Cerebrovascular diseases; It is the 3rd most common cause of death in the United States, and it is one of the leading causes of disability. Death and disability; is the result of ischemia causing either focal or diffuse infarction, or hemorrhages causing a compressive mass lesion
Ischemic Vascular Disease (Stroke-Stroke)
Ischemia and its consequent cerebral infarction can occur in the distribution area of any cerebral vessel ; thus the cerebrum, brainstem, or any part of the cerebellum may be affected. Ischemia and infarction are the most common in its distribution, as it provides the most blood to the brain through the carotid circulation. Ischemia may result from occlusion of the main arteries, from temporary or permanent occlusion of smaller diameter arterioles as a result of decreased flow as a result of stenosis or from intravascular embolism.
The most common cause of stenosis or occlusion of great vessels is atherosclerosis. This disease usually occurs in the extracranial neck segment of the internal carotid artery, but may also occur in the carotid siphon segment (inside the cavernous sinus), the distal internal carotid, or even the proximal middle cerebral artery.
Arterial embolism usually arises either from an ulcerated atherosclerotic plaque in the carotid bifuction or from a focus within the heart. Mural thrombus or atrial fibrillation after myocardial infarction are sources of embolism in the heart. Other risk factors for cerebral ischemia are high blood pressure, diabetes, high cholesterol, obesity, smoking and family history.
Since there are no effective drugs or surgical interventions for stroke, the aim of neurosurgery is to identify patients who are likely to have a stroke and to reduce the risk of cerebral ischemia. These high-risk patients are best seen as either transient cerebral ischemia or amaurosis fugax; They are determined by a history of transient ischemic attack (TIA). Transient cerebral ischemia within the carotid circulation usually consists of transient hemianesthesia, hemiparesis, or aphasia. Amaurosis fugax is the temporary loss of vision in one eye. Ischemia in the vertebrobasilar system can cause temporary diplopia, vertigo, dysarthria, dysphagia, weakness, drowsiness, vision loss and even memory loss.
The duration of most ischemic events is measured in seconds and minutes, and rarely 30 minutes. takes longer than If the neurological impairment regresses within 24 hours, the case is defined as a TIA. A reversible ischemic neurologic disorder (RIND) is one lasting 24 hours to 3 weeks. Ischemic disorders of longer duration are considered complete/settled paralysis. In careful inquiries with individuals with completed paralysis; It was found that 60% had a previous history of TIA, 20% had a gradual development of stroke, and only 20% had a sudden onset.
TREATMENT
Patients with TIA or slow-onset stroke are potential candidates for conservative surgery. Surgical interventions to prevent stroke aim to eliminate the embolism focus or to increase blood flow to the brain. Operations for these conditions include carotid endarterectomy and microvascular bypass. Potential candidates usually; They undergo CT and MRI scanning to assess the extent of the infarct in the brain and rule out other possibilities such as a tumor, subdural hematoma, or subarachnoid hemorrhage. They then undergo angiography covering the aortic arch, carotid, vertebral and cerebral vessels. Although the non-invasive examination of the carotid circulation provides less and more accurate information, it can be used for screening purposes because it carries low risk.
Carotid endarterectomy is indicated if symptoms such as ipsilateral cerebral ischemia or amaurosis fugax (loss of vision) are present and angiography shows advanced stenosis (usually greater than 75%) or ulceration. The procedure involves opening the involved portion of the carotid artery and removing the atherosclerotic plaque. In experienced hands, the mortality rate from carotid endarterectomy is 1%, and the neurological morbidity rate is 5%.
In a group of patients, ipsilateral cerebral ischemia may be seen with stenosis of a completely occluded internal carotid artery or surgically inaccessible internal carotid or middle cerebral artery segments. Microvascular bypass techniques are recommended for patients with such insufficient collateral circulation. The most widely used of these is the anastomosis of the superficial temporal artery and the middle cerebral artery (STA-MCA).
