Hypothenar hammer syndrome is due to posttraumatic vascular insuffi ciency of the hand caused by repetitive compression or blunt trauma to the hypothenar eminence injuring the terminal ulnar artery or
proximal superfi cial palmar arch (Figure 1). A dull ache and tenderness with insidious progression of ischemic symptoms for weeks to months are typical. Ischemic symptoms and signs include a cold sensation, paresthesias, blanching, cyanosis, and even atrophic ulceration. Symptoms may be similar to Raynaud’s disease, but in contrast spare the thumb.