The Journal of Bone and Joint Surgery

Image Quiz

Digital Ischemia of an Index Finger¹
(continued)

1.) Digital ischemia associated with a thrombosed aneurysm of the dorsal interosseous artery

2.) Congenital absence of the radial artery

Discussion

Spontaneous formation of an aneurysm in the upper extremity is unusual and ordinarily is the result of either repetitive or penetrating trauma. Kleinert et al. reported a series of eleven aneurysms of the hand and wrist, including an aneurysm of the dorsal interosseous artery that was treated with simple excision and ligation². Those authors found that a definitive diagnosis could be made if a positive Allen test was associated with a pulsatile mass or distal vascular insufficiency, and they rarely used arteriography preoperatively. This finding conflicted with that in our patient, as the aneurysm was not pulsatile because the vessel had become thrombosed. The result of the Allen test was misleading because of the congenital absence of the radial artery and the compression of the dorsal interosseous artery during the test. When a routine Allen test is performed, the examiner applies pressure by centering his or her thumbs over the radial and ulnar aspects of the volar side of the patient's wrist. When this is done, the examiner's index and long fingers and, occasionally, ring finger must rest on the radial and ulnar aspects of the dorsal side of the patient's wrist. To apply enough pressure with the thumbs to occlude the volar artery, the examiner must apply a large counterforce with the fingers on the dorsum of the wrist. Thus, the dorsal interosseous artery can be compressed inadvertently during the routine performance of the Allen test. The case of this patient demonstrates some interesting features. First, a very uncommon anatomical variant of the vasculature of the upper extremity led to a misinterpretation of the preoperative arteriogram by both the surgeons and the radiologist. The study might have been misinterpreted because it was performed in one plane. If operative reconstruction is considered, arteriography should routinely be performed in two planes. Second, the findings of the Allen test were misleading because, with the test performed in the classic manner, the thumb and the forefinger of the examiner compressed the dorsal interosseous artery. Finally, for patients who are seen because of acute digital ischemia due to intravascular thrombosis, prompt commencement of local continuous infusion of streptokinase may be needed to restore blood flow; when there is a predisposing cause, arterial reconstruction may prevent repeated episodes of digital ischemia.

Reference

1. O'Farrell DA, Cannon DP, Nunley JA. Digital ischemia associated with a thrombosed aneurysm of the dorsal interosseous artery. A case report. J Bone Joint Surg Am. 1997;79:441-3.
2. Kleinert HE, Burget GC, Morgan JA, Kutz JE, Atasoy E. Aneurysms of the hand. Arch Surg. 1973;106:554-7.