Occasionally, fullness in the involved ear is encountered. The patient may also experience tinnitus or ringing in the ear. Obviously hearing loss (the vast majority in one ear only) is the major symptom. Very few symptoms are usually experienced in patients with sudden SNHL. Sudden sensorineural hearing loss (SSNHL) is defined as a decline in hearing greater than or equal to 20 dB over three days or less without any identifiable cause. For most case of SNHL, including sudden SNHL, the external ear canal and the middle ear are normal. For most cases of sensorineural hearing loss, including sudden SNHL, the abnormality is within the cochlea itself. The auditory cortex is the region of the brain in which sound is heard. The inner ear loss can occur in the cochlea, the cochlear or auditory nerve, the brainstem, or the auditory cortex. Sensorineural Hearing Loss (inner ear hearing loss) - As described above, sensorineural hearing loss is an inner ear hearing loss.Other causes of conductive hearing losses include wax in the ear canal, middle ear fluid or infection, or any other process that would prevent sound from reaching the inner ear. Such a conductive hearing impairment may be due to a perforation (hole) in the ear drum, partial destruction or fixation of one or all of the three little ear bones, or scar tissue around the ear bones or in the ear drum. Conductive Hearing Losses - Any disease affecting the ear canal (external ear), ear drum, middle ear space, or the three small ear bones may cause a conductive hearing loss by interfering with the transmission of sound to the inner ear.When there is some difficulty in both the middle and inner ear, a combination of conductive and sensorineural impairment exists, called a mixed hearing loss. If the trouble lies in the inner ear, a sensorineural (SNHL) or nerve hearing loss is the result. If there is some difficulty in the external or middle ear, a conductive hearing loss occurs. The external ear and the middle ear conduct sound the inner ear receives it.
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