Hypothenar hammer syndrome: causes, sequelae, and diagnostic aspects.

Purpose: To investigate the reasons and disease course of Hypothenar Hammer Syndrom. Introduction: Occlusion of the ulnar artery at the level of the h amate bone due to repetitive trauma to the hypothenar eminence is implicate d as the cause of the rarely diagnosed hypothenar hammer syndrome (HHS). Th e thrombotic occlusion and the formation of an aneurysm of the ulnar artery and the superificial palmar arch with possible peripheral embolism of the digital arteries are a direct cause of the chronic damage to the vessel wal l. Generally, HHS is diagnosed too late for recanalisation to be a viable t herapeutic option. Methods: From 1996 to 1998 the diagnosis of an HHS was m ade in 8 patients at our hospital. Etiology, clinical settings and disease course were assessed. Results: Our analysis suggests that HHS may be caused by a single severe trauma in addition to repetitive injuries. The pathogen esis of the syndrome is dependent on the vascular anatomy of the individual hand. Interindividual variations in the arterial supply of the affected ha nd influences the clinical symptomatology with possible masking of arterial occlusions. Conclusion: An exact investigation concerning the pathogenesis of HHS is a precondition for treating the disease and may help to establis h HHS as an occupational disease. MR-angiography may be a new approach for assessing HHS.