Early seizure spread and epilepsy surgery: A systematic review

Area of Science:

• Neurosurgery
• Epileptology
• Clinical Neuroscience

Background:

• Delineating resection margins for epilepsy surgery is crucial for achieving seizure freedom.
• Understanding early seizure spread dynamics is vital for predicting and improving postsurgical outcomes.
• Current literature lacks a consensus on defining early seizure spread and its impact on seizure recurrence.

Purpose of the Study:

• To systematically review and summarize existing literature linking seizure spread to postsurgical seizure outcomes.
• To provide a framework for the quantitative assessment of early seizure spread in epilepsy.
• To evaluate the hypothesis that early seizure spread areas indicate seizure-generating cortex.

Main Methods:

• A systematic review adhering to PRISMA guidelines was conducted.
• Medline database search for English literature (1990-2019) on intracranial electrode-measured seizure spread.
• Inclusion criteria: ≥10 subjects, ≥1-year postoperative outcome, and data on seizure spread.

Main Results:

• Fifteen studies met the inclusion criteria out of 4562 initially identified.
• Seven studies supported the hypothesis that early seizure spread areas are seizure-generating.
• While methods were heterogeneous, 3-10 seconds of seizure spread correlated most strongly with seizure freedom.

Conclusions:

• The relationship between electrophysiologic seizure spread and seizure generation potential requires further investigation.
• Prospective studies are needed to validate epilepsy surgery targeting cortex involved in the initial 3-10 seconds of seizures.
• Defining and quantifying early seizure spread is essential for optimizing surgical strategies in epilepsy.