INTRODUCTION
*Superficial temporal artery pseudoaneurysms (STAPs) are rare. The first case was described from Bartholin in 1740 on a young patient after blunt head trauma1 . Four hundred cases have since been described, accounting for only 1% of all traumatic aneurysms2 . We reviewed the current literature regarding the causative process, the diagnosis and the treatment of these aneurysms. Additionally, we describe our experience with three patients managed at our institution.

REPORT OF CASES
The first patient was a 16-year-old male who presented with a bump on his left temple. It was formed after a motorcycle accident a week earlier and was progressively enlarging. He was not wearing a helmet. He complained of a headache. The mass was pulsatile and a colour duplex confirmed the diagnosis of a superficial temporal artery pseudoaneurysm (STAP), 2.0 cm in diameter, at the bifurcation of the superficial temporal artery (STA). The patient was treated by excision of the mass with proximal and distal STA branch ligations (Table).

The second patient was an 80-year-old male on anticoagulation who presented with a lump on his left frontal bone after a minor fall. A necrotic skin area sized 1.5×1.0 cm was apparent over the lump indicating direct injury. The mass was painful and pulsatile. A colour duplex confirmed the diagnosis of a STAP. The patient underwent aneurysmatectomy with necrotic skin removal and frontal STA ligation, under local anesthesia1.

The third patient was an 18-year-old male who presented with a visible mass on his left temple (Figure 1). He had a motorcycle accident and received medical care for penetrating skin injuries on his forehead 20 days before. Five days later a visible bulge appeared on his left temple, progressively enlarging. Physical examination revealed a painless, pulsatile temporal mass. Pulsation disappeared after proximal compression of the STA. A colour duplex confirmed the diagnosis of a STAP, measuring 1.4×1.1cm in diameter, while it also depicted the “to and fro” pattern and the “Yin-Yang sign” (Figure 2). The STA was ligated and the aneurysm was excised (Figure 3).

DISCUSSION
Arterial pseudoaneurysms (PSAs) may arise in trauma patients, mostly after focal transection of the vessel wall. The frontal branch of the STA is extremely vulnerable after traumatic head injury as it runs over the bone and a thin layer of pericranium. The risk is aggravated at the region where STA crosses the superior temporal line. Consequently, STAP may arise after direct injury to the vessel at the site of the aneurysm (patient 2) or due to shear damage after vessel overstretching from a remote blunt head injury (patients 1 and 3)1,2.

Generally, more than 95% of PSAs are traumatic in origin complicating iatrogenic procedures or caused by brawl, fall or sport activities. The remaining 5% are classified as spontaneous aneurysms of congenital or atherosclerotic etiology 2 . They manifest as pulsatile, painless masses when they affect superficial arteries. As they grow in size, they may present with neuropathic alterations. Differential diagnosis of a STAP includes a true aneurysm, an abscess, a cyst, a lipoma, a hematoma, an angiofibroma, a parotid tumor, a vascular tumor, an arteriovenous fistula and an aneurysm of the middle meningeal artery that eroded the temporal bone1,3

STAP is usually asymptomatic, but it may present with local pain. In case of a STA arteriovenous fistula (STA-AVF) isolated or combined with a STAP, a continuous ringing in the ear may arise3,4. Clinical examination shows a palpable pulsatile mass at a point along the course of the STA. Pulses are diminished after proximal compression. In case of an STA-AVF, a palpable thrill and an audible continuous murmur are usually diagnostic3,4. A history of head injury should raise the suspicion for a STAP if a mass appears at the temporal region. Although a detailed history and thorough physical examination are essential, confirmation of diagnosis is accomplished with imaging studies. Ultrasound (U/S) is the initial preferable technique due to its wide availability, noninvasiveness, cost-effectiveness, and its bedside applicability. Additionally, the superficial location of the STA enhances U/S resolution and moreover it may be easily used for follow-up5 . U/S gray scale imaging is used to assess the pseudoaneurysm size and the intra-sac thrombus, while colour duplex is used to evaluate the neck and to locate the feeding artery. It displays the “to and fro” waveform in the neck and the colour flow inside the sac, known as the “Yin-Yang” sign (Figure 2). Computer Tomography Angiography (CTA) is usually the first imaging study in multi-trauma patients which may depict a coexistent STAP. Magnetic Resonance Angiography (MRA) and Digital Subtraction Angiography (DSA) have also been used4,6.

According to recent literature, the proximal and distal artery ligation with excision of the pseudoaneurysm is the preferred surgical method. Surgical excision is indicated because of the risk of rupture, the necessity for pain management, and aesthetic concerns. This method is simple and safe, due to the superficial location of the STA and it may be carried out under local anesthesia, with the potential exception of large STAPs1,6. Due to the abundant collateral supply of the face and skull, the effects of STA ligation are insignificant. Therefore, surgical treatment remains the gold standard. STAPs located on the scalp are addressed with a direct linear incision, while preauricular inci sions have been used for STAPs located at the zygoma7.

Although conservative compression therapy has been proposed, it is often unfavorable because of the extended period of headaches, the possibility of rupture and aesthetic worries8 . Endovascular coiling embolization is a possible therapeutic option, but it has an inherent risk of stroke, poor cosmetics and the mixed evidence does not justify this procedure as first-line therapy9 . U/S guided thrombin injection is another alternative solution. Although it is the gold standard in common femoral PSAs management, it seems to have no role in STAPs treatment. It carries a high rate of recanalization, thrombosis of the underlying artery and embolization with ischemic stroke and seizures8,9. There is a risk of scalp ischemia and skin necrosis9,10. Patients may be disappointed due to poor cosmetic outcomes, since the thrombosed pseudoaneurysm needs up to 3 months to resolve. Numerous other surgical techniques have been used to address STAPs, albeit many of them are just of historical importance, such as external and common carotid artery ligation1.

CONCLUSION
Traumatic STAP is a rare clinical condition which may be associated with local skin necrosis or traumatic injuries at other sites. The diagnosis is based on patient’s history and physical examination and is confirmed with colour duplex. Surgical excision with arterial ligation under local anesthesia is advocated. It leads to a good clinical and cosmetic outcome with no recurrences.