PSYC 211 - Chapter 15

PSYC 211 Chapter - CHAPTER 15 Neurological Disorders Although the brain is the most protected organ many pathological processes can damage it or

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CHAPTER 15: Neurological Disorders Although the brain is the most protected organ, many pathological processes can damage it or disrupt its functioning. This chapter will describe the major categories of the neuropathological conditions that the brain can sustain- tumors, seizure disorders, cerebrovascular accidents, disorders of development, degenerative disorders, and disorders caused by infectious diseases. The chapter will then discuss the behavioural effects of these conditions and their treatments. Tumors A Tumor is a mass of cells whose growth is uncontrolled and that serves no useful function. Tumors can be benign or malignant Benign tumors are non cancerous (literally “harmless”). A benign tumor is encapsulated, meaning that there is a distinct border between the mass of tumor cells and the surrounding tissue and it can be easily cut out. Benign tumors cannot metastasize. Malignant tumors are cancerous (literally “harm-producing”). A malignant tumor grows by infiltrating the surrounding tissue so there will be no distinct border. If the surgeon removes the tumor some cells may be missed, and these cells will produce a new tumor. Malignant tumors may metastasize. Metastasis is the process by which cells break off of a tumor travel through the vascular system, and grow elsewhere in the body. Metastasis can occur in a malignant, but not a benign tumor. Tumors damage the brain tissue by two means: compression and infiltration. Any tumor growing in the brain, malignant or benign can produce neurological symptoms and threaten the patient’s life. Benign tumors occupy space and thus push against the brain which can destroy brain tissue directly or indirectly by blocking the flow of cerebrospinal fluid and causing hydrocephalus. Malignant tumors cause both compression and infiltration. As it grows, it invades the surrounding region and destroys cells in its path. Tumors do not arise from nerve cells, which are not capable of dividing. They arise from other cells found in the brain, or from metastases originating elsewhere in the body. The most serious types of tumors are metastases and the gliomas. A Glioma is a cancerous brain tumor composed of one of several types of glial cells. They are usually very malignant and fast growing. TABLE 15.1 Types of Brain Tumors Gliomas: Glioblastoma multiformae (poorly differentiated glial cells) Astrocytoma (astrocytes) Ependymoma (ependymal cells that line ventricles) 1
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Medulloblastoma (cells in roof of fourth ventricle) Oligodendrocytoma (oligodendrocytes) Meningioma (cells of the meninges) Pituitary adenoma (hormone-secreting cells of the pituitary gland) Neurinoma (Schwann cells or cells of connective tussue covering cranial nerves) Metastatic carcinoma (depends on nature of primary tumor) Angioma (cells of blood vessels) Pinealoma (cells of pineal gland) Some tumors are sensitive to radiation and can be destroyed by a beam of radiation focused on them. Usually, a neurosurgeon first removes as much of the tumor as possible, and then the
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This note was uploaded on 02/13/2011 for the course PSYC 211 taught by Professor Yogitachudasama during the Winter '09 term at McGill.

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PSYC 211 Chapter - CHAPTER 15 Neurological Disorders Although the brain is the most protected organ many pathological processes can damage it or

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