neuro critical care

Question 1

What are three types of cerebral edema?

Answer 1

1. vasogenic 2. cytotoxic 3. interstitial

Question 2

What is interstitial edema associated with?

Answer 2

seen in acute obstructive hydrocephalus; as the CSF is forced by hydrostatic pressure to move from the ventricular spaces to the interstitium of the parenchyma

Question 3

What is vasogenic edema?

Answer 3

an extracellular accumulation of fluid that is usually associated with a disruption in the BBB

Question 4

What is cytotoxic edema?

Answer 4

intracellular accumulation of fluid due to hypoxic-ischemic insult leading to depletion of ATP and subsequent failure of the Na+K+ ATPase, causing an alteration in the selective permeability of cellular membranes. This leads to intracellular edema

Question 5

What is the goal target for therapeutic hypothermia and how long do you maintain it for?

Answer 5

32 to 34 degrees Celsius and for 12 to 24 hours

Question 6

The evidence supports hypothermic therapy in cardiac arrest associated with what particular arrhythmias?

Answer 6

cardiac arrest from VF; limited evidence in the setting of non-VF rhythms, including PEA or asystole

Question 7

What are potential complications for hypothermic therapy? (4)

Answer 7

1. coagulopathy 2. arrhythmias 3. electrolyte abnormalities 4. risk of infections

Question 8

Uncal herniation presents with what 3 findings caused by compression of what 3 structures?

Answer 8

1. compresses parasympathetic fibers that mediate miosis resulting mydriasis (fixed dilated pupil localizes the side of the uncal herniation) 2. if uncus compresses ipsilateral cerebral peduncle - contralateral hemiparesis 3. compression of PCA - infarction

Question 9

What is the normal ICP range?

Answer 9

5-15 mmHg

Question 10

general txt of ICP (6)? specific txt of ICP (9)?

Answer 10

General txt: 1. head of the bed at 30 degrees 2. maintain normothermia 3. glucose control 4. BP control 5. adequate nutrition 6. prevention of complications specific txt: 1. hyperventilation 2. osmotic agents (ie mannitol) 3. hypertonic solutions 4. corticosteroids in select cases (ie brain tumor) 5. CSF drainage 6. surgical decompression in select cases 7. barbiturate coma 8. pharmacologic ppx 9. hypothermia

Question 11

How long does the effect of hyperventilation on ICP last for?

Answer 11

10 - 20 hours and subsequently a rebound phase with increased ICP may be seen

Question 12

How does hyperventilation work to decrease ICP?

Answer 12

hyperventilation –> reduction in partial pressure of CO2 –> hypocapnia –> cerebral vasoconstriction –> decrease cerebral blood vol –> reduction in ICP

Question 13

What is the target pCO2 in hyperventilation?

Answer 13

a reduction of pCO2 by 10 mmHg and or to a target of 30mm Hg

Question 14

How does mannitol work? What is the dose and the target serum osmolarity?

Answer 14

-raises the serum osmolarity producing an osmotic gradient that drives water from the interstitium to the intravascular compartment -boluses of 0.5 to 1.5g/kg -target level no higher than 320 mOsm/L

Question 15

Prolonged infusion of sodium nitroprusside can lead to what kind of toxicity? What is the treatment?

Answer 15

-cyanide and thiocynate toxicity (metabolites toxicity) txt: -sodium thiosulfate transform cyanide into thiocynate -although thiocynate is still toxic, it can be excreted by the kidneys -thus can also be treated with dialysis

Question 16

What is the appearance of SDH on head CT?

Answer 16

crescent or concave shape

Question 17

What causes SDH?

Answer 17

trauma that produces an acceleration force that causing tearing/rupture of the surface bridging veins

Question 18

When is surgical evacuation indicated for SDH?

Answer 18

if the SDH is more than 1 cm or if there is midline shift

Question 19

What is the appearance of epidural hematoma on head CT?

Answer 19

lenticular shaped or biconvex

Question 20

What causes epidural hematomas?

Answer 20

rupture of the middle meningeal artery (usually associated with a skull fracture)

Question 21

Describe Lundberg A, B waves, anc C waves in ICP monitoring. What is the significance of these waves, duration, and amplitude?

Answer 21

• Lundberg A waves are pathological; associated with decrease intracranial compliance, intracranial hypertension, with risk of ischemia. Also known as plateau waves. Duration 5 to 20 minutes. Amplitude ranges from 50 mmHg to 100 mmHg.
• B waves are normal; duration 1 -2 minutes; amplitude 20 to 50 mmHg
• C waves are normal; duration 4 to 5 minutes; amplitude < 20 mmHg

Question 22

What is the initial management of SAH? (5)

Answer 22

1. if cannot protect airway - intubate 2. avoid hypertension/control BP (one aneurysm is secured then you can be more liberal with BP) 3. aggressive isotonic fluids 4. ppx AED 5. mild sedation/optimize pain control

Question 23

What is the CCB of choice that has been shown to improve outcomes from vasospasm? What is the dose and duration of therapy?

Answer 23

Nimodipine; 60mg Q 4hours for 21 days

Question 24

What is triple H therapy?

Answer 24

hypervolemia, hypertension, hemodilution Recommended for treatment of vasospasm

Question 25

What are the risks of triple H therapy?

Answer 25

1. rebleeding from unsecured aneurysm 2. pulmonary edema 3. congestive heart failure 4. cerebral edema

Question 26

What is apneusis and where does it localize to?

Answer 26

respiratory pause at full inspiration and occurs from bilateral pontine lesions

Question 27

What is Cheyne-Stoke respiration? Where does it localize to?

Answer 27

hyperpnea alternates with apnea and depth of breathing increases and decreases gradually -poorly localizing; can be seen with forebrain impairment in the setting of intact brainstem respiratory reflexes, but also present in severe cardiopulmonary disease

Question 28

What is ataxic breathing and where does it localize to?

Answer 28

irregular respiratory pattern (gasping respiration) seen with lesion damaging the respiratory rhythm generator in the upper medulla

Question 30

What is the treating of ICH in the setting of Warfarin with an INR of 6?

Answer 30

1. withhold warfarin 2. give vitamin K dependent factors (FFP or prothrombin complex concentrates) 3. IV Vitamin K

Question 31

What is the treatment of ICH for pt who is on a NOAC?

Answer 31

some patients are on newer oral anticoagulants including factor Xa inhibitors and direct thrombin inhibitor. - Dabigatran is a direct thrombin inhibitor with reversal agent idarucizumab - no available reversal agents for Rivaroxaban and Apixaban

Question 32

What are risk factors for critical illness polyneuropathy and myopathy?

Answer 32

1. sepsis 2. SIRS 3. use of neuromuscular blocking agents 4. use of steroids 5. poor nutrition 6. abnormal glucose levels 7. low albumin levels

Question 33

What are the EMG findings for critical illness polyneuropathy? Histopathology findings?

Answer 33

- nerve conduction studies with reduction in CMAPs and SNAPs - normal or mildly reduced conduction velocities Histo: axonal degeneration of motor and sensory fibers and denervation atrophy

Question 34

What are the EMG findings in critical illness myopathy? Histology findings?

Answer 34

- SNAP \> 80% of the lower limit of normal - low amp CMAPs fibrillation potentials and positive sharp waves Histo: loss of thick myosin filaments and varying degrees of necrosis

Question 35

Requirements for the diagosis of brain death (6)

Answer 35

1. castrophic CNS condition leading to irreversible damage 2. absent brainstem reflexes 3. positive apnea test 4. absence of intoxication, neuromuscular blockade, pharmacologic sedation, or a medical condition that may obscure the clinical pic 5. normal or near normal core body temp ( \>36 degrees C) 6. SBP \> 90, or MAP \> 60

Question 36

How is apnea test performed?

Answer 36

1. preoxygenate for 10 miniunutes for FiO2 100% 2. baseline abg and pCO2 btwn 35 - 40 3. d/c ventilator but maintain O2 at 6L/min; observe for 10 minutes, look for chest or abdominal rise 4. check abg if pCO2 has risen to 60 or greater and there were no inspiratory attempt, it is consistent with brain death

Question 37

If there are doubts regarding the brain death testing, what other tests can be performed?

Answer 37

1. EEG showing electrocerebral silence for at least 30 mins 2. transcranial doppler with no flow signals or abnormal flow signals 3. nuclear medicine showing no isotope uptake in the brain parenchyma or no intracranial flow 4. angiography demonstrating no flow in the circle of Willis

Question 38

Where is the lesion in decorticate rigidity?

Answer 38

-decorticate: lesion above the red nucleus --\> resulting in disinhibition of the red nuclei with facilitation of the rubrospinal tracts (which enhances flexor tone in the upper extremities)

Question 39

where is the lesion in decerebrate posturing?

Answer 39

- lesion in the brainstem at or below the superior colliculi and the red nuclei, but above the vestibular nuclei - since the vestibular n are intact, enhances extensor tone without influence from the red nuclei.

Question 40

What is the Monroe-Kellie Doctrine state? What is the relationship between ICV and ICP?

Answer 40

the volume in the intracranial cavity is constant, and an increase in the volume of a ny of the components of this cavity will produce a displacement of other components ## Footnote -intially system is compliant with only small increases in ICP as volume increases. This compliance is limited, and as volume increases, pressure will rise exponentially

Question 41

What is normal CPP? What is the equation for CPP?

Answer 41

Cerebral perfusion pressure \> 70 mmHg is normal; CPP = MAP - ICP

Question 42

Factors that affect cerebral blood flow?

Answer 42

1. MAP 2. ICP 3. vascular autoregulation 4. pC02 (increases in pCO2 causes vasodilation) 5. lower hematocrit --\> increase cerebral blood flow

Question 43

What is the rate of correction of hyponatremia that is safe to reduce risk of central pontine myelinolysis?

Answer 43

12 mEq/L per day or 0.5 mEq/L per hour

Question 44

What are exam findings that are predictive of poor outcomes after cardiac arrest? (3)

Answer 44

1. no pupillary response at 24 to 72 hours 2. no corneal reflexes at 72 hours 3. no eye movements at 72 hours

Question 45

What ancillary tests are predictive of poor outcomes after cardiac arrest?

Answer 45

1. EEG showing burst suppression or generalized suppression 2. somatosenosry-evoked potentials with median nerve stim showing bilaterally absent N20 responses at day 1 to 3 3. neuron-specific enolase elevation

Question 49

Action of muscle: deltoid

Answer 49

shoulder abduction

Question 50

Action of muscle: biceps

Answer 50

elbow flexion, palm up

Question 51

Action of muscle: triceps

Answer 51

elbow extension

Question 52

Action of muscle: extensor carpi radialis

Answer 52

wrist extension

Question 53

Action of muscle: extensor digitorum

Answer 53

Finger extension

Question 54

Action of muscle: dorsal interossei

Answer 54

finger abduction

Question 55

Action of muscle: abductor pollicis brevis

Answer 55

thumb abduction

Question 56

Action of muscle: Ilipsoas

Answer 56

hip flexion

Question 57

Action of muscle: quadriceps

Answer 57

knee extension

Question 58

Action of muscle: hamstrings

Answer 58

knee flexion

Question 60

Action of muscle: tibialis anterior

Answer 60

ankle dorsiflexion

Question 61

Action of muscle: gastrocnemius

Answer 61

ankle plantarflexion

Question 62

Action of muscle: extensor hallucis longus

Answer 62

Great toe extension

Question 63

Action of muscle: rhomboids when to test?

Answer 63

retraction of the scapula; test by pressing the palm backwards from the small of the back; suspect lesion of C5

Question 64

Action of muscle: serratus anterior when to test?

Answer 64

scapular fixation (look for scapular winging); suspect lesion of long thoracic nerve

Question 65

Action of muscle: infraspinatus when to test?

Answer 65

shoulder external rotation; suspect lesion of C5, C6, trunk, suprascapular nerve

Question 66

muscle action: brachioradialis when to test?

Answer 66

elbow flexion with thumb up; suspect lesion of radial nerve

Question 67

Muscle action: pronator teres when to test?

Answer 67

forearm pronation; test C6, C7