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

Cortical spreading depression

Answer

Spinal cord ischemia

Answer

Motor cortex activation

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

Isolated single motor unit potentials

Answer

Electrical silence with no activity

Answer

Fibrillation potentials only

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

Continuously recording muscle activity

Answer

Recording brainstem potentials

Answer

Measuring intradiscal pressure

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

Correct screw placement within bone

Answer

Lateral screw malposition

Answer

Equipment malfunction

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

Masseter

Answer

Sternocleidomastoid

Answer

Trapezius

Question 6

During spinal deformity surgery, the L5 nerve root is best monitored using EMG from which muscle?

Accepted Answer

Tibialis anterior

Answer

Gastrocnemius

Answer

Adductor magnus

Answer

Vastus medialis