Wartenberg's sign is a clinical test associated with which nerve injury, and what does it indicate?

• A Median nerve injury at the wrist — loss of thumb opposition tested by abduction against resistance
• B Ulnar nerve injury at the elbow — spontaneous abduction of the little finger due to paralysis of the 3rd palmar interosseous and loss of ring finger adduction ✓
• C Radial nerve injury — inability to extend the index finger against resistance
• D Anterior interosseous nerve injury — pinch deformity (O-sign) with loss of FPL and FDP to index

Explanation

Wartenberg's sign is the spontaneous abduction of the little (5th) finger in ulnar nerve palsy. It occurs because the 3rd palmar interosseous muscle (which adducts the 5th finger) is paralysed, and the action of extensor digiti minimi (radial nerve) and the abductor digiti minimi (partly ulnar but weakened) remains unopposed, causing the little finger to drift into abduction at rest. It is not a specific test for a particular lesion level but a sign of intrinsic paralysis in ulnar nerve injury. Froment's sign tests adductor pollicis; Jeanne's sign tests first web space adduction.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.