Table 18.1 Nomenclature of bone tumors
Cerebrovascular accident (CVA) describes acute brain injury caused by decreased blood supply or hemorrhage.
A stroke occurs when a blood vessel bringing oxygen and nutrients to the brain bursts or is clogged by a blood clot or some other particle. This deprives the brain of blood, causing the death of neurons within minutes. Depending on its location, a stroke can cause many permanent disorders, such as paralysis on one side of the body and loss of speech.
Stroke often occurs in individuals over 65 years of age, yet a third are younger. Stroke tends to occur more in males and blacks and in those with diabetes, high blood pressure, heart disease, obesity, high cholesterol and a family history of stroke.
EPIDEMIOLOGY & DEMOGRAPHICS
INCIDENCE (IN U.S.):
• Occurs in 5 to 10/100,000 persons <40 years of age
• Occurs in 10 to 20/100,000 persons >65 years of age
PREVALENCE (IN U.S.): Estimated at 2 million persons
PREDOMINANT SEX: Incidence is 33% higher in males
PREDOMINANT AGE: 60+ years
PEAK INCIDENCE: 80 to 84 years
GENETICS: Family history a risk factor, but no distinct genetic etiology has been identified.
PHYSICAL FINDINGS & CLINICAL PRESENTATION
Motor and/or sensory and/or cognitive deficits, depending on distribution and extent of involved vascular territory.
• From 70% to 80% are caused by ischemic infarcts; 20% to 30% are hemorrhagic.
• 80% of ischemic infarcts are from occlusion of large vessels caused by atherosclerotic vascular disease, 15% are caused by cardiac embolism, 5% are from other causes, including hypercoagulable states and vasculitis.
• Small vessel occlusion is most often caused by lipohyalinosis along with chronic hypertension.
• Risk factors for ischemic stroke are described in Box 1-11.
• Mass lesion
STROKE. A stroke occurs when a blood vessel bringing oxygen and nutrients to the brain bursts or is clogged by a blood clot. This lack of blood can cause cell death within minutes. One theory is that the overexcited dying nerve cells release neurotransmitters, especially glutamate, onto nearby nerve cells. These nearby nerve cells become overexcited and overloaded with calcium and die. This is one of the places where scientists think they may be able to intervene to stop the process of cell death. Depending on its location, a stroke can have different symptoms. They include paralysis on one side of the body or a loss of speech. The effects of stroke are often permanent because dead brain cells are not replaced.
• Thorough history and physical examination, including detailed neurologic and cardiovascular evaluation to identify vascular territory and likely etiology
• Mandatory ECG
• Echocardiography, Holter monitor, or carotid Doppler should be seriously considered
• Platelet count
• PT (INR)
• BUN, creatinine
• Lipid panel
• Additional tests, depending on suspected etiology (in younger patients; e.g., coagulopathies)
• CT scan without contrast to identify hemorrhage or infarct.
• An MRI identifies abnormalities in the posterior fossa and, in particular, lacunar infarcts.
A flair image sequeue is mandatory in acute stage (less than 6 hours).
• Possibly MRA or x-ray angiography to identify aneurysms or other vascular malformations.
• Above the knee elastic stockings to prevent pulmonary emboli
• Carotid endarterectomy in suitable patients with carotid territory stroke associated with 70% to 99% ipsilateral carotid stenosis, performed by an experienced surgeon with low morbidity and mortality
• Modification of risk factors
ACUTE GENERAL Rx
• Box 1-12 describes initial considerations for patients with stroke.
• Judicious control of blood pressure; patients with chronic hypertension may extend the area of infarction if the blood pressure is lowered into the “normal” range.
• If patient presents <3 hr after onset of a nonhemorrhagic stroke, thrombolytic therapy in a specialized stroke center may be beneficial.
ACUTE SPECIFIC Rx
• Depends on several factors, including vascular territory involved, risk factors, and elapsed time from symptom onset to arrival at hospital.
• If on diffusion weighted MRI a fresh infarct is demonstrated and if onset of symptoms is less than 3 to 4 hours, including evaluation, rt PA is indicated. This is a relatively rare situation, even in large centers with stroke teams. If patient is in atrial fibrillation and/or a cardiac mural thrombus is found on echocardiography, heparin followed by warfarin is indicated.
• If a subarachnoid or intracerebral hemorrhage is found on CT, cerebral angiography is indicated to identify aneurysm. If no aneurysm is found and clot is expanding, neurosurgical evaluation of clot may be attempted, but outcomes are generally poor.
• If an interventional neuroradiologist is available, and if onset of symptoms is less than 6 hours, direct injection of the clot with a clot-busting agent can have an excellent outcome.
• Antiplatelet therapy (aspirin, clopidogrel [Plavix], or ticlopidine) reduces the risk of subsequent stroke.
• Aspirin alone is used first, and another agent is added if TIAs continue. Coumadin is usually reserved for patients with cardioembolic stroke.