Compression of the ulna nerve as it passes through the Cubital tunnel behind the medial epicondyle.

Compression of the ulna nerve as it passes through the Cubital tunnel behind the medial epicondyle.

History
2nd most common peripheral nerve entrapment, after carpal tunnel syndrome.
50-70 % idiopathic. Other causes include trauma, ganglion.
Most common in men.
Present with pins and needles/altered sensation in the little and ring finger. Symptoms aggravated by flexion of the elbow. May complain of elbow pain/ache on the inner aspect.

Examination
Tenderness over nerve at the elbow, behind the medial epicondyle.
Loss of sensation in the ulna 1 and 1/2 fingers.
Weakness in little finger abduction (away from the ring finger).
Loss of muscle bulk in the 1st dorsal interrosei muscle (between thumb and index finger).

Special tests
1.Tinel’s Test at the elbow. Tapping on the nerve causes the symptoms in the hand.
2.Wadsworth’s Test. Flexing the elbow to 90 degrees causes the symptoms at the wrist and hand. This is due to flexion narrowing the cubital tunnel by over 50%

Differential Diagnosis

• Cervical root lesion.
• Thoracic outlet syndrome.
• Guyons canal compression of the ulna nerve (at the wrist).
• Double crush phenomenon. Cubital tunnel syndrome as well as another nerve compression

Investigations
I think nerve conduction studies are worth doing on all patients for 3 reasons.

• The service at Poole is excellent now, with most tests being done in 2-4 weeks.
• It confirms the diagnosis. Remember however that there is a 5-10 % False –ve. i.e it says that there is no Cubital tunnel syndrome, when the patient does have the disorder.
• It gives a good prognostic indicator. If it shows severe compression, then one is able to warn the patient that a full recovery after surgery may not be possible. It also allows a comparison if post operative conduction tests are carried out in patients where there is a concern that they still have symptoms, even after surgical decompression.

Treatment

• Conservative. If symptoms are short lived and relatively mild then watch and wait is an option.
• Splints. These can be helpful if mild symptoms. Elbow should be kept at around 45 degrees. Wrist should be included as the ulna nerve can be trapped by one of the wrist flexors at the elbow (Flexor Carpi Ulnaris muscle).
• Steroid injection. No real role  in this condition. Does not help and may lead to problems including painful fat atrophy.
• Surgery. Most persistent cases require surgery. Simple decompression of the nerve leads to around 80% success. But patients with severe compression may not do well, and any improvement can take a year to fully occur. MAin reason to undertake the procedure in these patients is to stop symptoms getting any worse.

When to Refer

• Any concern of the diagnosis
• Persistent moderate symptoms.
• Any patient with severe symptoms