Can Spectral Power Be Used as a Candidate Seizure Marker of the Periodic Discharges Pattern?

Introduction: It remains controversial whether the periodic discharges (PDs) pattern is an ictal or interictal phenomenon. The aims of the study are to apply time-frequency and power spectrum analysis to study the PDs pattern and prediction of seizures. Methods: We retrospectively searched continuous electroencephalography (cEEG) recordings to identify patients exhibiting the PDs pattern. Artifact-free cEEG segments demonstrating the PDs pattern with stable baselines were chosen for time-frequency and power spectrum analysis. Results: In total, 72 patients (1.3%) exhibited the PDs pattern, with a mean age 36.0 +/- 20.7 years (range, 8-76 years). The median spectral power of PDs with a length of 60 s was 70.94 mu V-2 and that of PDs with a length of 20 s was 195.80 mu V-2. During follow-up, patients with spectral power of PDs of length 60 and 20 s lower than 28.65 and 36.09 mu V-2, respectively, exhibited no seizure. For predicting seizures, when the spectral power for PDs of 60 and 20 s equaled to 17.26 and 21.40 mu V-2, respectively, the diagnostic sensitivity was 100% and specificity was 86%. The locations of maximal spectral power of PDs, crude seizure onset zone (SOZ) judged from scalp EEG, and the most prominent regions of hyper- or hypo-metabolism on FDG-PET were congruent. Conclusions: Spectral power might be a candidate seizure marker of the PDs pattern. High spectral power predicted a high risk of seizures, and low spectral power was associated with a low risk of seizures.

Automated summary

The study suggests that spectral power could be a potential seizure marker for the PDs pattern, with high spectral power indicating a high risk of seizures and low spectral power associated with a low risk of seizures. The locations of maximal spectral power of PDs were consistent with the crude seizure onset zone judged from scalp EEG, as well as the most prominent regions of hyper- or hypo-metabolism on FDG-PET.