Have you ever heard of the term ‘ototoxicity’ before? Well, the incidence of it can be rare, affecting 1% of all patients. This is precisely why many are not even aware of the condition.
However, if we mention hearing loss, dizziness, or tinnitus, these may ring a bell. In literal terms, ototoxicity refers to ear poisoning due to external causes like toxic drugs. This condition usually affects the auditory nerve or cochlea but may also impact the vestibular system in some cases.
According to the World Health Organization (WHO), nearly 5% of the world’s population suffers from hearing loss. The two most common causes are age or loud noise. Naturally, ototoxicity gets pushed to the backburner.
Regardless of conventional conversational circles, it’s important to discuss this problem. This may help patients and healthcare providers avoid the issue or at least prevent it from getting worse.
A Serious Problem Identified by Medical Science
If you were of the impression that ototoxicity has been discovered only lately, you would be partially correct. The first-ever case of a toxic drug leading to temporary or permanent ear damage was recorded in the 17th century by Richard Morton.
However, much could not be discovered until the mid-1940s. This was around the time the drug Streptomycin was heavily used to treat tuberculosis. Though found to be effective, it was reported that multiple patients sustained irreversible damage to their vestibular system or cochlea.
Today, medical science knows a lot more about this condition. We have enough information and evidence to consider ototoxicity a serious problem. The main reason is that the condition damages the inner ear responsible for balance and hearing. What’s even more is that the damage is often irreversible.
Patients of ototoxicity may suffer from temporary or permanent hearing loss, a ringing sensation in the ears (tinnitus), loss of balance, and cognitive decline. As per the Cleveland Clinic, the following are the common symptoms of ototoxicity –
- Difficulty in hearing
- A constant ringing or humming sound in the ears
- Finding it challenging to balance oneself on the stairs
- Not being able to walk in the dark or at night
- Perceiving surrounding stationary objects to be moving (oscillopsia)
- Having to walk with legs wide apart due to a fear of losing balance
- Feeling exhausted or lightheaded
Which Drugs are Most Likely to Cause Ototoxicity?
Now, ototoxicity is most likely the result of certain drugs. They may contain chemicals that are toxic to the sensory cells present in the inner ear. The truth is that medical science has discovered around 200 drugs that may be ototoxic in nature.
Even then, some tend to be more toxic than the others. In some cases, the side effects may be mild and the benefits may outweigh the risks. In the case of some others, the ototoxic reactions only occur at extremely high doses.
The most dangerous ones are those that cause permanent ear damage, especially in the form of hearing loss. Based on that, let’s look at three of the most ototoxic drugs or drug categories.
Aminoglycoside Antibiotics
This category of drugs is most commonly used in treating bacterial infections. Streptomycin that we previously mentioned is a type of aminoglycoside antibiotics.
Other similar drugs include amikacin, tobramycin, neomycin, and vancomycin. In almost every patient treated with these drugs, some degree of renal toxicity and ear poisoning are observed.
The side effects are closely related to the dosage. This means aminoglycoside antibiotics in higher doses are more likely to cause hearing loss or tinnitus.
Chemotherapy Drugs
These drugs are used to treat different kinds of cancer. They work by interfering with the cell’s abnormal reproduction process. Besides being given orally, chemotherapy drugs may be administered intravenously.
These drugs help cure cancer by stopping or slowing cell growth and reducing the chances of a relapse. Chemotherapy medication is known to cause many side effects in the form of nausea, hair loss, mouth sores, and ototoxicity. The two main drugs that may cause ear poisoning include cisplatin and carboplatin.
Tepezza
This drug is specifically used in the treatment of thyroid eye disease or TED. Also known as Graves’ ophthalmopathy, this condition is an autoimmune disease of the thyroid gland affecting the eyes.
It is a rare disease affecting less than 200,000 American citizens. Some of the most common symptoms include double vision, pain behind the eye, difficulty moving the eye, and so on.
Given the seriousness of the condition, the Food and Drugs Administration (FDA) approved a drug called Tepezza by Horizon Therapeutics. It has shown to be an effective medicine, with 7 out of 10 patients responding well to the treatment.
However, the drug has been found to be highly ototoxic. According to TorHoerman Law, patients developed injuries like hearing loss, tinnitus, feeling of ear being plugged, and so on. Many of the side effects have been serious with irreversible damage.
The injured patients have filed a Tepezza lawsuit against the drug manufacturer. As of now, over 150 cases are awaiting fair settlements. This in itself conveys to us how grave the issue with Tepezza is.
Is Ototoxicity Preventable?
Many patients wonder whether ototoxic drug reactions can be prevented. The truth is that is not always possible. This is especially true in cases where a single class of drugs may be effective against an ailment.
Regardless of that, the healthcare provider may be able to manage symptoms better if ototoxicity is diagnosed early. If a patient is being treated using a drug known for ototoxicity, the doctor will closely monitor their response to the medicine.
If things seem serious, they may suggest diagnostic tests for ear poisoning. Healthcare providers also alert patients of ototoxicity symptoms so they can themselves inform if there are any issues.
How Is the Condition Diagnosed?
If one’s healthcare provider suspects that a patient may be exhibiting symptoms of ototoxicity, they may refer the case to an audiologist/otolaryngologist. This medical professional will run different tests to check the inner ear.
Even the healthcare provider prescribing the ototoxic drug will test the patient’s sense of balance and hearing. The following periodic diagnostic tests may help identify ototoxicity on time –
- Audiogram – This test measures the patient’s ability to hear and distinguish between different sounds and volumes.
- Otoacoustic Emissions Test (OAE) – This test measures how well the tiny hairs inside a patient’s ear will help them hear various sounds.
- Auditory Brainstem Response (ABR) test – This diagnostic test checks the health of the patient’s auditory nerve. It tests how well this nerve responds to sound.
- Vestibular Test Battery – This test is all about checking the patient’s sense of balance.
Treatment Options and Prognosis
Can the damage caused by ototoxic drugs be reversed? In most cases, no. This is true even if the drug’s dose is reduced or the patient stops consuming it altogether.
Another common issue is that ototoxic drugs are usually life-saving. This means it is not possible for the patient to stop using them abruptly. Healthcare providers monitor a patient’s response to the drug and try to manage any ototoxic symptoms.
If ear poisoning is detected, the following procedures or devices are used to manage the symptoms –
- Vestibular rehabilitation – The patient must work with a physical or vestibular therapist to help with balance problems.
- Hearing aids – This device is used to enhance hearing and aid communication by improving access to speech sounds.
- Cochlear implants – If hearing aids do not work, the healthcare provider may recommend cochlear implants to enhance hearing.
The prognosis of such treatments depends on how much damage the ototoxic drug has already caused. The doctor may recommend changing the patient’s long-term treatment plan to prevent further damage. This could improve treatment outlook.
On a final note, ototoxicity symptoms can show almost immediately after the first few doses of the toxic drug. In some cases, it may take as long as five years for symptoms to appear.
Since most of these drugs are essential, their benefits can outweigh the risks. This is something that is best determined by the healthcare provider.
One can discuss the warning signs for early treatment. If the symptoms are identified sooner, the doctor can intervene with a relevant care plan for faster and better recovery.
