Table 1.

Outline and key points of importance regarding the MMA

Outline	Key point	Recommended documents
Pathway for embolization of DAVFs	The MMA is the most commonly involved feeding artery for DAVFs, and the MMA runs along a path that is straight and fixed between the dura. Hence, the MMA is commonly used to access DAVFs. When DAVFs are embolized using a MMA approach, some complications can occur as a result of “dangerous anastomoses” between the MMA and other arteries.	[10, 11, 25]
AVFs of the MMA	A tear in the arterial wall can cause a traumatic AVF in the MMA. AVFs of the MMA that are caused by venous drainage can be divided into six types according to their presentation on angiography. Endovascular embolization and surgical resection are the most effective treatment methods.	[32, 34, 46]
Aneurysms of the MMA	Aneurysms of the MMA can be divided into pseudoaneurysms and true aneurysms. Pseudoaneurysms of the MMA are usually associated with trauma and iatrogenic injury, whereas true aneurysms are usually associated with increased hemodynamic stress or a pathological condition of the MMA. Endovascular embolization and surgical resection are the most effective treatment methods for aneurysms of the MMA.	[47, 50, 60, 70]
The MMA Contributes to MMD	The MMA is a very important component of MMD collateral circulation. The MMA appears to significantly contribute to revascularization on follow-up angiograms, in which it is increased in size and neovascularity compared to the superior temporal artery. Indirect revascularization via encephalo-duro-arterio-synangiosis (EDAS) and burr holes are effective treatments for MMD, and these operations mainly depend on the MMA.	[72, 73, 77, 81, 82]
MMA Embolization in CSDH	The vessels in the outer membrane of the CSDH cross the dura mater to connect to the MMA. This becomes the basis for performing MMA embolization. However, MMA embolization was only effective when diffuse dilatation of the MMA and the abnormal vascular networks could be observed. When embolizing the MMA, caution should be exercised to prevent aberrant flow into the dangerous anastomosis, which can cause complications.	[92, 94-96]
The MMA Contributes to Migraines	Treatments aimed at the MMA are effective in migraine patients. In addition to sumatripatan, MMA ligation may be useful for treating intractable migraines. However, in a morphological examination, when migraine attacks occurred, there was no evidence of MMA dilatation.	[107, 108]
Pathway for Embolization to Treat Meningioma	Preoperative embolization has been used to reduce intraoperative blood loss and facilitate microsurgical removal of meningioma tumors. The MMA is an ideal pathway through which to perform an embolization to treat a meningioma. Although embolization of meningeal tumors is considered a safe technique, serious neurological complications can occur. These include opening a dangerous anastomosis or uncontrolled reflux.	[110-112]
Protecting the MMA during Cranial Surgery	Because the ophthalmic artery can ectopically originate from the MMA, when cranial surgery is performed, caution should be taken to avoid damaging the MMA.	[114, 115]

MMA: middle meningeal artery; DAVF: dural arteriovenous fistula; AVF: arteriovenous fistula; MMD: moyamoya disease; CSDH: Chronic Subdural Hematoma