Hypothenar hammer syndrome. Form of reversible Raynaud's phenomenon.

Hypothenar hammer syndrome is a reversible yet uncommonly encountered cause of Raynaud's phenomenon. Characteristic findings include coldness in the dominant hand of a male, absence of triphasic color change and thumb involvement, and occupational or recreational use of the hand as a hammer. Angiography demonstrates the specific findings of irregularity or occlusion of the ulnar artery, downstream occluded proper digital arteries, and intraluminal emboli at the sites of distal obstruction. A vulnerable area of traumatic occlusion is provided by the anatomic relationship of the superficial branch of the ulnar artery to the hamate bone and the palmar aponeurosis. Pathologic studies separate the hypothenar hammer syndrome from clinically similar vasculitis. It is important to recognize the hypothenar hammer syndrome as a distinct entity because treatment is curative and consists of resection of the affected vascular segment and avoidance of the aggravating conditions.