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Chapter 14

Chapter 14 Human brain damage.docx

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Zachariah Campbell

Chapter 14- Human Brain Damage Causes of Brain Damage Tumors  Mass of new and abnormal tissue that is not physiologically beneficial to its surrounding structures o Also known as a space occupying lesion, which means that they are foreign objects that cause damage to the CNS by putting pressure on it and occupying space that is normally occupied by the CNS  Brain is one of the most common places for tumors, 2 to the uterus  Tumors differ from one another in terms of what type of cell gives rise to them, how rapidly they grow, whether they infiltrate and destroy the surrounding neural tissue or remain relatively encapsulated, and how likely they are to recur if removed  Benign tumors are not likely to recur, malignant ones are more likely to recur  4 major types of brain tumors: those that originate from glial cells, meninges, nervous tissue, or other parts already infected Tumors Arising from Glial Cells  Most common type of tumors that form in brain are gliomas  Two main types of gliomas: o Astrocytomas are tumors that arise from the growth of astrocytes, tend to not grow very quickly, rarely malignant  Slow growing benign tumor but can be dangerous if they start growing in inaccessible areas.  Chemotherapy is used when surgery isn’t practical o Glioblastoma grow quickly and are highly malignant  Tend to infiltrate the surrounding tissues, making them very difficult to excise surgically without the removal of the relatively healthy surrounding neural tissue  Chemotherapy is often used to treat gliobastomas  Less common type of glioma is the medulloblastoma, which is also highly malignant, infiltrating tumor o Tend to form around the cerebellum and brainstem early in life o Prognosis for individuals who develop medulloblastomas tend to be relatively poor. Chemotherapy is the most attractive option TUMORS ARISING FROM THE MENINGES  Meningiomas are tumors that grow out of the meninges  Most grow out of the dura mater, forming an ovoid shape, because they grow out of tissues found outside the CNS, meningiomas tend to be reasonably well encapsulated  Harmful effects tend to result from pressure applied at the site of the tumor as well as sites distal from the tumor  Most types of meningiomas are benign, but there are some malignant varieties of the tumor  Regardless of type, surgery is typically the best treatment for meningiomas, particularly because of their encapsulated nature and partly because of their location on the surface of the brain  When tumor is located in a relatively inaccessible part of the brain for surgery, chemotherapy or radiotherapy is used METASTATIC TUMORS  Secondary tumors that form from migrated tumor issue  Primary tumor site can be located in parts of the body such as the lungs, breasts, uterus, or kidneys  Far more common to be located outside the CNS but can also be in the CNS  Simple metastatic tumors occur when only one tumor forms at one site o Surgical or radiological treatment can be quite effective  in most cases, there are multiple metastatic tumors, spreading from the lungs to the CNS o Whole brain radiotherapy or chemotherapy is most common, but the prognosis is generally quite poor NEUROPSYCHOLOGICAL EFFECTS OF TUMORS  rates of tumors vary, a small slow growing infiltrating astrocytoma located near the primary visual cortex may gradually start to cause blindness in part of a persons visual field  tumors of the pituitary gland can have behavioral symptoms similar to those of a visual cortex tumor, despite having a very different location  pressure placed on the optic chiasm from pituitary tumors can also result in visual field defects  a more rapidly growing meningioma that remains relatively well encapsulated between the two hemispheres could apply pressure to the primary motor and sensory cortices in this region, causing numbness and paresis to the feet and legs  metastatic tumors that form in the left temporal lobe can cause speech disturbances, including receptive language problems, whereas tumors in the left parietal lobe can lead to apraxia  tumors can also cause epileptic seizures and release substances that are toxic to the brain  if the tumor releases toxins and is located in one of the ventricles the toxins can then be transported easily from one site of origin, producing lesions and behavioral deficits that are not confined to the region where the tumor is growing Cerebrovascular Disorders  occurs when the blood supply to the brain is interrupted  leading cause of disabling neurological damage and the third most common cause of death in the developed world  more common and precise medical term for stroke is the term cerebrovascular accident (CVA), which refers to a class of cerebrovascular disorders, all of which result in interruptions to the brain’s blood supply  a CVA results in cerebral ischemia, which is a lack of blood supply to the brain  if the cerebral ischemia is severe or long lasting enough to kill neurons, the damaged area is called an infarct  can be small if the CVA is restricted to small, minor arteries  If a blood clot forms within a cerebral blood vessel, this clot is called a thrombosis o Can also form outside the brain, if in the heart, it can cause a heart attack o Formation of a thrombosis can have several causes, most common one is atherosclerosis, in which fatty deposits build up insi
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