Neurosurgery overview Flashcards

1
Q

Preoperative considerations for neurosurgery include

A

general assessment- access
normal preoperative evaluation- systems, airway, mobility
neurological assessment- LOC, reflexes, motor/sensory function, evaluate for s/s of increased ICP, document preexisting neurological deficits

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2
Q

Describe preoperative considerations for medications & monitoring.

A

medications- anticonvulsants (frequency & continue), premedications, antibiotics, diuretics, steroids
monitoring- arterial line & intraoperative neuro monitoring

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3
Q

The types of intraoperative neuromonitoring include

A

MEP
SSEP
EMG

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4
Q

Describe MEP

A

used in surgeries where motor tract is at risk
direct & scalp electrodes
more sensitive to ischemia than SSEP by 15 minutes and degree detection
difficult to obtain due to pre-existing conditions or anesthetic conditions

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5
Q

Describe SSEP.

A

most commonly monitored
stimulation of peripheral sensory nerve
mapping in spinal cord and sensory cortex
ischemia detection in cortical tissue
reduce risk of spinal cord/brainstem- mechanical or ischemic insults
-may use paralytic but it does monitor some motor

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6
Q

Describe EMG

A

records muscle electrical activity needle pairs- continuous recording, triggered responses
uses- detect nerve irritation, nerve mapping, assess nerve function, monitoring cranial nerves

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7
Q

Stereotactic neurosurgery applies rules of

A

geometry to radiologic images to allow for precise localization within the brain, providing up to 1 mm accuracy

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8
Q

Stereotactic neurosurgery allows surgeons to

A

perform certain intracranial procedures less invasively

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9
Q

Smaller brain biopsies may be done

A

under local/MAC

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10
Q

_____ needs to be used for larger brain resections

A

GETA

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11
Q

With stereotactic neurosurgery, radiologically small markers are affixed to the scalp and forehead with adhesive and it is important that

A

these fudicials do not move between the time of imaging and entry into the OR
once in the OR the patient’s head is appropriately positioned & the locations of the fudicials are entered into a computer

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12
Q

Medications commonly found in the crani bag include

A

cleviprex, mannitol, keppra, phenylephrine, precedex, epi

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13
Q

Drips commonly used in craniotomies include

A

propofol at 40-100 mcg/kg/min ABW- max 40 mg/kg/min for asleep motor mapping and awake craniotomy
phenylephrine at 0.2 mcg/kg/min
remifentanil @ 0.2 mcg/kg/min IBW- no real max if patient needs it due to low propofol dose

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14
Q

Describe common induction medications for craniotomies.

A

fentanyl, propofol, rocuronium

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15
Q

Antibiotics for craniotomies include

A

vancomycin & cefazolin

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16
Q

Analgesics for craniotomies include

A

tylenol

narcotic (hydromorphone or fentanyl)

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17
Q

Antiepileptics for craniotomies include

A

keppra 1 g & vimpat

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18
Q

Drugs that decrease ICP in the setting of craniotomies include

A

decadron- 10 mg
mannitol- 50-100 mg (actual dose 0.25-0.5 g/kg)
+/- lasix

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19
Q

Specific drugs used for awake cranies include

A

caffeine- adenosine receptor antagonist

physostigmine- anticholinesterase

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20
Q

Types of mass lesions include

A

congenital
neoplastic (benign vs. malignant)
infectious (abscess or cyst)
vascular (hematoma or arteriovenous malformation)

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21
Q

Typical presentation of intracranial mass lesions include

A
HA (50-60%)
seizures (50-80%)
focal neurological deficits (10-40%)
sensory loss
cognitive dysfunction
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22
Q

Supratentorial masses can be found in

A

frontal: personality changes, increased risk taking, difficulty speaking
parietal: sensory problems
temporal: problems with memory, speech, perception, and language skills
occipital: difficulty recognizing objects, an inability to identify colors, and trouble recognizing words

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23
Q

Infratentorial/Posterior fossa masses can affect

A

cerebellar dysfunction: ataxia/poor balance, nystagmus, dysarthria, cannot perform rapid alternating movements, loss of muscle coordination
brainstem compression: cranial nerve palsy, altered LOC, abnormal respiration
edema, obstructive at 4th ventricle

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24
Q

Primary tumors include

A

glial cells- astrocytoma, oligodendroglioma, glioblastoma
ependymal cells- ependymoma
supporting tissues- meningioma, schwannoma, choroidal papilloma

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25
Q

Major considerations for intracranial mass lesions include

A

tumor location- determines position, EBL, risk for hemodynamic changes intraoperatively
ICP elevated
Growth rate & size- slow growing tumors are often asymptomatic

26
Q

Describe anesthetic goals for intracranial mass management

A

control ICP
maintain CPP
protect from position-related injuries
rapid emergence for neuro assessment

27
Q

Describe monitoring for intracranial mass lesion

A

standard monitors
arterial line (zero based on positioning)
foley catheter
+/- central line
PNS: do not monitor on hemiplegic side b/c you may end up overdosing paralytics
+/- ventriculostomy for ICP monitoring (zero at external auditory meatus)
possible IONM monitoring

28
Q

Describe positioning needs for intracranial mass lesions

A

anticipate turning HOB 90-180 degrees
ensure ability to access all vital equipment
adequate IV line extensions
long breathing circuit
PNS often on LEs
HOB elevated 10-15 degrees
pt may be supine, lateral, prone, or sitting
anticipate sympathetic response with placement of Mayfield head pins

29
Q

Preoperative considerations for intracranial mass lesions include:

A

determine presence or absence of increased ICP
document LOC & neuro deficits
review PMHx and general health status
Review medication regime: pay special attention to anticonvulsants, diuretics
Review lab findings: glucose levels, anticonvulsant drug levels, electrolyte disturbances, H/H
review radiological studies: evidence of edema, midline shift, change in ventricular size
premedications: avoid benzodiazepines/narcotics in pt with increased ICP, continue corticosteroids & anticonvulsants

30
Q

Describe maintenance for intraoperative mass lesions

A

no preferred anesthetic technique
hyperventilation (30)
avoid excessive PEEP (<10)

31
Q

Describe fluid management for intraoperative mass lesions.

A

glucose free crystalloids or colloids

replace blood loss with blood/colloids

32
Q

Describe ICP control for intraoperative mass lesions.

A

EVD/lumbar drain

increases in cerebral blood flow

33
Q

Emergence for intraoperative mass lesions must be

A

slow & controlled- straining or bucking can cause ICH or worsen cerebral edema
aggressive BP management (SBP <140 or <160)- risk for hemorrhage or stroke- clevidipine, labetalol, esmolol
surgical team will do neuro exam immediately after extubation; prior to OR departure

34
Q

Postoperative considerations for intracranial mass lesion

A
admit to ICU for observation
transport with HOB elevated- 30 degrees
manage hypertension
O2 for transport
minimal pain post craniotomy
observe for seizures, neuro deficits, increased ICP
35
Q

Describe an awake-awake craniotomy.

A

no infusions until closing

propofol or remi for pins

36
Q

Describe an asleep-awake craniotomy.

A

start under GA with LMA/ETT (don’t get them back breathing)
wake the patient up once tumor is exposed
propofol drip 40 mcg/kg/min ABW
remifentanil drip 0.2-0.4 mcg/kg/min IBW

37
Q

Describe an asleep craniotomy

A

TIVA-IONM, asleep motor mapping

GETA: no IONM

38
Q

Awake craniotomies are used for

A

epilepsy surgery and resection of tumors in frontal lobes & temporal lobes when speech and motor are to be assessed intraoperatively

39
Q

Patient considerations for awake craniotomies include

A

airway
temperature
anxiety

40
Q

Additional considerations for awake craniotomies include

A

asleep with LMA for exposure
awake for cortical mapping & tumor resection
sedated for iMRI deployment- evaluate resection
when tumor resection complete use appropriate anesthetic to keep comfortable

41
Q

Safety hazards for personnel in iMRI include

A

magnetic field strength
cold hazards
acoustic noises

42
Q

Monteris medical “LITT” may be used to intervene for

A

epilepsy
glioblastomas
recurrent brain metastases
radiation necrosis

43
Q

MR thermography uses

A

phase change to calculate real time temperature data at and around probe
thermal dose confirmed in real time using bio-thermodynamic theory

44
Q

Describe what the white line, blue line, and yellow line

A

white line- vaporized
blue line- dead
yellow line recoverable

45
Q

The contents of the posterior fossa include

A

cerebellum- movement and equilibrium
brainstem- autonomic nervous system, CV & respiratory centers, RAS, motor/sensory pathways
cranial nerves I-XII
large venous sinuses

46
Q

Brainstem injuries can be a result of

A

bradycardia & hypertension-trigeminal nerve stimulation (Cushing’s reflex)
bradycardia & hypotension- glossopharyngeal or vagus nerve stimulation
respiratory centers may be damaged and necessitate mechanical ventilation postoperatively
tumors around glossopharyngeal and vagus nerves may impair gag reflex and increase risk of aspiration
cranial nerves IX, X, and XI control pharynx and larynx

47
Q

Anesthetic considerations for posterior fossa surgery include

A

preoperatively- same considerations as those with intracranial lesions
positioning- may be sitting, modified lateral, or prone

48
Q

Sitting position advantages include

A
improved surgical exposure- more anatomically "correct"
less retraction and tissue damage
less bleeding
less cranial nerve damage
better resection of the lesion
access to airway, chest, extremities
49
Q

Disadvantages relating to CV compromise as a result of the sitting position include

A

postural hypotension
arrhythmias
venous pooling

50
Q

Describe nerve injuries related to the sitting position

A

ulnar compression-arms across abdomen, pad elbows
sciatic nerve stretch- pillow under knees
lateral peroneal compression- pad knees
brachial plexus stretch- pad under arms to support shoulders

51
Q

Describe pneumocephalus related to the sitting position.

A

open dura–> CSF leak–> air enters
after dural closure, air can act as a mass lesion as CSF reaccumulates
usually resolves spontaneously
tension pneumocephalus- Burr holes to relieve
symptoms include delayed awakening, HA, lethargy, confusion
if using N2O, discontinue before dural closure

52
Q

A venous air embolism occurs when

A

pressure in a vein is subatmospheric
level of incision is >5 cm higher than the heart
patients with PFO can have air enter arterial circulation

53
Q

The incidence of venous air embolism is

A

potentially lethal
sitting position 25-50%
prone, lateral supine: 12%

54
Q

Paradoxical air embolism is when

A

air enters left side of heart & travels to systemic circulation
occurs when right heart pressure is greater than left
common in patients with PFO

55
Q

Signs & symptoms of venous air embolism include

A
decreased ETCO2
decreased PaCO2
decreased SaO2
spontaneous ventilation 
mill-wheel murmur
detection of ET nitrogen
increased PaCO2
hypotension
dysrhythmias
56
Q

Monitoring for VAE is through

A

capnography
CVP/PA line
precordial doppler
** do not rely on one monitor alone to diagnose VAE. use monitors with different sensitivities to confirm

57
Q

Sensitivity for monitoring of VAE from most sensitive to least

A
TEE (5-10x more sensitive than doppler)
precordial doppler
ETCO2- decreases with 15-25 mL of air
PAP- increased with 20-25 mL of air
CVP
PaCO2
MAP
58
Q

Treatment for venous air embolism includes

A

100% O2, discontinue N2O
notify surgeon to flood field or pack wound
call for help
aspirate from CVP line (have stopcock close to insertion site, aspirate with 30-60 mL syringe)
volume load
inotropes/vasopressors
jugular vein compression
PEEP
position patient LLD with slight Trendelenburg
CPR if necessary

59
Q

Craniocervical decompression is when

A

the cerebellum protrudes through foramen magnum- compresses brainstem and cervical spinal cord
types I-IV
syringomyelia

60
Q

Anesthetic considerations for chiari malformation include

A

position- prone or sitting
EBL- large venous sinuses
vital sign instability due to brainstem manipulation
postoperative: pain management