Neurocritical Care

Question 1

warfarin-related intracranial hemorrhage with high INR. treatment?

Answer 1

worst to best:

1. IV vitamin K (takes 6-24 hours to make new coag factors)
2. FFP - provides many coag factors quickly, but need to test compatibility and administer correctly, only transient correction. risk of fluid overload, infusion rxn
3. PCC (prothrombin complex concentrates) - quickly correct INR if available. less complications.

Question 2

protamine sulfate used for what?

Answer 2

reverse anticoagulation due to heparin

Question 3

critical illness polyneuropathy - what kind of neuropathy is it? NCS/EMG findings?

Answer 3

axonal sensory and motor neuropathy that affects limbs and respiratory muscles - takes longer to recover than CIM

reduced CMAPs and SNAPs, with normal or mildly reduced conduction velocities

fibs and sharp waves on EMG

Question 4

predictive factors after cardiac arrest

Answer 4

no pupillary response 24-72 hours after arrest - bad
no corneal reflexes or eye mvtments 72 hours out - bad

EEG showing burst suppression or generalized suppression - bad
evoked potentials with median nerve stimulation showing bilateral absent N20 responses at 24-72 hours - bad (best biomarker early on)
neuron specific enolase elevated - bad

duration of arrest, CT edema, physical exam before 72 hours not reliable

Question 5

how to perform apnea test for brain death exam

Answer 5

preoxygenate x 10 minutes with FiO2 100%
baseline ABG - pCO2 should be 35-45

then disconnect from vent but give 6 L/min O2
observe for 10 min - look for chest rise/abd rise
after 10 min repeat ABG. if no resp movements and pCO2 > 60, supportive of brain death

BODY TEMP SHOULD BE 36.5 or higher and SBP >90

Question 6

ancillary tests to support brain death (4)

Answer 6

EEG showing electrocerebral silence x 30 min
TCDs showing no flow signals
PET scan showing no isotope uptake in brain, no intracranial flow
Angiography showing no flow in circle of willis

Question 7

decorticate rigidity - what does it look like and where is the lesion

Answer 7

arms flexed, legs extended
hemispheric dysfunction
lesion ABOVE RED NUCLEUS –> disinhibition of red nuclei, facilitation of rubrospinal tracts (which increase flexor tone in arms)

Question 8

decerebrate - what does it look like and where is the lesion

Answer 8

extension + hyperpronation of arms, extended legs
pinpoint pupils

lesion in brainstem at/below superior colliculus and red nucleus, but ABOVE VESTIBULAR NUCLEI (enhance extensor tone)

lesions below vestibular nuclei –> flaccid limbs

Question 9

Cerebral Perfusion Pressure equation

Answer 9

CPP = MAP - ICP

CPP ideally > 70
ICP normal 5-15
MAP >60

Question 10

subfalcine herniation

Answer 10

cingulate gyrus (which hugs the corpus callosum) herniates under the falx cerebri (the sagittal membrane)

pericallosal and callosomarginal arteries compressed

Question 11

uncal herniation

what sign occurs on exam?

Answer 11

medial temporal lobe herniates medially and down over tentorial edge

pushes onto midbrain –> fixed dilated pupil + contralateral hemiparesis (but if it pushes Kernohan’s notch on the other side, it can cause ipsilateral weakness)

PCA infarct can also occur

Question 12

tonsillar herniation

Answer 12

cerebellar tonsils are pushed down through foramen magnum, compress medulla and block 4th vent –> hydrocephalus

Question 13

transcalvarial herniation

Answer 13

brain tissue squeezes out through a skull defect (due to trauma or hemicrani)

Question 14

central transtentorial herniation

Answer 14

expanding lesion in middle of brain causes downward displacement, pushing against midbrain

Question 15

relationship between hematocrit and CBF

Answer 15

lower hematocrit = lower blood viscosity = increased CBF

Question 16

rise of end-tidal CO2 with anesthesia, then muscle rigidity, hyperthermia, AMS, rhabdo

Answer 16

malignant hyperthermia
autosomal dominant - ryanodine receptor mutation
treat with dantrolene (blocks release of calcium from sacroplasmic reticulum)

Question 17

patient on antipsychotics with hyperthermia, rigidity, AMS, autonomic instability

Answer 17

neuroleptic malignant syndrome

stop antipsychotics
tx with dantrolene and bromocriptine

Question 18

patient on SSRIs with hyperthermia, AMS, hyperreflexia, clonus, rigidity

Answer 18

serotonin syndrome

stop the meds
supportive tx - benzos

Question 19

how to prognosticate 30-day mortality for iCH?

Answer 19

low GCS, ICH volume > 30 mL, if IVH, if infratentorial, if > 80 –> extremely high risk of death within 30 days

if high GCS, ICH smaller than 30 mL, no IVH, supratentorial, and younger than 80 –> very low risk of death in 30 days

Question 20

precedex - dexmedetomidine

Answer 20

alpha 2 agonist

patients can be aroused without discontinuing

Question 21

propofol

Answer 21

GABA agonist

quick on, quick off

propofol infusion syndrome: prolonged use of high doses, bradycardia, rhabdo, renal failure, lactic acidosis

Question 22

lorazepam vs midazolam - duration of action

Answer 22

both work within 2 minutes

lorazepam lasts up to 12 hours, midaz only 1-2 hours