Coma Flashcards
what are the two types of alterations in consciousness?
- arousal
- cognitive and affective mental functioning
definition: coma
- unarousable unresponsiveness
- “a sleeplike state in which the patient makes no purposeful response to the environment and from which he cannot be aroused”
in order for a coma to occur, at least one of which three mechanisms must exist?
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
in which part of the brainstem does the reticular activating system reside?
posterior pons
all of the neuro exam may be performed on a comatose patient except for __________ and ____________
coordination and gait
are cerebral hemispheres assessable in a comatose patient?
no
the neuro exam in a comatose patient is designed to assess the __________
brainstem
normal respiration requires which brain areas to be intact?
brainstem and forebrain
which respiratory pattern is the only one that is NOT related to a brainstem dysfunction?
Cheyne-Stokes (hemispheric dysfunction)
as you go further down in the brainstem, how do brainstem patterns change?
more disorganized (worse)
what are the pupil features for lesions in the:
- thalamus
- midbrain
- pons
- uncus
which is most important? why?
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
downward eye deviation indicates a lesion where?
brainstem
for caloric testing (ice water in ear) - where do the eyes deviate in a COMATOSE patient? how does this differ from an awake patient?
- comatose: toward side of stimulus
- awake: opposite side of stimulus
the fast beat of nystagmus is driven by the ____________
hemispheres
is there “beating” / fast component in a comatose patient? why or why not?
- no
- fast beat is driven by the hemispheres, but in a comatose patient the hemispheres are knocked out
decorticate posturing
bilateral flexion at elbows and wrists with extension of the lower extremities
where is the lesion for decorticate posturing?
usually above brainstem
decerebrate posturing
bilateral extension of elbows with extension of the lower extremities
where is the lesion for decerebrate posturing?
usually bilateral midbrain or pontine
