Flashcards in The Approach to Coma and Altered Consciousness Deck (21):
Simply put, what is a coma?
a state of unarousable unresponsiveness
The first steps in coma evaluation are 1) ABCs 2) look for obvious etiology clues and 3) try reversing common reversible etiologies. What are the three "drugs" given for this purpose?
Essentially, what does the mental status exam entail in a coma patient?
level of consciousness -- see what they will respond to. Voice command? Loud voice? Sternal rub?
if they do respond to voice, try to assess attention, language, visuospatial function, etc.
What part of the neuro exam is most helpful to assess brainstem function in a coma exam?
In an unresponsive patient, how do you test cranial nerves II and III?
pupillary light reflex
In an unresponsive patient, how can you test CN III, IV, VI and VIII? (two ways...)
the oculocephalic reflex (doll's eyes)
calorics if necessary
What is a normal result for caloric testing?
inject 50 mL of ice water into each ear and observe for conjugate eye deviation toward the injected ear
In an unresponsive patient, how can you test trigeminal V1 and VII?
In an unresponsive patient, how can you test CN IX and X/XI?
In an unresponsive patient, how can you test visual fields?
check for blink in response to visual threat
In general, what are the two main ways in which consciousness can be depressed?
1. brainstem dysfunction
2. dysfunction in both cerebral hemispheres
(but also large hemispheric lesions that cause pressure on the other side)
The absence of a brainstem reflex suggests the dysfunction is higher or lower in the brainstem?
What is the typical first-step imaging modality for coma?
head CT (non-contrast is hemorrhage is a possibility)
Is it ever ok to do an LP before a CT in a coma patient?
No, even if bacterial meningitis is suspected, you're better off starting empiric antibiotics and then getting a CT prior to the LP in this situation
Elevated ICP can be an emergency if the patient has signs of herniation, but if there are no emergent signs, what are a few strategies to lower ICP?
raise the head of the bed
osmotic diuretic like mannitol
corticosteroids only with edema from tumors
What are the main prognostic factors in coma?
etiology and age
How does a persistent vegetative state differ from coma?
they have lost all awareness and cognitive function but may remain with their eyes open, exhibit sleep-wake cycles and maintain respiration
How does a locked-in patient differ from a coma patient/
Locked-in patients are awake and may not have any abnormalities of consciousness - they just can't move anything except their eyes
Where is the lesion in locked-in syndrome?
base of the pons
What are the typical guidelines for how brain death can be declared?
in general, patient must be comatose, with absent brainstem reflexes, no spontaneous respirations (even when pCO2 is allowed to rise)
no confounding factors of hypothermia or drug OD
EEG with electrocerebral silence or cerebral angiography with absence of blood flow to the brain