Neuro Flashcards
Delayed Emergence DDx
Pharma: residual anesthetic, inadequate reversal of NMB, other meds (anticholinergics/antihistamines), illicit drugs
Metabolic: hypoglycemia, electrolyte, pH, hypothermia, hyper/hypocarbia
Neuro: stroke, seizures/postictal, ICP inc, psych
PDPH
frontal/occipital headache
improves with recumbency
sensitive to light/sound
N/V, visual changes, neck stiffnessd
Blood patch (normal coags, no post op SQH)
Conservative (rest, hydration, caffeine)
Autonomic Dysreflexia
Rxn to sympathetic hyperreactivity in paraplegics above T6
Stimulation below injury
HTN, bradycardia, flushing, diaphoresis, piloerection, headache
Spinal/epidural for sympathectomy
Deepen anesthetic
Vasodilator - nicard/clev
ICP Management
Cushings Triad - htn, brady, pulse pressure widening
CPP > 60 nL
Limit volatile agents
HOB @ 30
Ensure venous drainag
Normothermia
Hyperventilation (not in TBI/stroke)
Mannitol - osmotic diuresis - avoid if BBB damaged
Glucocorticoids - good in tumors, avoid in TBI
Lasix
Propofol on Brain
CMRO2 - decreases
CBF - decreases
ICP - decreases
Etomidate on Brain
CMRO2 - decreases
CBF - decreases
ICP - decreases
Direct vasoconstrictor
Benzos on Brain
CMRRO2 - decreases
CBF - decreases
ICP - ? decreases
Opioids on Brain
CMRO2 - no effect
CBF - no effect
ICP - no effect
Barbituates on Brain
CMRO2 - decreases
CBF - decreases
ICP - decreases
Nitrous Oxide on Brain
CMRO2 - increases
CBF - increases
ICP - increases
NMDA receptor antag
Ketamine on Brain
CMRO2 - Increases
CBF - Increases
ICP - doesn’t increase if combined with GA and opioids
NMDA receptor antagonist
Somatosensory Evoked Potentials (SSEPs)
Standard of care - can indirectly monitor MEPs but lots of false negatives
Monitor POSTERIOR 1/3 spinal cord pathways
- have dual blood supply and less prone to ischemic injury
Motor Evoked Potentials (MEPs)
ANTERIOR 2/3 spinal cord pathways
- single arterial supply (Adamkiewicz)
Most sensitive to anesthetics - better to use ketamine, opioids, midaz, propofol
Avoid in seizures, cochlear implants, vascular clips
ischemic Optic Neuropathy
Risk: Anemia, large blood loss, prone, hypotension, external ocular pressure, surgery > 6 hours, head down
Anterior - from ocular pressure - ischemia to OPTIC DISC - most common
Posterior - from dec venous drainage - ischemic to OPTIC NERVE
Tx: ensure adequate hgb, O2 delivery, appropriate MAPs, Sit upright, encourage venous drainage, Ophtho c/s
Carotid Endarterectomy
Stenosis > 50%
Comprehensive cardiac eval - intermed risk surgery
Establish symptoms
GA Monitoring - EEG, BIS, SSEPs, carotid stump pressure (>50), cerebral oximetry
Cervical Plexus Block - (superficial) - posterior border of SCM
Glascow Coma Scale
Motor
6-spontaneous/commands
5-localizes pain
4-withdraws pain
3-decorticate
2-decerebrate
1- none
Verbal
5-spontaneous
4-confused
3-inappropriate speech
2-incomprehensible
1-none
Eyes
4-spontanous
3-to voice/command
2-to pain
1-none
Cerebral Perfusion Pressure
MAP - ICP or CVP (whichever is greater)
Normal 70-100
Cerebral Vasospasm
Risk 3-12 days after SDH
Prevent with postop nimodipine therapy
Dx: Transcranial Doppler, Cerebral Angiography, High Clinical suspicion
Tx: Triple H therapy
- hypervolemia
- hypertension
- hemodilution (lower viscosity)
Direct vasodilator therapy using IR
Neurogenic Pulmonary Edema
Sympathetic surge as result of CNS injury
Systemic vasoconstriction and redistribution of blood volume to lungs causing overcirculation
Sitting Position
Pros - superior surgical exposure, increased venous drainage and decreased edema, better ventilation
Cons - increase VAE risk, dec CO/CPP/hypotension, pneumocephalus, peripheral nerve injury, excessive neck flexion
Myasthenia Gravis
POSTsynaptic nAch receptors attacked by IgG antibodies
Ocular/bulbar weakness worsening with repeated stimulation.
Succinylcholine - resistant
NDMB - sensitive
If taking pyridostigmine (anti-Achase) -
- Sux - more sensitive, lasts longer
- NMBD- more resistant
Myasthenia Gravis - Predictors of Post Op Mechanical Ventilation
- disease > 6 years
- concomitant chronic lung disease
- pyridostigmine dose > 750 mg daily
- severe bulbar symptoms
- vital capacity < 40 mL/kg
Cerebral Salt Wasting
Hyponatremia
Hypovolemia
Urine osm low and Na high
Tx
- fluid replacement (NS or 3% saline)
- fludrocortisone/mineralocorticoid
Lambert Eaton Myasthenic Syndrome
Antibodies against pre-synaptic calcium channels
Usu paraneoplastic syndrome (lung cx)
Weakness improves with stimulation
Sensitive to both depolarizing and non-depolarizing.
