Hypothenar hammer syndrome: case report and review.

Background: Hypothenar hammer syndrome is a rare vascular overuse syndrome characterized by post-traumatic vascular insufficiency of the hand from repetitive compression over the hypothenar eminence. Patients with occupations predisposing to repetitive use of the hypothenar eminence as a tool are at high risk. Repetitive trauma compresses a superficial segment of the ulnar artery against the hook of hamate as it exits Guyon's canal, damaging the intimal layer of the artery and causing vasospasm, platelet aggregation, and thrombus formation, leading to pain and paresthesias that eventually progress to claudication and ischemia.