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Neurotrauma June 26, 2014

Neurotrauma June 26, 2014. Neurodevelopmental Disorders. Definition . An impairment of growth & development of the CNS (generally the brain) Cell death Deficiency in migration – brain size, axon growth When most severe?. Disruption in Development. Genetics

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Neurotrauma June 26, 2014

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  1. NeurotraumaJune 26, 2014

  2. Neurodevelopmental Disorders

  3. Definition An impairment of growth & development of the CNS (generally the brain) • Cell death • Deficiency in migration – brain size, axon growth When most severe?

  4. Disruption in Development • Genetics • Infections during pregnancy, infancy • Teratogens – drugs, chemicals, heavy metals • Radiation • Nutritional deficiencies • Trauma • Post-natal environment

  5. Ancephaly • Neural tube defect – fail to close (2-3 wks gestation) • Absence of forebrain; brainstem usually intact • No cognition, consciousness • No sensory capabilities

  6. Down Syndrome (Trisomy 21) • Chromosomal abnormality • Diminished or malformed growth of frontal & temporal lobes (connections) • Delayed speech, motor skills; severe cognitive delay • Visual, auditory disturbances

  7. Fetal Alcohol Syndrome • Alcohol exposure during gestation • Alcohol blocks glutamate, enhances GABA • Effects excitation, apoptosis, neuron migration • Hyperactivity, impulsiveness, attention issues, cognitive delays, motor problems, facial abnormalities

  8. Autism • Considerable variability • Difficulties in social interaction, interpreting intentions of others • Reduced communication skills

  9. The Case of “Genie” • 1970s, 13 yr old girl • Severe sensory deprivation • 20 words/phrases (average for 18 month old) • Could not chew, wore diapers, “sniffed, spat & clawed”, disordered motor control • Learned some vocalization, nonverbal communication • Case study in “critical periods” for development

  10. Mechanisms of CNS Injury

  11. CNS Damage Disruptions in CNS physiology, behavioral changes Short/long term impact Variability in extent, capacity for recovery

  12. Tumors Abnormal cell growth – benign, malignant (cancerous) • Meningioma – between meninges • Pressure on brainstem, distortion • Neuroma – nerve or tract (axons) • Most others are infiltrating • Metastasize, diffuse; difficult to remove • Gliomas

  13. Tumors • Effects rel. to location • Cranial nerves – sensory and motor • Brainstem – autonomic responses, consciousness • Cortex – cognitive

  14. Neurotoxins Chemicals toxic to CNS • Alter neural activity, neurotransmission • Na, K, Cl channels • Heavy metal poisoning – accumulate, alter behavior • Mercury – “mad hatter” • Lead – “crackpot” • Arsenic

  15. Neurotoxins • Drugs, including ethanol • Tetrodotoxin • No known antidote, fatal • Blocks Na channels • Biotoxin– defense mechanism

  16. CNS Infection Bacterial infections Encephalitis – inflammation of brain Meningitis – inflammation of meninges Myelitis – inflammation of spinal cord

  17. CNS Infection Bacterial infections Brain abscesses (immune cells, pus) Fever, confusion, sensory deficits Antibiotics Ex. Neurosyphilis – dementia, delerium

  18. CNS Infection Viral infections • Hijack cellular mechanisms • Preventative treatments Ex. Rabies – behavioral changes (rage) • Spread disease before killing host HIV, other viruses affect behavior

  19. CNS Infection Toxoplasmosis • Parasitic infection (cats as host) • At least 25% of population • Mild, flu-like symptoms • Behavior changes increase transmission Relate to schizophrenia? (exposure during gestation)

  20. Stroke Blood loss, death of tissue Ischemic – disruption in blood supply • Thrombosis – clump of tumor, blood clot, fat • Embolism – thrombosis travels, lodges • Arteriosclerosis – thickening of vessel walls Hemorrhage – rupture of blood vessels • Aneurysm (dilation)

  21. Stroke • High blood pressure, genetics, diet • Loss of blood  excessive neurotransmitter release • Effects over time

  22. Traumatic Impact Closed head injury  brain against skull • Contusions– internal hemorrhage, hematoma • Collection of blood, pressure on tissue • Head around axis, neck injury • Spinal cord injury

  23. Traumatic Impact Concussion – absence of contusion • Cognitive changes • Altered consciousness • Balance, autonomic functions • Headache • Cervical spine injury Sub-concussive injury

  24. Traumatic Impact • Implications for behavior • Can lead to dementia, long term problems • “punch-drunk”, chronic traumatic encephalopathy (CTE) Risks for professional athletes?

  25. Recovery from CNS Injury

  26. Response to Injury • Damage may trigger apoptosis • Uncontrolled • Varied return to normal activity • Age, gender, # of previous injuries • Neuroprotective effects of hormones, exercise

  27. Reorganization & Regeneration • Neuroplasticity • Allows for some recovery • “Reroute” information • Regeneration in some species • Regrowth of neurons • In humans – rare, inaccurate

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