Ulnar Nerve Palsy is paralysis caused by damage, compression or trapping of the ulnar nerve as it makes its way down the length of the arm. This occurs due to nerve compression at the elbow (cubital tunnel) or at the wrist (Guyon's canal). Muscle weakness and atrophy predominate the clinical presentation.
The cubital tunnel is in this region commonly referred to as the 'funny bone', the area where the ulnar nerve crosses the elbow joint. The wrist is made up of a number of small bones. Two of these bones and their associated ligaments form a canal that runs through the wrist (Guyon's canal). As the ulnar nerve crosses the wrist, it passes through this canal before it branches to supply some of the fingers in the hand.
Hence depending on the area of affection two clinical syndromes exist:
Cubital Tunnel Syndrome
Cubital Tunnel Syndrome occurs when this area becomes irritated.
Bending of the elbow causes the nerve to stretch several millimetres. Frequent bending of the elbow in activities such as pulling levers, reaching or lifting causes the nerve to become irritated and inflamed.
When the nerve is stretched over the elbow the nerve can sometimes move or actually snap over the medial epicondyle causing irritation.
Leaning on the elbow, resting it on an elbow rest during a long distance drive or running machinery may cause repetitive pressure and irritation on the nerve.
A direct hit on the cubital tunnel may damage the ulnar nerve.
The symptoms of Cubital Tunnel Syndrome primarily involve numbness and tingling in the ring and little finger and the sides and back of the hand. These complaints or symptoms worsen when the elbow is bent i.e when holding a telephone, resting the head on the hand and crossing the arms over the chest. The hand may become weaker resulting in trouble opening bottles or jars. The hand may not perform as well as it did before and there may be a tendency to drop things. Clawing may occur in the ring and little fingers.
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