Traumatic Middle Meningeal Arteriovenous Fistula Presenting with Delayed Contralateral Temporal Subcortical Hemorrhage after Surgery for Cerebral Contusion: A Case Report

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Traumatic middle meningeal arteriovenous fistula is an uncommon and likely underrecognized dural arteriovenous shunt that develops after head trauma and may occasionally present with delayed intracranial hemorrhage. We report a case of traumatic middle meningeal arteriovenous fistula with delayed contralateral temporal subcortical hemorrhage following surgery for cerebral contusion. A man in his 50s underwent emergency hematoma evacuation and decompressive craniectomy for progressive right temporal contusion after severe head injury. During follow-up, a low-density lesion gradually enlarged in the contralateral left temporal lobe. On day 14, his consciousness deteriorated, and computed tomography revealed left temporal subcortical hemorrhage. Contrast-enhanced computed tomography failed to show any vascular abnormality, whereas magnetic resonance angiography showed abnormal dilatation of the left middle meningeal artery. Cerebral angiography demonstrated traumatic middle meningeal arteriovenous fistula supplied by the left middle meningeal artery and draining through the middle meningeal vein into the pterygoid plexus. Although definite cortical venous reflux was not demonstrated on angiography, venous-phase internal carotid angiography showed stagnation in the superficial middle cerebral vein, which improved after fistula obliteration. Cone-beam computed tomography and four-dimensional digital subtraction angiography precisely localized the fistula, and complete obliteration was achieved with transarterial coil embolization. Thus, venous congestion or venous hypertension related to traumatic middle meningeal arteriovenous fistula may contribute to delayed contralateral hemorrhage, although pre-existing cortical venous reflux could not be excluded. In severe head trauma, traumatic middle meningeal arteriovenous fistula should be considered when unexplained deterioration in consciousness or progressive low-density changes develop during follow-up. Early vascular evaluation, including magnetic resonance angiography when contrast-enhanced computed tomography is unrevealing, may facilitate prompt diagnosis and safe treatment with transarterial coil embolization.