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Human Brain - Chapter 14.docx

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Ted Petit

Chapter 14 – Human Brian Damage - even successful rehabilitation is not restoration tot eh previous state - learning of new was to do the required learned tasks - more to do with compensation that recovery/restoring MODULE: Causes of Brain Damage Tumors - mass of new and abnormal tissue that is not physiologically beneficial to its surrounding structures [akak neoplasms – ‘new tisse’] - space-occupying lesions > foreign objects that cause damage to the CNS by putting pressure on it and occupying space that is normally occupied by the CNS - second most common site for tumors [uterus] - tumors differ > tipe of cell that cause, grow rate, whether they infiltrate and destroy the surrounding neural tissue or remain relatively encapsulated and how likely they are to recur if they are removed - encapsulated > tumor that has clear borders - infiltrate > tumor that moves into neural tissue w/ no clear boundaries - benign tumors > not likely to reoccur and good prognosis associated w/ it - malignant > more likely to reoccur and has a poor prognosis - four major types of brain tumors o originate form glial cells, the meninges, nervous system, or other parts of the body already affected w/ a tumor Tumors rising form glial cells - gliomas > tumors that arise form glial cells [most common brain tumors] - two types: o Astrocytomas: slow-growing benign tumors that arise form the growth of astrocytes [rarely malignant]  relatively encapsulated > damagage tends to come form compression of the surrounding tissues  other infiltrate the surrounding neural tissue  prognosis is good after removal [not if in inaccessible location]  if not surgery then chemotheraphy o Glioblastoma: quick-growing malignant tumor [opposite of above]  infiltrate the surrounding tissue > so diff to remove w/o removing healthy surrounding neural tissue [chemo – often] o Medulloblastoma: a rare but malignant infiltrating tumor that tends to occur in the cerebellum and brainstem early in life  since close to brainstem structures that support vegetative functions > prognosis is poor [chemo] Tumors arising from meninges - tumors that grow out of and remain attached to the meninges - grow out of dura matter, forming a ovoid shape > which are outside the CNS o tend to be encapsulated o effects tend to be form the pressure applied at the site of the tumor as well as sites distal form the tumor o most benign some can be malignant, surgery is best option [location] o if inbtwn hemispheres then > chemo/radiotherapy Metastatic tumors - secondary tumors that form from the migrated tumor tissue - primary site > lungs, breasts, uterus, kidneys - primary site can be w/I CNS but most likely not - simple metastatic tumors > rare cases in which metastasis involves only one tumor site [radiological/surgical] - multiple metastatic tumors > most cases, metastatic tumors that spread and involve multiple sites and multiple tumors [usually lungs > CNS] o whole-brain radiotherapy/chemotherapy > poor prognosis Neuropsychological Effects of Tumors - beh symptoms vary widely - primary visual cortex > blinding - pituitary gland > similar to visual cortex [due to proximity] - left temporal > speech disturbances, receptive language probs - left parietal lobe> apraxia - can also cause epileptic seizures and release substances that are toxic to the brain [if it releases toxins in ventricles it can be transported easilty] Cerebrovascular Disorders - occurs when the blood supply to the brain is interrupted - interruption can be sudden/gradual, complete/relative, permanent/transien - these disorders > leading cause of disabling neurological damage and 3rd most common cause of death in the developed world [1.cancer 2.heart attac] - primary source of lesion evidence from neuropsychologist trying to make inferences about the functions of areas of the brain - cerebrovascular accident [CVA]: medical term [to stroke], refers to class of cerebrovascular disorders - CVA results in a cerebral ischemia: a lack of blood supply to the brain - infarct: if the cerebral ischemia is long/severe enough o kill neurons the damaged area is this - can be small or major, interruption in BS > blocked/broken cerebral arteries, interruptions of blood supplt outside the CNS - thrombosis: a blood clot that forms w/I the cerebral blood vessel o most common cause atherosclerosis, which fatty deposits build up inside the walls of the bloof vessels, constricting the vessel more and more and possibly even completely blocking it [symp appear gradual] o often forms where 2 large arteries branch off from one, bifurcation o influences large areas of the brain - embolism: a clot, bubble or piece of fat that moves along the length of a vein or artery, blocking the flow of blood [move from a larger area to small > plug] o may not completely block artery then get to a smaller area and comple o treat > surgically, anticoagulant drugs - hemorrhage: interruption in blood supply to brain caused by the breakage of a blood vessel [either pressure on artery walls/artery malformed] o aneurysm > areas of veins/arteries that dilate because of local weaknesses, resulting in a ballonlike expansion o hypertension > abnormally high BP o piercing of a blood vessel by a foreign object [bullet]  blood can be toxic to the neural tissue o force of bleeding >compromise brain structure/move to other areas o intracerebral hemorrhage > occurs w/I the brain  caused by hypertension  damages result of > restrict BF, toxicity of blood, pressure  prognosis > poor [do not reoccur] o subarachnoid hemorrhage > bleeding into the subarachnoid space  caused by hypertension > primary threat is pressure  sudden onset/symptoms [no specific functional symp]  do not reoccur, prognosis > poor - CVA can also be caused by physical defects in the cerebral vasculature - present at birth [congenital] or caused by trauma o arteriovenus malformation [AVM]: malformed arteries/vessels that have extra or missing connections resulting in abnormal blood flow, which tend to form along the middle cerebral artery [congenital]  tend to bleed at some point or many  bleed diff > small amounts over long periods > more than once  bleed less so damage not due to pressure but lack of irrigation/toxicity of the blood itself o aneurysm is another common defect > early in life or late  bleed/burst or no problems [if slow > better]  if suddenly burst > intracranial hemorrhage > fatal - factors influencing treatment > size of effected area, location and medical hist - can be treated by clipping them w/ small clips [now not magnetic > can MRI] - draining procedures, surgery remove/break thromboses/embolism, anticoagulant drugs > blockage from T/E Head Injuries Traumatic Brain Injury [TBI] - le
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