What is Sudden Sensorineural Hearing Loss?
Sudden sensorineural hearing loss (SSHL) is hearing loss that damages the inner ear (e.g. “sensorineural”). SSHL most frequently happens in one ear. Patients often wake up with the sound of an ear that sounds “blocked,” “congested,” or “clogged” ear. They may also have other symptoms such as ringing in the ears or tinnitus. About half of patients may experience spinning dizziness called vertigo. Together, these symptoms indicate that the inner ear that provides sensations for hearing and balance are being damaged.
SSHL is an emergency of the ear. Early treatment within 2 weeks can recover hearing in 80% of cases.
- Sudden sensorineural hearing loss affects nerves of the inner ear. It is unrelated to earwax.
- Symptoms include sudden hearing loss or a “blocked ear” that develops rapidly over hours. It may lead to sudden deafness. It rarely affects both ears. Although a cold may be present, ear pain and infection is not common.
- It is an emergency and you should call your ENT as soon as possible.
- Treatment involves recovering hearing to prevent permanent loss of hearing. For those who have incomplete recoveries, there are several options for improving hearing.
What are the causes of SSHL?
SSHL is rare and is thought to result from autoimmune, viral, or genetic causes. The immune system is the body’s defense mechanism against infectious agents such as bacteria and viruses. Autoimmune disorders occur when the body’s immune system attacks itself. SSHL can also occur from tiny blood clots that disrupt the circulation of the inner ear. Some patients may have sudden hearing loss from hereditary conditions. Unfortunately, determining the underlying cause of sudden hearing loss is elusive. Ninety-nine times out of 100, diagnostic testing fails to reveal the cause of sudden hearing loss. Because of this, leading researchers do not recommend an extensive array of blood testing and medical imaging to search for underlying causes.
How is SSHL diagnosed?
Timely diagnosis is critical because the window for treating SSHL with steroids is only 4 weeks from onset. It is critical to determine that any sudden hearing loss is indeed sensorineural (e.g. from the inner ear).
A hearing test known as an audiogram can differentiate between sensorineural and other types of hearing losses. Sudden hearing loss can also occur from ear wax, congestion from a cold or allergies, or water in the ear. Eustachian tube problems can produce hearing loss similar to that experienced during ascent/descent on an airplane. These causes of hearing loss are termed “conductive hearing loss.” Unfortunately, patients often experience delays in diagnosis because healthcare providers mistake SSHL for ear wax or congestion from colds and allergies. A hearing test can easily help differentiate between different types of hearing loss.
It is imperative that patients be evaluated by an ENT (ear, nose, and throat) physician. An ENT will closely inspect the ear canal and eardrum with a microscope. They will also perform a neurologic and vestibular (balance system) evaluation. A hearing test will evaluate the different parts of the ear.
A brain MRI will examine for neurological problems that can cause SSHL. These problems can include tumors, multiple sclerosis, or stroke.
How is SSHL treated?
Treating SSHL involves reducing inflammation in the inner ear. Treatment within 2 weeks can recover hearing in 80% of patients. After 4 weeks, it is very unlikely that treatment will recover any functional hearing. Because of this, treatment is not delayed for hearing testing or MRI.
Treatment consists of steroids which reduce inflammation. These may be taken by mouth or injected behind the eardrum. Believe it or not, behind-the-eardrum injections are very, very well tolerated.
Hyperbaric oxygen is another treatment possibility. This involves entering a chamber that has high pressures of oxygen. This treatment is repeated 10-20 times over the course of several weeks. It is expensive and not always covered by insurance. Because of this, patients with milder hearing losses usually elect not to receive hyperbaric oxygen.
Repeated audiograms are used to monitor the course of the hearing loss.
SSHL is very stressful for many with SSHL. Hearing loss cuts us off from other people. SSHL can also cause the remaining hearing to be very distorted. Louder sounds can be inappropriately painful (hyperacusis). Tinnitus can be especially debilitating in the early stages of SSHL.
It is important to address mental health and anxiety during this difficult time. This can be as simple as good self-care by establishing and focusing on daily life routines, healthy diet, regular exercise, journaling, and sleep hygiene. It is important to optimize other medical conditions to minimize stress in other areas of life. For some, a therapist, medication, and a psychiatrist may be necessary.
What is the prognosis of SSHL?
Prognosis of SSHL is by “thirds.” One-third of patients recover their hearing, one-third have no change, and one-third worsen. Patients who experience dizziness (vertigo) with SSHL have a worse prognosis for hearing recovery. Severe tinnitus usually subsides to manageable levels after about 8 months.
After completing steroids, treatment of any hearing loss depends on the extent of hearing loss and the status of the other ear. Hearing aids may amplify sounds and filter out background noise. Hearing loss can be so severe that hearing aids do not provide benefit. In these cases, CROS hearing aids and “osseointegrated cochlear stimulators” can take the sound from the poorer ear with no hearing aid and transmit them to the better hearing ear. Cochlear implants are also an option for treating single sided deafness.
With single-sided deafness, it is important to take care of the remaining ear. Using noise protection and seeing an ENT physician within 24 hours of onset for any problems in the other are both critical to preserving remaining hearing. For single-sided deafness, patients are strongly discouraged from scuba diving.