Hypothenar hammer syndrome: a discrete syndrome to be distinguished from hand-arm vibration syndrome.

BACKGROUND Hypothenar hammer syndrome (HHS) is a cause of vascular insufficiency to the hand and may be manifest as Raynaud's phenomenon. The cause is trauma to the vulnerable portion of the ulnar artery as it passes over the hamate bone, which may result in thrombosis, irregularity or aneurysm formation. AIM This review was undertaken in order to clarify the features of HHS that may differentiate it from hand-arm vibration syndrome. METHODS A tiered review of world literature was undertaken using Medline and EMBase as the primary search engines. Fifty-two relevant articles were critically reviewed. CONCLUSION Colour and temperature changes occur more diffusely in HHS than in classical Raynaud's phenomenon and the absence of the triphasic colour change may alert clinicians to the diagnosis, which may be confirmed by Allen's test. Doppler or arteriographic studies are required for confirmation. It is important to recognize the possibility of HHS in the occupational setting as a potentially curable cause of Raynaud's phenomenon, distinct from hand-arm vibration syndrome. The possibility exists of HHS occurring as a result of repeated hypothenar trauma from vibrating tools, in which case the nature and magnitude of the individual episode of trauma may be more important than the weighted acceleration level of vibration exposure.