Sudden Hearing Loss is a fairly rare condition, with most studies estimating it occurs in 5-20 cases per 100,000 persons. However, the condition is likely undereported as some patients will have improvement without seeking any medical services. It effects men and women equally, with the median age being 40-54 years.
The most common cause of the condition is believed to be a viral infection-inflammation that occurs in the inner ear. This scenario is similar to Bell’s palsy, which a virus causes a facial muscle paralysis with facial droop. Other less likely causes include embolism (stroke), Meneire’s Disease, autoimmune inner ear disease, or a brain tumor.
Patients typically present with waking up in the morning and noticing a signifcant HL in one ear (very rarely does this condition affect both ears). Some patients will notice other symptoms such as tinnitus (ringing or buzzing noises in the ear), dizziness or vertigo, and pressure in the ear. The patient should not have pain or drainage from the ear as this would represent another problem such as infection.
On examination, the patient will have a clinical HL but the remainder of the head and neck examination will be normal. To determine the degree of hearing loss, a formal hearing test is required. The audiological definition (or criteria) is a 30dB drop in hearing at 3 contiguous pure tone averages within a 3 day period.
Once the diagnosis is made, then the patient is started on a specific treatment regimen. Steroids are the mainstay of therapy, and typically are required from 2-4 weeks. Recent studies show that steroids injected through the eardrum into the middle ear space (which is done safely in the clinic) also enhance the success for hearing restoration. Other treatments, such as vasodilator medications and Hyperbaric oxygen treatments, have been studied but not shown to yield significant clinical improvement. Other studies have shown no other treatments, including antibiotics or antivirals, offer any clinical advantage to imporve the SSNHL.
The overall prognosis is generally good, with 2 out of 3 patients having partial to complete hearing restoration. However, that means that one-third of patient have no signifcant improvement in their hearing. The patients with a poorer prognosis generally are older (age over 65 years), have a severe to profound HL on initial hearing test, or have dizziness associated with the initial episode. However, the most important piece to increase the prognosis is starting medical treatment as soon as possible, ideally within the first 3 days. Studies have shown that patients who do not get steroids started within this time frame, have a signifcant poorer rate of hearing restoration.
Finally, patients that do not fully recover their hearing need a MRI scan of the brain to evaluate for an acoustic neuroma (a benign brain tumor of the acoustic nerve) or another tumor. Once the hearing loss is stable, then moving forward with hearing amplification, typically in the form of a hearing aid, is indicated. It is also imperative that these patients protect their ears from noise damage in order to minimize the normal age-related hearing loss that occurs over time.
SSNHL is a treatable condition, but prompt evaluation with an ENT examination, a formal hearing test, and medical management is required to give the patient the best prognosis for complete restoration of their hearing. Contact your local ENT physician for any questions.
Robert Wilson, MD.