89b - Brain States and Coma

Question 1

List the following brain states from most responsive to least responsive:

Coma, obtundation, stupor

Answer 1

• Obtundation - Most responsive; similar to stupor but w/ a milder reduction in arousal level
• Stupor - Vague term, between alert an in a coma
  
  • Patient can respond purposefully, but requires constant stimulation to engage
• Coma - Unresponsive; Patient cannot be stimulated to responsd purposefully
  
  • no evidence of awarenss, no eye opening, or evidence of circadian rhythm

Question 2

What is the medical definition of brain death?

Answer 2

Brain Death = irreversible loss of all functions of entire brain; based on function, not anatomic death (every neuron doesn’t have to die for someone to be brain dead)

• No purposeful response to any stimuli
  
  • Including noxious stimuli
• No brainstem reflexes
• No spontaneous respiratory movments
• Clear underlying etiology
  
  • Not due to medications or sedatives

May be present:

Simple reflexes, circadian rhythm, autonomic function

Question 3

How will a patient with abulia present/act?

Answer 3

Abulia = apathetic state w/ cognitive behavioral slowing (psychomotor retardation) but intact cognitive function

• Slowing of cognitive and behavioral function
• Intact cognitive function
• Apathy

Often caused by medial frontal lobe injuries

Question 4

How can you tell if a patient is in a coma or “locked in”?

Answer 4

A person who is locked in may be able to move their eyes up in response to commands

• Patients with locked in syndrome are conscious, but unable to effectuate muscles

Question 5

What is the difference between a vegetative state and a minimally conscious state?

Answer 5

• Vegetative state
  
  • No purposeful response to stimuli
    
    • No environmental awareness
  • No brainstem reflexes
  • No spontaneous repsiratory movements
  • Eyes may open and rove randomly
• Minimally conscious state
  
  • May require respiratory support
  • Behavioral evidence of self or environmental awareness
  • Eyes may lock onto familiar faces, objects rather than just roving eye movements

Question 6

Which part of the brain mediates arousal and sleep/wake changes?

Answer 6

• Ascending Reticular Activating System (ARAS) is a small collection of nuclei that start in the brainstem and induce arousal using ACh and NE.
  
  • starts in the midbrain, then to interlaminar nuclei of thalami, then to cortex

Damage to ARAS and/or pathway results in impaired arousal

Question 7

What is the difference between a coma and a vegetative state?

Answer 7

Patinets who are brain-dead will progress from coma to vegetative state in 10-30 days

In both states, the patient cannot respond purposefully, has no respiratory drive, and no brainstem reflexes

• Coma
  
  • No eye opening
  • No circadian rhythm
• Vegetative state
  
  • some Circadian rhythm restored
  • Periods of eye opening, roving eye movement
  • Autonomic changes observed

Question 8

Injury at which 3 areas of the brain can result in decreased level of arousal?

Answer 8

• Ascending Reticular Activating System (ARAS) is a small collection of nuclei that start in the brainstem and induce arousal using ACh and NE.
  
  • starts in the midbrain interlaminar nuclei of thalami cortex
  • this means that impairment of arousal is due to injury to ARAS in midbrain, injury to both thalami that interrupt transmission to cortex, or widespread dysfunction of both cerebral hemispheres
    
    • even large focal brain injuries do not cause coma by themselves

Question 9

What is the difference between abulia and akinetic mutism?

Answer 9

• Abulia = apathetic state w/ cognitive behavioral slowing (psychomotor retardation) but intact cognitive function
  
  • caused by medial frontal lobe injuries
• Akinetic mutism = extreme form of abulia caused by bilateral basal-medial frontal lobe injuries involving the hypothalamus

Both involve slowing of cognitive and behavior functions

Question 10

Injury to the ______ results in locked in syndrome

Describe the syndrome

Answer 10

Injury to the pons results in locked in syndrome

Patients are paralyzed except upward eye movments - no cognitive impairment

patients are conscious but unable to move muscles

Question 11

What is cardiac death vs. brain death?

Answer 11

• Cardiac death = when heart quits beating and can’t be induced to resume
• Brain Death = irreversible loss of all functions of entire brain; based on function, not anatomic death (every neuron doesn’t have to die for someone to be brain dead)
  
  • brain dead criteria: no purposeful responses to stimuli, no brainstem reflexes, no spontaneous respiratory movements
    
    • must have identified a clear cause of the massive brain injury
    • make sure that there is nothing confounding the exam findings
  • movements generated by spinal cord may be seen (ex. reflexes)