Wartenbergs tegn

Wartenberg’s Sign refers to a slight abduction of the little finger, commonly seen in cases of ulnar nerve palsy. It results from weakness or paralysis of the palmar interossei muscles, which normally adduct the little finger. When these muscles fail, the radial-innervated muscles (extensor digiti minimi and extensor digitorum communis) dominate, leading to abduction of the little finger. This makes it difficult for the patient to bring the little finger toward the ring finger.

Wartenberg’s Sign was first described by Robert Wartenberg in 1939 in a letter to the editor, emphasizing that this finding could be an early or late sign of ulnar nerve palsy. It is important to distinguish Wartenberg’s Sign from Wartenberg’s Syndrome, which involves entrapment of the superficial branch of the radial nerve and presents only with sensory symptoms.

Purpose

Wartenberg’s Sign is used to assess the function of the ulnar-innervated hand muscles, particularly the palmar interossei. The test helps detect ulnar neuropathy and provides clinical information about impaired adduction of the little finger.

Clinical Signs

• Slight abduction of the little finger at rest or during attempted finger adduction

• Inability to bring the little finger against the ring finger when the fingers are extended

• May be accompanied by sensory changes in the ulnar nerve distribution (ulnar half of the ring finger and the little finger)

• A positive sign shows persistent abduction of the little finger, while the other fingers can adduct normally

Execution

Technique 1 – Goldman et al.

• The patient sits with the wrist in neutral position and forearm fully pronated

• The patient is asked to extend all fingers fully

• The patient is then instructed to abduct all fingers and subsequently adduct them

• A positive test is present if the little finger remains in slight abduction and cannot fully adduct

Technique 2 – Magee

• The patient sits with the hand resting on a table

• The examiner passively spreads the patient’s fingers

• The patient is then asked to bring the fingers together again

• Inability to bring the little finger against the ring finger indicates a positive finding

Interpretation

• Positive test: The little finger remains abducted and cannot be brought against the ring finger, indicating weakness of the ulnar-innervated interossei muscles

• Negative test: The patient is able to bring the little finger to the ring finger without difficulty

Differential Diagnoses

• Ulnar neuropathy: Most common cause; may result from compression in Guyon’s canal, cubital tunnel syndrome, or more proximal sites along the nerve

• Radial nerve involvement: Can cause weakness of extensor muscles but does not typically produce isolated little finger abduction

• Other causes: Syringomyelia, local injury, scar tissue, contractures, or muscular injuries may also lead to abduction of the little finger without primary ulnar neuropathy

Evidence

Studies have shown that Wartenberg’s Sign may be a late indicator of ulnar neuropathy but is not always specific. Goldman et al. found that although the sign was not commonly observed, it was significant when present. Other studies have noted Wartenberg’s Sign in patients without ulnar nerve damage, including those with ligament and soft tissue injuries. This highlights the need for careful clinical judgment when interpreting a positive finding.

Limitations

• A positive finding alone is not diagnostic of ulnar neuropathy; it must be interpreted with other clinical findings (e.g., Froment’s sign, sensory testing)

• May also occur in non-neurological conditions such as scar tissue, contractures, or muscle atrophy

• In cases of combined radial and ulnar nerve palsy, the test may be negative because radial muscle weakness masks the abduction

Clinical Significance

Wartenberg’s Sign is a useful clinical observation when assessing ulnar nerve palsy, but it is neither necessary nor sufficient to establish a diagnosis on its own. It can help localize interosseous muscle weakness, but further evaluation (neurological examination and possibly nerve conduction studies) is often required to confirm the diagnosis and determine the level of compression.

Treatment

Since Wartenberg’s Sign is a symptom and not a disease, treatment must target the underlying cause of ulnar neuropathy. This may include:

• Conservative treatment: Ergonomics, activity modification, exercises, or splinting

• Surgical treatment: Decompression or transposition of the nerve in cubital tunnel or Guyon’s canal syndrome

• Electrostimulation and physiotherapy: To strengthen remaining musculature and prevent contractures

Summary

Wartenberg’s Sign is a clinical observation in which the little finger rests in slight abduction due to weakness of the ulnar-innervated adductor muscles, with predominance of radial-innervated extensor activity. A positive finding may indicate ulnar neuropathy but must always be interpreted in the context of other clinical signs and differential diagnoses. The test is simple to perform but should not be used as the sole diagnostic tool.

Sources

1. A.J. Larner; A Dictionary of Neurological Signs; Springer Science & Business Media, 12-Nov-2010; page 369

2. Tosun N, Tuncay I, Akpinar F. Entrapment of the sensory branch of the radial nerve (Wartenberg's syndrome): an unusual cause ;Tohoku J Exp Med. 2001 Mar;193(3):251-4.

3. Robert Wartenberg, M.D ;A SIGN OF ULNAR PALSY ;JAMA. 1939;112(17):1688. doi:10.1001/jama.1939.62800170002011a.

4. Dutton, M. (2008). Orthopaedic: Examination, evaluation, and intervention (2nd ed.). New York: The McGraw-Hill Companies, Inc.

5. Goldman SB, Brininger TL, Schrader JW, Curtis R, Koceja DM. Analysis of clinical motor testing for adult patients with diagnosed ulnar neuropathy at the elbow. Arch Phys Med Rehabil 2009;90:1846-52

6. David J. Magee: Orthopedic Physical Assessment: chapter 6-elbow ;sixth edition; Elsevier Health Sciences, 2008

7. Kilgus M , Burg D, Loss M, Weishaupt D, Meyer VE.: Wartenberg's Sign of Ulnar Nerve Lesion. A Contribution to Pathophysiology and to the Differential Diagnosis; Handchir Mikrochir Plast Chir. 2003 Jul;35(4):2518.

8. Goldman, S. B., Brininger, T. L., Schrader, J. W., Curtis, R., & Koceja, D. M. (2009). Analysis of clinical motor testing for adult patients with diagnosed ulnar neuropathy at the elbow. Archives of physical medicine and rehabilitation, 90(11), 1846–1852. https://doi.org/10.1016/j.apmr.2009.06.007

9. Jan van Aaken, Jin Zhu, Jean H. D. Fasel, Jean-Yves Beaulieu ; Investigation of radialization and rerouting of the extensor digiti minimi (EDM) in the abduction deformity of the little finger: a cadaver study ; HAND June 2011, Volume 6, Issue 2, pp 202-205