In the upper extremity, trauma is by far the most common cause of aneurysms. True aneurysms result from repetitive blunt trauma and weakness in an arterial wall; false (pseudo) aneurysms result from penetrating trauma and arterial perforation. The false aneurysms are often eccentric and do not have an endothelial lining. Usually, a small arterial puncture bleeds, a clot is formed and is eventually surrounded by fibrous tissue. As the clot begins to lyse, the pressure in the fibrous sac increases creating new leaking and a new clot which, again, may be surrounded by a fibrous scar. This bleed, clot, lyse and bleed again cycle can cause the aneurysm to slowly enlarge over weeks or months. The enlarging pulsatile aneurysms can cause pain, compress nerves and be the source of distal emboli with secondary ischemia. True aneurysms include all layers of the arterial wall with weakening of the internal elastic lamina. Traumatic aneurysms in the hand can arise from acute causes or from chronic occupational related repetitive injury. Aside from trauma, true aneurysms can also be idiopathic, arteriosclerotic or mycotic.
Related Anatomy
- Ulnar artery and branches
- Guyon’s canal
- Hamate
- Hypothenar eminence
- Radial artery and branches
- Scaphoid edge of trapezium
- First metacarpal
- First dorsal interosseous muscle
Incidence and Related Conditions
- In the hand, ulnar artery aneurysms are most common; 70% from blunt trauma, 20% from penetrating trauma and 10% with no history of trauma
- Digital artery aneurysms are very rare
Differential Diagnosis
- Ganglion cyst
- Synovial cyst
- Dermal cyst
- Abscess
- Neural tumor
- Muscular fibroma
- Raynaud’s disease
- Venous aneurysm
