Cause nerve damage to the ulnar nerve
There are three different locations of damage to the ulnar nerve: Elbow, wrist and palm. The elbow can be damaged by fractures, incorrect positioning during surgery, inflammation or age-related tissue decay. On the wrist, the most common causes are cuts, and in the palm, long-lasting pressure (e.g. from tools or cycling).
The earlier the nerve is damaged, the more pronounced the overall extent of the loss symptoms. However, there is always the image of a claw hand. This posture is caused by the failure of the muscles supplied by the ulnar nerve and the now predominant pull of their opponents.
The basic joints of the fingers are overstretched, middle and end joints are bent. This is most clearly visible on the ring and little fingers. In the case of damage at the level of the elbow, the thumb can no longer be drawn sideways to the ring finger and sensory disturbances (numbness, tingling) of the half of the hand on the side of the ring and little finger occur. Injuries at wrist level also cause accompanying, albeit less pronounced, sensory disturbances. If the location of the injury is in the palm, however, only the image of the claw hand is seen.
Claw hand after a stroke
The targeted examination of muscle functions and postural changes is already a groundbreaking diagnostic tool. In cases of severe paralysis, the patient is no longer able to hold a piece of paper between thumb and index finger without bending the thumb in the final joint (Fromment-sign). In addition, the thumb is often overstretched in the base joint (Jeanne’s sign).
The patient is asked to bend the wrist on the ring and little finger side as well as the base joints of the fingers against resistance, to spread the long fingers and to make snapping movements with thumb and index finger against the flat hand of the examiner. Weaknesses here indicate paralysis. Electroneurography should be used for a reliable diagnosis.
An electrical stimulus is applied and the electrical potentials of the nerve are deduced. Among other things, the nerve conduction speed is tested. A reduction speaks for a damage. This diagnostic method is very sensitive, but does not allow any statement about the cause of the damage.
