Idiopathic Sudden Sensorineural Hearing Loss
(ISSHL)
ISSHL Rapid Treatment Pathway
What is ISSHL?
ISSHL commonly referred to as ‘sudden deafness’ is an unexplained rapid loss of hearing which may occur suddenly or over a few days. It typically affects only one ear but may occur on both sides. Some patients may notice other symptoms in addition to decreased hearing which may include a feeling of fullness in the affected ear, dizziness, or ringing in the ears (‘tinnitus’).
What causes ISSHL?
Many underlying causes are proposed for ISSHL including infection, head trauma, autoimmune disease, medications, poor circulation, neurologic conditions, and disorders of the inner ear itself. However, in most patients an actual cause is rarely identified (less than 10%). It is postulated that these conditions may lead to swelling that damage the nerves. Swelling may cause damage by compressing the blood vessels that feed the ear structures causing ischemia ('oxygen starvation') and by exerting direct mechanical pressure causing damage to the ear nerves themselves.
How is ISSHL Diagnosed?
Prompt assessment is needed by an ENT (Ear, Nose, and Throat) physician who will assess patients for a reversible cause (obstruction of the ear by wax or fluid). Following this, patients will be sent for audiometry testing (hearing test) and the diagnosis can be made when there is a 30db hearing loss across three separate frequencies. Additional tests may be ordered by the ENT physician to rule out any alternative diagnosis.
How is ISSHL Medically Treated?
Although the exact cause of ISSHL is not often identified, treatment is focused on decreasing swelling. The main medical treatment is through the use of steroid medications either taken by mouth or injected directly into the ear structures by an ENT physician. Other medications may be added including anti-viral medications and vasodilators (medications that open up blood vessels).
How is ISSHL Treated with Hyperbaric Oxygen Therapy?
A recent meta-analysis study demonstrated that using hyperbaric oxygen therapy along with medical therapy (steroids) resulted in a 60% increased chance of attaining full hearing recovery and a 40% increased chance of seeing any improvement when compared to medical therapy alone. As such, hyperbaric oxygen therapy is an important adjunct treatment for ISSHL and is therefore fully covered under OHIP. Hyperbaric oxygen therapy is effective for ISSHL as the increased pressure in the hyperbaric chamber raises the pressure gradient for swollen tissue to work against thus decreasing swelling in the ear structures. Simultaneously hyperbaric oxygen therapy drastically increases the levels of oxygen in the blood supply of the ear which is critical to the repair of ear nerve structures and hearing recovery. Early treatment is vital and hyperbaric oxygen therapy should be started within 30 days of diagnosis.