Electromyography (EMG) and Nerve Monitoring Flashcards

Which anesthetic consideration is MOST important for free-running EMG monitoring to be reliable?

Answer: Avoidance of neuromuscular blocking agents after intubation

Neuromuscular blocking agents prevent muscle response to nerve root irritation, making free-running EMG completely unreliable; only short-acting NMB for intubation is acceptable.

The S1 nerve root is best monitored using EMG from which muscle?

Answer: Gastrocnemius and abductor hallucis

The gastrocnemius and abductor hallucis are primarily S1-innervated muscles and are the best myotomes for EMG monitoring of S1 nerve root integrity.

During anterior cervical spine surgery, EMG monitoring of which muscle is most useful for detecting C5 nerve root injury?

Answer: Deltoid

The deltoid is the primary C5 myotome muscle and is most sensitive for detecting C5 nerve root injury, a common complication of anterior cervical decompression.

Pop and burst EMG patterns during free-running monitoring are considered:

Answer: Lower-risk, brief responses to transient mechanical contact

Pop and burst patterns are brief, transient EMG responses to mechanical contact (touching the nerve) that are lower risk than sustained neurotonic trains but still warrant alerting the surgeon.

Which recording parameter is critical for obtaining accurate EMG recordings from muscles intraoperatively?

Answer: Electrode impedance below 5 kΩ

Electrode impedance below 5 kΩ is required for reliable EMG recordings to ensure adequate signal quality and minimize electrical noise contamination.

Electrical interference from the surgical cautery (electrosurgery unit) in EMG recordings is best managed by:

Answer: Having the surgeon temporarily stop cautery, noting the artifact, and confirming it does not persist after cessation

Electrocautery produces intense artifact; communicating with the surgical team to pause cautery use when EMG activity is observed confirms whether the activity is artifact or genuine nerve activity.