A cerebrovascular malformation is a congenital condition in which some of the blood vessels in the brain are damaged as a vascular system structure.In other words, in normal blood vessels, arteries branch and become capillaries, which supply nutrients and oxygen to tissues, carbon dioxide and waste products enter the capillaries on the vein side again, and the capillaries join to form veins. and circulates back to the heart.A vascular malformation is an abnormality in the structure of the vascular system that prevents normal circulation.It causes cerebral infarction and high blood pressure in the arteries because it does not fulfill the role of normal blood vessels (the role of sending oxygen and nutrients from the lungs and gastrointestinal tract to the brain, and the role of sending carbon dioxide and waste products to the lungs and liver and kidneys). Cerebral hemorrhage may occur due to venous contact.Cerebrovascular malformations are those in which arterial pressure is applied directly to veins due to the absence of capillaries (cerebral arteriovenous malformations), abnormal masses of blood vessels independent of arteries and veins (cavernous hemangioma), and no arteries. It is divided into those in which only veins are present (venous malformations).Arteriovenous malformations, in particular, cause cerebral hemorrhage because arteries flow into veins through an abnormal vascular network called a nidus.Cavernous hemangioma can also cause cerebral hemorrhage, although not as much as cerebral arteriovenous malformation.Both arteriovenous malformations and cavernous hemangiomas should be considered for surgery once they bleed.Venous malformations do not cause cerebral hemorrhage or stroke and do not require treatment.

Arteriovenous malformation = AVM (arterio-venous malformation)・The male to female ratio is 1.1 to 2.0:1, and it is more common in males.・The detection rate is 0.9 to 1.2 per 100,000 people. It is said to be seen in 1/6 to 1/10 of subarachnoid hemorrhage. 60% had hemorrhagic episodes and 20% had epilepsy.・For cerebral arteriovenous malformation, resection is performed after suppressing blood flow by endovascular surgery. Endovascular surgery is performed, but radiation therapy (gamma knife) may be effective for small tumors (diameter of 2.5 cm or less) (80% or more disappear 2 years after gamma knife).

Cavernous hemangioma: In many cases, there is no abnormality on angiography, but there is a mass of mulberry-like blood vessels in the brain, which sometimes occurs multiple times and bleeds, in which case resection is performed.For surgery using the brain sulcus for cavernous hemangioma of the vermis, please see "Ingenuity of craniotomy for tumor removal (surgery using the sulcus)".

Venous malformation or developmental venous anomaly=DVA: Abnormal veins are visible on angiography, although the arteries are normal. Bleeding is rare and is thought to require follow-up only.