[Hypothenar hammer syndrome. Apropos of 2 cases]

The ulnar artery, as it emerges from Guyon's canal, is fixed to the surrounding structures over a length of 2 to 3 cm. Repetitive trauma of this region can cause an arterial thrombosis. This lesion is encountered among workers who use their hypothenar eminence as a hammer on levers or other hard tools. The subcutaneous thickening, the tenderness on compression and percussion of the hypothenar eminence or Raynaud's phenomenon of the last fingers should arise the suspicion of this syndrome, which will be confirmed by a positive Allen's test, Doppler examination or digitalized angiography. The sensory branch of the ulnar nerve can be compressed by the fibrous thickening or by an aneurysm. Two typical cases which necessitated surgery are described.