What is the most likely sensitivity setting for the EEG in a polysomnogram?

What is the most likely sensitivity setting for the EEG in a polysomnogram?

• A. 3 uV/mm
• B. 15 uV/mm
• C. 7 uV/mm
• D. 1 uV/mm

Answer: (C)

Sensitivity is how much voltage is needed to move the EEG trace a certain amount vertically. In a sleep study you want to clearly see both large waves and smaller, transient features like sleep spindles and K-complexes without clipping or losing detail. A middle-ground setting of seven microvolts per millimeter is commonly used because it provides enough vertical resolution to display typical EEG amplitudes and those transient features, while keeping the trace within the recorder’s dynamic range. If the gain is set too high (more sensitive, like one or three µV/mm), large waves or artifacts can saturate the trace and obscure interpretation. If the gain is too low (less sensitive, like fifteen µV/mm), small but important features become hard to see, making accurate sleep staging more difficult.

Sensitivity is how much voltage is needed to move the EEG trace a certain amount vertically. In a sleep study you want to clearly see both large waves and smaller, transient features like sleep spindles and K-complexes without clipping or losing detail. A middle-ground setting of seven microvolts per millimeter is commonly used because it provides enough vertical resolution to display typical EEG amplitudes and those transient features, while keeping the trace within the recorder’s dynamic range. If the gain is set too high (more sensitive, like one or three µV/mm), large waves or artifacts can saturate the trace and obscure interpretation. If the gain is too low (less sensitive, like fifteen µV/mm), small but important features become hard to see, making accurate sleep staging more difficult.