Coma

Question 1

what are the two types of alterations in consciousness?

Answer 1

• arousal

- cognitive and affective mental functioning

Question 2

definition: coma

Answer 2

• unarousable unresponsiveness
• “a sleeplike state in which the patient makes no purposeful response to the environment and from which he cannot be aroused”

Question 3

in order for a coma to occur, at least one of which three mechanisms must exist?

Answer 3

must knock out either BOTH HEMISPHERES or the BRAINSTEM

• DIFFUSE, bilateral, and widespread destruction of hemisphere cortex
• discernable lesion that destroys brainstem structures
• DIFFUSE subcellular or molecular / metabolic dysfunction

Question 4

in which part of the brainstem does the reticular activating system reside?

Answer 4

posterior pons

Question 5

all of the neuro exam may be performed on a comatose patient except for __________ and ____________

Answer 5

coordination and gait

Question 6

are cerebral hemispheres assessable in a comatose patient?

Answer 6

no

Question 7

the neuro exam in a comatose patient is designed to assess the __________

Answer 7

brainstem

Question 8

normal respiration requires which brain areas to be intact?

Answer 8

brainstem and forebrain

Question 9

which respiratory pattern is the only one that is NOT related to a brainstem dysfunction?

Answer 9

Cheyne-Stokes (hemispheric dysfunction)

Question 10

as you go further down in the brainstem, how do brainstem patterns change?

Answer 10

more disorganized (worse)

Question 11

what are the pupil features for lesions in the:

• thalamus
• midbrain
• pons
• uncus

which is most important? why?

Answer 11

thalamic - small but reactive
midbrain - midposition and fixed
pontine - pinpoint but reactive
uncal - dilated, asymetric and fixed

uncal - indicates impending death because brain is herniating

Question 12

downward eye deviation indicates a lesion where?

Answer 12

brainstem

Question 13

for caloric testing (ice water in ear) - where do the eyes deviate in a COMATOSE patient? how does this differ from an awake patient?

Answer 13

• comatose: toward side of stimulus

- awake: opposite side of stimulus

Question 14

the fast beat of nystagmus is driven by the ____________

Answer 14

hemispheres

Question 15

is there “beating” / fast component in a comatose patient? why or why not?

Answer 15

• no

- fast beat is driven by the hemispheres, but in a comatose patient the hemispheres are knocked out

Question 16

decorticate posturing

Answer 16

bilateral flexion at elbows and wrists with extension of the lower extremities

Question 17

where is the lesion for decorticate posturing?

Answer 17

usually above brainstem

Question 18

decerebrate posturing

Answer 18

bilateral extension of elbows with extension of the lower extremities

Question 19

where is the lesion for decerebrate posturing?

Answer 19

usually bilateral midbrain or pontine