Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Peripheral Nerve Injuries

Injuries to the peripheral nerves are relatively common, and, if unrecognized can have a devastating effect on the athlete. These nerves can be damaged especially by compression or traction. When nerves such as the common peroneal nerve at the proximal fibula head or the ulnar nerve at the medial epicondyle of the elbow are lying superficially, they can be compressed by excessive pressure. A fracture or a dislocation can cause nerve injury when the nerve is overstretched. Damage to the ulnar nerve in the elbow can be caused by stretching during pitching or throwing. An inversion injury to the ankle can cause injury to the peroneal nerve. Mechanical failure of a nerve may take place at 30–70% elongation. Uncommon causes for nerve injury are poor circulation which can occur by entrapment, compartment syndrome, or in connection with fracture or dislocation. Laceration and direct injury to the nerve are unusual causes of injury, but can occur in contact sports such as ice hockey, skiing, and American football.

Symptoms and diagnosis

The injury can be difficult to diagnose as the symptoms are sometimes not obvious in the acute phase. They may begin insidiously. The athlete may complain of numbness, tingling, and pain radiating down the extremity.

– Pain or referred pain can sometimes be present. It can limit muscle strength testing. Localized or referred pain can sometimes be temporarily released by an anesthetic injection to allow full assessment of muscle strength.

– Strength testing against resistance is important; nerve injury may cause weakness.

– Hypotrophy (loss of mass) may be seen after 2 weeks and can become extensive.

– Reflex testing is mandatory to look for a peripheral nerve or nerve root injury.

– Sensory abnormalities can produce numbness, tingling or pain.

– Different nerve injuries have special tests. A Tinel test(a light tap over the nerve) can be positive, producing radiating tingling or numbness along the nerve segment. There are other specific tests available.

– Electromyographic (EMG) studies allow localization of the peripheral nerve injury and give information about the prognosis. An EMG test consists of two parts: nerve conduction studies (both motor and sensory) and needle electrode examination. These studies should ideally be carried out 3 weeks after the injury. An EMG is performed if a peripheral nerve plexus or nerve root injury is suspected, to confirm the presence of nerve injury, as well as assessing its severity and location. These studies are usually carried out by a neurologist.

Treatment

These syndromes are often self-limiting, but can result in permanent damage. Compression or entrapment injuries can be treated by releasing the pressure in the area. The treatment depends on the mechanism of injury, type of injury, location, and symptoms.

Prognosis and return to sport

In general, proximal nerve injuries have a poor prognosis for neurologi-cal recovery. There are many factors affecting the regeneration and recovery of a nerve injury, such as scarring around the area which causes disorganization of the healing tissue. Prolonged injury affects muscle function recovery. There are also other factors to be considered when the prognosis of a nerve injury is predicted. The electromyogram (EMG) studies will help in this evaluation, as well as consultation with an expert.

Peripheral nerve injuries are more common in the upper extremities. One example of peripheral injury is the burner syndrome, which can be seen not only in American football, but also in wrestling, basketball, ice hockey, etc. Other nerves injured in the shoulder are the long thoracic nerve and the suprascapular nerve. The axillary nerve can be injured in 9–18% of anterior shoulder dislocations. In the arm, the median nerve is involved in carpal tunnel syndrome; the ulnar nerve and the radial nerve can also be involved. In the lower extremity, the sciatic nerve is the most important nerve, but is rarely damaged in sports injuries. The common peroneal nerve is a continuation of the sciatic nerve and can be injured when it passes behind the fibular head. This injury can produce pain radiation, numbness, and pain on the dorsum of the foot, as well as weakness. The superficial peroneal nerve entrapment in the distal lateral aspect of the lower leg can cause radiating pain. The tibial nerve can be injured at the tarsal tunnel level. The nerve can be entrapped distal to the tarsal tunnel and can cause problems in the foot. In the groin, the lateral femoral cutaneous nerve, ilioinguinal nerve, genitofemoral nerve, and obturator nerve can be entrapped.

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