Is 20 Minutes Duration of EEG Mandatory?

Abstract

Objective: Our hypothesis was that an EEG recording of 20 minutes' duration would yield more
information than a 10-minute EEG in capturing epileptiform abnormalities.
Methods: The study was conducted in electrophyriology section of neurology department of
services hospitals, Lahore during 2012. Total 171 consecutive EEG patient were evaluated.
Results: We prospectively studied 171 consecutive EEGs (patients of 16-29 years old) of 20
minutes' duration performed at Services Hospital. Although the majority (89%) of interictal EEG
abnormalities can be identified within the first 20 minutes of a routine EEG, extending the time of a
routine EEG may increase the yield. The single electrical abnormality was found to appear
between 11 to 14 minutes.
Conclusion: It should be emphasized that every EEG should be done for atleast 20 minutes
duration as recommended, especially when the first 10 minutes are normal.