What is Single Sided Deafness?
SSD, or unilateral hearing loss, refers to total hearing loss in one ear - the other ear can have perfect hearing.

It occurs when sounds cannot reach the working inner ear (cochlea), or when sounds reach the inner ear perfectly, but due to inner ear damage are not turned in to neural impulses which are sent to the brain.

It is estimated that over 9,000 new cases are diagnosed every year, indicating that at any one time tens of thousands of Britons are affected by this condition.

What are the symptoms?

The symptoms of SSD are dependent on each case.

In addition to having impaired hearing on the deaf side, some people may have difficulty determining the direction of sounds.

This can make simple tasks - such as crossing a road - difficult.

Some people with SSD may also experience what is known as the head shadow effect - the inability to hear sounds at all from a particular direction.

However, the most common symptom is the inability to separate background noise from target sounds.

Some sufferers find this a major problem when interacting in social situations as group conversations become very difficult to follow.

As a result, many people with SSD find themselves feeling socially excluded and isolated - even to the point that some stop going out.

What Causes SSD?

SSD may be a result of a number of different conditions each of which affects the ear differently. Causes include:
Sudden deafness - suddenly going deaf without a known cause
Physical damage to the ear
Pressure on the hearing nerve
Inner ear problems including infections (viral or bacterial)
Diseases such as Measles, Mumps, Meningitis

Tumours in the ear or brain
Disorders of the circulatory system
Severe Meniere's disease
Trauma - eg head injury
How is it treated?
There is no cure for SSD, however people affected by the condition can be rehabilitated and devices can be used to restore the sensation of hearing from both sides.

At present there are two treatment options available in the UK, both of which rely on transferring sound to the hearing ear to create the impression of stereo sound.

The BAHA (bone anchored hearing device) has recently been cleared by the US Food and Drug Administration for treatment of SSD, and is available both privately on the NHS.

The device involves a small titanium fixture which is implanted behind the ear and is attached to a sound processor. The sound processor picks up noise and transfers it to the working ear via the skull bone.

The more traditional option is the CROS Aid (contralateral routing of signal), which relies on an external wire to connect the bad ear with the hearing ear.