Wartenberg's sign is a neurological

sign A sign is an object, quality, event, or entity whose presence or occurrence indicates the probable presence or occurrence of something else. A natural sign bears a causal relation to its object—for instance, thunder is a sign of storm, or me ...

consisting of involuntary abduction of the fifth (little) finger, caused by unopposed action of the

extensor digiti minimi The extensor digiti minimi (extensor digiti quinti proprius) is a slender muscle of the forearm, placed on the ulnar side of the extensor digitorum communis, with which it is generally connected. It arises from the common extensor tendon by a thi ...

.Wilkinson, Iain and Lennox, Graham (June 2005). Essential Neurology (4th ed.). Wiley-Blackwell. p. 1184 . This commonly results from weakness of some of the

ulnar nerve In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or bone, so injury is ...

innervated intrinsic hand muscles -in particular the palmar interosseous muscle to the little finger- caused by damage to their nerve supply (

denervation Denervation is any loss of nerve supply regardless of the cause. If the nerves lost to denervation are part of the neuronal communication to a specific function in the body then altered or a loss of physiological functioning can occur. Denervation ...

). There may be different causes for this denervation and muscle imbalance including: * An ulnar nerve neuropathy usually from

ulnar nerve entrapment Ulnar nerve entrapment is a condition where the ulnar nerve becomes physically trapped or pinched, resulting in pain, numbness, or weakness, primarily affecting the little finger and ring finger of the hand. Entrapment may occur at any point from ...

somewhere along its course (most commonly around the

cubital tunnel The cubital tunnel is a space of the dorsal medial elbow which allows passage of the ulnar nerve around the elbow. It is bordered medially by the medial epicondyle of the humerus, laterally by the olecranon process of the ulna and the tendinous arc ...

at the elbow where the nerve is exposed to tension, friction and compression). This muscle imbalance between the (intact)

radial nerve The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial comp ...

innervated extensor digiti quinti and the (weak) ulnar innervated interossei in the context of ulnar neuropathy is what Wartenberg described. *

Cervical myelopathy Myelopathy describes any neurologic deficit related to the spinal cord. The most common form of myelopathy in humans, '' cervical spondylotic myelopathy (CSM)'', also called ''degenerative cervical myelopathy'', results from narrowing of the spina ...

most commonly due to mechanical compression of the spinal cord in the neck as occurs in spondylotic

cervical spinal stenosis Cervical spinal stenosis is a bone disease involving the narrowing of the spinal canal at the level of the neck. It is frequently due to chronic degeneration, but may also be congenital. Treatment is frequently surgical. Cervical spinal stenosis ...

but also seen in other spinal cord disease including post-traumatic

tetraplegia Tetraplegia, also known as quadriplegia, is defined as the dysfunction or loss of motor and/or sensory function in the cervical area of the spinal cord. A loss of motor function can present as either weakness or paralysis leading to partial or t ...

. This finding of weak finger

adduction Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

in cervical myelopathy is also called the "finger escape sign". *

Upper motor neuron Upper motor neurons (UMNs) is a term introduced by William Gowers in 1886. They are found in the cerebral cortex and brainstem and carry information down to activate interneurons and lower motor neurons, which in turn directly signal muscles t ...

disorders of the cerebral cortex such as mild hemiplegic stroke or hemiplegic migraine where the same clinical finding has been called the "digiti quinti sign" Differentiation of the cause of Wartenberg's sign is based on associated clinical findings in the history and examination and sometimes involves investigations including radiographs and/or MRI of the cervical spine, elbow/wrist/hand and/or nerve conduction studies and EMG. Wartenberg's sign is not a feature of, and should not be confused with, Wartenberg's syndrome. The latter involves compression at the wrist of the superficial ''sensory'' branch of the radial nerve which does not innervate hand muscles.

Robert Wartenberg Robert Wartenberg (June 19, 1887 – November 16, 1956) was a clinical neurologist and professor. Born in the then-Russian Empire, he attended university and established his career in Germany. As a Jew, he was fired from his position as the U ...

(1887-1956) was a neurologist born in

Belarus Belarus,, , ; alternatively and formerly known as Byelorussia (from Russian ). officially the Republic of Belarus,; rus, Республика Беларусь, Respublika Belarus. is a landlocked country in Eastern Europe. It is bordered by R ...

who worked in Germany until 1935 when he emigrated to the United States. He was widely published and described a number of neurological signs and clinical tests.

References

{{DEFAULTSORT:Wartenberg's Sign Symptoms and signs: Nervous system