Cerebral arteriovenous malformation
Signs and symptoms[edit]
The most frequently observed problems related to a cerebral arteriovenous malformation (AVM) are headaches and seizures, cranial nerve afflictions including pinched nerve and palsy,[2][3] backaches, neckaches, and nausea from coagulated blood that has made its way down to be dissolved in the cerebrospinal fluid. Perhaps 15% of the population at detection are asymptomatic.[3] Other common symptoms are a pulsing noise in the head, progressive weakness, numbness and vision changes as well as debilitating, excruciating pain.[4][5]
In serious cases, blood vessels rupture and cause bleeding within the brain (intracranial hemorrhage).[a] In more than half of patients with AVM, this is the first symptom.[7] Symptoms due to bleeding include loss of consciousness, sudden and severe headache, nausea, vomiting, incontinence, and blurred vision, amongst others.[4] Impairments caused by local brain-tissue damage on the bleed site are also possible, including seizure, one-sided weakness (hemiparesis), a loss of touch sensation on one side of the body and deficits in language processing (aphasia).[4] Ruptured AVMs are responsible for considerable mortality and morbidity.[8]
AVMs in certain critical locations may stop the circulation of the cerebrospinal fluid, causing it to accumulate within the skull and giving rise to a clinical condition called hydrocephalus.[5] A stiff neck can occur as the result of increased pressure within the skull and irritation of the meninges.[9]
Pathophysiology[edit]
A cerebral AVM is an abnormal anastomosis (connection) between the arteries and veins in the human brain and are most commonly of prenatal origin.[10] In a normal brain, oxygen-enriched blood from the heart travels in sequence through smaller blood vessels going from arteries, to arterioles and then capillaries.[10] Oxygen is removed in the capillaries to be used by the brain.[10] After the oxygen is removed, blood reaches venules and later veins which will take it back to the heart and lungs.[10] A cerebral AVM causes blood to travel from arteries to veins through the abnormal connections, disrupting normal circulation.[10][11]
Grading[edit]
Spetzler-Martin (SM) Grade[edit]
A common method of grading cerebral AVMs is the Spetzler-Martin (SM) grade.[13] This system was designed to assess the patient's risk of neurological deficit after open surgical resection (surgical morbidity), based on characteristics of the AVM itself. Based on this system, AVMs may be classified as grades 1–5. This system was not intended to characterize risk of hemorrhage.[14]
Epidemiology[edit]
The annual new detection rate incidence of AVMs is approximately 1 per 100,000 a year. The point prevalence in adults is approximately 18 per 100,000.[3] AVMs are more common in males than females, although in females pregnancy may start or worsen symptoms due to the increase in blood flow and volume it usually brings.[30] There is a significant preponderance (15–20%) of AVM in patients with hereditary hemorrhagic telangiectasia (Osler–Weber–Rendu syndrome).[6]