Central Nervous System Vascular Malformations

Pathophysiology Arteriovenous malformations (AVMs) are defects of the circulatory system that are generally believed to arise during embryonic or fetal development or soon after birth. They are comprised of snarled tangles of arteries and veins. Arteries carry oxygen-rich blood away from the heart to the body’s cells; veins return oxygen-depleted blood to the lungs and heart. The absence of capillaries—small blood vessels that connect arteries to veins—creates a short-cut for blood to pass directly from arteries to veins. The presence of an AVM disrupts this vital cyclical process. Although AVMs can develop in many different sites, those located in the brain or spinal cord—the two parts of the central nervous system—can have especially widespread effects on the body. The purpose of this text is to provide patients who are diagnosed with central nervous system vascular malformations with some background information regarding the nature of their problem and the possible alternatives in terms of treatment. It is written in terminology that is designed to minimize medical jargon and technical terms. When possible, simple diagrams are used to help explain points. The intent of this text is to provide basic background information. Specific details regarding any particular patient's vascular malformation should be obtained through discussions with their physician. The text is divided into the four major types of vascular malformations that are known to occur.

Diagnosis: When a patient is first diagnosed with a cerebrovascular malformation, many questions arise. The malformation may be diagnosed after a hemorrhage or as a result of a seizure or possibly as a result of headaches. With improved techniques used to visualize the brain with newer radiographic studies, the diagnosis of an asymptomatic or minimally symptomatic lesion is increasing. Regardless of how the diagnosis is made, once it is decided that a vascular malformation is present, the next step is to ascertain the exact type of vascular malformation, which influences heavily the need for treatment and the exact details of potential treatment. There are typically four distinct types of vascular malformations which may occur throughout the central nervous system

Glossary: Arteriography , Angiography , cerebral angiography, arteriogram. A test to visualize the blood vessels in the head. This is an invasive procedure which requires that a catheter be inserted, usually in the groin or directly into the neck vessels, and threaded into the base of the skull. The dye material is then injected which shows up on x-ray, and rapid succession x-rays are taken to get a picture of the blood vessels in the head as they fill and empty with the dye material. MRI: Magnetic resonance imaging : A technique where a large magnet is used to visualize the contents of the cranium including the brain and blood vessels. This technique is noninvasive with the exception of an intravenous catheter which might be needed to give a contrast agent to better see brain lesions.

STATISTICS: The authors present a statistical survey of the general incidence, age distribution, and preferential sites of 25, 122 tumors of the central nervous system (CNS), from 12 centers in China. Of these tumors, 22,457 were intracranial and the rest intraspinal. Of the 22,457 intracranial neoplasms collected tumors of neuroepithelial tissue comprised 43.85%, meningiomas 16.58% tumors of nerve sheath cells 9.5%, pituitary adenoma 9.52%, congenital tumors 8.46%, secondary tumors 6.8%, vascular malformations and tumors 3.82%, and primary sarcomas 0.72%. Nearly 20% of tumors of the CNS occurred before 20 years of age. The male:female ratio was 1.53:1; the only tumor with a definite preponderance of females over males was the meningioma