Neuromonitoring (FINAL EXAM) Flashcards
(28 cards)
Anesthesia for S-EMG & T-EMG
For reliable EMG: Train-of-Four must be 4/4 with minimal/no fade
Somatosensory Evoked Potentials (SSEPs)
Monitor somatosensation
Stimulation at peripheral nerve
Recording at scalp (or periphery) and measures a cross section of the spinal cord
SSEEPs monitoring and response type
Monitoring points at different stages of pathway
Responses tiny
Multiple trials averaged
Note: causes foot/hand twitching – NOT motors
SSEPS alert criteria?
Monitor amplitude and latency of waveforms
Alert criteria:
50% amplitudedecrease
10% latency increase
Anesthesia for SSEPs
Max 1.0MAC inhalation agent, though <0.5MAC ideal (or no gas, institution specific)
Steady state important, including BP
Paralytics OK with SSEPs
Anesthesia + IOM goal: decipher surgically relevant changes
Transcranial Motor Evoked Potentials (tcMEPs)
Monitor voluntary movement
Stimulation at scalp
Recording at muscles throughout body
Causes whole body twitch/bite – can cause severe tongue laceration
Bilateral soft bite blocks!!
Anesthesia for TcMEPs
TOF 4/4, bilateral soft bite blocks, TIVA
Why TIVA:
- Increased reliability & accuracy
- Less stimulation
- ALERTs – not anesthesia’s fault!
- Sometimes responses still obtainable at 0.5MAC, but not ideal
Precedex and MEPs
New literature shows dose dependent effect on MEPs – no loading dose and infusions <0.5mcg/kg/hr
EEG
Monitoring electrical activity in brain
Commonly utilized in CEA/TCAR procedures to ensure adequate perfusion during carotid cross clamping.
Anesthesia for EEG – steady state is important. Bolusing propofol can cause burst suppression
What is burst suppression?
BAER
Monitoring auditory pathway
Wave I-V and their generators
Commonly utilized in MVDs, Acoustic Neuromas, etc.
Anesthesia for BAERs – least sensitive to anesthesia
VEP
Monitoring optic nerve, visual pathway
P100
Highly sensitive to anesthesia and not commonly used modality in OR
Communication with neuromonitoring
Neurophysiologist tries to relay pertinent information that will help outcome of case
Regular communication with anesthesia essential to provide best information to surgical team
Relay complete & accurate information/interpretation as opposed to partial information that only confuses
Summary of modalities and anesthesia
Anesthesia Effects on IOM
Anesthesia Gas Causes _____
Dose-dependent decrease in amplitudes
Propofol causes ___
Less severe dose-dependent decrease in amplitudes
Paralytic causes ____
Unreliable EMG & TcMEPs
Decreased BP causes ____
Dampened SSEP &TcMEP amplitudes
Ketamine causes ____
Increased signals
Opioids cause ____
Mild decrease in amplitudes
Precedex causes ____
Dose-dependent decrease in TcMEP amplitudes
Requested Anesthesia for SSEPs
0.5MAC, NMB is OK
Requested Anesthesia for S/T-EMG
TOF 4/4, gas is OK
Requested anesthesia for TcMEPs
TOF 4/4, bilateral bite blocks, TIVA
Requested anesthesia for BAERs
none, does not require anything special because anesthesia doesn’t impact it
