A 23-year-old man presented to an outside hospital’s ED for evaluation of a wound on his right hand, which he sustained after he accidentally stabbed himself with a steak knife. At presentation, the patient’s vital signs were: heart rate, 90 beats/min; respiratory rate, 16 breaths/min; blood pressure, 150/92 mm Hg; and temperature, 98.1°F. Oxygen saturation was 98% on room air. Examination revealed a laceration on the patient’s right hand measuring 2 cm in length. The emergency physician (EP) closed the wound using four nylon sutures and administered a Boostrix shot. The patient was discharged home with a prescription for cephalexin capsule 500 mg to be taken four times daily for 5 days. He was instructed to return in 10 days for suture removal, but failed to follow-up.
The patient presented to our ED two months after the initial injury for evaluation of a 1.5-cm round pulsatile mass on his right palm, at the base of the middle finger, from which exuded a small amount of sanguineous fluid. The patient complained of numbness and difficulty extending his right index and middle fingers.Video 1); the Doppler study showed pulsatile-flow through the neck of the mass (Video 2); and a still ultrasound image (Figure) demonstrated a classic yin-yang sign consistent with a pseudoaneurysm.
A pseudoaneurysm, also referred to as a traumatic aneurysm, develops when a tear of the vessel wall and hemorrhage is contained by a thin-walled capsule, typically following traumatic perforation of the arterial wall. Unlike a true aneurysm, a pseudoaneurysm does not contain all three layers of intima, media, and adventitia. Thin walls lead to inevitable expansion over time; in some cases, a patient will present with a soft-tissue mass years after the initial injury. Compression of nearby structures can cause neuropathy, peripheral edema, venous thrombosis, arterial occlusion or emboli, and even bone erosion.1,2
Hand pseudoaneurysms are more likely to occur on the palmar surface, involving the superficial palmar arch,3 and are due to a penetrating injury or repetitive microtrauma. Hypothenar hammer syndrome occurs when repetitive microtrauma is applied to the ulnar artery as it passes under the hook of the hamate bone into the hand. This condition is also referred to as “hammer hand syndrome” because it frequently occurs in laborers such as mechanics, carpenters, and machinists as a result of repetitive palm trauma. Cases have also been reported in baseball players and cooks who also expose their hands to repetitive trauma.3 Likewise, elderly patients who use walking canes can also present with bilateral hammer hand syndrome,3 and patients who need crutches for a prolonged period of time may also develop axillary artery aneurysms.1,2
Although rare, there have also been cases of spontaneous hand pseudoaneurysms in patients on anticoagulation therapy;4,5 however, pseudoaneurysms are not an absolute contraindication to initiating or continuing use of anticoagulants.
Physical Examination. The patient’s mass in this case was clearly pulsatile on examination, but physical examination alone is not a reliable indicator of pseudoaneurysm, as patients may present only with soft-tissue swelling, pain, erythema, or neurological symptoms.3,6,7
Ultrasound Imaging. In the emergency setting, POC ultrasound should be performed to evaluate any soft-tissue hand mass, especially in the context of trauma or any neurovascular findings, since palmar pseudoaneurysms can easily be confused with an abscess, foreign body, cyst, or even a tendon tear.6 Ultrasound studies using the linear vascular probe should always be done before any attempt to incise and drain the mass.
Three ultrasound characteristics of pseudoaneurysms include expansile pulsatility, turbulent flow with a classic yin-yang sign on Doppler, and a hematoma with variable echogenicity. Variable echogenicity may represent separate episodes of bleeding and rebleeding.8 A “to-and-fro” spectral waveform is pathognomonic for palmar pseudoaneurysms.8
Computed Tomography and Magnetic Resonance Angiography. Definitive imaging for operative management includes computed tomography or magnetic resonance angiography to assess for the exact location and presence of collateral circulation.