Cochlear vascular pathology and hearing loss

Normal vascular function is essential for hearing. Abnormal blood flow to the cochlea is an etiologic factor contributing to various hearing disorders and vestibular dysfunctions, including noise-induced hearing loss, sudden deafness, presbyacusis, genetically-linked hearing loss, and endolymphatic hydrops such as Meniere's disease. Progression in blood flow pathology can parallel progression in hair cell loss and hearing impairment. To sustain hearing acuity, a healthy blood flow must be maintained. The blood supply not only provides oxygen and glucose to the hearing organ, it is also responsible for transporting hormones and neurotrophic growth factors to the tissue critical for organ health. Study of the vascular system in the inner ear has a long and rich history. There is a large body of evidence demonstrating a relationship between disturbances in cochlear microcirculatory homeostasis and decreased auditory sensitivity. This chapter focuses on recent discoveries relating the physiopathology of the microvasculature in the cochlear lateral wall to hearing function.