Cubital Tunnel Syndrome

What is it? 
Cubital tunnel syndrome is compression or irritation of the ulnar nerve in a tunnel on the inside of the elbow (where your ‘funny bone’ is). The ulnar nerve provides sensation to the little finger and part of the ring finger, and power to the small muscles within the hand. 

What are the causes? 
Most cases arise without an obvious cause, but the tunnel can be narrowed by arthritis of the elbow joint or by an old injury. Many patients develop symptoms as a result of leaning on the elbow or from direct pressure over the ulnar nerve when using a computer at a desk.

What are the symptoms? 
Numbness or tingling of the little and ring fingers are usually the earliest symptom. It is frequently intermittent, but may later become constant. Often the symptoms can be provoked by leaning on the elbow or holding the elbow in a bent position (e.g. on the telephone). Sleeping with the elbow habitually bent can also aggravate the symptoms. 

In the later stages, the numbness is constant and the hand becomes weak. There may be visible loss of muscle bulk in severe cases, particularly noticeable on the back of the hand between the thumb and first finger, with loss of strength and dexterity. 

What is the Natural History?
Most people know the symptoms of cubital tunnel syndrome from leaning on the elbow for a prolonged period, such as sleeping on a long haul flight. The symptoms of cubital tunnel syndrome generally come and go, and the condition will often settle completely with simple measures such as avoiding direct pressure on the nerve, and avoiding prolonged full flexion of the elbow.

What is the treatment? 
Modification of activity is the mainstay of treatment in the early stages. This should include a workstation assessment. Prolonged flexion should be avoided, and any activity which puts direct pressure on the nerve should be modified. Computer keyboards should be placed at the edge of the desk, and a workstation chair should not have an arm rest. 

Surgery to decompress the nerve is required in severe cases, or in those that do not respond to the non-surgical treatments above. Surgery frequently improves the numbness, but its chief objective is to prevent the progressive muscle weakness and wasting that tends to occur in severe untreated cases. 

Surgery is performed through a short incision on over the nerve at the elbow, and the thick fibrous tissue overlying the nerve is divided, taking pressure off the nerve.

What is the outcome? 
The outcome depends upon the severity of the compression being treated. Numbness frequently improves, though the improvement may be slow. Surgery generally prevents worsening of the muscle weakness, but improvements in muscle strength are often slow and incomplete. 

In the mild cases you can expect there to be full resolution of symptoms in most cases, the more severe the case the less predictable the long term outcome in regard to the nerve function fully recovering. The overall satisfaction rate at 1 year following surgery is 85%.

© Fife Hand Service 2020

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