Single sided deafness
Single sided deafness (SSD) or unilateral hearing loss is the situation where a patient has normal hearing in one ear and deafness in the other ear. Deafness is defined as hearing loss of such a severity that a patient cannot benefit with a conventional hearing aid (non serviceable).
Some patients are born with SSD due to developmental problems of the cochlea. Viruses, meningitis, Meniere’s disease and acoustic neuroma can cause SSD. Viruses known to cause single sided deafness include mumps, shingles, herpes simplex (HSV-1) and HIV. Surgical removal and radiation of acoustic neuromas can also cause SSD. Head trauma causes deafness due to bleeding in the inner ear or a fracture of the temporal bone. In older patients and those with cardiovascular risk factors a small clot or spasm of a blood vessel can cause a “stroke” of the inner ear with hearing loss. In many cases the cause is unknown. It is then referred to as idiopathic hearing loss.
Patients complain of difficulty in localizing sound, following conversations in back ground noise and hearing speech on the deaf side. Some patients may also suffer from dizziness and balance problems. In smaller children SSD can often go unnoticed. This is sad as it can influence the development of the child.
Patients with SSD should see an ENT surgeon to rule out a cause. A MRI may be requested to rule out an acoustic neuroma. In cases of trauma high resolution computed tomography (CT scan) may show a temporal bone fracture.
There are many viable solutions for patients with SSD. Before one is chosen, all options should be trialled to determine which one best suits the challenges that a patient is experiencing.
The available options include frequency modulation (FM ) systems, soft band bone conducters, contralateral routing of signal (CROS) and bone-conduction transcranial CROS devices. Surgical options include bone-anchored hearing systems (BAHA, Ponto, Sophono or Bonebridge) and cochlear implantation (CI).