CASE                               45                               

The patient is a 48-year-old, diabetic, male smoker who presents to the emergency room after sustaining a laceration to the volar aspect of his palm with a tablesaw (Fig. 4–22). In addition to injuring multiple tendons, the patient has injuries to multiple digital nerves and digital arteries. He is brought to the operating room urgently for exploration and repair; his fingers are revascularized and his digital nerves and tendons are repaired. Postoperatively, the patient inquires about his expected neural recovery.

Figure 4–22

What is the typical rate of nerve regeneration following repair?

1. 0.1 to 0.2 mm/day

2. 0.2 to 0.5 mm/day

3. 1 to 2 mm/day

4. 5 to 10 mm/day

5. 1 to 2 cm/day

Discussion

The correct answer is (C). There are many factors that contribute to the rate of regeneration of peripheral nerves, including mechanism of injury, time until repair, and individual host factors, among others. Most evidence suggests that the average rate of nerve regeneration in peripheral nerves is approximately 1 to 2 mm/day after a brief latency period.

Postoperatively, the patient has incomplete neural recovery of the radial side of his long finger and develops sharp, neuropathic pain at the site of his initial injury with a positive Tinel sign.

What is the likely cause of his neuropathic pain?

1. Tinel lesion

2. Tendon adhesions

3. Joint stiffness

4. Neuroma

5. Wallerian degeneration

Discussion

The correct answer is (D). This patient has developed a neuroma, which is manifest clinically by increased sensitivity and pain following traumatic injury to a nerve. Neuromas can be caused by scarring and incomplete nerve recovery. There are many possible interventions to ameliorate this problem, including embedding the nerve stumps in bone or muscle, injection of substances such as alcohol or phenol, and further resection or cauterization.

What are possible cause(s) of this complication?

1. Failure to resect damaged ends of the digital nerve prior to coaptation

2. Undue tension on the nerve repair

3. Too early wrist and finger extension following repair

4. Unrecognized extent of the zone of injury

5. All of the above

Discussion

The correct answer is (E). There are many possible causes of neuroma following digital nerve repair, including failure to recognize the extent of the injury and resect injured segments of the nerve, undue tension on the nerve repair, and inappropriate mobilization of the nerve coaptation site. Any of these factors, individually or in

conjunction, can lead to a painful neuroma.

Objectives: Did you learn...?

Identify the rate of nerve degeneration?

Explain the causes of nerve pain in a damaged nerve? Describe the causes of neuroma?