Wartenberg's Sign

Historical Overview

• Wartenberg’s sign is named after Robert Wartenberg, the “Sherlock Holmes” of clinical neurology. He first described this sign in 1930.¹

Description

• Wartenberg’s sign evaluates a patient’s inability to adduct the small finger; this inability shows a weakness of the third palmar or volar interosseous.²
• Interosseous weakness can also be accompanied by a contracture of hypothenar muscles.

Pathophysiology

• Wartenberg’s sign can help to diagnose ulnar nerve palsy or chronic cubital tunnel syndrome.
• In addition to cases of neurogenic origin, a positive Wartenberg’s sign may also indicate the contracture of hypothenar muscles after a compression injury, or the beginning of multiple sclerosis with cerebellar lesions.
• Insertion of extensor digiti minimi on the ulnar aspect of the base of the proximal phalanx of the little finger leads to persistent abduction of the little finger unopposed owing to palsy of the third volar interossesous muscle

Instructions

1. Obtain an accurate and complete patient history. Ask the patient to rate on a scale from 1 to 10 how much pain s/he usually experiences in the affected small finger.
2. Check for difficulty with reaching into a pocket or putting on a coat.
3. Ask the patient to place all fingers in extension and abduction.
4. Ask the patient to adduct all fingers to midline.
5. If ulnar nerve palsy is a probable diagnosis, also check for clawing of the ulnar fingers, loss of key pinch, loss of flexion sequence of the fingers and loss of the metacarpal arch.^2,3
6. Examine the contralateral hand.

Related Signs and Tests

• Bouvier
• Bunnell
• Duchenne
• Froment’s sign
• Jeanne’s sign
• Intrinsic muscle test²

Diagnostic Performance Characteristics

• Wartenberg’s sign should be used in conjunction with other physical tests to improve reliability.
• This test is not used as “stand-alone” test in clinical practice. Therefore, its diagnostic performance characteristics have not warranted significant investigation.
• Causes other than neurogenic origin have been reported, such as traumatic palmar interosseous muscle rupture, closed ligament injury, and necrosis and contracture of hypothenar muscles after compression injury as well as in cases of cerebellar disease and of beginning multiple sclerosis with cerebellar lesions.