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I&M for Anesthesia - Fall 2013 > Neuro Monitoring > Flashcards

Neuro Monitoring Flashcards

0
Q

MEP - Appropriate Measurement

A

Motor strip surgeries

Spine surgery

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1
Q

Motor Evoked Potentials (MEP) - Pathway

A

True MEP are stimulated on the cortical motor strip and recorded by sensors on peripheral muscle
Transcranial MEP (TceMEP) are stimulations by scalp electrodes placed over motor strip
Direct spinal cord MEP stimulation via epidural electrodes

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2
Q

MEP - Limitations of Measurement

A

Interference of anesthetics
Difficulty in establishing baseline due to electrocautery, NMB, and positioning
Does pt have diagnosed disease such as multiple sclerosis

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3
Q

MEP - Compatibility/Interference

A

Volatile/N2O - increase latency, decrease amplitude
Propofol/benzos/dexmetetomidine - increase latency, decrease amplitude
Etomidate - decreases latency, increases amplitude
Ketamine - no effect latency, increase amplitude
Opiates - no effect
NMB - eliminates

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4
Q

MEP vs EMG

A

EMG is a measurement, MEP is a measured response

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5
Q

MEP - Best Method

A 
Protect ETT from biting
Avoid additional MR after intubation
Steady infusions, avoid boluses
TIVA
Realize the pt will move
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6
Q

EMG - Appropriate Measurement

A

Pedical screw placement or other hardware placement

Works by stimulating the hardware, if EMG is detected, then hardware is through the nerve

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7
Q

Electromyographic (EMG) - Pathway

A

Is a local measurement of muscle activity

No pathway exists

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8
Q

EMG - Compatibility/Interference

A

Volatile - no effect at 1 MAC
NMB - eliminates response
Other - no effect

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9
Q

EMG - Limitations of Measurement

A

Intrinsic muscle disease or NMJ disease such as myasthenia gravis or polio

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10
Q

EMG - Best Method

A

Protect ETT from biting
Be cautious of needles
No NMB after intubating dose

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11
Q

NIM EMG - Pathway

A

Trigeminal… Glossopharyngeal… Internal branch superior laryngeal… Recurrent laryngeal

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12
Q

NIM EMG - Appropriate Measurement

A 
Neck Dissection
Thyroidectomy
Parathyroidectomy
Brainstem surgery
Carotid surgery
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13
Q

NIM EMG - Limitations of Measurement

A

Avoidance of paralytics may result in requiring an increase in anesthetic doses which may result in suppression of EMG signal
Only tests nerve tract patency, airway compromise may occur with hypocalcemia following parathyroidectomy
Not for long term intubation
Decreased signal can indicate nerve stretching, not true damage
Expense
No pediatric sizes

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14
Q

NIM EMG - Compatibility/Interference

A

NMB - eliminates
Local/topical - decreases

Other - no effect

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15
Q

NIM EMG - Best Placement

A 
Avoid paralytic agents
Do not se gel or lubricant on tube
No topical anesthetic
Visualize placement
Not exact relation to incisors/gum
Note orientation of anterior marking
Save all included wires and connectors
Anticipate 0.5-1 larger tube than expected
Dispose in sharps container
Do not leave in place for long term intubation
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16
Q

Brainstem Auditory Evoked Potentials (BAEP) - Pathway

A

Assesses CN VIII (vestibulocochlear aka acoustic nerve through its tract to the pons)

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17
Q

BAEP - Tract Anatomy

A

Ear stuff

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18
Q

BAEP - Appropriate Measurement

A

Vestibular nerve
Acoustic neurons
Facial nerve
Cochlear nerve

Acoustic neuroma on vestibulocochlear nerve puts pressure on facial nerve

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19
Q

BAEP - Limitations of Measurement

A

Difficult to assess permanent injury vs stretch

Often used in surgery with no other alternative (leave a bit of tumor vs hearing loss)

20
Q

BAEP - Compatibility/Interference

21
Q

BAEP - Best Method

A

Plain ol anesthesia

Decrease of BAEP is fairly reliable indicator of Stage 4

22
Q

Visual Evoked Potentials - Pathway

A

Retina to occipital cortex

23
Q

Visual Evoked Potentials - Tract Anatomy

A

Visual cortices
Optic chiasm
Optic nerve

24
Visual Evoked Potentials - Appropriate Measurement
Craniopharyngiomas Suprasellar masses
25
Visual Evoked Potentials - Limitations of Measurement
Very sensitive to any anesthetic technique Not considered reliable intraoperatively due to high incidence of false positives
26
Visual Evoked Potentials - Compatibility/Interference
Volatile/benzo/opiates - increase latency, decrease amplitude N2O - no effect latency, decrease amplitude Propofol/dexmedetomidine** - decreases Etomidate - increases Ketamine - no effect latency, increase amplitude NMB - ???
27
Visual Evoked Potentials - Best Method
No established recommendations Seldom utilized Avoid hypotension Avoid high conc of single agent
28
Facial Nerve Monitoring - Pathway
Facial nerve...
29
Facial Nerve Monitoring - Tract Anatomy
7th cranial nerve Brainstem
30
Facial Nerve Monitoring - Appropriate Measurement
``` Wide local exclusions of face and ear Parotid surgery Maxillary surgery Mastoid-translabrynthine surgery Excision of acoustic neuromas Brainstem surgery (pontine and medullary) ```
31
Facial Nerve Monitoring - Limitations
Exacting needle placement Can get response from V2 and V3 nerve
32
Facial Nerve Monitoring - Compatibility/Interference
NMB - eliminates Dexmedetomidine - none? Others - none
33
Facial Nerve Monitoring - Best Method
Protect ETT from biting No scalp block Watch for needle displacement
34
Cortical Mapping - Tract Anatomy
Precentral - Motor cortex "positivity" Postcentral - Somatosensory cortex "negativity"
35
Cortical Mapping - Appropriate Measurement
Exact mapping of sensory and motor areas of cerebral cortex Measures plasticity
36
Cortical Mapping - Limitations
Placement of electrodes can be difficult Placement can be impossible of craniotomy window is not aligned with frontal cortex strips
37
Cortical Mapping - Compatibility/Interference
``` Volatile/propofol/opiate/NMB - no effect Nitrous - interferes Etomidate/ketamine - enhances Benzos - decreases Dexmedetomidine - unknown ```
38
Cortical Mapping - Best Method
Optimize cerebral perfusion Limit cerebral edema
39
Somatosensory Evoked Potentials (SSEP) - Pathway
Stimulus... Peripheral nerve... Dorsal root ganglion... 1st order fibers ipsilateral posterior columns... 2nd order fibers crossing to opposite side... Medial lemniscus to thalamus... 3rd order fibers to frontal parietal cortex
40
SSEP - Tract Anatomy
Gray matter... White matter...
41
SSEP - Appropriate Measurement
Spinal surgery with instrumentation where manipulation can result in disruption of blood supply to anterior spinal cord Brachial plexus surgery Surgery involving sensory cortex Thalamic surgery Thoroco-abdominal aneurysm repair Repair of aortic coarctation Carotid surgery to assess cortex integrity Aneurysm - especially after anterior cerebral
42
SSEP - Limitations
False negatives - 1% for neuro cases, higher for aortic False positives Not a true measure of motor tract integrity Greater loss of CBF needed for SSEP change vs EEG Electrode placement may not be feasible in aneurysm surgery due to location of surgical field
43
SSEP - Compatibility/Interference
Volatile/benzos/opiates - increases latency, decreases amplitude Nitrous - no effect latency, decreases amp Propofol/dexmedetomidine**- decreases latency and amp Etomidate - increases latency and amp Ketamine - no effect latency, increases amp NMB - increases signal
44
SSEP - Best Method
Anesthesia - TIVA propofol ketamine infusion Analgesia - opioid or ketamine infusion Paralysis - any Infuse agents or pressors instead of administering as a bolus Inform monitoring staff of changes in anesthetic agents 1/2 MAC is OK for board exams Normotensive and normothermic patients
45
Change in signal
``` Alert surgeons Review recent changes Assess perfusion Normalize ABG Normalize BP Consider change to technique to enhance ```
46
Functional Magnetic Resonance Imaging (fMRI) - Advantages
Differentiates left brain for right brain function Capacity to show exact location responsible for certain tasks such as eloquent speech and motor areas
47
fMRI - Disadvantages
Neural conduction time is much more rapid than MRI pulse sequence Cost Time and training of personnel Multiple foci may show up Difficult to approximate in relation to surgical site Does not show tracts, only shows cortical grey matter Pt has to be awake during scan and be cooperative

I&M for Anesthesia - Fall 2013 (13 decks)

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