CT angiography axial images of head & neck
A 59-years-old man arrived with a hemorrhage from a pulsatile and expanding mass in the right parieto-occipital region of his scalp that he had for the last 8 years. On examination, we found a soft pulsatile, bluish and non-tender lesion over the right parieto-occipital region. The overlying skin was dry & thickened.
The CT angiography (CTA) demonstrated multiple, tortuous dilated leash of vessels in the right parieto-occipital region within the scalp fed by branches from bilateral superficial temporal and occipital arteries. No calvarial bony defect, intracranial extension, or communication was seen.
Head and neck digital subtraction angiogram (DSA) revealed a widespread tangle of vessels forming nidus of size 5.2 x 4.6 cm in the right parieto-occipital region within the scalp, supplied by dilated and tortuous bilateral superficial temporal and occipital arteries and their branches. Minor feeders have been seen from the branches of the right posterior auricular artery.
The numerous dilated and tortuous scalp veins show early drainage of the lesion. Numerous venous pouches are also seen in the vicinity of the nidus. There were no arterial feeders detected from bilateral CCA, ICA, or vertebral arteries. No communication with the dural venous sinus or cortical veins of the brain.
Arteriovenous malformations (AVMs) are characterized by an aberrant tangle of arteries that allows direct arteriovenous shunting without an intermediate capillary bed. They can arise everywhere in the body, but the brain is the most prevalent location. They might be congenital or acquired as a result of trauma.
Extra-cranial scalp (AVMs) are extremely uncommon, accounting for only 8.1% of all AVM cases.
They are vascular abnormalities that occur during the fetal stage and are caused by the inability of embryonic vasculature to differentiate into arteries and veins. About 10 to 20% of scalp AVMs arise as a result of penetrating or non-penetrating scalp trauma.
The most prevalent terms for these lesions are cirsoid aneurysm, plexiform angioma, scalp arteriovenous fistula/aneurysm, and arteriovenous malformation.
It usually presents in late childhood, adolescence, or early adulthood. Typically, patients present with a scalp bulge that has grown in size gradually since birth or after head trauma. Rapid size increases have been documented during adolescence and pregnancy.
Growing pulsatile mass, scalp deformation, pain, throbbing headache, tinnitus, convulsion, haemorrhage, and dizziness, and psychomotor retardation are all clinical features, although it can also be asymptomatic. . It can also cause massive haemorrhages due to dryness of the overlying skin and injuries. Large lesions have also been associated with scalp necrosis.
AVMs cause direct shunting of high-volume arterial blood through low-resistance arteriovenous fistulae, which frequently results in venous hypertension, hypoperfusion of arteries and tissue downstream, and diminished brain perfusion (the steal phenomenon).
A complete scalp AVM excision necessitates a thorough understanding of the feeding arteries, draining veins, and nidus. Catheter angiography has been the gold standard for diagnosis but CTA can also give very high imaging resolution and the observation of associated bone structures, which may be useful for surgical planning, as in this case. MRI can help detect the intracranial extension & communication.
Treatment of scalp AVMs offers several options and individualization is essential. A Combination of ultrasound-guided thrombin injection (UGTI) and transarterial coil embolization is a minimally invasive treatment for scalp AVM that overcomes the need for surgical excision.
When endovascular therapy is difficult or not possible, surgical excision is highly beneficial.  Use of temporary clipping of feeding arteries (enables total excision of giant AVMs with minimal blood loss for a definitive cure.
Complications of surgical therapy include bleeding, necrosis of the scalp, and sepsis caused by a wound infection.
In this patient, Trans-arterial coil embolization was done for the major feeders followed by percutaneous glue embolization of dilated veins. Surgical removal of the nidus is planned with plastic surgery reconstruction of the scalp.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images.
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