The hypothenar hammer syndrome.

The superficial palmar branch of the ulnar artery is the major source of blood to the fingers. Repetitive blunt trauma to it may lead to spasm, thrombosis, or aneurysm formation; or cause a palpable hypothenar mass, digital ischemia, or unilateral Raynaud's phenomenon—the “hypothenar hammer syndrome.” When other causes of digital ischemia cannot be excluded clinically, arteriography becomes mandatory. While direct vascular reconstructive procedures have been performed with good results, the most common surgical procedure is an upper dorsal sympathectomy which relieves the associated reflex vasoconstriction.