The ear, the organ of hearing, is made up of three main parts: external, middle, and inner ear. The external ear includes the outer portion (auricle) and the external auditory canal. The middle ear is a cavity separated from the external ear by the eardrum, and it contains three small bones. The inner ear contains the cochlea (which is responsible for hearing), the vestibule (which senses position in space and motion), and the semicircular canals (which control equilibrium). Figure 10-2 shows the anatomy of the ear.

Figure 10-2. Anatomy of the ear

Organ damage

Ears and hearing can be damaged by chemotherapy, high-dose radiation, and some antibiotics.

Chemotherapy

Some anticancer drugs, primarily cisplatin, can cause substantial hearing loss in the high- to ultra-high-frequency range—6,000 to 12,000 Hertz (Hz). If more damage occurs, the lower frequencies also can be affected. Carboplatin is also associated with hearing loss but to a much lesser degree. Radiation to the head can intensify the hearing loss from cisplatin.

The damage generally occurs in both ears and is irreversible. Sometimes ringing in the ears (tinnitus) or a sensation of drifting in space or having objects drift around you (vertigo) can also occur. Children most at risk for chemotherapy-caused hearing loss are those treated for brain tumors, germ cell tumors, osteosarcoma, and neuroblastoma.

Radiation

Survivors who had head and neck tumors treated with higher doses of radiation and/or older radiation techniques (from the 1950s and 1960s) often develop hearing loss. The most common diseases treated with high-dose radiation that can affect the ears are as follows:

• Nasopharyngeal carcinomas

• Parameningeal sarcomas

• Brain stem gliomas

• Medulloblastomas

• Ependymomas

Children treated with less than 2400 cGy of cranial radiation (e.g., for leukemia or prior to stem cell transplantation) rarely develop any late effects in the ears.

Outer ear infections, which are common after high-dose radiation, can impair hearing by drying out and thickening the external ear canal and eardrum. Chronic middle ear infections (otitis media) can also be caused by radiation due to damage to the eustachian tube, which is responsible for drainage of the middle ear. When the eustachian tube cannot drain properly, middle ear infections can become chronic.

The glands that produce earwax (cerumen glands) may produce less wax, and what is produced sometimes gets crusty and impacted. While the earwax is impacted, hearing is decreased and trapped moisture can increase the risk for ear infections. This late effect can also occur in survivors who developed graft-versus-host disease after stem cell transplantation. Impacted earwax can be removed by your healthcare provider. Using cotton-tipped applicators or other objects in the ear canal is strongly discouraged because they can actually push impacted earwax further into the ear canal.

An extremely unusual late effect of radiation to the ear is inflammation of the cartilage (chondritis), which can lead to cartilage damage and infection. This can occur after radiation doses of more than 7800 cGy given for brain stem gliomas.

The risk factors for permanent hearing loss in children or teens treated for cancer are as follows:

• Treatment with cisplatin, and to a lesser extent, carboplatin

• High doses of radiation to the head and/or neck

• Younger age at time of treatment

• Surgery involving the ear, brain, or auditory nerve

• Treatment with certain antibiotics such as gentamicin and amikacin (generally used for serious infections or fever when blood counts are low)

• Chronic ear infection

• Treatment with diuretics (drugs that help the body get rid of excess water)

• Poor kidney function

Signs and symptoms

Hearing loss should be suspected if your child:

• Does not startle or respond to loud noises.

• Does not respond to your voice consistently.

• Has a hard time understanding or following directions after age 3.

• Does not have clear speech.

• Fails to develop sounds or words that are appropriate for her age.

• Uses gestures instead of words.

Signs and symptoms of hearing loss typically associated with chemotherapy may be less obvious but should be suspected if your child:

• Confuses like-sounding words.

• Drops sounds off words or reports not hearing sounds such as th, f, sh, s, t, k, g, ch, and v.

• Reports he can hear but not understand words and speech.

• Has difficulty hearing in noisy situations or environments.

School-aged children who have lost some hearing may withdraw socially or have trouble in school. They may also describe ringing in their ears or dizziness.

Screening and detection

After treatment ends, appointments at the follow-up clinic should include an ear examination to look for infection, wax buildup, and eardrum perforation or scarring. Survivors should also have their hearing tested periodically following completion of treatment, because chemotherapy can have an impact on hearing up to 5 years after completion of the last round. Healthcare providers of survivors who had head or brain radiation may recommend periodic hearing tests because hearing problems can also sometimes develop several years after radiation. Anyone with abnormal test results should be referred to an audiologist or otolaryngologist (ear, nose, and throat doctor) for a thorough evaluation to determination whether assistive technology would be helpful.

The most widely used method to test the hearing of children with cancer is pure tone audiometry. These tests should be administered by an experienced pediatric audiologist. Extended high-frequency audiometry may be used to test for hearing loss in the high-frequency range (4,000 to 20,000 Hz). This is especially important for younger children with limited language because many consonants (“th”, “f”, “p”, “s”) are in this range. If a child cannot hear these consonants it may be very hard for her to acquire clear speech, so early intervention can make an important difference.

Degrees of hearing loss, measured in decibels (dB), are:

• Mild (25–40 dB): Difficulty hearing distant speech, soft voices, or voices in a noisy place.

• Moderate (45–60 dB): Difficulty hearing speech in a quiet place.

• Severe (65–90 dB): Cannot hear loud voices or sounds.

• Profound (more than 90 dB): May hear only very loud sounds, and must rely more on vision than hearing to understand communication if they are not wearing hearing aids or have a cochlear implant.

Children at risk for hearing loss should also be tested for speech and language disorders. Assessments such as the Rossetti Infant Toddler Language Scale (used with children from birth to 36 months), the Preschool Language Scale 5th edition (used on children from birth to age 7), and the Goldman-Fristoe Test of Articulation 2nd edition (used on children ages 2 to 21) are used to identify speech and language disorders and evaluate the effectiveness of hearing aids, auditory training, and speech therapy programs.

Medical management

Medical management includes treating middle or external ear infections, and in some cases, placing tubes in the ears. Survivors with tinnitus (ringing in the ears) may benefit from intervention and should be evaluated by an audiologist or otolaryngologist. State-of-the-art hearing aids are needed for those with permanent hearing impairment. Newer digital technology can minimize background noise and maximize speech sounds, unlike hearing aids of the past. Proper fitting and follow-up testing are crucial. It is also important to develop a routine for maintaining the aids, cleaning the ear molds, and replacing the batteries. Ear molds will need to be replaced periodically; an indication that they should be checked is “feedback” or high-pitched noise coming from the hearing aids. Fostering language development with speech reading and signing is vital for those with profound hearing loss. Using the closed captioning while watching television can also be helpful. Coping with the emotional and psychological effects of hearing loss in children and teens is an essential component of care.

Educators sometimes need the support and direction of medical caregivers. For instance, an FM system (a special type of assistive listening device) can be used by hearing-impaired children in school to amplify the teacher’s voice. The teacher wears a microphone that transmits her voice via radio waves to a receiver that can be attached to the child’s hearing aids, in a speaker mounted in the classroom, or to a personal speaker on the child’s desk. Your child’s healthcare provider should give you detailed information about educational regulations for young people with hearing loss. For more information about education, see Chapter 4 .

The American Academy of Audiology offers information about hearing loss on its consumer website at www.howsyourhearing.org . Links to various websites related to hearing loss in children can be found at www.cdc.gov/ncbddd/hearingloss/links.html . In addition, the Children’s Oncology Group’s survivorship guidelines include an informational resource about hearing loss at www.survivorshipguidelines.org .