Chapter 10

• Tumor (Neoplasm)


  Mass of cells that grows independently of the rest of the body
• Brain tumors


  • Can come from meninges, glial cells, and blood streams
• Meningiomas


  Tumors that grow between the meninges
• Encapsulated tumors


  Tumors that grow within their own membrane
• Acoustic neuromas


  Tumors that grow on nerves or tracts
• Benign tumors


  Tumors that are surgically removable with little risk of further growth in the body
• Infiltrating tumors


  Grow diffusely through surrounding tissue, usually malignant
• Malignant tumors


  Difficult to remove or destroy them completely, any cancerous tissue that remains after surgery usually continues to grow
• Gliomas


  Brain tumors that develop from glial cells, infiltrating, rapidly growing, most common form of malignant brain tumors
• Metastatic tumors


  Grow from infiltrating cells that are carried to the brain by the bloodstream from some other part of the body
• All brain tumors are easily identified by a CT Scan
• Strokes


  Sudden-onset cerebrovascular disorders that cause brain damage
• Strokes are the fifth leading cause of death, the major cause of neurological dysfunction, and a leading cause of adult disability
• Common consequences of stroke

  • Amnesia
  • Aphasia (language difficulties)
  • Psychiatric disorders
  • Dementia
  • Paralysis
  • Coma
• Infarct


  Area of dead or dying tissue produced by a stroke
• Penumbra


  Dysfunctional area surrounding the infarct, tissue may recover or die depending on various factors
• The primary goal of treatment following stroke is to save the penumbra
• Cerebral hemorrhage


  Internal bleeding, occurs when a cerebral blood vessel ruptures and blood seeps into the surrounding neural tissue and damages
• Aneurysm


  Pathological balloonlike dilation that forms in the wall of an artery, common cause of intracerebral hemorrhage
• Cerebral ischemia


  Disruption of the blood supply to an area of the brain
• Main causes of cerebral ischemia

  • Thrombosis
  • Embolism
  • Arteriosclerosis
• Ischemia-induced brain damage


  • Takes a while to develop, does not occur equally in all parts of the brain - particularly susceptible are neurons in certain areas of the hippocampus
• Glutamate


  Brain's most prevalent excitatory neurotransmitter, plays a major role in ischemia induced brain damage
• Glutamate-induced ischemia damage


  1. Excessive glutamate release

  2. Glutamate over-activates NMDA receptors

  3. Large numbers of Na+ and Ca2+ ions enter postsynaptic neurons

  4. Triggers release of more glutamate and internal reactions that kill postsynaptic neurons
• Effective treatments of stroke

  • Administration of tissue plasminogen activator
  • Endovascular therapy
• Closed-head TBIs


  Brain injuries produced by blows that do not penetrate the skull
• Contusions


  Closed-head TBIs that involve damage to the cerebral circulatory system, producing internal hemorrhaging and a localized collection of blood in the brain
• Subdural hematoma


  A "puddle" of blood in the subdural space between the dura mater and arachnoid membrane
• Contrecoup injuries


  The blow causes the brain to strike the inside of the skull on the other side of the head
• Mild TBI (mTBI)


  Once called concussions, a disturbance of consciousness following a blow to the head with no evidence of contusion or other structural damage
• Chronic Traumatic encephalopathy


  Dementia in those who have experienced repeated mTBIs
• Brain infection


  Invasion of the brain by microorganisms
• Encephalitis


  Resulting inflammation of brain infection
• Cerebral abscesses


  Pockets of pus in the brain formed when bacteria infect the brain
• Meningitis


  Inflammation of the meninges
• Penicillin and other antibiotics sometimes eliminate bacterial infections of the brain, but they cannot reverse brain damage that has already been produced
• Syphilis


  Passed from infected to noninfected individuals through contact with genital sores, infecting bacteria then go into a dormant stage for several years before attacking many parts of the body, including the brain
• General paresis


  Syndrome of mental illness and dementia that results from a syphilitic infection
• Viral infections of the nervous system

  Those that have a particular affinity for neural tissue, and those that attack neural tissue but have no greater affinity for it than for other tissues
• Rabies


  Virus that has a particular affinity for the nervous system, usually transmitted through the bite of a rabid animal