Myelination of the Auditory Nerve: Functions and Pathology

Myelination is essential for the rapid propagation of action potentials along axons in both the central and peripheral nervous systems, and the Schwann cells are the responsible of myelin sheath production in the peripheral nervous system. In the cochlea, sensory hair cells and neurons are in close association with several types of glial cells. Whereas hair cells are surrounded by supporting cells, spiral ganglion neuron axons are myelinated by Schwann cells. This myelin contributes to axonal protection and allows for efficient action potential transmission along the auditory nerve. Because in the last decade, myelin research has been notably focusing on the molecular and cellular mechanism of demyelination process and the associated axonal loss, in this review we summarize the role of the myelin sheath in auditory nerve and how Schwann cell demyelination results in a reduction in the velocity of action potential propagation, and an increase in nerve conduction vulnerability.

Keywords: Myelin; Schwann cell; Auditory system; Hearing loss; Demyelination