# Temporal Patterns of Skin-Fixed Depth Electrodes During Stereotactic Electroencephalography Recording

## TL;DR

This study compares how two methods of fixing brain electrodes affect their movement over time during epilepsy evaluations.

## Contribution

The study provides a detailed analysis of temporal dislocation patterns in skin-fixed SEEG electrodes compared to anchor bolt fixation.

## Key findings

- Skin-fixed electrodes showed significantly more longitudinal migration (4.34 mm) compared to anchor bolts (0.16 mm).
- Electrode migration was most pronounced during bilateral implantation procedures.
- Lateral displacement averaged 0.87 mm in the skin fixation group with no migration-related complications observed.

## Abstract

Introduction: Stereotactic electroencephalography (SEEG) is increasingly used to evaluate patients with refractory epilepsy. While anchor bolts are widely used for depth electrode fixation, their lack of insurance coverage or technical limitations may necessitate alternative methods, such as fixation to the skin. Few studies have investigated how fixation methods affect electrode dislocation during recording.

Methods: To clarify the time-dependent pattern of skin-fixed electrode dislocation, depth electrode dislocation during recording was evaluated in 41 electrodes from four patients with anchor bolt fixation and 66 electrodes from five patients with skin fixation.

Results: Twenty-nine electrodes in the anchor bolt group and 45 electrodes in the skin fixation group were targeted to the anterior temporal or perisylvian regions. The mean cumulative migration in longitudinal direction during recording was 4.34 ± 2.43 mm in the skin fixation group compared to 0.16 ± 0.43 mm in the anchor bolt group (p < 0.0001). In the skin fixation group, the net migration during recording was -2.53 ± 2.20 mm, and the net migration from the original position was +0.37 ± 1.87 mm in the skin fixation group (negative values represent inward migration). Electrode migration was most prominent during the bilateral implantation procedure (+6.01 ± 3.48 mm). The mean electrode shift (lateral displacement) in the skin fixation group was 0.87 ± 0.68 mm. No migration-related complications were observed.

Conclusion: Temporal pattern of skin-fixed depth electrode dislocation was evaluated in detail. Fixation to the skin carries a higher risk of electrode migration compared to anchor bolts. Although this rarely causes clinical complications, caution is warranted both for risk prevention and when interpreting anatomo-electrophysiological relationships.