Your nerves transmit sensory (feelings of touch, pressure or temperature) and motor (movement of muscles) impulses to and from your brain. Damage to nerves may result in reduction or a complete loss of sensation, weakness and dry skin.
When one of your nerves is cut or damaged, it will try to repair itself. The nerve fibres (axons) shrink back and ‘rest’ for about a month; then they begin to grow again. Axons will regenerate about 1mm per day. The extent to which your nerve will recover is variable, and it will always be incomplete. Recovery is improved if the cut nerve ends are brought together and repaired surgically.
If your nerve ends are not brought together, the nerve fibres still attempt to grow and find the other end. However, often the result is a lump of nerve ends (a neuroma) that is tender to knocks or pressure and in some cases can be uncomfortable all the time.
Regeneration time depends on how seriously your nerve was injured and the type of injury that you sustained. If your nerve is bruised or traumatized but is not cut, it should recover over 6-12 weeks. A nerve that is cut will grow at 1mm per day, after about a 4 week period of ‘rest’ following your injury. Some people notice continued improvement over many months.
Sensory nerves are more resilient than motor nerves and can recover sensation months or years after injury.
Motor nerves have a time limit for healing. The reason for this is a structure called the ‘motor endplate’, where the nerve joins into the muscle. If the motor endplate receives no nerve impulse for more than 18-24 months, it dies away and there is no longer any way that the muscle can be activated by the nerve. The muscle then whithers away. Thus surgical repair of motor nerves needs to happen within 12-18 months of the injury.
Before sensation returns to the injured area, your limb is at risk of damage as it has no protective sensation. Please be careful of your hands or feet, especially around hot or sharp objects. Similarly, before the motor nerves recover your hand or limb may not be able to move normally or may develop abnormal postures. Hand therapy or physiotherapy will allow movement to be maintained while the nerve cells regenerate.
As your nerve recovers, the area the nerve supplies may feel quite unpleasant and tingly. This may be accompanied by an electric shock sensation at the level of the growing nerve fibres; the location of this sensation should move as the nerve heals and grows. Over time, these feelings subside and the area should begin to feel more normal.
Unfortunately, nerves never recover completely after they have been cut. The degree of your nerve’s recovery depends on a number of factors:
I use a microscope or magnifying glasses (loupes) to repair your cut nerve with sutures finer than a human hair. This type of nerve repair surgery has the best recovery rates. Whether or not I can perform direct nerve repair on your injured limb depends on the injury your nerve has suffered.
Sometimes I cannot directly repair your nerve ends, for example, if there is a piece of nerve missing or a delay in repair.
With nerve grafting, I take a length of nerve from somewhere else in your body and place it as a graft. I perform this repair using a microscope, too. You will have a scar from the surgery and often a numb patch in the area I took the nerve graft from.
Possible donor nerves include sensory nerves of skin of the forearm and leg. Having a numb patch on the side of your arm or foot is usually less bother than having a numb area on your hand.
As with all procedures I perform, we will have an in-depth consultation about all aspects of the surgery and recovery, including possible donor nerves, risks etc.
The nerve may have been repaired, and some recovery of function may have occurred, however scar tissue around the nerve causes tethering and discomfort when you move your hand. The scar tissue can also limit nerve cell regeneration. I can surgically release the scar tissue from around the nerve.
Your nerve may fail to recover due to a neuroma (link to the top of the page), or there is a persistent gap in the nerve. During the procedure, I cut back your nerve ends until I can see healthy ends, and I place a piece of nerve graft to facilitate normal re-growth of your nerve. The function (sensation and power) of your nerve is initially worse and then should gradually improve – it will be like beginning recovery all over again. Unfortunately, your hand’s function will never return to normal but should be improved with nerve grafting. The pain and discomfort you feel at the site of injury improves as recovery progresses.
Sometimes a nerve is persistently tender. This is usually due to a neuroma. Wrapping a vein, fat or another substance around your nerve provides padding around the nerve and will make the area less sensitive.
After a nerve is injured, sometimes painful neuromas develop in smaller nerves of your hand. They are usually in locations that are not suitable for nerve repair such as amputated fingers. I can cut away the neuroma and bury the nerve end deep in a muscle or bone. This prevents the nerve end from being knocked and should reduce the electric shock like pain. The area that the nerve supplied will be completely numb, and this is permanent.
Improvements of your symptoms may be minimal, or there may be no improvement at all.
This occasionally requires a return to theatre.
You will be given antibiotics at the beginning of your procedure and occasionally after your operation. Antibiotic use is carefully monitored to reduce antibiotic resistance. The signs of infection to look out for include increasing redness, swelling, pain and purulent discharge. Most wound infections will respond quickly to antibiotics. Very occasionally further surgery may be required to clean out a deeper infection. Infection can lead to delayed recovery and increased stiffness.
This may require dressings from the district nurses.
Can be improved with massage and moisturizing cream.
I may ask you see an expert hand therapist to provide you with a splint and complete a personalised regime of exercises to reduce stiffness. Please read more about the hand therapists that I work with.
Some people have hands that are very sensitive to surgery or trauma and become very painful, stiff and swollen following surgery. This is treated with special kinds of pain relief and physiotherapy. Read more about Complex Regional Pain Syndrome.
You will be left with a scar and a numb area on your arm or leg where the donor nerve was taken from. In rare cases, a painful lump at the site of the donor nerve may develop requires further surgery. Please read more about Complications following Hand Surgery.