Hearing loss

Recognizing The Symptoms Of Hearing Loss

Hearing loss can manifest in a variety of ways, often subtly at first. Recognizing these symptoms early and seeking help can significantly improve your quality of life. Common symptoms include:

• Difficulty understanding conversations, especially in noisy environments;

• Trouble hearing high-pitched sounds like the voices of women and children;

• Feeling that people are mumbling or speaking too softly;

• Asking others to repeat themselves frequently;

• Turning up the volume on the television or radio higher than usual;

• Finding that certain sounds seem muffled;

• Difficulty following conversations on the phone;

• Experiencing a ringing sensation in the ears, known as tinnitus;  

 

 If you suddenly find yourself unable to hear out of one ear, please seek help from a healthcare provider immediately or schedule an urgent audiogram. You could suffer from "sudden hearing loss", and early treatment can make a significant difference.

Hearing loss has a significant impact on social isolation, cognitive decline, and the risk of dementia. Research shows that individuals with hearing loss are more likely to experience social isolation because they struggle to communicate, leading to withdrawal from social interactions. This isolation can contribute to feelings of loneliness, which has been linked to poorer mental health and faster cognitive decline. A study published in The Lancet found that hearing loss is one of the largest modifiable risk factors for dementia, increasing the likelihood of developing the condition by up to 40% if left untreated. Additionally, research from Johns Hopkins University found that mild hearing loss doubles the risk of dementia, while moderate loss triples it. These studies suggest that treating hearing loss, such as using hearing aids, may help reduce the risk of cognitive decline and delay the onset of dementia.

Understanding The Types Of Hearing Loss

To explain hearing loss, I often compare the ear to a radio: you can adjust the volume and tune the channel. The radio volume corresponds to hearing levels (measured in decibels on an audiogram, learn more here), while the radio channel relates to speech discrimination (indicates the clarity of sound). For instance, when the volume of a radio is decreased (representing lower hearing levels), the sound becomes softer; however, it remains clear due the channel being still properly tuned (representing good speech discrimination). To address this problem, one can simply increase the volume, analogous to using hearing aids. However, if the channel tuning is lost (representing bad speech discrimination), raising the volume will only amplify white noise which is not desired nor helpful, and in such cases, hearing aids will not be effective. Understanding these two concepts (hearing levels and speech discrimination) is critical, as the various types of hearing loss can influence them in distinct ways, which in turn affects the treatment approach for your hearing loss.

Hearing loss is categorized into three main types: sensorineural, conductive, and mixed.

• Sensorineural hearing loss occurs when there is damage to the inner ear sensors (called "hair cells") or the auditory nerve. This type of hearing loss will typically first affect hearing levels (sounds being perceived as softer in volume), and eventually will lead to lower speech discrimination (less distinct/more muffled in clarity).This type of hearing loss is not reversible. Common causes include, among other things:
  • aging (presbycusis),
  • prolonged exposure to loud noise,
  • cochlear hydrops - Ménière's disease 
  • skull base tumors (vestibular schwannomas and meningioma most commonly), 
  • cochlear malformations and congenital hearing loss,
  • acoustic trauma (brief but loud sound),
  • barotrauma (pressure-induced trauma),
  • head trauma,
  • infections (viral or bacterial commonly),
  • certain medications that are toxic to hearing (ototoxicity) such as certain antibiotics or chemotherapy, 
  • sudden hearing loss.

• Conductive hearing loss occurs when sound waves are unable to travel efficiently through the outer or middle ear to reach the inner ear for mechanical reasons. This type of hearing loss will usually only affect hearing levels (sounds will appear softer), but will rarely cause any damage to speech discrimination (sounds will remain clear). This type of hearing loss can often be corrected medically or surgically. This can be caused by, among other things:
  • middle ear infections (otitis),
  • cholesteatomas (skin cyst in the ear),
  • ossicular chain abnormalities (issues with the hearing bones),
  • fluid in the middle ear (serous effusion),
  • earwax buildup,
  • abnormal bone growth in the ear (otosclerosis),
  • eardrum perforation.

• Mixed hearing loss is a combination of both sensorineural and conductive hearing loss, indicating that there is damage in both the outer/middle ear and the inner ear or auditory nerve. This type of hearing loss can be partially corrected medically or surgically.

When To Seek Medical Advice?

If you notice any signs of hearing loss (listed above), it’s crucial to consult a healthcare provider promptly. Early intervention can prevent further deterioration and enhance your hearing and overall quality of life.

Seek urgent medical advice if you experience sudden hearing loss, hearing loss in one ear, or if your hearing is accompanied by dizziness or imbalance. These could be signs of more serious underlying conditions that require immediate attention. Early treatment can make a significant difference.

Additionally, if you find yourself increasingly isolated, withdrawing from social situations, or struggling with day-to-day communication, it’s time to seek professional help. An ENT specialist can diagnose the cause and extent of your hearing loss and recommend appropriate treatment options.

Medical Evaluation And Diagnosis

During a hearing loss consultation, your doctor will begin by taking a detailed medical history, including questions about the onset, duration, and severity of the hearing loss, the type and dose of medication you're taking, any exposure to loud noises, family history, history of ear surgeries or ear infections in young age, and associated symptoms like ear pain, ringing (tinnitus), or dizziness.

The clinician then performs a physical examination, which will include inspecting the ear canal and eardrum with an otoscope to check for obstructions or infections. This part of the physical examination is critical. I personally always evaluate the ear under the microscope for added anatomical detail. The doctor might also perform a series of tests to assess your hearing capability and the functioning of your middle ear with a tuning fork. A vestibular exam (checking the balance function) may also be performed to check the health of the vestibular system, which is an essential function of the ear. Lastly, an endoscopy (using small fiberoptic flexible camera) might be performed to look at the Eustachian tube. A thorough medical history combined with a comprehensive physical examination typically allows me to narrow the diagnosis to a few potential causes.

The next step is usually a hearing evaluation, with the most common being an audiogram, which measures both the ability to hear sounds at different pitches and volumes (hearing levels or pure-tone audiometry) and evaluates how well the patient understands spoken words (speech discrimination or speech audiometry). The audiogram is key to help us determine the type (sensorineural, conductive or mixed) and severity of the hearing loss in each ear separately. The combination of the hearing thresholds and the presence or absence of an air-bone gap will help achieve a correct diagnosis. Tympanometry is a diagnostic procedure used to assess how well the middle ear is ventilated by measuring how the eardrum moves in response to variations in air pressure. It can help determine issues such as Eustachian tube dysfunction or middle ear fluid. Other more advanced audiological evaluations may be ordered depending on your situation (see "Diagnostic tests" section).

In some cases, additional tests like imaging studies, such as MRI of the internal auditory canals or CT scans of the temporal bones, may be ordered to rule out neural causes, tumors, or structural issues. Typically, I would order an MRI of the internal auditory canals (MRI IAC) if there is an asymmetric sensorineural hearing loss, a sudden hearing loss (there are other indications to obtain an MRI). The MRI helps assess the integrity of the hearing nerve and related nervous structures of the auditory system, and to a lesser extent the anatomy of the inner ear. The CT temporal bone is helpful when I try to evaluate the cause of a suspected or proven conductive hearing loss. It provides detailed information about the bony structures of the middle ear and is excellent to assess for inner ear malformations (among other things). 

This comprehensive approach helps in determining the type and severity of hearing loss, guiding the treatment plan.

Treatment Options

Treatment options vary depending on the type and severity of the hearing loss.

• For sensorineural hearing loss, there are no medical or surgical cures at this time. Hearing aids are one of the most common and effective treatments for managing sensorineural hearing loss (learn more here). While hearing aids do not cure this type of hearing loss, they significantly improve a person's ability to hear by amplifying sounds. These small, electronic devices are worn in or behind the ear and are designed to make speech and other sounds louder, clearer, and more distinct. Modern hearing aids are highly advanced, with features like noise reduction, directional microphones, and Bluetooth connectivity, making it easier for users to follow conversations in noisy environments or connect to smartphones and other devices. By improving sound clarity and enhancing communication, hearing aids can help reduce the social isolation and cognitive decline often associated with untreated hearing loss. They are an essential tool in helping individuals maintain an active and engaged lifestyle despite hearing difficulties. Hearing aids are suitable for nearly all levels of hearing loss, provided that speech discrimination (WRS%) is higher than 50%.
  
  On average, studies show that many individuals do not acquire hearing aids immediately after diagnosis, with delays of 5 to 10 years being common. Researchers identified that factors like age, cost, denial of the hearing loss severity, and social stigma associated with using hearing aids often delay the decision to acquire them. This is unfortunate as we now know that hearing loss is one of the reversible causes of cognitive decline and dementia. 
  
  In more advanced cases or for individuals who cannot wear a conventional hearing aid, a bone-anchored hearing aid may be suggested. It stimulates the inner ear by sending sound vibrations directly through the bone. Lastly, for patients with severe hearing loss, cochlear implants may be recommended to bypass damaged parts of the ear and directly stimulate the auditory nerve. 
  
  
• Conductive hearing loss treatments often involve medical or surgical interventions. The surgery will vary depending on the cause of the hearing loss (stapedectomy to fix otosclerosis, tympanoplasty to fix a perforated eardrum, etc). Easier treatments include can removing earwax or treating ear infections with antibiotics. Alternatively, an individual with conductive hearing loss might opt for hearing aids instead of undergoing surgery to avoid the risks associated with an intervention. While I am a neurologist (ENT specialized in ear surgery), I always advise my patients with conductive loss that their surgery is elective (in most cases) and that they generally have one of three options : opting for observation and repeating an audiogram in a year, undergoing surgery or using hearing aids. 

• Mixed hearing loss treatment may require a combination of these approaches. 

Additionally, assistive listening devices and communication strategies can support individuals in managing their hearing loss effectively.

Future Prospects in Hearing Loss Treatment?

Future treatments for sensorineural hearing loss, such as gene therapy and stem cell research, are advancing rapidly and could revolutionize how we address hearing loss.

Gene therapy is all about fixing or swapping out faulty genes that cause hearing loss, especially those that help sensory hair cells in the cochlea do their job. These cells are crucial for turning sound vibrations into signals our brains can understand. In recent animal studies, scientists have used viral vectors to deliver healthy genes straight into the cochlea, which has led to the regrowth of these hair cells. A standout example is the Atoh1 gene, which has been shown to kickstart hair cell growth when introduced into damaged cochleas in mice. While human trials are still in the early stages, the results are promising and suggest that gene therapy could potentially restore partial or even full hearing for people with certain genetic mutations.

Stem cell therapy holds similar promise by aiming to regenerate lost hair cells or auditory neurons. Stem cells can develop into different types of cells, and researchers are working on ways to program them into becoming functional hair cells or other critical parts of the auditory system. This technique could replace damaged cells that cause hearing loss, offering a regenerative solution. Early-stage studies have successfully shown the potential for stem cells to integrate into the auditory system and begin restoring hearing in animal models. Clinical applications in humans, though still under development, may one day provide a permanent cure for sensorineural hearing loss rather than just managing it with devices like hearing aids or cochlear implants.

If you think you suffer from hearing loss, tinnitus or other symptoms related to your ear, consult your health care provider. A hearing test (audiogram) is often the first step in the medical work up, you can schedule one here.