traumatic arteriovenous fistula ( avf ) is a pathology characterized by arteriovenous shunting secondary to blunt or penetrating trauma of artery and vein running in parallel , but avf of the superficial temporal artery ( sta ) is rare . in this article
, we report a case of histopathologically confirmed avf of sta , which was surgically treated 1 month after surgery for right acute epidural hematoma caused by a traffic accident .
computed tomography scan had shown an acute epidural hematoma on the right surface of frontal lobe , which was emergently treated by surgical evacuation .
one month later , he began to complain of pulsatile tinnitus in the left ear .
a head magnetic resonance angiogram showed an extremely dilated vein in the left temporal region ( fig .  1 ) .
an angiography revealed a direct shunt between the left parietal branch of the sta and the superficial temporal vein ( stv ) in the preauricular region as well as an aneurysm in the left frontal branch of the sta ( fig .  2 ) .
histopathological examination demonstrated that the artery was connected to the vein through the thin - walled vessels lacking internal elastic lamina and muscularized media , suggesting that the connecting vessels were newly formed ( fig . 
figure  2:left external carotid arteriography showed a high - flow avf from the parietal branch of the sta ( thin arrow ) to the stv ( wide arrow ) , and an aneurysm on the frontal branch of the sta ( arrowhead ) . 

( b ) the sta ( arrow ) was connected to the stv ( asterisk ) . 

figure  4:histopathological photomicrograph with elastica van gieson stain showed that a thin - walled vessel lacking in internal elastic membrane ( arrow ) connected the artery ( a ) and the vein ( v ) .
left external carotid arteriography showed a high - flow avf from the parietal branch of the sta ( thin arrow ) to the stv ( wide arrow ) , and an aneurysm on the frontal branch of the sta ( arrowhead ) .
( b ) the sta ( arrow ) was connected to the stv ( asterisk ) .
histopathological photomicrograph with elastica van gieson stain showed that a thin - walled vessel lacking in internal elastic membrane ( arrow ) connected the artery ( a ) and the vein ( v ) .
blunt trauma to the sta may cause both aneurysm and avf , but the incidence of avf is lower than that of aneurysm , with a ratio of 23:131 , and only 36 cases have been reported as of 2007 . as in this case , the preauricular region is one of the most commonly affected areas due to its anatomy : sta and stv run in parallel with each other over the temporal bone .
traumatic avf is treated with direct surgery or endovascular therapy . in direct surgery , since the block of the incoming blood vessel has a risk of recurrence , complete resection of the lesion is essential .
endovascular treatments include percutaneous coil embolization , embolization with liquid embolic agents such as isobutyl l-2-cyanoacrylate   or onyx , direct - puncture coil embolization , and injection of absolute alcohol , all of which have been reported with good outcomes
. however , avf in the external carotid arterial system , which has potential complex collateral circulation , may be difficult to treat again if incomplete embolization ends in relapse .
 traumatic arteriovenous fistula ( avf ) of the superficial temporal artery ( sta ) is rare . 
 we report a case of surgically treated , histopathologically confirmed traumatic avf of the sta . 
 a 24-year - old male was admitted to our hospital after a traffic accident . computed tomography scan on admission showed an acute epidural hematoma on the right surface of frontal lobe , which was emergently treated by surgical evacuation . 
 one month later , he was aware of pulsatile tinnitus around the left ear . 
 digital subtraction angiogram showed an avf , mainly fed by the left sta . 
 after total removal of the fistula , his tinnitus immediately disappeared . 
 histopathological examination demonstrated that the artery was connected to the vein through the thin - walled vessels lacking internal elastic lamina and muscularized media , suggesting that the connecting vessels were newly formed . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONFLICT OF INTEREST STATEMENT