Brain Death & Coma Flashcards
Define coma
UNarousable & UNresponsive
(don’t use stupor or obtunded; it is too subjective)
What keeps humans awake and alert
(system?)
Ascending Reticular Activating System (ARAS)
ARAS receives input from the _______ & ______.
- vestibular
- auditory apparatus
ARAS sends information received from the auditory and vestibular apparatus to the ________ → _______ → cortex
raphe & reticular nuclei → intra-laminar thalamic nuclei
_____ provides a relay of inputs to the cerebral cortex.
intralaminar thalamic nuclei
(this gives us conscious perception)
4 Primary mechanisms of coma (causes)
- toxic
- metabolic
- infection
- hypothermia
(always check glucose)
coma patient: upon arrival, what do you do (3)?
- interview EMT
- friends/fam
- check medical alert bracelet or old charts
If a patient abruptly becomes comatose, it is likely due to ______.
subarachnoid hemorrhage or seizure
If a patient gradually becomes comatose, it is likely due to ______.
brain tumor
If a patient fluctuations into coma, it is likely due to _____ (3).
- metabolic
- subdural hematoma
- recurring seizure
If the coma patient has focal signs prior to LOC, it is likely due to ______.
structural lesion
If a coma patient has transient visual sx prior to LOC, it is likely due to _______.
structural lesion
If a coma patient has headache and N/V prior to LOC, it is likely due to _______.
Subarachnoid hemorrhage
(they would also lose consciousness abruptly)
Coma patient presents & blood gas shows acidosis. If they are hyperventilating, the cause is ______. If they are hypoventilating, the cause is _______.
- metabolic acidosis (uremia, DKA, alcohol)
- respiratory acidosis (respiratory failure or peripheral NS disease)
Coma patient presents & blood gas shows alkalosis. If they are hyperventilating, the cause is ______. If they are hypoventilating, the cause is _______.
- respiratory alkalosis (hepatic failure, sepsis)
- metabolic alkalosis (vomiting, alkali ingestion)
ipsilateral mydriasis in a coma patient indicates______.
intracranial herniation
(MC is uncal)
Coma patients with mid/fixed pupils indicate _____ or _____ (location of lesion).
- midbrain/upper pons
- medulla
If a coma patient has pinpoint/fixed pupils, this indicates lesion location in the _______.
lower pons/medulla
A coma patient with a vestibulo-ocular reflex indicates a _______ lesion location
diencephalic
(all others will have absent VOR)
deCORTicate indicates ______ lesion location; deCEREbrate indicates _______ lesion location.
- diencephalic
- midbrain/upper pons
Triple flexion in a coma patient indicates _______ lesion location.
lower pons/medulla
define Triple flexion (motor response)
foot stimulation → thigh & leg flexion, dorsiflexion
Cheyne-stokes breathing indicates a ______ lesion location.
(pronounced “shane-stokes”, ramps up and ramps down)
diencephalon
Hyperventilation indicates a ______ lesion location.
midbrain
Apneustic breathing indicates a ______ lesion location.
(pronounced “app-new-istic”; slow & stops at times)
rostral pons
Ataxic breathing indicates a ______ lesion location.
lower pons
Respiratory arrest indicates a ______ lesion location.
upper medulla
Decorticate posturing has the arms in ______ and the lesion is ______ to the red nucleus.
- flexion
- caudal
(Decerebrate is the opposite)
Asterixis
flapping and extended arms and wrists
asterixis indicates
hepatic encephalopathy
(commonly seen in alcoholics)
If a patient is conscious with altered consciousness, what are 3 exams you can utilize to asses the cause?
- kernig (lift their knee)
- brudzinski (lift their brain)
- MMSE
Conditions that are mistaken for coma
- Locked-in syndrome
- Akinetic mutism
(also psychogenic unresponsiveness/dissociative attack)
2 requisites for locked-in syndrome
(often mistaken for coma)
- alert & retain cognitive ability
- paralysis of limbs and oral structures w/some blinking & vertical eye movement
_______ causes locked-in syndrome
(commonly mistaken for coma).
focal injury to base of pons (embolic occlusion of the basilar a.)
DDx: locked-in syndrome (4)
- myopathy/neuropathy
- severe upper spinal cord lesion
- NMJ disease
- extreme muscle rigidity
Akinetic mutism is due to _____ injury
prefrontal or premotor
Akinetic mutism patients can _______, but does NOT _____.
- follow with eyes
- initiate other movements or obey commands
_____ (3) remains in tact with akinetic mutism patients
- tone
- reflexes (including cold calorics)
- postural reflexes
psychogenic unresponsiveness: key to diagnosis
resist passive eye opening
psychogenic unresponsiveness patients will roll away from _____ and turn their eyes ______.
- painful stimuli
- toward the floor no matter which side they are lying on
psychogenic unresponsiveness diagnosis is supported by _______.
cold caloric stimulation
(positive test also indicates akinetic mutism)
vegetative state
no awareness of self or environment, but cycling of arousal states and periodic eye opening
persistent vegetative state
vegetative state > 30 days
Persistent vegetative state patients can be maintained for ______ (time); brain dead patients can be maintained for _____ (time)
- 37 years
- 3 months
Persistent vegetative state patients are legally alive and have lost ______ function; brain dead patients are legally dead and have lost ______ function
- cerebral ONLY
- cerebral & brainstem
Prognosis for persistent vegetative state? Brain death?
- can maintain for 37 years; rare recovery
- 3 months; NO recovery cases
Locked-in syndrome lesion location
pontine
coma lesion location
bilateral cerebral or upper brain stem
Akinetic mutism lesion location
- bifrontal deep gray matter
- upper brain stem
Catatonia lesion location? Persistent vegetative state?
- NONE
- diffuse cerebral hemisphere
Glasgow Coma Scale Eye opening scale
4-1
Glasgow Coma Scale for verbal
5-1
Glasgow coma scale for motor function has _____ possible points. What are the items on the list?
- 6
- follows commands
- localizes to pain
- withdraws from pain
- abnormal flexion
- abnormal extension
- none
Best possible score on Glasgow Coma Scale
15
(10T if intubated; -5 because they can’t talk)
Worst possible Glasgow Coma Scale Score
3
(2T when intubated)
Define brain death (4)
- absence of consciousness
- lack of motor response to noxious stimuli
- NO brainstem reflexes
- NO respiratory drive
(irreversible)
Before determining the brain death, you must check for _______ (5 clinical features).
- medications/toxins
- clear C-spine
- no severe electrolyte or endocrine disturbance
- normal SBP
- euthermic
Brainstem reflexes (5)
- pupillary response
- ocular movements
- corneal reflex
- no fascial muscle movement to noxious stimulus
- gag reflex absent
Oculocephalic or oculovestibular: abnormal reflex
eyes stuck in head/fixed when head is moved
(normally they will move with the head, but lag)
Caloric testing : normal response
(make sure he head of bed is 30 raised & have intact TMs)
- 50 mL ice water into RIGHT ear w/head straight up: eyes will deviate to right (left mid-brain intact)
- nystagmus toward midline (left frontal lobe in tact)
What does it indicate when caloric testing is done by inserting ice water into the RIGHT ear and eyes deviate to RIGHT w/no nystagmus
no cortical response
(must wait 1 minute)
What does it indicate when caloric testing is done by inserting ice water into the RIGHT ear and eyes do NOT deviate and there is no nystagmus
no midbrain or cortical response
(wait 3-4 minutes and examine the other side)
Caloric testing: what is the normal response if you insert cold water into both ears at once?
- both eyes initially go down
- vertical nystagmus
corneal reflex
touch cornea with wisp of cotton → blinking
(V1 sensory → VII motor response of obicularis oculi)
How do you test for facial muscle movement in response to noxious stimuli (2)?
- press on mandibular condyles at TMJ
- press on subraorbital ridge
How do you test the cough/tracheal reflex?
catheter into the trachea to carina → 2 sweeps suction motions → cough
How do you perform the apnea test?
oxygenate to >95% → unplug the respirator → put oxygen near face → blood gas
(positive if second blood gas is < 62 mmHg)
Test to confirm brain death (5)
- EEG
- Cerebral or CT angio
- Nuclear scan
- Transcranial doppler
- MRI/MRA
