What type of electrode is considered sensitive during CN VII recordings?

The correct answer highlights the use of a bipolar concentric EMG needle electrode during CN VII (facial nerve) recordings. This type of electrode is particularly sensitive because it is designed to reduce the interference from extraneous electrical signals while providing a focused measurement of the activity from the targeted muscle groups.

Bipolar concentric EMG needle electrodes consist of an inner and an outer wire, which creates a limited recording area that helps to isolate the electrical activity generated by the facial muscles. This is crucial in a surgical setting where nerve integrity monitoring is performed, ensuring that any neurophysiological changes indicative of nerve damage can be detected promptly.

Surface electrodes, while useful for certain types of recordings, tend to pick up more noise and interference from surrounding muscles and tissues, which can compromise the specificity of the signal from the facial nerve. Single monopolar needles can also be used but are less sensitive compared to bipolar configurations, and they can be more prone to artifacts from other muscle activity. Indifferent electrodes serve as a reference point and do not actively contribute to sensing the electrical activity of the facial nerve.

The use of bipolar concentric design in needle electrodes thus represents an optimal choice for achieving sensitive and specific recordings during monitoring of cranial nerve functions.