Which of the following montages would best display the amplitude of a left temporal spike?

• A. Anterior to posterior bipolar chain
• B. Left temporal to ipsilateral ear
• C. Left temporal to contralateral ear
• D. Transverse bipolar chain

Answer: (C)

The most suitable montage for displaying the amplitude of a left temporal spike is the one that records from the left temporal area and the contralateral ear. This arrangement effectively captures the electrical activity from the left temporal region while providing a reference from the opposite side, allowing for a clearer representation of the spike's amplitude.

In an EEG, when monitoring specific regions of the brain, using a montage that includes the area of interest (in this case, the left temporal lobe) and a point of reference from the other side (the right ear) helps to compare the activity between these two locations. This method enhances the detection of spikes, which can sometimes be subtle, by comparing the relative amplitude of the spike against the reference signal.

In contrast, the other montage options either do not provide as clear a representation of left temporal activity or are designed for different purposes. An anterior to posterior bipolar chain would track frontal to occipital activity, potentially missing localized spikes. The left temporal to ipsilateral ear configuration could reduce the sensitivity to the spike amplitude by not contrasting it with a signal from the other hemisphere, and the transverse bipolar chain focuses more on lateral activity across the scalp rather than specifically isolating spikes in the left temporal region.