Nerve injury in the Upper Limb & Hand
What is this?
There are three different types of nerves in the body;, sensory nerves, motor nerves and autonomic nerves.
Motor nerves carry messages from your brain via the spinal cord to reach the hand/limbs to create movement by muscle contraction.
Sensory nerves sends signals from the hand/limbs via the spinal cord to brain about sensations of temperature, pressure, pain and vibration.
Nerves are the tissues that carry electrical signals to and from the brain and the rest of the body. Nerves have an outer myelin layer (insulating layer) that protects the hundreds to thousands of thin inner nerve fibres called axons. Axons conduct the electrical signals very rapidly, with some conducting the equivalent of 130 miles/hr!
What is the cause?
Traumatic is the most common cause of nerve injury in the hand, Nerve injury can be caused by a variety of trauma such as severe cuts (lacerations) from knives and tools. The nerve may also be injured by stretching such as when joints dislocate. They may also be crushed. Nerve injury can also happen if you are burnt or exposed to extreme cold temperatures, electric shock or radiation.
An individual who has high blood sugar levels, such as in diabetes, is also at risk of generalised nerve damage throughout the body This may cause weakness, altered sensation in the hands/feet and also pain.
Symptoms
Altered sensation such as numbness or tingling.
Sharp sensation or burning pain
Trouble with moving or inability to move joints or fingers.
Reduced strength.
Treatment
In trauma that involves a cut or penetrating injury, the nerve in most cases must be explored. In such situations, the majority of nerves have been cut. If left unrepaired the loss of sensory nerve or motor nerve function, will not return. Furthermore, the unrepaired nerve may produce a painful condition called a neuroma. A neuroma is a nerve scar that can result in a hypersensitive injured area and rarely also lead to a limb disabling condition called complex regional pain syndrome.
In non-traumatic conditions, any underlying medical conditions would firstly be addressed. This is to treat the condition that is causing the nerve damage in the first place. This will prevent the condition from spreading and may reverse its effects.
Non-surgical treatment
In cases of nerve damage where there is no wound and minor cases no tests will be necessary and the individual will be given the advice of the ‘wait and see policy’. Anti-inflammatory medication can be given. However if symptoms persist further investigation such as
nerve conduction studies are carried out by a
Consultant Neurophysiologist.
Surgical treatment
Surgery consists of nerve exploration and repair. Surgery is offered to the individual in whom the benefit will outweigh the risks. However if the wound has been crushed or dirty, the nerve exploration may be delayed until the skin has healed.
Nerve repair involves the insulation around both nerves to be sewn together. The aim in repairing the nerve is to seal the insulating cover hoping that when new axons grow the nerve will then work again.
In some cases the nerve ends cannot be brought in contact because the nerve ends have shortened. This is called a nerve gap. The gap may occur because the nerves have shortened due to delay or that the nerve ends have been surgically trimmed back to undamaged nerve ends. When a nerve gap occurs, Mr Miranda has 3 options to treat it - a nerve graft, allograft or nerve conduit.
Nerve graft means taking a nerve from another part of the body to bridge the gap. This of course results in some loss of function in that part of the body so nerves to be sacrificed as a graft are chosen carefully in discussion with his patient so ensure that this loss of function wil not cause additional problems.
With new technology allograft or nerve conduits (synthetic nerve tubes) are available. Allograft is donated human nerves that have been processed for high quality tissue and free from infections and proteins that can cause tissue rejection. Nerve conduits are tubes to place the nerve ends in so the gap is within the conduit and protected from scar formation inhibiting nerve healing.
For at least the first two or three weeks after surgery the operative area and movement may be protected to ensure the nerve repair is not stretched as the stitches are delicate.
Mr Miranda will provide advice and involve the Hand Therapists to assist in your recovery. Advice may include, being careful if sensory nerves are damaged as there will be no feeling in the affected area, making it vulnerable to accidental injury.
The Hand Therapists will teach you techniques to prevent the joints from becoming stiff. They will also teach sensory re-education which is training the brain to learn normal sensation. Depending on the injury, nerves repair at 1mm per day, but results have been known to take up to 2 years or more. Mr Miranda at your consultation will advise on the risks, benefits and expected time of recovery following your nerve repair.