Before an EEG to diagnose seizures, which instruction is correct?

• A. Avoid caffeine, stimulants, and depressants
• B. Sleep deprivation for 24 hours
• C. Eat a large meal before the test
• D. Wear contact lenses during the procedure

Answer: (A)

Before an EEG, the goal is to obtain a clean baseline recording of brain activity so that any abnormal epileptiform discharges can be seen clearly. Substances that alter CNS activity or create artifacts should be avoided because they can blur or mimic patterns seen in seizure activity. Caffeine and other stimulants increase cortical arousal and can produce EEG changes or muscle activity that contaminate the tracing, making interpretation less reliable. Depressants, such as alcohol or sedatives, suppress brain activity and can shift or obscure the waveforms, potentially masking abnormalities. By avoiding these substances, the test can more accurately reflect the brain’s typical electrical activity.

Sleep deprivation is not routinely required for every EEG and can be unsafe or uncomfortable for some patients; it’s used selectively to provoke findings. Eating a large meal can cause discomfort or movement that interferes with the recording, and wearing contact lenses does not affect the EEG, so neither is a standard preparatory instruction.