Arteriovenous malformations of the Scalp
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Arteriovenous Malformations of the Scalp were first described by Hunter in 1757 and later termed cirsoid aneurysms as they resemble dilated veins. These malformations occur within fatty subcutaneous tissue and are fed by normal scalp vessels. As with intracranial AVMs most scalp AVMs are congenital, although trauma (including craniotomy) is another etiology. In the latter, an artery and adjacent veins might be ruptured simultaneously and heal together. Alternatively, endothelial cells from disrupted arterial adventitia may migrate into the surrounding hematoma and anastamose with nearby veins. Lesions may present with scalp swelling, headache, audible bruit, and in extreme cases, high output cardiac failure. Angiography should be performed for diagnosis and to rule out intracranial extension.
Vasopressin is injected prior to incision, which is carried out in short segments to maximize hemostasis. An inverted U-flap is made across the main feeding vessels, including those from the Temporalis muscle, which are then ligated or coagulated. The pericranium is then cauterized and dissected off, feeding vessels beneath it are ligated, and the subcutaneous portion of the AVM removed. Alternative treatment options include transarterial or transvenous embolization, injection of sclerosing agent into the nidus, or electrothrombosis. '