Cubital Tunnel Syndrome
What is it?
The ulnar nerve is one of the three important nerves for hand function. Nerves are important for transmitting electrical signals to and from the brain to muscles and skin. This allows us to feel sensation through our skin and move our fingers etc. with muscles supplied by the nerve. The ulnar nerve supplies feeling/sensation to the skin of the little finger and half of the adjacent ring finger., some of the muscles that bend the little and ring fingers and some of the small muscles in the hand and thumb. The ulnar nerve can be squashed or stretched as it courses around the elbow, behind a bone called the medial epicondyle. When we hit our “funny bone” we are catching the ulnar nerve – giving the unpleasant pins and needles/numbness sensation..
Cubital tunnel syndrome symptoms usually include pain, numbness, and/or tingling. The numbness or tingling most often occurs in the ring and little fingers. The symptoms are usually felt when there is pressure on the nerve, such as sitting with the elbow on an arm rest, or with repetitive elbow bending and straightening. Often symptoms will be felt when the elbow is held in a bent position for a period of time, such as when holding the phone, or while sleeping. Some patients may notice weakness while pinching, occasional clumsiness, and/or a tendency to drop things. In severe cases, sensation may be lost and the muscles in the hand may lose bulk and strength.
What is the causes?
In the vast majority of cases we do not find an underlying cause. It is more common as we get older. Pressure on the ulnar nerve at the elbow can develop in several ways. The nerve is positioned right next to the bone and has very little padding over it, so pressure on this can put pressure on the nerve. For example, if you lean your arm against a table on the inner part of the elbow, your arm may fall asleep and be painful from sustained pressure on the ulnar nerve. If this occurs repetitively, the numbness and pain may be more persistent. In some patients, the ulnar nerve at the elbow clicks back and forth over the bony bump (medial epicondyle) as the elbow is bent and straightened. If this occurs repetitively, the nerve may be significantly irritated. This we call a subluxing ulnar nerve. The nerve can also be stretched by keeping the arm bent at the elbow for prolonged periods of time.
Such sustained bending of the elbow may tend to occur during sleep. Sometimes the connective tissue over the nerve becomes thicker, or there may be variations of the muscle structure over the nerve at the elbow that cause pressure on the nerve. There may be an extra muscle that can cause direct compression of the nerve –(anconeus epitrochlearis) Cubital tunnel syndrome occurs when the pressure on, or stretching of the nerve is significant and sustained enough, to disturb the way the ulnar nerve works.
Diagnosis of Cubital Tunnel Syndrome
Diagnosis can often be made from the clinical history (the account of events and symptoms from the patient) and the clinical examination. The examination will examine for muscle weakness, irritability of the nerve to tapping and/or bending of the elbow, and changes in sensation. Other medical conditions may need to be evaluated such as thyroid disease or diabetes. A test called electromyography (EMG) and/or nerve conduction study (NCS) may be done to confirm the diagnosis of cubital tunnel syndrome and stage its severity. This test also checks for other possible nerve problems, such as a pinched nerve in the neck, which may cause similar symptoms.
Treatment of Cubital Tunnel Syndrome
Symptoms may sometimes improve without surgery, particularly if the EMG/NCS testing shows that the pressure on the nerve is minimal. Changing the patterns of elbow use may significantly reduce the pressure on the nerve. Avoiding putting your elbow on hard surfaces may help, or wearing an elbow pad over the ulnar nerve and “funny bone” may help. Avoid sitting with your elbow bent for prolonged periods of time for example when at work or on a computer. Keeping the elbow straight at night with a splint also may help. A session with a therapist to learn ways to avoid pressure on the nerve may be needed.
When symptoms are severe or do not improve, surgery may be needed to relieve the pressure on the nerve. There are two types of surgery. The first is a cubital tunnel release, this involves releasing any constricting bands of tissue over the surface of the nerve. This removes any element of compression on the nerve but does not help if the problem is caused by the nerve being stretched. The second type of surgery is a more extensive operation which involves moving or “transposing” the nerve to the front of the elbow, which relieves pressure and tension on the nerve. The nerve may be placed under a layer of fat, under the muscle, or within the muscle. Some surgeons may recommend trimming the bony bump (medial epicondyle). Following surgery, the recovery will depend on the type of surgery that was performed. Restrictions on lifting and/or elbow movement may be recommended. Therapy may be necessary. The numbness and tingling may improve quickly or slowly, and it may take several months for the strength in the hand and wrist to improve. Cubital tunnel symptoms may not completely resolve after surgery, especially in severe cases where there is muscle wasting.
The exact type of dressing will depend upon the type of surgery undertaken. You will usually have a bulky bandage and dressing on for about 2 weeks after the operation. The surgical incision will be closed with dissolving stitches and paper stitches over the top. You will need to keep the wound clean and dry until it is healed at approximately 2 weeks after surgery. You will need to bend and straighten your elbow within the limitations of the bulky bandage dressing and keep your wrist, fingers and thumb moving. Movement of the elbow reduces the tendency of the nerve to develop adhesions, nerves normally glide a limited amount over the underlying tissues. The arm should be elevated when possible to reduce swelling and throbbing.
Once the wound is well healed the scar and surrounding tissues should be massaged using small circular movements to reduce the sensitivity. You can rub simple hand cream or pure vegetable oil into the scar to soften it, for five minutes several times a day. You may need physiotherapy/hand therapy for elbow mobilisation and further management of the surgical scar. There is usually no need for physiotherapy.
Returning to work will depend on your circumstances and type of work. If your job is light you may return after 2-3 weeks, but if it is heavy/manual you may require 6 weeks or more off work.
Following a cubital tunnel release procedure you should not drive for at least 2 weeks following your operation. If you have a cubital tunnel release and transposition procedure you will be unable to drive for 4-6 weeks after surgery. You need to be able to perform an emergency stop safely and use the gear stick, steering wheel and hand brake without difficulty.
What are the potential complications?
The majority of patients are very satisfied with the outcome of surgery. Whilst uncommon, all surgical procedures are associated with some risks. Every effort is made to minimize these to ensure the best possible outcome from your surgery.
Infection - Uncommon occurs in approximately 1% of operations and usually treated very successfully with antibiotics. Very rarely would require further surgery.
Delayed healing - Smokers and those with diabetes are more prone to this.
Painful/Tender/thickened Scars - the vast majority of patients complain of some discomfort around the scar but it generally resolves with time. Wound care and desensitization as directed by your physiotherapist/hand therapist will improve this.
Nerve injury – small nerves that supply the skin around the scar may be injured giving a numb patch or unpleasant sensation round the scar. The use of magnification glasses ( Loupes) by your surgeon and very careful dissection will be used to minimise this complication.
Stiffness - Operations to the elbow may cause stiffness, this can be minimized by working closely with your hand therapist and getting your hand moving as early as possible.
Incomplete resolution of your symptoms - this may occur if you have had severe compression of the nerve, or have had the symptoms for a long time.
CRPS – complex regional pain syndrome, this is an uncommon but serious complication. It can on rare occasions leave you with a less function hand with on-going pain stiffness and swelling. See section on CRPS. The exact incidence or rate of CRPS after surgery is unknown. It probably occurs in a significant form in approximately 1-2% of cases.