Nerves conduct sensation to the spinal cord and from there to the brain they also convey signal to control muscles. If bruised by injury (contused) the nerve should recovery fully in a short time. The more significant the contusion the longer will recovery take and the more likely it is to be incomplete. Where a nerve is completely divided it will not recover and will need to be repaired. The recovery after any nerve injury is variable and is less good the older we get. After an injury to a nerve there will be loss of sensation and weakness in the muscles supplied by that nerve. The site of nerve injury can usually be pin-pointed with a fair degree of accuracy.
If there is a wound and the nerve has been divided then a surgical repair will be undertaken. If there is no wound and the nerve is thought to be contused then it is wise to wait to see how much recovery will occur before considering surgery. Nerve testing in the form of nerve conduction studies may be used to monitor progress. If a nerve requires repair this is undertaken using magnification and if needed an operating microscope. Recovery of nerve function is slow and incomplete after nerve repair and it may take 18 months to two years for the final outcome to be known. If a section of nerve is damaged then the damaged section may be removed and a nerve graft used to fill the defect. If a nerve end is left divided a painful nerve stump can develop (a neuroma), this gives electric shock like pains if knocked and a nerve repair will reduce the incidence of this but does not eliminate it entirely. There may be the perception of unpleasant sensations in the territory of the nerve (sensory dysaesthesia) that can be distressing.
Nerves can be damaged by compression as in carpal and cubital tunnel syndromes. Problems may affect the brachial plexus in the neck. In the brachial plexus nerves from five spinal cord levels give rise to the nerves which control all of the sensation and motor movement of the upper limb. Injuries at this level can have devastating consequences and are difficult to treat.
Carpal tunnel syndrome
Carpal tunnel syndrome (CTS) results from the median nerve being compressed as it passes through a short tunnel at the wrist. This tunnel also contains the tendons that bend the fingers and thumb. CTS commonly affects women in middle age but can occur at any age and in either sex. It is more common in pregnancy and can occur with diabetes, an underactive thyroid and rheumatoid arthritis. but most people with CTS have none of these. Compression of the nerve can occur because of swelling of the synovium around tendons or can be caused by reduction in the size of the tunnel such as with arthritis. In most patients no definite cause can be found.
Patients often complain of tingling in the fingers that is worse at night or on waking, and may come on with using the hand especially with activities that involve gripping such as driving or cycling. Feeling may be reduced over the thumb, index, middle and ring fingers and it is unusual for the little finger to be involved. At the start numbness and tingling are only occasional with the hand returning to normal in between. If it becomes worse, the reduced feeling may become continuous, and can lead to weakness of the muscles at the base of the thumb. The hand may be described as being clumsy and there may be complaints of the patient dropping things. There may be some associated pain in the forearm.In some cases nerve conduction tests may be recommended.
Non-surgical treatments may be recommended such as the use of wrist splints, especially at night, and steroid injection into the carpal tunnel. Surgery is often required and this involves dividing the ligament at the top of the tunnel to relieve the pressure on the nerve.. The operation is usually performed under a local anaesthestic. Night pain and tingling in most cases disappear after the operation. However where there is severe compression of the nerve where there is constant numbness and muscle weakness the recovery may be limited. Whilst initially the hand is weak, patients can use the hand for light activities from the day after the operation and can resume driving at around two weeks. The scar is tender for four to six weeks and it takes four to six months to regain full strength in the hand.
Cubital tunnel syndrome
Cubital tunnel syndrome is caused by compression of the ulnar nerve in a tunnel on the inside of the elbow (if this is knocked it is very painful and gives tingling down the side of the forearm into the fingers and we sometimes refer to it as the ‘funny bone’). Most cases have no obvious cause for the compression but sometimes an old injury is responsible. Numbness or tingling of the little and ring fingers are usually occur first and is occasional but can become constant. Bending the elbow or leaning on it can reproduce the symptoms. In the more severe stages the hand can become weak with wasting of the small muscles between the bones of the hand, most noticeable on the back of the hand between the thumb and index finger. This causes loss of strength and clumsiness. Investigations often include nerve conduction studies or elbow x-rays.
The use of a splint especially at night can be effective at reducing excessive bending of the elbow with relief of the symptoms in the early stages. When more advanced surgery to decompress the nerve may be required in those cases that do not respond to simple splinting. Surgery often improves the numbness, but the main aim of the procedure is to prevent the progressive muscle weakness that occurs in severe untreated cases. There are a variety of operations which can be used. These include simply relieving the pressure on the nerve by opening the cubital tunnel (decompression), moving the nerve to a new position in the front of the elbow (transposition) or by removing a bony prominence around which the nerve is stretched during bending of the elbow (medial epicondylectomy). You will be advised on the most appropriate procedure for your problem. The improvement in the symptoms depends upon the severity of the nerve compression. Numbness often improves but can be slow and incomplete and recovery in the muscle weakness and wasting is often slow and rarely recovers completely, however the main aim of the operation is to halt progression of the problem and deterioration in the symptoms.