In this study, we aim to evaluate the yield of activation procedures in routine EEGs, with a specific focus on hyperventilation and photic stimulation.

We conducted a retrospective review of all outpatient EEGs performed at our institution between July 2022 to June 2023 in patients >18 years of age. The use of activation procedures, in particular, hyperventilation and photic stimulation, and any associated abnormalities were noted. Descriptive statistics were performed to determine the yield of activation procedures in detecting abnormalities in routine EEGs.  

494 routine EEGs were performed at the MedStar Health Franklin Square Hospital over a year period. Hyperventilation was performed in 84 (17%) studies and was associated with diffuse slowing in 37 (44%) of cases. Only 1 (1.2%) study showed generalized epileptiform activity associated with hyperventilation. On the other hand, photic stimulation was performed in 489 (99%) of studies and occipital driving was seen in 46 (9.4%) studies. No epileptiform abnormality was associated with photic stimulation.

Our results show that activation procedures performed during routine EEGs in adult patients does not significantly increase the yield of the studies. Individualized use of these procedures may increase the yield of detecting abnormalities, particularly in cases of suspected epilepsy or other seizure disorders. Further studies are needed to determine the effectiveness of these procedures in different patient populations and clinical settings.