Hypothenar Hammer Syndrome

It is the thrombosis of the superficial palmar arch of the ulnar artery in the hand caused by repetitive trauma over the hook of the hammate. Vascular insufficiency of the hand causes a syndrome similar to Reynaud's.



  • Manual labor, use of vibrating tools
  • Sports, such as golf, mountain biking, baseball (catching)
  • Pre-existing arterial abnormalitites and pro-thrombotic factors

Signs and Symptoms


  • Paresthesias in fingers
  • Pain in fingers caused by cold or repetitive movements
  • Reynaud's that spares thumb


  • A hypothenar mass or callus
  • Tenderness of the hypothenar eminence
  • Raynaud's phenomenon in the fingers on the ulnar side of the hand (as above)
  • Positive Allen's test (see below)
  • Dependent rubor
  • Ulceration of fingertips or gangrene

Allen's Test

The Allen test is often used before cannulating the radial artery or in assessment of hand trauma. The technique is as follows:

  • Patient elevates the hand and makes a fist for 20 seconds
  • Firm pressure is held against both the radial and ulnar arteries
  • The patient opens the hand and it should blanche white
  • The examiner releases compression of the ulnar but not radial artery
  • A normal hand flushes within 5 to 7 seconds
  • If the hand remains white there is abnormal circulation


  • Doppler Ultrasound
  • MR Angiography
  • CT Angiography
  • Arteriography (gold standard)

Differential Diagnosis

  • Hand-arm vibration syndrome
  • Raynaud's phenomenon

MR Findings in this patient

History of numbness in thumb and index finger in left hand. Patient is a metal worker.

  • Nonvisualization of the superficial palmar arch of the radial artery which may be secondary to thrombosis/occlusion versus congenitally absent. Finding can also be consistent with hypothenar hammer syndrome in the proper clinical setting.

  • The thoracic aorta follows a normal course and caliber. There is a three-vessel arch. Visualized portions of the great vessels are unremarkable. Specifically, the left subclavian artery is widely patent. The left brachial, profunda brachial, radial and ulnar arteries are widely patent following a normal course and caliber.

  • Within the left hand the superficial palmar branch of the radial artery is not identified. The princeps pollicis artery is patent. Digital arteries to the second finger arise from the deep palmar arch. The digital arteries along the ulnar side of the third digit and radial side of the fourth digit arise from the superficial arch. The digital artery along the radial side of the fifth digit also arises from the superficial bulbar arch.

  • The deep palmar arch is patent. The superficial palmar arch is patent from the digital arteries supplying the third and fourth fingers proximally along to the ulnar artery. The soft tissues are unremarkable.




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