(A) 2
(B) 4
(C) 6
(D) 8
(E) 12

The correct response is Option A.

In neonates who have brachial plexus palsy at birth, neurologic outcome correlates directly with the severity of the brachial plexus injury. The evaluation and management of brachial plexus palsy remains somewhat controversial. A recognition of the natural history of this condition, along with more uniform evaluation procedures, has resulted in better care of affected neonates. One author recommends using the rate of biceps recovery as an indication for early operative exploration of the brachial plexus. However, the course of biceps recovery over time has been shown to incorrectly predict outcome in 13% of patients. A more complete evaluation of elbow flexion and extension of the wrist, finger, and thumb seems to be more predictive of outcome.

Nevertheless, those infants with C5-6 injuries who begin to exhibit some function of the deltoid and biceps muscles by age 2 months will most likely have normal arm function. In contrast, infants who do not exhibit strong biceps contractions by age 6 months will likely not ultimately attain completely normal arm function.

References
1. Clarke HM, Curtis CG. An approach to obstetrical brachial plexus injuries. Hand Clin. 1995;11:563-581.
2. Gilbert A. Long-term evaluation of brachial plexus surgery in obstetrical palsy. Hand Clin. 1995;11:583-595.
3. Michelow BJ, Clarke HM, Curtis CG, et al. The natural history of obstetrical brachial plexus palsy. Plast Reconstr Surg. 1994;93:675-681.

A 40-year-old man has marked swelling of the entire left hand and severe pain with passive movement of the fingers six hours after sustaining a crush injury to the left hand and forearm. Radiographs show no evidence of fracture. Which of the following incisions is most appropriate for release of the adductor pollicis and associated interossei?

(A) Dorsal second metacarpal
(B) Radial edge of the first metacarpal
(C) Thenar crease
(D) Third metacarpal
(E) Transverse palmar

The correct response is Option A.

Signs of compartment syndrome include pain accentuated by passive muscle stretch, paresthesia, weakness, and swelling, tenderness, and tenseness of the compartments of the forearm. Pallor and pulselessness are rare, late
findings. In the alert, competent patient, pain accentuated by passive stretching of the involved muscle compartment is the most consistent early sign and is considered to be diagnostic. In patients with signs of compartment syndrome, the four dorsal compartments, three volar interossei compartments, adductor pollicis compartment, thenar eminence compartment, and hypothenar eminence compartment all need to be released.

Fasciotomies of the intrinsic muscles of the hand can be performed through four incisions to decompress all ten compartments. All of the interossei and the adductor muscles can be released through two dorsal longitudinal incisions made over the second and fourth metacarpals. The hypothenar and thenar eminences are released through incisions over the ulnar fifth metacarpal and radial first metacarpal, respectively. Palmar incisions are not performed.

Reference
1. Rowland SA. Fasciotomy: the treatment of compartment syndrome. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;1:689-710.

A 38-year-old woman has had a clenched-fist deformity involving the right hand for the past 18 months. She sustained an anoxic brain injury 14 years ago. Physical examination shows maceration and wounding of the palmar skin caused by the fingernails. The patient has no voluntary motor control of the arm, and passive motion produces pain in the joints and flexor tendons.

Which of the following is the most appropriate initial management?

(A) Application of a cast with the arm in an intrinsic-plus position
(B) Injection of botulinum toxin (Botox) into the profundus and superficialis muscles
(C) Release of the profundus and superficialis tendons
(D) Transfer of the superficialis tendon to the profundus tendon
(E) Z-plasty for lengthening of the profundus and superficialis tendons

The correct response is Option B.

Because reconstructive surgery is especially difficult in patients who have spasticity following brain injury, operative procedures should be performed only if conservative treatment is not successful. Injection of botulinum toxin will provide temporary relief of spasticity and facilitate splinting or physical therapy.

If these measures fail, muscle release or transfer of the superficialis tendon to the profundus tendon may be considered in this patient. Tendon transfer would correct the extensor tendon imbalance but would result in hygienic, rather than functional, improvement in a patient with no voluntary motor control.

Casting is not indicated in poorly compliant patients who have severe contractures and painful joints. Although release of the superficialis and profundus tendons would relieve the flexion contractures, it is most likely to result in unopposed action of the extensor tendons. Z-plasty lengthening will not adequately release the tendons in a patient with a clenched-fist deformity because the muscles are severely contracted.

References
1. Brashear A, Gordon MF, Elovic E, et al. Intramuscular injection of botulinum toxin for the treatment of wrist and finger spasticity after a stroke. N Engl J Med. 2002;347:395-400.
2. Rowland LP. Stroke, spasticity, and botulinum toxin. N Engl J Med. 2002;347:382-383.
3. Swanson AB, de Groot Swanson G. Evaluation and treatment of the upper extremity in the stroke patient. Hand Clin. 1989;5:75.

A 38-year-old woman has had a clenched-fist deformity involving the right hand for the past 18 months. She sustained an anoxic brain injury 14 years ago. Physical examination shows maceration and wounding of the palmar skin caused by the fingernails. The patient has no voluntary motor control of the arm, and passive motion produces pain in the joints and flexor tendons.

Which of the following is the most appropriate initial management?

(A) Application of a cast with the arm in an intrinsic-plus position
(B) Injection of botulinum toxin (Botox) into the profundus and superficialis muscles
(C) Release of the profundus and superficialis tendons
(D) Transfer of the superficialis tendon to the profundus tendon
(E) Z-plasty for lengthening of the profundus and superficialis tendons

The correct response is Option B.

Because reconstructive surgery is especially difficult in patients who have spasticity following brain injury, operative procedures should be performed only if conservative treatment is not successful. Injection of botulinum toxin will provide temporary relief of spasticity and facilitate splinting or physical therapy.

If these measures fail, muscle release or transfer of the superficialis tendon to the profundus tendon may be considered in this patient. Tendon transfer would correct the extensor tendon imbalance but would result in hygienic, rather than functional, improvement in a patient with no voluntary motor control.

Casting is not indicated in poorly compliant patients who have severe contractures and painful joints. Although release of the superficialis and profundus tendons would relieve the flexion contractures, it is most likely to result in unopposed action of the extensor tendons. Z-plasty lengthening will not adequately release the tendons in a patient with a clenched-fist deformity because the muscles are severely contracted.

References
1. Brashear A, Gordon MF, Elovic E, et al. Intramuscular injection of botulinum toxin for the treatment of wrist and finger spasticity after a stroke. N Engl J Med. 2002;347:395-400.
2. Rowland LP. Stroke, spasticity, and botulinum toxin. N Engl J Med. 2002;347:382-383.
3. Swanson AB, de Groot Swanson G. Evaluation and treatment of the upper extremity in the stroke patient. Hand Clin. 1989;5:75.

A 36-year-old man has pain in the forearm and paresthesia in the hand that are exacerbated with activity. He also has decreased sensation and paresthesia in the radial side of the palm, at the base of the thenar eminence, in the thumb, index, and long fingers, and along the radial side of the ring finger.

These findings are most consistent with which of the following syndromes?

(A) Anterior interosseus syndrome
(B) Carpal tunnel syndrome
(C) Cubital tunnel syndrome
(D) Pronator syndrome
(E) Radial tunnel syndrome


The correct response is Option D.

This 36-year-old man has findings consistent with pronator syndrome, or proximal compression neuropathy of the median nerve. The median nerve may be entrapped beneath the supracondylar process and ligament of Struthers in the distal third of the humerus or at the lacertus fibrosis, the pronator teres muscle, or the arch of the flexor digitorum superficialis muscle.

Functional testing can be used to determine the site of compression. Compression at the ligament of Struthers is indicated by exacerbation of symptoms with flexion of the elbow against resistance. In patients who have compression of the median nerve at the lacertus fibrosis, symptoms are exacerbated by active flexion of the elbow with the forearm in pronation. Patients who have pain with resisted pronation of the forearm during wrist flexion should undergo surgical exploration of the median nerve where it passes through the pronator teres muscle. However, if resisted flexion of the superficialis muscle of the long finger exacerbates symptoms, the superficialis arch should be inspected carefully during surgical exploration.

Electrodiagnostic studies can be used to confirm the diagnosis and determine the level and severity of nerve injury.

Release of the median nerve is appropriate management. During the procedure, the median nerve should be explored starting at a point 5 cm proximal to the elbow and continuing distally. Each of the potential sites of compression should be carefully divided to ensure that the nerve is adequately released.

Patients with anterior interosseous syndrome have poorly defined pain in the proximal forearm that is relieved with rest. They also have weakness or paralysis of the flexor digitorum profundus tendon of the index and long fingers, flexor pollicis longus tendon, and pronator quadratus muscle.

Carpal tunnel syndrome is the most common compression neuropathy of the upper extremity. It is characterized by pain, especially at night, and numbness and weakness in the distribution of the median nerve at the wrist. Numbness in the region innervated by the palmar cutaneous nerve is uncommon.

Cubital tunnel syndrome, or entrapment of the ulnar nerve at the elbow, manifests as pain over the medial aspect of the proximal forearm. Numbness is noted in the dorsoulnar aspect of the hand, small finger, and ulnar aspect of the ring finger. Weakness can be demonstrated in the flexor digitorum profundus tendons of the ring and small fingers and in the ulnar intrinsic tendons, especially the first dorsal interosseous and abductor digiti minimi tendons.

Patients with radial tunnel syndrome have aching pain localized just below the elbow in the extensor mass and along the course of the radial nerve. Although there are four potential sites of compression within the radial tunnel, most patients have entrapment at the arcade of Frohse, which forms a ligamentous band over the deep radial nerve as the nerve enters the supinator muscle. Radial tunnel syndrome manifests as pain rather than specific numbness or weakness.

References
1. Eversmann WW. Entrapment and compression neuropathies. In: Green DP, ed. Operative Hand Surgery. 3rd ed. New York, NY: Churchill Livingstone, Inc; 1993;2:1341-1385.
2. Fuchs PC, Nathan PA, Myers LD. Synovial histology in carpal tunnel syndrome. J Hand Surg. 1991;16A:753-758.
3. Heithoff SJ, Millender LW, Malebuff EA. Median epicondylectomy for treatment of ulnar nerve compression at the elbow. J Hand Surg. 1990;15A:22-29.
4. Hilburn J. General principles and use of electrodiagnostic studies in carpal and cubital tunnel syndromes. Hand Clin. 1996;12:205-221.

A right-handed 34-year-old man has been unable to flex the distal interphalangeal joint of the right index finger and interphalangeal joint of the thumb for the past six months. There is no history of trauma. Physical examination shows normal two-point discrimination of the right hand; the muscles innervated by the ulnar nerve are unaffected.

Which of the following is the most likely cause of these symptoms?

(A) Anterior interosseus syndrome
(B) Cubital tunnel syndrome
(C) Posterior interosseous syndrome
(D) Pronator syndrome
(E) Radial tunnel syndrome


The correct response is Option A.

The most likely diagnosis is anterior interosseous syndrome (also known as Kiloh-Nevin syndrome). This condition is characterized by absence of function of motor units innervated by the anterior interosseous nerve. These motor units include the flexor pollicis longus tendon, the profundus tendons to the index and long fingers, and the pronator quadratus muscle. In affected patients, there is absence of flexion of the interphalangeal joint of the thumb and distal interphalangeal joints of the index and long fingers and weakness of pronation with the elbow in flexion. Anterior interosseous syndrome results in pure motor deficits; there are no sensory abnormalities.

In patients with this condition, the anterior interosseus nerve may be compressed within the tendinous bands (the deep head of the pronator teres tendon, origin of the flexor digitorum superficialis tendon of the ring finger, and origin of the flexor carpi ulnaris tendon) or accessory muscles (anomalous band connecting the flexor digitorum superficialis tendon to the flexor digitorum profundus, accessory flexor pollicis longus, and palmaris profundus tendons). Other causes include vascular anomalies (thrombosis of ulnar collateral vessels or an aberrant radial artery), bicipital bursa, trauma, fractures, or compression resulting from intravenous devices.

Cubital tunnel syndrome, or compression of the ulnar nerve at the elbow, results in sensory deficits of the ring and small fingers and the dorsoulnar aspect of the hand and motor deficits in the intrinsic and extrinsic muscles innervated by the ulnar nerve. Posterior interosseous syndrome is similar to anterior interosseous syndrome in that it also causes pure motor deficits without sensory findings. Affected patients have weakness in the muscles of the wrist and extensors of the thumb and fingers. Compression of the median nerve by the pronator muscle is unlikely because this patient does not have changes in sensation. Compression of the radial nerve in the radial tunnel primarily results in pain in the distribution of the radial nerve.

References
1. Gabel GT. Nerve entrapment. In: Herndon JH, ed. Surgical Reconstruction of The Upper Extremity. Stamford, Conn: Appleton & Lange; 1999:367-390.
2. Szabo RM. Entrapment and compression neuropathies. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;2:1404-1447.

A 48-year-old dock worker has effort-associated carpal tunnel syndrome. Which of the following muscles is the most likely cause?

(A) Abductor digiti quinti
(B) Adductor pollicis
(C) Lumbrical
(D) Palmaris brevis
(E) Third volar interosseus


The correct response is Option C.

The lumbrical muscles, which aid in flexion of the metacarpophalangeal joints, typically originate from the radial side of the flexor digitorum profundus tendons, with the exception of the third lumbrical, which originates from the ulnar side of the long finger and radial side of the ring finger. These muscles insert into the radial sagittal band and also assist in extension of the interphalangeal joints. Because the lumbrical muscles rest within the carpal canal during grip functions and can become edematous with prolonged use, carpal tunnel syndrome may be aggravated in patients with muscular hands.

Each lumbrical muscle is innervated by the same source as its flexor digitorum profundus tendon of origin. The median nerve supplies innervation to the first and second lumbricals, and the ulnar nerve supplies the third and fourth lumbricals.

None of the other intrinsic muscles pass within the carpal canal.

References
1. Clemente CD, ed. Gray's Anatomy of the Human Body. 30th ed. Philadelphia, Pa: Lea & Febiger; 1984.
2. Moore KL, Dailey AF, eds. Clinically Oriented Anatomy. 4th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 1999.