Hypothenar hammer syndrome is caused by repetitive trauma to the ulnar artery against the hook of hamate. This is typically seen in men in their 40s whose occupation or recreation involves chronic repetitive trauma to the heel of the hand (e.g. carpenter, bricklayer, baker, as well as some sports). There may be aneurysm formation, occlusion or distal embolization. Patients may present with pain, claudication, paresthesia or blanching.