A peripheral nerve injury occurs when any nerves in the body that are not in the brain or spinal cord are damaged. If a peripheral nerve is damaged then muscles supplied by that nerve do not receive information from the brain and, therefore, they become weakened or paralysed. The nerve damage also means that the brain does not receive information from the body. This can present as altered sensation such as numbness or pins and needles. Unlike the spinal cord, peripheral nerves have the ability to heal.
Peripheral nerve injuries can be caused by:
- an extreme stretch of a nerve (eg. during a joint dislocation)
- reduced blood supply to a nerve (eg. when someone falls asleep in a position that puts pressure on a nerve – such as with their arm over the back of a chair)
- an electrical burn
- a cut of a nerve (eg. from a knife or a traumatic fracture)
All the nerve fibres in the injured section of nerve are damaged, causing total loss of muscle power and sensation below the level of the injury.
Some of the nerve fibres in the injured nerve are damaged and others are unaffected. Some muscle power and sensation will be present below the level of the injury. An incomplete nerve injury means that some of the nerve remains intact and, therefore, the chances of a full recovery being made are improved.