Dr. Von Rosen was the first to describe “ulnar artery thrombosis,” in 1934, and his management strategy was to resect the patient’s involved segment. Dr. Conn applied the term “hypothenar hammer syndrome” (HHS) in 1970 to specify the condition as arising among those who use the ulnar side of the hand as a striking tool, or hammer. Hypothenar hammer syndrome typically results in the formation of an isolated thrombus among otherwise healthy vessels. Therefore, conservative treatment or bypass of the thrombosed vessels is possible in hypothenar hammer syndrome .
Pathophysiology
Hypothenar hammer syndrome is caused by trauma to the ulnar artery: the intravascular injury may be diffuse (eg, resulting from intra-arterial injection) or localized (eg, repetitive compression or blunt force). When the trauma is repetitive, aneurysm with or without thrombosis and occlusion of the ulnar artery may result. It is hypothesized that thrombosis related to intra-arterial injection results from endothelial injury and subsequent platelet activation as well as the presence of particulate debris in the injected solution. These circumstances cause distal vasomotor disturbances and varying degrees of vascular insufficiency. Moreover, emboli from the thrombus may occlude digital vessels, worsening perfusion deficits. An associated aneurysm may also occur. These are urgent conditions, requiring prompt diagnosis and treatment (“time is tissue”).
Related Anatomy
- Blood supplying the hand originates from the radial and ulnar arteries.
- On the medial aspect of the wrist, the ulnar artery enters the hand through Guyon’s canal and supplies the superficial volar arch. The ulnar artery joins the dorsal portion of the radial artery to form the deep palmar arch, and may join the volar portion of the radial artery (35% of patients) to form a complete superficial palmar arch.
- The vulnerable position of the superficial branch of the ulnar artery puts it at risk of compression against the hook of hamate.
Incidence and Related Conditions
- Considered rare; precise incidence unknown because either ulnar artery occlusion is asymptomatic or individuals do not present for evaluation
- Possibly more common than believed, hypothenar hammer syndrome has been reported in mountain bikers, tennis players, golfers, and a variety of other athletes and in a drummer
- Hypothenar hammer syndrome is an uncommon cause of digital ischemia, which occurs in <2% of 1300 patients with hand ischemia
Differential Diagnosis
- Autoimmune disease
- Buerger’s disease
- Guyon’s canal syndrome
- Hand-arm vibration syndrome
- Raynaud’s phenomenon
