Contrecoup Injury-Induced Middle Meningeal Arteriovenous Fistula Detected by Time-of-Flight Magnetic Resonance Angiography and Magnetic Resonance Arterial Spin Labeling: Case Report and Review of the Literature

Traumatic middle meningeal arteriovenous fistulas (MMAVFs): an exploratory systematic review

This study aims to systematically review case reports and case series in order to compare the postoperative course of conservative, endovascular and surgical treatments for traumatic dural arteriovenous fistulas predominantly supplied by the middle meningeal artery (MMAVFs), which usually occur following head trauma or iatrogenic causes. We conducted a comprehensive search of PubMed, Embase, Scopus, Web of Science, and Google Scholar until June 23rd, 2024. Three cohorts were defined based on the treatment modality employed. The primary outcomes were the rates of overall obliteration and postoperative complications, with all-cause mortlality considered as secondary outcome. A total of 61 studies encompassing 78 pooled MMAVFs were included in the qualitative analysis. The predominant demographic consisted of males (53.9%) with a median age of 50.5 (IQR: 33.5-67.5) years. The main etiologies for fistula formation were head trauma (75.6%), cranial neurosurgical procedures (11.5%) and endovascular embolization (8.97%). Venous drainage patterns were categorized as follows based on anatomical confluence: Class I (16.7%), II (14.1%), III (12.8%), IV (14.1%), V (7.7%), and VI (3.9%). Regarding treatment efficacy, the overall obliteration rate was 89.74%, achieved through endovascular (95.83%), surgical (64.29%) or conservative (93.75%) approaches. In terms of safety, the overall postoperative complication rate was 6.49% with an all-cause mortality rate of 8.97%, predominantly observed in the surgical group (35.71%). Our systematic review highlights the challenging management of traumatic MMAVFs, frequently associated with head injuries. Endovascular therapy has emerged as the predominant treatment modality, demonstrating markedly higher rates of fistula obliteration, reduced all-cause mortality, and fewer postoperative complications.

Spontaneous Middle Meningeal Arteriovenous Fistula Caused by Aneurysm Rupture: A Case Report

Middle meningeal arteriovenous fistula (MMAVF) is a shunt between the middle meningeal artery and the vein surrounding the artery. We report an extremely rare case of spontaneous MMAVF; then, we evaluated the effectiveness of trans-arterial embolization for spontaneous MMAVF and the possible cause of spontaneous MMAVF. A 42-year-old man with tinnitus, a left temporal headache, and pain surrounding the left mandibular joint was diagnosed with MMAVF on digital subtraction angiography. Trans-arterial embolization with detachable coils was conducted, which resulted in a fistula closure and symptoms' diminishment. The cause of MMAVF was thought to be the rupture of the middle meningeal artery aneurysm. A middle meningeal artery aneurysm can be a cause of spontaneous MMAVF, and trans-arterial embolization might be an optimal treatment.

Two Cases of Idiopathic Middle Meningeal Arteriovenous Fistula Initially Diagnosed by Magnetic Resonance Angiography

Reports of middle meningeal arteriovenous fistula (MMAVF) are relatively rare, and reports of idiopathic MMAVF are extremely rare. In the past, diagnoses of MMAVF have been confirmed by cerebral angiography, but magnetic resonance angiography (MRA) resolution is improving. Here, we report two cases of idiopathic MMAVF that were diagnosed by unreconstructed time-of-flight MRA (MRA-TOF) and successfully treated by trans-arterial embolisation with endovascular treatment. Both patients suffered from pulsatile tinnitus, and MRI was performed. Two dilated vessels were revealed in the middle temporal fossa by unreconstructed MRA-TOF imaging. These dilated vessels were thought to be the middle meningeal artery and middle meningeal vein; therefore, we diagnosed both patients with MMAVF. Following angiography, both patients had coil embolisation with endovascular treatment, and their conditions improved. In cases of idiopathic MMAVF without a history of trauma, brain surgery, or endovascular surgery, unreconstructed MRA-TOF may be useful as a primary diagnostic tool, and endovascular treatment before bleeding may produce better outcomes.

'De Novo' Brain AVMs-Hypotheses for Development and a Systematic Review of Reported Cases

Background and Objectives: Brain arteriovenous malformations AVMs have been consistently regarded as congenital malformations of the cerebral vasculature. However, recent case reports describing "de novo AVMs" have sparked a growing debate on the nature of these lesions. Materials and Methods: We have performed a systematic review of the literature concerning de novo AVMs utilizing the PubMed and Google Academic databases. Termes used in the search were "AVM," "arteriovenous," "de novo," and "acquired," in all possible combinations. Results: 53 articles including a total of 58 patients harboring allegedly acquired AVMs were identified by researching the literature. Of these, 32 were male (55.17%), and 25 were female (43.10%). Mean age at de novo AVM diagnosis was 27.833 years (standard deviation (SD) of 21.215 years and a 95% confidence interval (CI) of 22.3 to 33.3). Most de novo AVMs were managed via microsurgical resection (20 out of 58, 34.48%), followed by radiosurgery and conservative treatment for 11 patients (18.97%) each, endovascular embolization combined with resection for five patients (8.62%), and embolization alone for three (5.17%), the remaining eight cases (13.79%) having an unspecified therapy. Conclusions: Increasing evidence suggests that some of the AVMs discovered develop some time after birth. We are still a long way from finally elucidating their true nature, though there is reason to believe that they can also appear after birth. Thus, we reason that the de novo AVMs are the result of a 'second hit' of a variable type, such as a previous intracranial hemorrhage or vascular pathology. The congenital or acquired characteristic of AVMs may have a tremendous impact on prognosis, risk of hemorrhage, and short and long-term management.

Idiopathic middle meningeal artery and middle meningeal vein fistula presenting as temporal intraparenchymal hemorrhage

Middle meningeal artery (MMA) and middle meningeal vein (MMV) fistula is a rare lesion. Hemorrhagic propensity for this pathology has not been widely recognized. We encountered a case of idiopathic MMA-MMV fistula presenting as intracerebral hemorrhage. MMA and MMV showed a single fistula and the enlarged MMV coiled around the MMA, resembling a varix. We treated the case using endovascular techniques. This case highlights the anatomy along the course of the MMV and is unique, since no backward leptomeningeal drainage was observed. A bone defect in the meningeal groove on computed tomography and a "green caviar appearance" on angiography may be characteristic of this rare pathology.

Spontaneous Thrombosis of a Middle Meningeal Arteriovenous Fistula With Subsequent Pseudoaneurysm Formation: Case Report and Review of Literature

BACKGROUND AND IMPORTANCE

Middle meningeal artery (MMA) pseudoaneurysms and middle meningeal arteriovenous fistulas (MMAVFs) are rarely reported after head injury. We report an unusual case of delayed MMA pseudoaneurysm formation after spontaneous thrombosis of an MMAVF, and review existing literature on MMAVF treatment and results.

CLINICAL PRESENTATION

A 59-yr-old male presented with a 5-d history of worsening left-sided headaches, followed by nausea, lethargy, and difficulty with speech. Non-contrast computed tomography demonstrated a left temporal intraparenchymal hemorrhage (IPH) and an acute left-sided subdural hematoma (SDH). Cerebral angiography found abnormal shunting between the right MMA and the right sphenoparietal sinus, consistent with an MMAVF. During the course of admission, the patient's neurological condition deteriorated requiring craniotomy for evacuation of SDH and IPH. Given the presumed incidental nature of the contralateral MMAVF, conservative management was recommended. Follow-up imaging 2 mo after surgery revealed spontaneous thrombosis of the right MMAV. Repeat imaging 5 mo later revealed an MMA pseudoaneurysm at the prior fistulous site, which was subsequently embolized with Onyx, occluding the pseudoaneurysm and the MMA both proximal and distal to the pseudoaneurysm.

CONCLUSION

Spontaneous thrombosis of an MMAVF is rare and only seen in 13.1% of cases. However, subsequent delayed formation of an MMA pseudoaneurysm has not been described. Our case therefore demonstrates that MMAVF thrombosis may not indicate complete healing of the underlying injury to the MMA, and suggests the need for continued follow-up of such lesions despite initial apparent resolution.

Traumatic Middle Meningeal Arteriovenous Fistula of Non-fractured Site Detected by Four-dimensional Computed Tomography Angiography: A Case Report

Middle meningeal arteriovenous fistula (MMAVF) of a non-fractured site is extremely rare, and the clinical characteristics are still unclear. We report a case of delayed onset of venous infarction due to an MMAVF following a fall accident. A 69-year-old man sustained multiple trauma due to a fall accident. Head computed tomography (CT) showed traumatic subarachnoid hemorrhage, a left subdural hematoma, and skull fracture in his right temporal bone, all of which were managed conservatively. Five days after his admission, he suddenly exhibited total aphasia and right hemiparesis. Emergent CT revealed sporadic low-density areas in his left cerebral hemisphere, and four-dimensional CT angiography (4D-CTA) showed dilatation of the left middle meningeal artery and early venous drainage in the cavernous sinus and anterior temporal diploic vein (ATDV). A series of hemodynamics of 4D-CTA revealed early venous filling of ATDV interrelated with retrograde upward flow to high convexity in the venous phase. The MMAVF was successfully obliterated by transarterial coil embolization. We herein describe this case of MMAVF in which 4D-CTA was useful for the diagnosis.