CNIM Electromyography (EMG) and Nerve Monitoring

Question 1

Free-running (spontaneous) EMG monitoring during spine surgery is used primarily to detect:

Accepted Answer

Nerve root irritation or injury from surgical manipulation

Answer

Free-running EMG detects spontaneous electrical activity (trains of potentials) generated when nerve roots are mechanically irritated, stretched, or injured during surgery.

Question 2

Neurotonic discharges in free-running EMG during lumbar surgery are characterized by:

Accepted Answer

Sustained high-frequency trains of motor unit potentials indicating nerve irritation

Answer

Neurotonic discharges are sustained, high-frequency trains of motor unit activity that are highly significant for nerve root mechanical irritation and require surgical team notification.

Question 3

Triggered EMG (t-EMG) is used to assess pedicle screw placement by:

Accepted Answer

Stimulating the screw and measuring the threshold current needed to elicit a muscle response

Answer

Triggered EMG assesses pedicle screw integrity by stimulating the screw and determining the minimum current required to elicit a CMAP response; low thresholds suggest cortical wall breach.

Question 4

A triggered EMG threshold of less than 6–7 mA for a pedicle screw suggests:

Accepted Answer

Possible medial wall breach with proximity to the nerve root

Answer

Threshold values below 6–7 mA for pedicle screws are considered concerning for a medial cortical wall breach, placing the screw close to the adjacent nerve root.

Question 5

EMG monitoring of which muscle confirms the integrity of the facial nerve (CN VII) during parotid or posterior fossa surgery?

Accepted Answer

Orbicularis oculi and orbicularis oris

Answer

The orbicularis oculi (upper face) and orbicularis oris (lower face) are the primary muscles monitored for CN VII integrity, representing the upper and lower branches of the facial nerve.

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM Electromyography (EMG) and Nerve Monitoring