Thrombosis of the ulnar artery at Guyon’s canal (hypothenar hammer syndrome) is the most common thrombosis in the hand. It is usually secondary to repeated blunt trauma to the hypothenar eminence. Patients complain of a tender mass in the region. The mass often compresses the ulnar nerve in Guyon’s canal, giving numbness to the small finger and ulnar border of the ring finger. Ischemia of the ring and small fingers may develop from emboli, vasospasm, or an incomplete arch. Examination is noted for an Allen’s test that shows no flow through the ulnar artery and a tender mass in Guyon’s canal. Treatment consists of cessation of smoking and initiation of vasodilators, such as calcium channel blockers. The thrombosed segment may require surgical excision with reconstruction. Transection of the segment improves digital blood supply by interrupting the sympathetic nerve fibers to the fingers. Reconstruction of the involved segment improves blood supply to the hand.

Thrombosis of the radial or ulnar arteries also may come from an inadvertent intraarterial injection. Patients usually complain of immediate and intense burning
pain. The spasm can lead to thrombosis and occlusion of the vessels. Initial treatment consists of vasodilators, a sympathetic nerve block, and either anticoagulants or systemic thrombolytic therapy. If an isolated clot is present proximally, thrombectomy or excision and grafting of the involved segment may be helpful. The outcome is often related to the agent that was injected.

There are two types of aneurysms. True aneurysms involve the intima, media, and adventitia. They are usually secondary to blunt trauma. They are likely to produce distal emboli. False aneurysms come from penetrating trauma or arterial perforations. The periarterial hematoma endothelializes and forms a false wall. A painful, pulsatile mass is often present on physical examination. A thrill may be present with palpation over the mass.