[A study on the propagation characteristics of epileptic spike signals based on simultaneous intracranial and scalp...

Spikes, as a key electrophysiological marker of abnormal synchronized neuronal discharges, can be identified and detected by scalp electroencephalography (EEG), and are of great value for localizing epileptic foci and investigating the mechanisms of epilepsy. However, spike propagation is strongly influenced by the skull, making it difficult to infer the precise intracranial origin of spikes from scalp EEG alone. Therefore, based on simultaneous intracranial and scalp EEG recordings, this study investigated the propagation characteristics of spikes from the intracranial space to the scalp. The study mainly focused on four aspects: the characteristics of simultaneous intracranial and scalp spikes, the scalp visibility of intracranial spikes, the spatial distribution of scalp spikes, and the influence of epileptogenic and non-epileptogenic regions on spike propagation. The results showed that spikes detectable on the scalp differed significantly in energy-related features from those not detectable on the scalp ［ MD = 2.6 × 10 ^-6 (2.5 × 10 ^-6, 2.6 × 10 ^-6), P < 0.01］. When the intracranial spike activation area was less than 10 cm ², the scalp detection rate was 18.9%; when the area reached 30～40 cm ², the detection rate increased to 62.5%, showing an increasing trend. After spikes propagated to the scalp, the detection rate decreased by 63.5% when the horizontal distance of their spatial distribution exceeded 4 cm. In addition, there was no statistically significant difference in scalp detection rate between spikes originating from epileptogenic and non-epileptogenic regions ( P > 0.05). In summary, these findings are important for elucidating the propagation characteristics of spikes and may provide quantitative evidence for electrophysiological analysis and focus localization in epilepsy.