Differential diagnosis includes carpal tunnel syndrome (CTS ) and cervical radiculopathy . The pattern of sensory loss in Fig. 10.1 is more likely to be seen in carpal tunnel syndrome, especially with the sharp demarcation at the ring finger. The palmar cutaneous branch of the median n arises proximal to the wrist and crosses superficial to the transverse carpal ligament , causing sensation in the palm to be usually spared in CTS. The patient is at high risk for CTS due to diabetes and manual labor. The absence of pain radiating from the neck down to the arm also makes radiculopathy less likely.

Tinel’s sign: tapping over the median n at the carpal tunnel causes pain and/or numbness radiating down to the fingers, occasionally up to the forearm.

Phalen’s test [1]: full wrist flexion reproduces the symptoms. Fig. 10.2A . Phalen’s test as initially described. Fig. 10.2B . Phalen’s test as commonly practiced.

Reverse Phalen’s test (Fig. 10.3): sustained wrist extension reproduces the symptoms.

Durkan’s test [2]: applying pressure over the carpal tunnel causes pain and/or numbness in the fingers.

Scratch collapse test [3]: the elbows are flexed 90°, and the examiner tries to push the patient’s hands together against resistance. The test is repeated after scratching over the median n in the carpal tunnel . The side with CTS collapses faster (fails to resist).