Consciousness

Question 1

describe “top-down” activation

Answer 1

• top-down activation is facilitated by long range bidirectional re-entrant/recursive association fibers connecting prefrontal and parietal regions to sensory regions

Question 2

conscious perception also relies on ____/_____ bidirectional _____ loops

Answer 2

conscious perception also relies on re-entrant/recursive bidirectional thalamocortical loops

Question 3

describe the levels of unconsciousness

Answer 3

• lethargic: patient can be fully aroused
• obtunded: patient cannot be fully aroused
• stuporous: sleep-like status
• comatose: no purposeful response to stimuli

Question 4

describe vegetative state (“awake coma”)

Answer 4

• develops after coma
• loss of ability to think, speak and respond
• no awareness of environment
• functions that remain intact:
  
  • breathing and circulation
  • autonomic fxns
  • non-cognitive fxns
  • normal sleep patterns
  • spontaneous emotional expressions

Question 5

describe locked-in syndrome

Answer 5

• blockage of basilar artery –> pons infarction
• tetraplegia: paralysis of all voluntary muscles with exception of vertical eye movements
• fxns still intact:
  
  • fully aware of environment
  • cognition: thinking, remembering, visualizing
  • EEG and cortical metabolic activity are typically normal

Question 6

describe brain death

Answer 6

• irreversible loss of all brain fxns
• etiology:
  
  • anoxia
  • ischemia
  • intracranial hemorrhage
  • trauma
  • brain tumors
  • increased intracranial pressure and uncal herniation

Question 7

describe what is seen in this CT scan

Answer 7

• CT of a pt with bilateral middle cerebral artery infarcts
• the RAS in the intact midbrain (arrows) allows wakefulness but the bihemispheric lesions prevent awareness

Question 8

describe how to diagnose brain death

Answer 8

• not responsive to speech, pain or other stimuli
• no spontaneous respiration
• pupils dilated, not reactive to light
• no vestibulo-ocular reflex (COWS)
• no corneal reflex
• isoelectric EEG

Question 9

describe what is seen in the CT scan

Answer 9

• CT of a pt with basilar artery occlusion who exhibits “locked-in” syndrome
• the pontine infarction (arrows) is below the level of the RAS, allowing wakefulness but the bilateral descending motor tracts have been trasected

Question 10

describe the Glasgow coma scale scoring

Answer 10

8 is the critical score

• ≤ 8: 90% are in coma
  
  • ≤ 8 at 6 hours: 50% will die
• ≥ 9: not in coma

Question 11

describe this respiratory pattern and where the lesion is located

Answer 11

Question 12

describe the resp. pattern and where the lesion is located

Answer 12

Question 13

describe the resp. pattern and where the lesion is located

Answer 13

Question 14

describe the resp. pattern and where the lesion is located

Answer 14

Question 15

describe the response to a local painful stimulus in a comatose patient with an upper midbrain injury (bilateral)

Answer 15

• decorticate posturing

Question 16

describe the local response to painful stimulus in comatose patients with injury below the midbrain (to the upper pons)

Answer 16

Question 17

describe the pupillary light response when lesions are at different areas

Answer 17