1. Define the terms ischemia and infarction.
Ischemia- local decrease in blood supply Infarction- death & deterioration of tissue resulting from lack of blood supply. 2. What is a stroke? Name the two main types of strokes and describe the mechanism(s) by which each type occurs. Cerebrovascular Accident- condition in which brain tissue is deprived of blood supply. The most common stroke symptoms are: Numbness or weakness (paresis) of the face, arm, or leg, sometimes only on one side; Confusion, trouble speaking or understanding speech (aphasia)
Trouble walking or dizziness; loss of balance or coordination (ataxia) Severe headache with no known cause
1. Ischemic stroke (~83%) – blood vessel supplying brain tissue is blocked by a blood clot. a. cerebral thrombus b. cerebral embolism
2. Hemorrhagic stroke (~17%) – A blood vessel breaks open, causing blood to leak into the brain. 3. Define the term collateral blood flow, and describe how this and other factors affect the development of stroke. The brain has s circular vascular structure called the circle of Willis and two pairs of arteries that feed the circle. So most areas of the brain receive blood from more than one collateral blood vessel. The type, and severity of stroke symptoms depends on the location of the severity of brain ischemia. 4. List the risk factors that predispose an individual to suffer a stroke. What are the five warning signs that indicate an individual is having a stroke? Which of the risk factors and warning signs did Mr. Dexter possess based on the clinical history? Risk factors for ischemic stroke include hypertension, age, cigarette smoking, male gender, family history, race, previous stroke, carotid stenosis >80%, atrial fibrillation, congestive heart failure, mitral stenosis, prosthetic cardiac valves, myocardial infarction, and drug abuse (e.g., cocaine).
7 Other factors that may contribute to stroke are diabetes, obesity, a sedentary lifestyle, and an elevated serum cholesterol level. Risk factors for hemorrhagic stroke include intracranial vascular anomalies, hypertension, family history, polycystic kidney disease, systemic lupus erythematosus, neurofibromatosis, Pregnancy, cigarette smoking, atherosclerosis. 5. What are Brodman areas and how do they relate to the neurological deficits that occur as the result of stroke? Many of the areas Brodmann defined based solely on their neuronal organization have since been correlated closely to diverse cortical functions. For example, Brodmann areas 1, 2 and 3 are the primary somatosensory cortex; area 4 is the primary motor cortex; area 17 is the primary visual cortex; and areas 41 and 42 correspond closely to primary auditory cortex. Higher order functions of the association cortical areas are also consistently localized to the same Brodmann areas by neurophysiological, functional imaging, and other methods (e.g., the consistent localization of Broca’s speech and language area to the left Brodmann areas 44 and 45).
However, functional imaging can only identify the approximate localization of brain activations in terms of Brodmann areas since their actual boundaries in any individual brain requires its histological examination. 6. What is the functional relationship between Broca’s area and Wernicke’s area? Broca’s area (anterior to inferior part of premotor cortex, usually on left hemisphere) – directs muscles involved in speech production, but also active as we prepare to speak and as we plan many other voluntary motor activities. Wernicke’s area (area on posterior part of temporal lobe and inferior parietal lob just above that, usually on left hemisphere) – function in understanding language and in putting words together in cogent order. Both areas work together along with the basal nuclei to allow understanding, motor planning, motor control and speaking composed thoughts. 7. Define the terms ipsilateral and contralateral as they apply to the functionality of the central nervous system. Ipsilateral refers to body functions that are associated with areas of the brain hemisphere on that same side (R body: R hemisphere). Contralateral refers to body functions associated with areas of the brain hemisphere on the opposite side (R body: L hemisphere).
8. Explain the significance of the findings of brisk deep tendon reflexes and Babinski sign on the affected side of Samuel’s body. Deep Tendon Reflexes (DTRs, aka Stretch Reflexes) – are all ipsilateral and monosynaptic the fact that his are normal indicates that there is no peripheral nerve damage or spinal cord damage at the level tested. Babinski- gently strokes the outer soles of the patient’s feet with the mallet while checking to see whether or not the big toe extends out as a result. In children under the age of one and a half years, the big toe will extend out with or without the other toes. This is due to the fact that the fibers in the spinal cord and cerebral cortex have not been completely covered in myelin, the protein and lipid sheath that aids in processing neural signals. In adults and children over the age of one and a half years, the myelin sheath should be completely formed, and, as a result, all the toes will curl under (planter flexion reflex). An adult or older child who responds to the Babinski with an extended big toe may have a lesion in the spinal cord or cerebral cortex. Different responses on the two sides of the body may indicate unilateral cortical or spinal damage.
9. Based upon the historical and physical exam findings, what specific area(s) of Samuel’s brain have been damaged as the result of his stroke? Sensory Tracts- Anterior spinothalamic (pain sensation), Fasiculus cuneatus and gracilus (discriminative touch, prprioception). Motor Tracts- Lateral and Anterior corticospinal tracts all decussate (cross over) between the cerebral cortex and the spinal cord. Samuel’s motor and sensory deficits are on his right side, therefore his CVA must involve his left cerebral hemisphere. His type of aphasia also indicates involvement of Broca’s area (also on the L cerebral cortex). The fact that he has both right side sensory and motor deficits and speech deficits, indicate damage to the motor and sensory cortex located on the frontal and parietal lobes, both of which would mainly be supplied with blood by the left middle cerebral artery.
Samuel’s CVA is most likely due to a clot there. 10.Describe the means by which individuals who survive a stroke regain at least part of their lost abilities. In my personal opinion, I think that brain cells can made a by-pass with another working or living brain cell. With the fast action of a MD, and a proper rehabilitation this could happen. There are numerous approaches to stroke rehabilitation, some of which are still in the early stages of development. Behavioral performance in any area, such as sensory-motor and cognitive function, is most likely to improve when motor activity is willful, repetitive and task specific. Stroke rehabilitation may include some or all of the following activities, depending on the part of the body or type of ability affected.
Strengthening motor skills involves using exercises to help improve your muscle strength and coordination, including therapy to help with swallowing. Mobility training may include learning to use walking aids, such as a walker or canes, or a plastic brace (orthosis) to stabilize and assist ankle strength to help support your body’s weight while you relearn how to walk. Constraint-induced therapy, also known as forced-use therapy, involves restricting use of an unaffected limb while you practice moving the affected limb to help improve its function. Range-of-motion therapy uses exercises and other treatments to help lessen muscle tension (spasticity) and regain range of motion. Sometimes medication can help as well.
Technology-assisted physical activities:
Functional electrical stimulation involves using electricity to stimulate weakened muscles, causing them to contract. This may help with muscle re-education. Robotic technology uses robotic devices to assist impaired limbs with performing repetitive motions, helping them regain strength and function. A recent large study showed no clear advantage to using robotic technology to improve motor recovery after stroke. Wireless technology, such as a simple activity monitor, is being evaluated for its benefit in increasing post-stroke activity. Virtual reality, such as the use of video games, is an emerging, computer-based therapy that involves interacting with a simulated, real-time environment. Noninvasive brain stimulation. Techniques such as transcranial magnetic stimulation (TMS) have been used with some success to help improve a variety of motor skills.
Cognitive and emotional activities:
Therapy for communication disorders can help you regain lost abilities in speaking, listening, writing and comprehension. Psychological evaluation and treatment may involve testing your cognitive skills and emotional adjustment, counseling with a mental health professional, or participating in support groups. Medications are sometimes used to treat depression in people who have had a stroke. Drugs that affect movement are also used.
Biological therapies, such as stem cells, are being investigated, but should only be used as part of a clinical trial. Alternative medicine treatments, such as massage, herbal therapy and acupuncture, are being evaluated.