Dynamic changes of interictal post-spike slow waves toward seizure onset in focal cortical dysplasia type II

Area of Science:

• Neuroscience
• Epileptology
• Computational Neuroscience

Background:

• Post-spike slow waves (PSS) are a component of spike-and-slow-wave discharges, potentially involved in inhibiting epileptic activity.
• Focal cortical dysplasia (FCD) type II is a common cause of drug-resistant epilepsy, often requiring invasive monitoring.

Purpose of the Study:

• To investigate dynamic changes in PSS power leading up to seizure onset in pediatric patients with FCD type II.
• To compare PSS power and distribution between interictal and preictal periods, focusing on the seizure onset zone (SOZ).

Main Methods:

• Invasive monitoring using subdural grids in 10 pediatric patients with FCD type II.
• Averaging PSS based on spike-triggering in 30-second epochs during interictal and preictal states.
• Quantitative measurement and comparison of PSS power and distribution within and outside the SOZ.

Main Results:

• PSS power was significantly elevated in all brain areas during the preictal period compared to the interictal period.
• Preictal PSS power was significantly higher within the SOZ than outside the SOZ.
• The number of electrodes exhibiting high PSS power increased within the SOZ and decreased outside the SOZ from interictal to preictal periods.

Conclusions:

• PSS power increases globally and becomes increasingly localized to the SOZ as seizure onset approaches in FCD type II.
• The observed increase and spatial confinement of PSS power correlate with the transition to seizures in FCD type II patients.