History: 30 y/o male oil rig worker. Finger pain. Numbness and discoloration of the third finger.
Diagnosis: Hypothenar Hammer Syndrome. There is “corkscrew” elongation and ectasia of the ulnar artery extending into the proximal portions of the deep and superficial palmar arches. There are also findings of microemoblic disease to the radial digital artery to third finger.
This case demonstrates the classic “cork-screw” morphologic elongation and ectasia of the ulnar artery beginning from just beyond Guyon's canal and extending partially into the superficial and deep palmar arches. The findings are seen on the conventional MRI but better delineated on a noncontrast MRA. CT angiography best demonstrates the anatomy of the ulnar artery and also shows significantly reduced contrast filling the radial digital artery to the third digit; correlating with the patient’s ischemic symptoms.
In more severe cases, there can be near-complete to complete occlusion of the ulnar artery, aneurysm formation, and ulnar artery thrombosis. These can mimic soft tissue masses on conventional MRI. The archetypal scenario is that of a construction worker with frequent use of a jackhammer presenting with ischemic changes in the fingers. The accepted etiology is chronic/repetitive impingement of the ulnar artery against the hook of the hamate.
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