CNIM Motor Evoked Potentials (MEP) 2

Question 1

Which tcMEP stimulation parameter is most commonly adjusted to optimize responses intraoperatively?

Accepted Answer

Stimulus intensity (voltage or current)

Answer

Pulse duration only

Answer

Stimulation frequency

Answer

Number of channels

Question 2

Multi-pulse (train) stimulation is used for tcMEPs rather than single pulses because:

Accepted Answer

Multiple pulses summate to overcome the higher threshold of the spinal motor neurons under anesthesia

Answer

Single pulses produce excessive patient movement

Answer

Train stimulation reduces seizure risk

Answer

Single pulses cannot penetrate the skull

Question 3

An alarm for complete tcMEP loss in all four limbs simultaneously during thoracic spine surgery most likely indicates:

Accepted Answer

A systemic event such as hypotension, anesthetic bolus, or neuromuscular blockade administration

Answer

Spinal cord injury at the surgical level

Answer

Electrode displacement in one channel

Answer

Normal intraoperative variability

Question 4

The C3/C4 electrode positions are used for tcMEP stimulation to preferentially activate:

Accepted Answer

Upper extremity motor cortex

Answer

Lower extremity motor cortex

Answer

Visual cortex

Answer

Somatosensory cortex

Question 5

Relative contraindications to transcranial electrical MEP monitoring include:

Accepted Answer

Intracranial metal clips, cochlear implants, or cardiac pacemakers

Answer

Spinal stenosis

Answer

Cortical electrodes placed subdurally

Answer

Use of propofol anesthesia

Question 6

Which surgical procedure most commonly uses both SSEP and MEP monitoring together?

Accepted Answer

Thoracic and cervical spinal cord surgery

Answer

Hip arthroplasty

Answer

Peripheral nerve repair

Answer

Cranial bone flap elevation