American Board of Internal Medicine (ABIM) Certification Practice Exam

Which characteristic indicates the need for decompression surgery in patients with carpal tunnel syndrome?

1. Persistent pain without motor deficits

2. Active motor denervation on nerve conduction studies

3. Mild numbness in the hand

4. Intermittent tingling sensations

The correct answer is: Active motor denervation on nerve conduction studies

The need for decompression surgery in patients with carpal tunnel syndrome is indicated by active motor denervation on nerve conduction studies. This finding suggests that there is significant dysfunction of the median nerve, which can result from prolonged compression leading to nerve damage. If nerve conduction studies show evidence of motor denervation, it typically indicates that the nerve is being severely affected, which increases the risk of permanent motor deficits if not addressed surgically. In clinical practice, the presence of motor denervation on nerve conduction studies serves as a signal that conservative management may not be enough and that surgical intervention may be warranted to relieve the pressure on the median nerve and prevent irreversible damage. Symptoms such as persistent pain, mild numbness, or intermittent tingling sensations alone may not provide adequate justification for surgical intervention, particularly if motor function remains intact. Therefore, the presence of active motor denervation is crucial in determining the right approach to treatment in carpal tunnel syndrome.