Nerve Compressions
The median nerve
The median nerve may be compressed at several levels in the arm: by the ligament of Struthers, in the forearm at the level of the lacertus fibrosus, pronator teres or at the origin of the flexor digitorum superficialis. There is activity related discomfort in the forearm and median nerve paraesthesia. Forced repetitive pronation in weight training may be a cause. The ‘true’ Tinel’s sign (sustained pressure directly over the nerve) reproduces paraesthesia; what is now called Tinel’s sign will be positive at the site of compression and so define the exact level of compression. Symptoms will be reproduced by resisted elbow and wrist flexion (compression at lacertus), resisted pronation (at pronator), or resisted long and ring finger PIPJ flexion (at superficialis arch). Nerve conduction studies are unreliable. Treatment is rest and modification of aggravating factors. Surgical release is occasionally needed.
Carpal tunnel syndrome
Carpal tunnel is no different in the athlete. Mild symptoms are treated with splinting the wrist (in neutral). Surgical release gives excellent relief, but be warned of the persistence of ‘pillar pain’ at the incision site associated with forcible grip for about three months. Note that Kienböck’s (avascular necrosis of the lunate) disease can sometimes present as carpal tunnel syndrome.
Ulnar nerve (handlebar palsy)
The ulnar nerve may be compressed in Guyon’s canal in cyclists as a result of wrist hyperextension and direct pressure from handlebars. Numbness in the ulnar two and a half fingers is the usually presentation. Motor signs are often present. Avoid prolonged riding (for a time); use padded gloves and modify handlebars (may persist for several months) otherwise the most common cause of ulnar nerve compression at this level is a ganglion (picked up on ultrasound).
Anterior interosseous nerve compression
Anterior interosseous nerve compression may present with vague forearm pain and occasionally weakness of flexor pollicis longus, index profundus and pronator quadratus (not able to make ‘OK’ sign Fig. 8). Cause maybe: Anatomic variations in vessels, muscle origins or nerves; Space occupying lumps such as ganglia and lipoma. Management as for pronator syndrome.
Radial nerve (radial tunnel syndrome, RTS)
Radial nerve compression may be confused with or be associated with lateral epicondylitis. Provocative tests for lateral epicondylitis (with straight elbow passive flex wrist or ask patient to hold wrist dorsiflexed against resistance) produces pain over the extensors a few centimetres distal to the lateral epicondyle. Test for RTS: arm straight resisted compression long digit, tenses ECRB and reproduces symptoms. Rested and splinting the forearm in neutral generally resolve symptoms. Numbness in the radial sensory nerve is rarely seen in runners who maintain marked elbow flexion throughout their gait cycle. Technique modification is usually all that is required.
Distal posterior interosseous nerve syndrome
An unusual cause of dorsal wrist pain. Diagnosis is secured if injection of local anaesthetic into the fourth dorsal compartment eliminates symptoms. Transaction of the nerve maybe needed.
Repetitive trauma to the ulnar digital nerve of the thumb occurs in ten pin bowlers, and racquet sports. Equipment and technique modification are necessary to avoid permanent damage. Neurolysis is necessary for more severe cases.