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Arteriovenous Malformation
Nearly half of the deaths in US are due to certain blood vessel disease with major risk factors being diabetes, abnormalities in lipid or fat metabolism, obesity, age and genetic factors. Out of all blood vessel disorders, atherosclerosis leads the race followed by hypertension. Small blood vessel disease is normally associated with infarcts or small hemorrhages of size less than 1 cm in diameter and may be associated with focal neurological signs that over a prolonged period result in clinical deterioration leading to varying degrees of dementia.
Major Blood Vessel Diseases
Atherosclerosis
Atherosclerosis
Atherosclerosis may begin from childhood only with build-up of fatty streaks within the blood vessels, characterized by thickening of innermost layer of vein or artery with focal deposition of fats, influx of monocytes (blood component), proliferation of smooth muscles and fibrosis. It mainly affects the upper side of the basilar artery, internal carotid arteries, extra cranial and intracranial blood vessels. Patients may show transient episodes of ischemic attacks and are at increased risks of suffering from stroke. Atherosclerosis is involved with vertebral arteries and there, it leads to cerebral infarction and thrombosis.
Vascular Malformations
Many different forms of vascular malformations may occur depending upon the configuration of vascular channels and type of blood vessels. These are known to be congenital in their origin.
Arteriovenous Malformation
It is the most significant form of vascular malformation and is highly like to bleed. It may be present at any age, but usually observed in people in their 20s to 40s. They may remain asymptomatic and normally extend from brain parenchyma to subarachnoid space with presence of abnormal vessels of varying thickness.
Venous Angiomas
Venous angiomas are the most observed incidental vascular malformations that are encountered at autopsy and are normally asymptomatic. They can also be present in association with haemorrhage and epileptic fits, but such probability is quite rare.
Hypertension
Hypertension
Increased blood pressure puts a high levels stress over small blood vessels that can lead to breakdown of auto regulation, resulting in higher blood flow that is proportional to the rise in the pressure. High blood pressure disrupts the blood brain barrier, with deposition of plasma proteins in the small wall of blood vessels, causing progressive disruption of smooth muscles and eventually fibroid necrosis. Weakened blood vessels may result in small aneurysms that are prone to rupturing, and can lead to small haemorrhages. The cerebral function may get deteriorated depending upon the number and site of haemorrhages.
Sudden rise of blood pressure may occur in toxaemia of pregnancy and malignant hypertension, resulting in serious cerebral oedema that may lead to fibrinoid necrosis and rupturing of the small blood vessels, leading to haemorrhages. Hypertension and haemorrhage occurs mainly in basal ganglia region and cerebellum.
Arterial Dissection
Arterial dissection mainly occurs in middle aged or even at times in young individuals. It occurs more spontaneously and is followed by trauma, mainly at the side of the head and neck. It involves intra cranial and external parts of the carotid artery or vertebral arteries. In case, haemorrhage tracks down the adventitia, it ruptures into the subarachnoid space.
Fibromuscular Dysplasia
Fibromuscular dysplasia occurs in renal arteries and involves small to medium sized arteries, but pathogenesis is not known. It results in narrowing of the lumen and dilates alternatively. It affects any arterial wall layer and results in hyperplasia of fibrous tissue and muscles.
Photo Credit: http://ehealthforum.com/pages/atherosclerosis/pictures