Neuro Monitoring

Question 1

Considerations of Neurophysiologic Monitoring:

Answer 1

1. Pathway
2. Tract Anatomy
3. Concomitant Disease
4. Appropriate measurement
5. Limitation of Measurement
6. Compatibility/Interference of Anesthetic Techinique
7. Best Method

Question 2

Methods of Neurophysiologic Monitoring:

Answer 2

1. MEP
2. Transcranial MEP
3. EMG
4. NIMS
5. BAEP
6. Visual Evoked Potentials
7. Facial Nerve Monitoring
8. COrtical Mapping
9. SSEP

Question 3

Imaging Modalities of Neurophysiologic Monitoring:

Answer 3

1. fMRI
2. DTI Tractography
3. PET/CT

Question 4

Patient Participation

Answer 4

• Wake up testing
• Awake craniotomy

Question 5

Over-riding Principles for Neurophysiologic Monitoring:

Answer 5

• Neuropathway being monitored must be at risk
• If changes occur, an option for intervention must be available
• If both criteria are not met, you are wasting time and resources
• Baseline testing should be performed prior to any potention manipulations
• Don’t get stuck by needles
• Anesthetic goals may conflic with montioring
• 10/50 Rule - You should be concerned about 10% increase in latency or 50% decrease in amplitude

Question 6

Motor Evoked Potentials (MEP): Pathways

Answer 6

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

Question 7

MEP: Appropriate Time To Measure

Answer 7

• Motor strip surgeries
• Spine surgery

Question 8

MEP: Limitations

Answer 8

• Interference of anesthetics
• Difficulty in establishing baseline due to electrocautery, NMB, and Positioning
• If patient has undiagnosed disease as multiple sclerosis

Question 9

Compatibility/Interference:

Volatile Anesthetics

Answer 9

Latency: Significant Increases

Amplitude: Significant decreasae

Question 10

Compatibility/Interference:

NO2

Answer 10

Latency: Significant Increases

Amplitude: Significant Decreace

Question 11

Compatibility/Interference:

Propofol

Answer 11

Latency: Increases

Amplitude: Decreases

Question 12

Compatibility/Interference:

Etomidate

Answer 12

Latency: Decreases

Amplitude: Increases

Question 13

Compatibility/Interference:

Ketamine

Answer 13

Latency: No effect

Amplitude: Increases

Question 14

Compatibility/Interference:

Dexmetetomidine

Answer 14

Latency: Increases

Amplitude: Decreases

Question 15

Compatibility/Interference:

Benzodiazapines

Answer 15

Latency: Increases

Amplitude: Decreases

Question 16

Compatibility/Interference:

Opiates

Answer 16

Latency: No effect

Amplitude: No effect

Question 17

Compatibility/Interference:

NMB

Answer 17

Latency: Eliminates

Amplitude: Eliminates

Question 18

MEP: Best Method

Answer 18

• Protect ETT from “biting”
• Avoid additional muscle relaxant after intubation
• Steady infusions, avoid boluses
• TIVA
• The pt will move

Question 19

What is the difference between MEP and EMG?

Answer 19

An EMG is a measurement; a MEP is a measured response

Question 20

Electromyographic (EMG)

Answer 20

• A local measurement of muscle activity
• No pathway exists

Question 21

When is it appropriate to use EMG?

Answer 21

• Pedical screw placement or other harware placement
• Works by stimulating the hardware, if EMG is detected then hardware is through the nerve

Question 22

Limitations of EMG

Answer 22

Intrinsic muscle disease or NMJ disease such as Myesthenia Gravis or Polio