Neuro Cases and Considerations Flashcards
do you give benzos preop for Neuro cases
no, when they wake up postop the surgeon will want to do a neuro exam. if they cant, its aNeStHeSiAs fAuLt
in general, anesthetic drugs do what to CMR?
depress CMR
anesthetic drugs that do not depress CMR
ketamine and nitrous oxide
preop considerations
general assessment including IV access
normal postop eval
neuro assessment
med assessment (anticonvulsants)
medications used intraop
continue antiseizure usually ancef and vanc as abx diuretics mannitol steroids (usually a big dose up front)
preop considerations: head positioning with mayfield pins
premedicate before stimulation with 2cc remi or prop bolus
-these pins are sharp, patient will bleed
MEP neuromonitoring (motor evoked potentials)
used in surgeries where motor tract is at risk
direct and scalp electrodes
more sensitive to ischemia than SSEP by 15 minutes and degree detection
pt bleeds when these are taken out-theyre like screws
SSEP neuromonitoring (somatosensory)
most commonly monitored
stimulation of peripheral sensory nerve
mapping in spinal cord and sensory cortex
ischemia detection in cortical tissues
reduce risk of spinal cord/brainstem
mechanical or ischemic insults
-can use paralytic if needed
-does have motor monitoring, not as specific.
-does not measure deficits
-hypothermia can increase latency and decrease amplitude
EMG neuromonitoring (electromyography)
records muscle electrical activity using needle pairs
continuous recording
triggered responses
uses: detect nerve irritation, nerve mapping, assess nerve function, monitoring cranial nerves.
good for spinals to detect if screws are misplaced
which two drugs increase neuromonitoring wave amplitude
ketamine and etomidate
what is stereotactic neurosurgery
applies the rules of geometry to radiologic images to allow for precise localization within the brain, providing up to 1mm accuracy. less invasive approach to certain intracranial procedures. small markers (fudicials) are affixed to scalp and forehead with adhesive. important that these fudicials do not move between time of imaging and entry into OR
anesthesia for stereotactic neurosurgery
smaller brain biopsies may be done under local/mac
GETA for larger resections
craniotomy meds to decrease ICP
decadron 10mg
mannitol 50-100g (.25-.5g/kg)
lasix (+/-)
craniotomy induction meds
fentanyl, prop, rocuronium
craniotomy maintenance meds
TIVA with prop at max 40mcg/kg/min ABW for asleep motor mapping and awake crane
remifentanil .2mcg/kg/min IBW(why doe?)
neo gtt strung up
-increase remi before increasing prop if patient is light
for what types of surgeries can you consider redosing rocuronium
aneurysms, pituitary tumors
craniotomy meds: antiepileptics
keppra 1g, vimpat
craniotomy meds: abx
usually vanc and ancef
craniotomy meds: analgesics
tylenol 30m before close
hydromorphone or fentanyl
drugs specifically for awake crani
caffeine 60mg/3mL (adenosine receptor antagonist)
physostigmine (anti cholinesterase) .5-1mg q2m
why are cranies usually a delayed wake up (not anesthesia related)
CT reveals air that will absorb, delays wake up
types of intracranial mass lesions
congenital
neoplastic (benign versus malignant)
infectious (abcess or cyst)
vascular (hematoma or av malformation)
typical presentation of intracranial mass in order from most reported to least reported sx
HA, seizures, focal neurological deficits, sensory loss, cognitive dysfunction
supratentorial intracranial mass lesions sx (general)
seizures, hemiplegia, aphasia
supratentorial intracranial mass lesions sx: frontal
personality changes, increased risk taking, difficulty speaking (damage to brocas area)
supratentorial intracranial mass lesions sx: parietal
sensory problems
supratentorial intracranial mass lesions sx: temporal
problems with memory, speech, perception, and language skills
supratentorial intracranial mass lesions sx: occipital
difficulty recognizing objects, an inability to ID colors, trouble recognizing words
infratentorial/posterior fossa intracranial mass lesions sx: cerebellar dysfunction
ataxia, poor balance, nystagmus, dysarthria, cannot perform rapid alternating movements, loss of muscle coordination
infratentorial/posterior fossa intracranial mass lesions sx: brainstem compression
cranial nerve palsy, altered LOC, abnormal respiration, edema, obstructive hydrocephalus at 4th ventricle
intracranial mass lesions: primary tumor types
glial cells (most common), ependymal cells, supporting tissues
intracranial mass lesion: management major considerations
tumor location-determines patient positioning, EBL, risk for hemodynamic changes intraoperatively
growth rate and size: slow growing tumors are often asymptomatic
ICP elevation
intracranial mass lesion: anesthetic goals
control ICP maintain CPP protect from position related injuries rapid emergence for neuro assessment (remi wake up) SBP <160 is postop goal so keep in mind
intracranial mass lesion: positioning
supine with bump under shoulder for tilt. tape ETT on opposite side.
anticipate HOB 90-180
adequate IV line extensions
long breathing circuit
PNS often on LE’s
HOB often elevated 10-15 degrees
supine, lateral, or prone. sitting out of favor
anticipate sympathetic response with mayfield pin positioning if applicable (prop or remi bolus)
intracranial mass lesion: intraoperative monitoring
standard monitors
aline
foley
central line (+/-)
PNS (do not monitor on hemiplegic side because you may end up overdosing paralytics)
ventriculostomy (zero at auditory meatus) (+/-)
IONM possible
if you do a CVC, where would you insert it
subclavian because theoretically IJ can decrease drainage for maintenance of ICP
intracranial mass lesion: preoperative considerations
determine presence of absence of increased ICP
document LOC and neuro deficits
review PMH/general health status
review meds (anticonvulsant schedule, diuretics)
review lab findings (glucose, anticonvulsant drug levels, electrolyte disturbances, H/H)
review radiological studies
premedication (avoid benzos/narcs in patient with increased ICP, continue corticosteroids and anticonvulsants)
incracranial mass lesions and intraoperative ventilation, fluid, ICP control
hyperventilation (near 30), avoid excessive PEEP (<10), glucose free crystalloids or colloids, replace blood loss with blood or colloids, EVD/lumbar drain, watch for increases in CBF
intracranial mass lesions: emergence
must be slow and controlled because straining or bucking can cause ICH or worsen cerebral edema
aggressive BP management for SBP <140 or <160 r/t risk for hemorrhage or stroke. (clevidipkne, labetalol, esmolol)
surgical team will do neuro exam right after extubation before leaving OR
intracranial mass lesion: postoperative considerations
will be admitted to ICU for observation transport with HOB 30 degrees manage HTN O2 for transport minimal pain post craniotomy (HA) observe for seizures, neuro deficits, increased ICP
awake-awake craniotomy considerations
no infusions until closing, only prop bolus for mayfield pins.
asleep-awake craniotomy considerations
start under GA with LMA/ETT
wake patient up once tumor is exposed for cortical mapping and tumor resection
prop gtt 40mcg/kg/min ABW
remi .2-.4mcg/kg/min IBW
-if LMA is in, control ventilation and do not get them back breathing
sedated for iMRI (not always a thing during these)
sedate once tumor is removed/complete and they are closing
asleep craniotomy considerations
TIVA, IONM, asleep motor mapping OR
GETA if no IONM, can still do a remi gtt so no paralytic is needed
when are awake craniotomies considered
used for epilepsy surgery and resection of tumors in frontal and temporal lobes when speech and motor need to be assessed intraop
safety hazards of iMRI for medical personnel includes
magnetic field strength, cold hazards, acoustic noises
in which cases/with what technology is the iMRI employed
awake tumor resection laser ablation (monteris) cytokine delivery (medicenna) ROSA (zimmer biomet) clearpoint
which interventions is the monterrris medical LITT used for
epilepsy
glioblastomas (that a regular craniotomy cannot get)
recurrent brain mets
radiation necrosis
MR thermography use
uses phase change to calculate real time temperature data at and around probe. thermal dose confirmed in real time using bio thermodynamic theory.
blue line-dead
white-vaporized
yellow-recoverable
“scan, move probe, scan, move probe, scan, move probe”
3-6h case
contents in posterior fossa include
brainstem (ANS, CV/resp center, motor/sensory pathways)
cerebellum (movement/equilibrium)
CN’s 1-12
large venous sinuses
posterior fossa lesions: brainstem injuries sx
bradycardia and HTN (trigeminal nerve stimulation-cushings)
bradycardia and HoTN (glossopharyngeal and vagus nerve stimulation)
resp centers may be damaged-may need postop mechanical ventilation
tumors around glossopharyngeal and vagus nerves may impair gag reflex and increase risk of aspiration
which cranial nerves, located in posterior fossa, control pharynx and larynx
CN IX, X, XI
advantages of sitting position
improved surgical exposure (more anatomically correct) less retraction and tissue damage less bledding less CN damage better resection of lesion access to airway, chest, extremities
disadvantages of sitting position
postural HoTN arrhythmias venous pooling pneumocephalus (tension=burr holes) if using N2O, d/c before dural closure nerve injuries (ulnar compression, sciatic nerve stretch, lateral peroneal compression, brachial plexus stretch
VAE: when it occurs
level of incision >5cm higher than heart
what rules out sitting position r/t VAE risk
PFO. creates opportunity for paradoxical air embolism where air gets to left heart and out to systemic circulation
VAE s/sx
decreased EtCO2 (r/t increased dead space), decreased PaO2, SaO2 mil wheel murmur, detection of ET nitrogen, increased PaCO2, HoTN, dysrhythmias
ways to monitor for VAE:
capnography (EtCO2 decreases with 15-25mL of air)
CVP/PA line (PAP increases with 20-25mL of air)
precordial doppler
TEE (5-10x more sensitive than doppler)
MAP
what constitutes a “large” VAE
> 2mL/kg
VAE tx
100% O2, d/c N2O
notify surgeon to flood field or pack wound
call for help
aspirate from CVP with stopcock and 30-60mL syringe
volume load
inotropes/vasopressors
jugular vein compression
PEEP
position patient LLD with slight trendelenburg
CPR if necessary
valsalva increases venopressure, slows entrainment, helps surgeon ID leak
main goal is get the head down!
craniocervical depression (chiari malformation)
cerebellum protrudes through foramen magnum. compresses brainstem and cervical spinal cord. types 1-4, syringomyelia
type 3: tonsils herniated through foramen magnum
chiari malformation anesthetic considerations (positioning, EBL, postop)
positioning is prone or supone
EBL is large r/t venous sinuses
VS instability d/t brainstem manipulation anticipated
postoperatively, pain management is biggest consideration
head injury: linear skull fracture sx
subdural or epidural hematomas
head injury: basilar skull fracture sx
CSF, rinorrhea, pneumocephalus, cranial nerve palsies, battle sign, raccoon/panda eyes
head injury: depressed fracture
creates a brain contusion
head injury classification: primary
biomechanics effect of forces on brain at time of insult. includes contusion, concussion, laceration, hematoma
head injury classification: secondary
represents complicating processes r/t primary injury. minutes, hours, days after primary injury.
intracranial: hematoma, increased ICP, seizures, edema, vasospasm
prehospital head injury management
C-A-B (idk)
stabilize prior to transport
GCS <9, level 1 trauma center
ex)intracranial hematoma
ED head injury management (based on severity)
mild: recovery rate high
moderate: emergency CT, admission, observation
severe: stabilization, CT, surgery
head injury: airway considerations
assume c spine injury until otherwise proven radiographically
in line stabilization
intubate early
full stomach precautions
awake FOI if difficulty aw is anticipated
blind nasal intubation contraindicated in basilar skull fractures
head injury: anesthetic considerations
HoTN, bradycardia, maintain Hct >30%, seizure prophylaxis, DIC may be seen with severe head injuries, pituitary dysfunction possible (DI, SIADH), patient remains intubated
non secretory nonfunctioning pituitary tumors
arise from growth of transformed cells of anterior pituitary. generally well tolerated until 90% of gland is nonfunctional
secretory functioning pituitary tumors
cushings disease (ACTH), acromegaly (GH), prolactinomas (prolactin), TSH adenomas (TSH)
pituitary: intraoperative considerations
transphenoidal approach necessitates HOB raised 10-20 degrees
oral RAE or reinforced ETT
avoid hyperventilation-reductions in ICP result in retraction of pituitary into sella tursica, making surgical access difficult
potential for mass hemorrhage as carotid arteries lie adjacent to suprasellar area
mouth and throat pack: placed to absorb glottic blood and minimize PONV
OGT
avoid positive airway pressure upon extubation
pituitary: preop evaluation
visual field evaluation s/sx increased ICP endocrine labs lytes steroids"
pruitary: postop managment
DI is common after surgery and usually self limiting (7-10 days). tx with vasopressin or DDAVP
SIADH
cerebral aneurysm
leading cause of non traumatic intracranial hemorrhage, commonly located in anterior circle of willis
unruptured cerebral aneurysm sx
HA, unsteady gait, visual disturbances, facial numbness, pupil dilation, drooping eyelid, pain above or behind eye
ruptured cerebral aneurysm sx
sudden, extremely severe HA
n/v, LOC decreased, focal neuro deficits, hydrocephalus, seizure, s/sx of increased ICP
which hess and hunt grading scale grades require intervention within 24-48h for chance of survival
1-2
ruptured cerebral aneurysm: vasospasms
causes ischemia or infarction, exact mechanism unknown
digital subtraction angiography is gold standard for dx (not detectable until 72h post SAH), use CCB’s
ruptured SAH and rebleeds
peaks seven days post incident, major threat during delayed surgery. antifibrinolytic tx
tx for ruptured cerebral aneurysm and vasospasms
HTN (SBP 160-200 MAP 80-100)
hemodilution 33% HCT
hypervolemia CVP >10 or PCWP 12-20
-also prophylactic CCB regiment
end-vascular coiling in IR: anesthetic plan and considerations intraop
GETA with complete muscle paralysis
control CPP via BP, usually lower during vcase
aline preferred
minimal to no blood loss
heparin for ACT 200-250
same postop concerns and with clipping
careful with volume because they use over 1L to clip and flush
advantages fo end-vascular aneurysm coiling
shorter stay, less anesthetic requirements, uncomplicated positioning, minimally invasive
complications of end-vascular aneurysm coiling
rupture/SAH (lower BP and go to OR, hyperventilate and keep sedated)
vasospasm
CVA
incomplete coiling
cerebral aneurysm in OR
most commonly tx by microsurgical flip ligation
crani approach: parent vessel giving rise to aneurysm ID’s
clip placed across aneurysm neck excluding it from circulation
deep circulatory arrest may be necessary with giant aneurysms (prop bolus or adenosine)
cerebral aneurysm goals of anesthesia intraop
maintain CPP, decrease CPP rapidly if rupture occurs during clipping
maintain transmural pressure (MAP-ICP)
decrease intracranial volume and provide slack in brain
minimize CMRO2
cerebral aneurysm: preinduction anesthetic managment
limit sedation (hypercapnia), aline, 2 large bore PIV’s, type and cross with 2-4U PRBC, remember HOB turned 90-180
cerebral aneurysm: induction anesthetic managment
smooth induction, aggressive BP and HR control with narcotics, BB, deep anesthetic
cerebral aneurysm: maintenance anesthetic managment
TIVA or gas with paralytic (doesnt matter but usually gas), temporary occlusion of cerebral artery, maintain BP 15-20% below baseline to precent vasospasm, decrease EBL, and allow for best exposure. reduce ICP and employ cerebral protection methods.
cerebral aneurysm: fluid management
keep euvolemic, expand blood volume with colloids, have PRBC’s avail, no glucose containing solutions
cerebral aneurysm: control BP
surgeon may ask for BP 20-30% above baseline for collateral flow if feeder vessel is clamped for clipping
post clipping, keep map 80-100
likely times of intraop aneurysm rupture
dural incision, excessive brain retraction, aneurysm dissection, during clipping or releasing of clip
tx of intraop aneurysm rupture
immediate aggressive resuscitation and replacement of blood
prop bolus for brain to decrease MAP and blood loss
surgeon may apply temp clip on parent vessel to control bleeding, restore BP after clipping to improve collateral flow
AVM
tx includes intravascular embolization, surgical excision, radiation. preop considerations same as with aneurysm, potential for significant blood loss is much higher
cranial nerve decompression
treats disorders of cranial nerves (trigeminal neuralgia, hemifacial spasm, glossopharyngeal neuralgia)
unilateral
usually caused by compression of vascular structure like a blood vessel
CN decompression considerations and anesthetic approach
positioning lateral with bump, supine, or prone
monitor facial nerves, BAER (brainstem activity evoked responses), EMG
TIVA and brain relaxation during maintenance
multimodal PONV approach
