Arousal Coma And Unconsciousness

Question 1

Define arousal

Answer 1

State of wakefulness - self aware and can communicate

Question 2

Define consciousness

Answer 2

Arousal and content

Awareness of both self and the external environment determined by a motor response to internal or external stimuli

Question 3

Define coma

Answer 3

Total absence of awareness of both self and the external environment
Severest impairment of arousal is the inability to
- obey commands
- speak
- open eyes to pain
GCS 3-8
Sleep like but cannot be roused

Question 4

What is the lowest GCS

Answer 4

3

Question 5

What are the three parameters assessed in the GCS

Answer 5

Eye opening
Best verbal response
Best motor response

Question 6

Eye opening types and equate to what number

Answer 6

Spontaneous 4
To speech 3
To pain 2
Non 1

Question 7

Best verbal response types and number

Answer 7

Orientated 5
Confused 4
inappropriate 3
Incomprehensible sounds 2
None 1

Question 8

Best motor response and number

Answer 8

Obeys commands 6
Localised pain 5
Flexion to pain 4
Flexion abnormal 3
Extension 2
None 1

Question 9

What does consciousness depend on

Answer 9

Functioning reticular activating system in Thalamus - works as a relay station - connects to cortex without is in for cannot come in and out the brain
Functioning cortex -brain not damaged

Question 10

Arousal and awareness require …

Answer 10

… an intact reticular activating system

Question 11

Cognition and consciousness require …

Answer 11

… intact cerebral cortex

Question 12

What is the main component of the ascending reticular activating system

Answer 12

Tegmental tract
Receives - info from the surrounding neural tissue
Conveys - impulses through multineuronal, polysynaptic pathways to hypothalamus and thalamus and thence to the cerebral cortex

Question 13

Altered states of consciousness - acute

Answer 13

• clouding of consciousness - attention lack, slow thinking, confusion, memory loss, drowsiness - alcohol
• delirium - as above + disorientation and hallucinations
• stupor- sleep like state, rousable with vigorous stimulation unlike a coma
  Can be caused by drugs or lack of oxygen

Question 14

Altered states of consciousness - chronic

Answer 14

Dementia - mental function, memory, comprehension and speech
Hypersomnia - excesssive drowsiness intermittent wakeming
Vegetative state - after severe brain injury awake but no evidence of conscious intelligence

Question 15

Causes of a coma

Answer 15

Lesions causing diffuse brain dysfunction
Supratentorial mass lesions causing brain stem compression- cerebral
Infratentorial lesions causing brain stem compression - cerebellar and brain stem
Intrinsic lesions of the brain stem itself
Psychiatric states that may mimic comatose states - drugs

Question 16

How do you know the conscious state of the lesion causing coma ?

Answer 16

• pupillary signs
• oculicephalic and oculovestibular signs
• motor response to painful stimulus
• respiratory system

Question 17

Pupil size and reaction contorted by

Answer 17

PS pupillary constrictor - runs with the occulomotor nerve from the EW nucleus innervate ciliary constructed causes the pupil to constrict

S pupillary dilator - nerve arise from the post sympathetic nerves arising from the superior cervical ganglion

Question 18

Parasympathetic pathway

Answer 18

Retina -> optic N -> optic tract -> lateral geniculate nucleus -> 90% to occipital cortex -> 10% to EW nuclei -> PS Pre G with III -> ciliary ganglion -> PS post G -> short ciliary nerve -> constrictor muscle -> constrict

Question 19

Sympathetic pathway

Answer 19

Hypothalamus -> via brainstem and cervical spinal cord -> thoracic 1 -> via ventral roots and sympathetic chain -> Sup Cervial Gang -> via carotid artery and cranial cavity -> III -> levator palp superioris + nasocilary/ciliary G BV of eye and nasociliary and long ciliary pupil

Question 20

What are the metabolic causes of fixed dilated pupils

Answer 20

Anoxic encephalopathy
Anticholinergics - atropine
Botulism

Question 21

Oculocephalic reflex

Answer 21

Conscious - eyes move with head

Unconscious - rotate head to one side and eyes remain in original position and slowly relate to mid position

Question 22

Oculovestibular reflex -

Answer 22

Head to 30 degrees
Cold water in ear - normal: slow deviation to side and then fast opposite
Comatose: patient tonic deviation to cooled side
No reaction indicates severely damaged brain stem
Metabolic coma can show normal or depresses

Question 23

Other patterns associated with damage

Answer 23

Motor reflexes
Abnormal patterns of breathing
Automatic breathing

Question 24

Causes of coma

Answer 24

Diffuse brain dysfunction
Supratentorial lesion
Uncal / tentorial herniation
Subtentorial lesions