ULNAR NERVE COMPRESSION
(Cubital tunnel syndrome/ulnar neuritis)
What is ULNAR NERVE COMPRESSION (Cubital tunnel syndromeulnar neuritis)?
Cubital tunnel syndrome is entrapment of the ulnar nerve typically at the elbow. It is the second commonest cause of nerve entrapment in the body (the commonest cause is carpal tunnel syndrome with entrapment of the median nerve). The typical symptoms are of numbness and tingling in the ring and little fingers and on the little finger side of the palm. It may be associated with weakening of the muscles, and sometimes wasting (thinning) of the small muscles in the hand and in time contractures of the ring and little fingers may develop. Typically the onset is gradual, starting with numbness and tingling, particularly at night, and it may then become continuous. Occasionally the onset may be very sudden often for no obvious reason. Some patients present only with weakness in the hand and others only with numbness but commonly there is a combination, particularly as the condition progresses.
Why does it occur?
In cubital tunnel syndrome the ulnar nerve which runs behind the inner side of the elbow through a short (c. 3cm) norrow tunnel. The base and sides are made of bone from the inner of the elbow and completed by a roof made up of a fibrous ligament. Normally the pressure in the canal is very low. It increases as the elbow is bent up. Even then the pressure is not normally enough to trouble the nerve. With ageing and associated with various conditions such as elbow fractures (breaks) and arthritis the background pressure in the elbow increases. Any further increases due to the posture of the elbow then leads to a high enough pressure that the blood supply to the nerve is compromised and it complains with symptoms of pain/numbness and tingling. In many cases the cause is unclear but it may be associated with a history of past injury or localised underlying arthritis. Some people have a tendency to multiple entrapments and may have entrapment in the opposite ulnar nerve although this is less common than in carpal tunnel syndrome.
What happens if nothing is done?
(This is referred to as the natural history i.e. what happens if Nature runs its own course.)
In most people the symptoms progress gradually although on some occasions this can be sudden. In some people particularly with mild intermittent symptoms spontaneous recovery may occur. In most people the numbness/tingling gradually increase leading to continuous numbness. The weakness progresses to wasting and profound weakness. These reduce hand function considerably. They usually progress together although generally the numbness or weakness will preodominate. Sometimes only one of the numbness/weakness will be present. Thus the symptoms of numbness, weakness and sometimes pain will increase and become more intrusive. Many people are particularly troubled by night waking often in the early hours of the morning.
Making the diagnosis
The Hand specialist who sees the patient will ask questions about their symptoms, when they started, how they progressed, what treatment (if any) they have had and other questions relevant to the problems. They will then examine the patient looking at the patient's elbows, wrists and hands and typically also their neck as this can give numbness and tingling in the hands. Special clinical tests such as tapping over the nerve and holding the elbow bent are performed to try to reproduce the symptoms to help confirm the diagnosis.
What test(s) might be performed?
Tests (also known medically as Investigations) include X-rays, scans, blood tests and particularly in the hand electrical tests (known as EMGs or Neurophysiology). These may be used to help make or confirm a diagnosis after a patient has described their symptoms and been examined.
In ulnar neuritis the diagnosis is usually obvious after listening to and examining a patient. Sometimes the surgeon will organise an X-ray of the elbow but that is not routine. The commonest test is an electrical test. It is almost always requested if surgery is planned. This is performed at a later date by a specialist (Neurophysiologist). Mild electric shocks are sent up and down the arm and the strength and speed of their conduction is measured. This gives a measure of nerve function. Like all tests it is not completely reliable so it can be normal although the patient has ulnar neuritis and it can be abnormal when the patient does not have ulnar neuritis. Your Hand specialist will interpret the results in the light of the previous description of symptoms and examination and advise you accordingly.
The other common possible causes of the symptoms are nerve entrapment in the neck and carpal tunnel syndrome (see information sheet).
What are the non-operative treatments?
Treatment should start with non-operative options. These include activity modification (which usually does not give much benefit or has already been tried by the patient) and an elbow night extension splint. The splint is mainly worn at night to prevent waking. It limits the elbow from bending up far and so helps protect the nerve from being squeezed at night. Avoidance of prolonged bending of the elbow is also helpful such as avoiding using the arm to hold the phone for prolonged periods.
What does the operation involve?
The operation is called an ulnar nerve decompression. We almost always perform the operation under local anaesthetic in a technique we devised and have reported in the scientific literature. A band, like a blood pressure cuff, is placed around the top of the arm. It is inflated (tightened) during the operation to reduce bleeding, which makes the operation easier and safer. It can be a little uncomfortable, but is almost always well tolerated for the 15-20 mins or so that it is inflated (this happens just before the surgeons starts the operation). Before that the arm is painted with an antiseptic with a pink dye in it. This is used to help minimise the risk of infection.
An incision of 3-4cm is required, just behind the bony prominence on the inner side of the elbow. If, at the end of the release, the nerve is tending to ride forwards a lot, this, too, can cause further problems and part of the bony prominence on the inner side of the elbow (medial epicondyle) will be removed. This allows the nerve to sit in a more comfortable position, reducing the chances of recurrent compression or a poor result. If, however, the nerve sits nicely, then this further procedure would not be undertaken as it increases the discomfort in the initial post-operative period. Rarely the nerve will need to be formally removed in front of the medial epicondyle (prominent bone). If this is required it will have been identified pre-operatively and the operation will need to be performed under a general anaesthetic, as a substantially longer incision will be required. At the end of the operation the wound is stitched usually with absorbable sutures. A supportive dressing is applied and the patient's arm elevated.
The total time in hospital is usually2-3 hours.
What happens in the next few weeks?
The care of the hand in the post-operative period is very important in helping to ensure a good result. Initially the aims are comfort and elevation. These are met by keeping the hand up (elevated) especially in the first few days and by use of a long acting local anaesthetic (Bupivicaine). The local anaesthetic lasts at least 12 hours and sometimes 48 hours. Patients should start taking painkillers before the pain starts i.e. on return home and for at least 24 hours from there. This way most of our patients report little or any pain.
The bandage can be removed after 2-7 days, leaving a sticky dressing beneath. The patient or GP practice nurse can do this. If well healed at that stage then the wound can be left open (exposed). If in doubt it can be covered with a light dressing for a few more days. The patient is reviewed in clinic between 2-4 weeks following the operation. Typically dissolvable stitches are used so they should not require to be removed.
The hand can be used for normal activity after the first few days. Most patients can drive after a week or two. Most patients return to work in 2-3 weeks, but this varies with occupation; heavy manual work usually takes about 6 weeks. The wound should be massaged by the patient 3 times a day with a bland soft cream for 3 months once the wound is well healed (typically after 2 weeks). This reduces the scar sensitivity which can be a nuisance. If this is marked a Physio may be organised to help reduce the scar tenderness but this is rarely required. Patients should avoid pressing heavily on the scar for 3 months following the operation as this will be quite painful.
What are the results of the operation?
The aim of the operation is primarily to prevent the condition deteriorating further with recovery a secondary aim. By these criteria at least 85% of patients in studies say they have a good or excellent result following this operation, with relief of the pain and no progression of their symptoms. In most patients there is at least partial recovery of their symptoms. Recovery of full nerve function is unreliable. This may be because the nerve is trapped further away from where the hand needs the supply or because patients typically come for surgery with more established continuous symptoms. It may take 2 years for the improvement in sensation, muscle bulk and strength to optimise.
Are there any risks?
All interventions in medicine have risks. In general the larger the operation the greater the risks. For ulnar neuritis the risks include:
- The scar may be tender, in about 20% of patients. This usually improves with scar massage, over 3 months.
- Aching in the elbow usually settles within 1-2 months. Grip strength can also take a few months to return to normal.
- Stiffness may occur in particular in the elbow. This is usually short-term and only infrequently requires physiotherapy.
- Numbness can occur around the scar but this rarely causes any functional problems.
- Wound infections occur in about 1% of cases. These usually quickly resolve with antibiotics.
- Recurrence - Recurrent symptoms are recorded. They may occur due to further deterioration in the elbow if there is an underlying problem or for reasons that are not entirely clear. The risk of recurrence is of the order of 2-5% in the long term. Often this will settle or at least improve with redo surgery.
- Chronic Regional Pain Syndrome "CRPS". This is a rare but serious complication, with no known cause or proven treatment. The nerves in the hand "over-react", causing swelling, pain, discolouration and stiffness, which improve very slowly.
- Any operation can have unforeseen consequences and leave a patient worse than before surgery.