Timothy C. Hain, MD. Hearing Page Page last modified: April 17, 2011
|Figure 1: The outer ear consists of the auricle (unlabelled), the external auditory canal, and the lateral surface of the tympanic membrane (TM). The middle ear includes the medial surface of the eardrum, the ossicular chain, the eustachian tube, and the tympanic segment of the facial nerve. The inner ear includes the auditory-vestibular nerve, the cochlea and the vestibular system (semicircular canals). The auditory nerve, also called the cochlear nerve, transmits sound to the brain.|
Radiation to the area of the ear is often associated with a chronic, progressive hearing deterioration (Wang et al, 2004). Sometimes the radiation has been purposely delivered to treat at tumor of the inner ear area (such as an acoustic neuroma), but more commonly the radiation has been delivered to treat a cancer in the same region. For head and neck cancers, the temporal bone (which contains the inner ear), is often included in the radiation field.
The hearing loss is usually delayed -- with no hearing loss in the first month post surgery but about 50% hearing loss by one year (Yilmaz et al, 2008). OAE testing in the first month can predict which patients are more likely to deteriorate.
Possible adverse effects of radiation to the ear include:
Chemotherapy may be combined with radiation, which can also independently cause reduced hearing (generally sensorineural hearing loss) due to ototoxicity (Meyer and Young, 2009). Cisplatin is the main ototoxic drug that is combined with radiation.
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