Single sided deafness 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).
It is estimated that 60 000 patients are diagnosed with this condition in the USA every year. Viruses, injuries, Meniere’s disease and acoustic neuromas often cause single sided deafness (SSD). In many cases the cause is unknown.
Patients complain of difficulty in localizing sound, following conversations in back ground noise and hearing speech on the deaf side. In smaller children it can often go unnoticed.
Patients with SSD should see an ENT surgeon to rule out a cause.
There are many viable solutions for patients with single sided deafness or unilateral hearing loss. Before one is chosen, all options should be trialled to determine which one best suits the challenges that a patient is experiencing. Unfortunately a trial is not possible for a cochlear implant (CI).
In some patients, especially in school children and students, a non invasive FM system can aid in delivering a clear signal to the unaffected ear. This bypasses all the background noice interference in class.
Two other non-invasive methods are available, namely the CROS (contralateral routing of signal) and bone-conduction transcranial CROS devices.
Other options include bone conduction systems which can be worn with a headband. This is often selected for children.
Surgical options include bone-anchored hearing systems (BAHA, Ponto, Sophono or Bone bridge) and CI. In those patients with an intact nerve a CI can be considered. It has now been shown that the brain is able to fuse acoustic stimulation from one ear and electrical stimulation from an implanted ear. An important prerequisite for a successful implant is careful patient selection. The duration of deafness is one important factor. CI remains the only option for true binaural hearing.
