[1][2] This commonly results from weakness of some of the ulnar nerve innervated intrinsic hand muscles -in particular the palmar interosseous muscle to the little finger- caused by damage to their nerve supply (denervation).
There may be different causes for this denervation and muscle imbalance including: 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.
The latter involves compression at the wrist of the superficial sensory branch of the radial nerve which does not innervate hand muscles.
[citation needed] Robert Wartenberg (1887-1956) was a neurologist born in Belarus 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.