An 86-year-old man was brought to our medical center with severe consciousness disturbance following a road traffic accident. Upon arrival, Glasgow Coma score was 3, while the pupils were dilated and reactions to light reflex were absent bilaterally. Head CT findings demonstrated a massive acute subdural hematoma (ASDH) with heterogeneous density causing an extensive brain shift (Figure 1a), with a linear temporoparietal bone fracture extending to the root of the zygoma also noted (Figure 1b). Subsequent CT angiography (CTA) revealed contrast media extravasation arising from the middle cranial fossa (Figure 1c, d). Furthermore, extravasation was noted within a low-density area, suggesting ongoing bleeding (Figure 1c). 3D-reconstructed CTA images showed a ribbon-like structure from the middle meningeal artery (MMA) arising from the foramen spinosum, with findings also indicating disruption of the posterior MMA division near the inferior edge of a skull fracture and subsequent extravasation (Figure 2a–c). Burr hole evacuation of the ASDH was attempted in the emergency room, during which active bleeding from the subdural space was encountered. The patient died the next day.

Figure 1.

(A) Non-contrast CT image showing massive acute subdural hematoma with heterogeneous density in left convexity (arrow). (B) 3D-CT image revealing linear fracture in temporo-parietal region extending to root of the zygoma (arrowheads). (C, D) CT angiography images showing extravasation of contrast media from the middle cranial fossa (arrows). Extravasation within the low-density region of the hematoma was noted in axial images (A, C; arrows).

Figure 2.

(A) 3D-CT angiography (3D-CTA) image with stereoscopic view showing internal maxillary artery and middle meningeal artery (MMA) with ribbon-like structure. (B) Lateral view of 3D-CTA image of left hemisphere indicating disruption of the MMA and subsequent contrast media extravasation, along with a skull fracture. (C) An MMA arising from the foramen spinosum (thick arrow) caused disruption and subsequent contrast media extravasation near the inferior edge of the temporal bone fracture (arrow). Arrowhead indicates foramen ovale.

The MMA is the most important dural artery and is usually found divided from the internal maxillary artery, one of the major branches of the external carotid artery, and subsequently passing into the foramen spinosum along with the middle meningeal vein and recurrent branch of the mandibular nerve. ^{Reference Ginsberg, Pruett, Chen and Elster1} In the pterional region, the artery divides into anterior and posterior divisions, which provide for vascularization over a wide area of the cranial dura mater. ^{Reference Bonasia, Smajda, Ciccio and Robert2} Before bifurcation, the MMA gives off a petrosal branch that runs along the petrous apex. An extradural hematoma can develop when the MMA and its branches are injured, while bleeding from dural sinuses, emissary veins and venous lakes is also a causative factor. The MMA is known as the bleeding source of an extradural hematoma, usually seen in adolescents and young adults. On the other hand, traumatic ASDH caused by MMA bleeding is an unusual finding. For cases with delayed ASDH following head trauma, an MMA pseudoaneurysm is an important etiological factor. ^{Reference Aoki, Sakai and Kaneko3}

In addition to ASDH, acute or delayed intraparenchymal hemorrhage onset can also occur as a result of an MMA pseudoaneurysm rupture following trauma. ^{Reference Montanari, Polonara and Montalti4} As a possible etiological factor for hemorrhage presentation, MMA pseudoaneurysm growth causes thinning of adjacent dura mater, leading to a subsequent subdural or intraparenchymal rupture. In addition, MMA laceration can cause a middle meningeal arteriovenous fistula, which is concomitant with findings shown by contrast media of extravasation and MMA pseudoaneurysm formation.Reference de Andrade, Figueiredo and Caldas ^{5 ,} Reference Kidani, Ozaki and Nakajima ⁶ CTA findings in the present case indicated active contrast media extravasation of a vascular-like structure presumably from the injured MMA within the hypodense ASDH, whereas pseudoaneurysm formation was not depicted. Lack of cerebral angiography and post-mortem study findings is a limitation for precise understanding of the etiological factors in this case. Contrast media extravasation findings, resembling a spot sign in a CTA examination of acute intracerebral hemorrhage, have been reported as a predictor of hematoma expansion in patients with traumatic ASDH, ^{Reference Romero, Kelly and Delgado Almandoz7} though no findings of vascular mimics were noted. The MMA is located in the outer portion of the dura mater and tends to become embedded in the groove and adhere to the inner skull with increasing age. In elderly patients with dura mater tightly adhered to the skull, concomitant MMA injury and dura mater laceration occurrence can lead to ASDH following trauma.