brain damage

• Brain damage


  An injury to the brain caused by various conditions such as head trauma, inadequate oxygen supply, infections, or intracranial hemorrhage
• Brain damage may be associated with a behavioral or functional abnormality
• Brain tumor (Neoplasm)


  • A group of cells growing independently from rest of body
  • Encapsulated grow within own membrane
  • Infiltrating grow diffusely through surrounding tissue
• Gliomas


  Originate from glial cells (often infiltrating)
• Meningiomas


  Grow in the meninges (encapsulated and benign)
• Metastatic tumors


  Originate in one organ and spread to another
• Types of brain tumors

  • Meningioma
  • Multiple metastatic tumor
  • Acoustic neuroma
• Stroke


  A cerebrovascular disorder of sudden onset

  
• Infarct


  An area of dead or dying tissue surrounded by penumbra
• Causes of stroke


  • Cerebral hemorrhage (Can result from bursting aneurysms)
  • Cerebral ischemia (Thrombosis, Embolism, or Arteriosclerosis)
• Ischemic brain damage


  • Takes a while to develop
  • Does not occur equally in all regions of the brain
  • Physiological mechanism varies

  
• Mechanism of ischemia


  1. Excessive release of excitatory amino acids

  2. Glutamate released when blood vessels blocked

  3. Excess glutamate release causes release of glutamate on receiving cell and can kill postsynaptic cell

  
• NMDA receptor blockers are a new research area for stroke treatment
• Closed-head injuries


  • Contusion
  • Concussion
  • Subdural hematoma
• Contusion


  • Injury includes bleeding without laceration
  • Results in hematoma
  • Caused by brain hitting skull
  • Can be countrecoup (on other side of brain from blow)
• Concussion


  • When a blow to the head disrupts consciousness
  • No evidence of contusion or other structural damage
  • Effects on cognition, motor movements, and neurological function can last many years
  • Chronic traumatic encephalopathy occurs in people who have had many concussions over time
• Infections of the brain

  • Encephalitis
  • Bacterial (Treated with antibiotics, Can cause meningitis, Brain abscesses, General paresis)
  • Viral (Some preferentially attack CNS, May play a role in etiology of many disorders, Can be dormant)

  
• Neurotoxins


  • Heavy metals (Toxic psychosis)
  • Drugs to treat neurological or psychiatric disorders (Tardive dyskinesia)
  • Endogenous (Antibodies against CNS components)
• Genetic factors


  • Can be accidents of cell division
  • Down Syndrome is an extra 21 chromosome (Disfigurement, Intellectual impairments, Medical complications)
  • Abnormal recessive or dominant genes (Most diseases involve numerous loci on chromosomes)
• Programmed cell death


  • Apoptosis (Occurs in cells that are dysfunctional, More adaptive than necrosis, Nucleus is impacted early in process)
  • Necrosis (Neuron dies passively due to injury, Can cause inflammation, Nucleus is impacted late in process)
• Epilepsy


  • Seizures recur spontaneously
  • Convulsions make diagnosis easier (Clonus/Tonus, Loss of balance/Loss of consciousness)
  • Some seizures involve changes in thought, mood, and/or behavior with no convulsions
  • Epileptic spikes may be evident in EEG
  • Auras

  
• Types of epileptic disorders

  • Focal (Simple partial, Complex partial)
  • Generalized (Tonic-clonic, Absence)
• Epilepsy treatments


  • Anti-epileptic medication
  • Vagal nerve stimulation
  • Transcranial magnetic stimulation
  • Ketogenic diet
  • Surgery
• Epilepsy EEG and neuron activity

  • Cortical EEG recorded during epileptic seizures
  • Bursting of an epileptic neuron, recorded by extracellular unit recording
  • Bilaterally symmetrical, 3-per-second spike-and-wave EEG discharge associated with absence seizures

  
• Parkinson's disease


  • Occurs in 1% of population over 55
  • More often in males
  • Symptoms (Tremor or stiffness in fingers, Tremor at rest, Muscular rigidity, Slowness of movement, Mask-like face)
• Causes of Parkinson's disease

  Degeneration of dopamine neurons in substantia nigra

  
• Parkinson's disease treatments


  • L-DOPA
  • Deep brain stimulation

  
• Huntington's disease


  • Motor disorder
  • Inherited
  • Associated with dementia
  • Symptoms (Complex jerky movements, Do not show up until 40 to 50 years of age)
  • Caused by single dominant gene (Huntingtin)
• Multiple sclerosis


  • Degeneration of myelin
  • Symptoms (Ataxia, Weakness, Numbness, Tremor, Poor vision)
  • Causes (Perhaps faulty immune system)

  
• Epidemiological studies show higher concordance in monozygotic twins (25%) than dizygotic twins (5%), occurs more in females (3X), and is higher in Caucasians and populations living in colder climates
• Multiple sclerosis lesions


  • Areas of sclerosis in the white matter
• Alzheimer's disease


  • Symptoms (Decline in memory, Emotional instability, Loss of speech function, Total dementia, Loss of ability to do simple tasks (swallow), Terminal)
  • Diagnosis (Amyloid plaques, Neurofibrillary tangles, Loss of cells in hippocampus, amygdala, entorhinal cortex)
  • Causes (Genetics)

  
• Alzheimer's disease treatments


  • Increase acetylcholine function
  • Reduce amyloid plaques
  • Treatments based on relationship between Downs and Alzheimer's
  • Treatments directed toward misfolded protein hypotheses
• Alzheimer's disease pathology


  • Amyloid plaques
  • Neurofibrillary tangles
• Kindling model of epilepsy

  • Procedure (Electrical brain stimulation once per day, Within a few days stimulation will elicit convulsion, Eventually will develop generalized convulsions, Can also be produced by chronic administration of convulsive drugs, It is a permanent procedure)
  • How it is used to study epilepsy (Convulsions mimic human epilepsy, The physiological changes that occur with kindling may mimic mechanism of developing epilepsy)
• Transgenic mouse models of Alzheimer's disease

  • Mouse embryos injected with genes that accelerate amyloid development
  • Mimics Alzheimer's
  • Mice do not develop neurofibrillary tangles
  • They do not show memory impairment
  • Helpful in the development of amyloid vaccines
• MPTP model of Parkinson's disease


  • Model development (Arose from human accident, 1982 young people report with Parkinson's symptoms, Discovered they had injected a neurotoxin called MPTP)
  • Utility of the model (Can be made in primates, not rats, Primates lose neurons in substantia nigra and have reduced dopamine, Primates develop symptoms like humans)

  
• Types of neural degeneration

  • Anterograde degeneration
  • Retrograde degeneration
• Spread of neural degeneration

  • Anterograde transneuronal degeneration
  • Retrograde transneuronal degeneration

  
• Neural degeneration and transneuronal degeneration

  • Following axotomy