We thank Dr. Myoung Soo Kim for his thoughtful comments and valuable insights regarding our recent case report on traumatic middle meningeal artery (MMA) pseudoaneurysm presenting with acute intraparenchymal hemorrhage (IPH) [5]. We appreciate the opportunity to clarify and expand upon the points raised.

We acknowledge the importance of providing high-quality imaging to diagnose vascular pathologies accurately [6]. In our case, a CT angiography (CTA) was performed preoperatively and revealed a well-defined pseudoaneurysm of the right MMA adjacent to the hematoma (see Case Description, p.61 and Fig. 1B). The published Figure aimed to demonstrate the radiological findings, and we can make out the aneurysm in Fig. 1B adjacent to the bony defect. In order to assist readers in locating the same, we are including the Figure with an arrow to show the exact site of the aneurysm.

You are correct in noting that the vast majority of MMA pseudoaneurysms present with Epidural Hematoma (EDH) , while acute IPH is extremely rare. Our case adds to the small body of literature (only nine such cases previously) where IPH is the primary presentation. Intraoperatively, we observed a linear, undisplaced fracture of the right temporal bone with an associated underlying dural tear in line with the pseudoaneurysm, but there was no significant epidural hematoma. The pseudoaneurysm was located approximately 3 cm from the sphenoid ridge, in association with the dural tear, which served as a trajectory for the blood to extravasate into the temporal lobe, resulting in the intraparenchymal hemorrhage seen on imaging. This finding aligns with the mechanism proposed by Moon et al. and Lim et al., where dural tears enable communication between epidural and parenchymal spaces.

The inner dural surface of the pseudoaneurysm was not explicitly mentioned in the case report, as we thought the same was well implied due to the location of the hematoma next to the aneurysm. There was no evidence of pre-existing cerebral contusion at the site of the parenchymal hematoma once the clot was cleared.

In our case, while an additional minor contusion in the contralateral temporal lobe was noted, the main hematoma (right temporal) was directly contiguous with the pseudoaneurysm and the dural tear, with active arterial bleeding observed upon evacuation. No contused brain tissue was observed underlying the hematoma intraoperatively, which argues against contusion as a primary mechanism at this site. Therefore, we infer that the acute IPH resulted from direct extravasation through the dural tear from the ruptured MMA pseudoaneurysm, not from a cerebral contusion, which would typically have a different radiological and operative appearance.

Indeed, pseudoaneurysms differ from true aneurysms because they lack all normal vessel wall layers [4]. Instead, they consist of a fibrous wall formed by surrounding tissues. Our histopathological analysis revealed an aneurysmal sac lined with a fibrin clot and a clear tear, classical features of a pseudoaneurysm (described in Case Description, p.62). While we did not include images of the hematoxylin and eosin (H&E) stained sections in the article (due to a limit on the number of images allowed in a case report), we agree with your suggestion. We would happily include such microphotographs in future reports to aid in educational and diagnostic illustration.

In line with the cases noted by Lim et al., our review and Table 1 provide a comprehensive context for IPH caused by ruptured MMA pseudoaneurysms, confirming its rarity and highlighting the necessity for high clinical suspicion [1], especially in the context of temporal fractures with underlying parenchymal hemorrhage [3].

We appreciate your constructive critique and the opportunity to clarify our case and literature review. Your comments underscore the importance of detailed imaging, histopathological correlation, and operative notes in elucidating rare pathologies and their mechanisms. Our case, with accompanying literature review and follow-up, contributes meaningfully to the understanding of this rare clinical entity and emphasizes the need for vigilance in cases of traumatic brain injury with unusual hemorrhagic patterns [2].