Steven Ward

Pronator Teres Syndrome

Median nerve entrapment in the forearm near the elbow may be observed in two forms, these consisting of the pronator teres syndrome and the syndrome of the anterior interosseous nerve (Kiloh-Nevin). Both syndromes are infrequently encountered, but entrapment of the anterior interosseous nerve by the deep head of the pronator teres and the flexor superficialis arch is said to be more frequently recognized. Although many of the clinical manifestations may resemble those of involvement of the median nerve by a supracondylar process and/or Struthers’ ligament, each of the two syndromes mentioned above will be dealt with separately and involvement by the Struthers’ ligament will be described where it fits the pattern.

Lateral Femoral Cutaneous Nerve of the Thigh

Meralgia paresthetica is a benign disturbance of a sensory nature localized to the outer thigh, which at best is annoying but which may become severely painful and occasionally disabling. It occurs in both men and women, usually of middle age. The disturbance involves the lateral femoral cutaneous nerve of the thigh, which is formed immediately before it passes through the tunnel in the inguinal fascia adjacent to the anterior superior spine. It is at this point that angulation may occur, giving rise to symptoms (Fig. 28).

Posterior Interosseous Nerve Entrapment

Entrapment of the posterior interosseous nerve occurs frequently, and may be manifested by weakness of the forearm extensor muscles, by forearm pain alone, or by both muscle weakness and pain. The disturbance may mimic the peripheral symptoms of a cervical spondylosis and may be related to the occurrence of a rheumatoid arthritis as well. The nerve is a branch of the radial nerve supplying extensor muscles in the forearm. There is no cutaneous sensory distribution. The disturbance has been referred to as “tennis elbow” and may be manifested as forearm pain without clinical evidence of muscular weakness.

Common Peroneal Nerve Entrapment

Because of its course at the head of the fibula, the peroneal nerve and its branches are subject to various forms of entrapment, each having relatively specific symptomatology. Because of the superficial position of the nerve resting on the underlying bone, the common peroneal nerve is vulnerable to entrapment with numerous etiologic factors (Fig. 23). Peroneal nerve entrapment may involve either the superficial peroneal nerve, the deep division, or the common trunk, each of which will be dealt with separately.

Tarsal Tunnel Syndrome

This syndrome is a result of compression of the posterior tibial nerve in the lower extremity where the nerve passes beneath the flexor retinaculum, which forms a tunnel at the medial aspect of the foot. The nerve is the final continuation of the sciatic nerve, passing inferior to the medial malleolus just anterior to the Achilles tendon, at which point entrapment may occur. The neuropathy may involve the posterior tibial nerve proper or one of the branches distal to the tunnel. The plantar nerves will be considered separately. The tunnel has a bony floor with the flexor retinaculum as the roof, an ideal situation in which nerve compression may occur.

Suprascapular Nerve Entrapment

This disturbance is not rare or unusual, but must be taken into consideration in evaluating patients suspected of having a tear in the rotator cuff. At times, the differentiation may be difficult, requiring the combined use of an arthrogram and EMG studies, along with a careful history and examination. It must also be considered in chronic shoulder disability, and may be associated with a history of acromioclavicular separation or fractures of the proximal humerus or of the scapula itself.

Abdominal Nerve Entrapment

This disturbance affects the abdominal cutaneous nerves as they pass through the rectus abdominis muscle sheath, producing pain that may simulate surgical or genitourinary disease. The nerve angulates sharply as it enters the rectus muscle and is tethered posteriorly. At this point, it is vulnerable to entrapment. The disturbance is generally below the level of the umbilicus.

Deep Peroneal Nerve Entrapment

This branch of the common peroneal nerve descends in the leg to its termination on the dorsum of the foot where it is subject to injury. The nerve has both muscular and sensory components, and either or both may be involved in trauma. The disturbance is seen more often in females and often in those with venous problems.

Occipital Nerve Neuralgia

There is a question as to whether or not occipital neuralgia should be included in the entrapment syndromes. Involvement of the nerve is a common cause of severe headache. Cox has divided occipital nerve pain into two categories, those having a relationship to the thoracic outlet syndrome, and symptoms arising from direct involvement of the nerve.

Ulnar Nerve (Deep Motor Branch)

There are a number of variations in the syndromes affecting the distal portion or major portion of the ulnar nerve. These may be categorized as follows: A. Motor weakness affecting all the ulnar-innervated muscles B. Motor weakness affecting all ulnar-innervated muscles, except those of the hypothenar group C. Involvement giving rise to a pure sensory deficit D. A mixture of motor and sensory deficit E. A mixture of motor and sensory deficit sparing the hypothenar muscle group.