Ototoxicity is damage to the hearing or balance functions of the inner ear caused by drugs or chemicals. The inner ear contains the hearing mechanism, the end organ of the balance mechanism and the vestibulocochlear nerve, which sends hearing and balance information to the brain. Damage to these areas by ototoxic treatments may cause hearing loss, tinnitus (ringing or noise in the head or ears) and vertigo or sense of imbalance.
The extent of ototoxicity varies with the drug, the dose, duration of exposure and other conditions. In some cases, there is full recovery of any acquired hearing loss, tinnitus, or balance disturbance after the drug has been stopped. In other cases, the extent of damage is limited but permanent. An example of limited damage is high-frequency hearing loss, in which damage to the ear makes it difficult to hear high-pitched speech sounds such as “s,” “th,” “f” and “sh” and other high-pitched sounds such as musical notes or birds chirping. In more rare cases, there may be more wide spread hearing loss.
Many drugs can cause ototoxicity. Patients receiving certain treatments known or suspected to have ototoxic side effects (such as cisplatin, carboplatin, radiation, loop diuretics, or aminoglycoside antibiotics) may experience hearing loss, tinnitus, and dizziness/vertigo. Ototoxic medications can affect the hearing and/or balance portions of the inner ear. The rate of ototoxicity is dependent on the drug dosage, whether the medication is given along with other ototoxic treatments, and other individual patient factors.
Other drugs and chemicals may also cause ototoxicity. Hundreds of prescription drugs and over the counter medications are recognized as having the potential to be ototoxic and can result in temporary or permanent changes in hearing and balance function.
Why Should Testing Be Completed?
Ototoxicity may often be undiagnosed as patients may not recognize the relationship between their treatment and the changes in their hearing and balance. It is common for patients receiving ototoxic medications to report hearing loss, plugged sensations in their ears, ringing or buzzing noises, and mild to more significant balance concerns. These changes can occur gradually and may be more difficult for a patient to notice. This is why a pre-treatment baseline hearing test is recommended as well as monitoring hearing testing to track any changes that may be occurring. Monitoring any changes during treatment will allow your physician to determine if a change in medication, dosage or exposure time may be beneficial.
If permanent hearing loss does occur, an audiologist can counsel the patient regarding the hearing loss as well as offer strategies and options to improve hearing, communication and understanding. Hearing Aids and other Assistive Listening Devices (such as amplified telephones) can be discussed and generally are fit on a 30 day trial basis.
Ototoxicity Hearing Monitoring Program
Before receiving treatment involving therapeutic drugs known or suspected to have ototoxic side effects (such as cisplatin, aminoglycosides, or loop diuretics), the patient should undergo audiologic testing. Tests would include a Comprehensive Hearing Evaluation (including ultra high frequency testing) as well as Distortion Product Otoacoustic Emission (DPOAE) which evaluates the status of the outer hair cell function of the cochlea. Immittance testing will also be performed to assess middle ear function.
Ongoing Audiologic Monitoring
Ototoxicity protocols indicate the need for ongoing monitoring during treatments with ototoxic medications. These are usually scheduled 24 hours before each round of ototoxic medication, or weekly, depending on the type of medication the patient is taking. Because permanent drug-induced hearing loss may be delayed weeks or months after therapy, we continue to perform hearing evaluations immediately following completion of ototoxic drug therapy as well as at three- and six-month post-treatment intervals or for several years following head and neck radiation treatments.
Counseling Regarding Communication
Every appointment with an audiologist includes counseling regarding any patient specific concerns. It is important that patients are aware of how hearing and balance disorders can affect daily activities. Communication strategies and realistic expectations are an important part of living with hearing loss.
It is important to limit your exposure of hazardous noise levels and wear hearing protection in loud environments. Prolonged exposure to loud sounds (whether you consider it noise or something more pleasant such as music) can worsen the effects of ototoxic drugs. Hearing protection should always be worn in the presence of these loud sounds, however, it is especially important during the entire course of cancer treatment and for at least 12 months after ototoxic therapy, to avoid the combined effects of high volume exposure and ototoxic drug therapy on the inner ear. Custom-made and disposable ear protection is available through the Audiology Service at Froedtert Hospital.
Additional Audiology Services Provided
Hearing Aid Technology
Tinnitus Evaluation and Management
3rd Floor 92 Street Area
(Formally West Clinics)
9200 W. Wisconsin Ave.
Milwaukee, WI 53226
8 a.m. - 4:30 p.m.
Monday – Friday
Greenway Medical Complex
3365 S. 103 St., Suite 210
Greenfield, WI 53227
8:00 a.m. – 4:30 p.m.
Monday - Friday
Please inform the scheduler that your appointment is for ototoxicity. Baseline and follow-up evaluations for ototoxicity are given special scheduling consideration. We will work with the patient to ensure their tests are performed prior to their next scheduled cancer treatment.