Does stereoelectroencephalographic depth electrode insertion alter seizure frequency? A baseline versus endpoint...

Area of Science:

• Neurology
• Neurosurgery
• Epilepsy Research

Background:

• The implantation effect is a temporary decrease in seizure frequency after intracranial electrode insertion for epilepsy.
• This phenomenon occurs independently of any therapeutic interventions.

Purpose of the Study:

• To investigate clinical and demographic predictors of the implantation effect.
• To analyze seizure reduction rates and seizure freedom in patients undergoing stereoelectroencephalography (SEEG).

Main Methods:

• Retrospective analysis of 51 epilepsy patients who underwent SEEG between December 2018 and February 2020.
• Follow-up at 1, 3, 6, and 12 months post-implantation to assess seizure frequency reduction (≥50% defined responders).

Main Results:

• Responder rates were 71.4% at 1 month, decreasing to 33.3% at 6 months, and rising to 50.0% at 12 months.
• Complete seizure freedom was achieved by 42.9% at 1 month and 20.0% at 3 months.
• No significant associations were found between seizure reduction and patient demographics, imaging, stimulation, electrode number, or medication type/load.

Conclusions:

• The lack of predictive variables suggests microlesions from electrode implantation may transiently disrupt epileptogenic networks.
• Electrode quantity did not impact outcomes, implying implantation location is more critical.
• Further prospective studies are required to elucidate the mechanisms of the implantation effect.