genetic modifications (syndromic and non-syndromic), the degeneration of sensory neurons (i.e., the spiral ganglion neurons, SGNs) or hair cells (HCs) in the auditory pathway and the demyelination along the cochlear nerve. Hearing loss (HL) is one of the most common sensorineural impairments in humans and a heterogeneous disorder with a complex etiology (deeply reviewed in refs. Combining the biomolecular bench-side approach to the clinical bedside practice may be helpful for the diagnosis, prediction, and therapeutic approach in otology. In this review, we enlighten some of the mechanisms at the base of SCs transformation, VS development, and progression, likely leading to HL, and we pose great attention on the environmental factors that, in principle, could contribute to HL onset or progression. ![]() Despite the mechanisms and factors controlling their biological processes (i.e., proliferation, migration, differentiation, and myelination) have been largely unveiled, their role in VS and HL was poorly investigated. Following an injury, the SCs reprogram, expressing some stemness features. Importantly, SCs are the main glial cells ensheathing axons and forming myelin in the peripheral nerves. Notably, a benign SC-derived tumor of the acoustic nerve, named vestibular schwannoma (VS), has been indicated as cause of HL. Among cells of the acoustic nerve (VIII cranial nerve), in the cochlea are present the hair cells, the spiral ganglion neurons, the glia-like supporting cells, and the Schwann cells (SCs), which alterations have been considered cause of HL. Hearing loss (HL) is the most common and heterogeneous disorder of the sensory system, with a large morbidity in the worldwide population.
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