Accuracy of Boltless Frame-Based Stereo-Electroencephalography Electrode Implantation

Area of Science:

• Neurosurgery
• Medical Devices
• Stereotactic Techniques

Background:

• Boltless implantation of stereo-electroencephalography (SEEG) electrodes offers an alternative to traditional anchor bolt methods, particularly in resource-limited settings or for patients with thin skulls.
• While anchor bolt accuracy is established, data on boltless SEEG implantation accuracy and reliability remain limited.
• Potential drawbacks of boltless SEEG include electrode dislodgement, necessitating further investigation into its accuracy and safety profile.

Purpose of the Study:

• To evaluate the accuracy of boltless SEEG electrode implantation.
• To determine the permissible error for accurate electrode placement within the grey matter.
• To assess the incidence and factors influencing delayed electrode dislodgement in boltless SEEG procedures.

Main Methods:

• A total of 120 SEEG electrodes were implanted in 15 patients using a Leksell Stereotactic G Frame, with electrodes secured by sutures.
• Target point error was measured as the Euclidean distance between planned and actual electrode tips via post-implantation CT scans.
• Delayed dislodgement was quantified by comparing immediate post-implantation CT and delayed MRI scans, with accuracy factors analyzed using multiple linear regression.

Main Results:

• The median target point error for boltless SEEG implantation was 2.6 mm (IQR: 1.7-3.5 mm), with a permissible error of 3.2 mm.
• Delayed electrode dislodgement had a median of 2.2 mm (IQR: 1.4-3.3 mm).
• Factors significantly influencing delayed dislodgement included temporal muscle penetration (P = 5.0 × 10⁻⁴), scalp thickness (P < 5.1 × 10⁻³), and insertion angle (P = 3.4 × 10⁻³).

Conclusions:

• Boltless SEEG electrode implantation demonstrates accuracy comparable to anchor bolt methods.
• For optimal planning, target points should be within 3.2 mm of the gray-white matter junction.
• A potential delayed dislodgement of 2.2 mm should be anticipated and considered in clinical practice.