Does delayed removal of stereo-EEG electrodes following radiofrequency thermocoagulation increase haemorrhage?

Stereo-electroencephalography (SEEG) guided radiofrequency thermocoagulation (RF-TC) is used in the assessment and treatment of medically refractory epilepsy, typically with electrode removal immediately following ablation. Our SEEG-guided RF-TC protocol includes the option of three further days of recording following thermocoagulation, prior to electrode removal. It is not known whether delayed removal of electrodes following RF-TC may increase the risk of haemorrhage.

To compare the rate and volume of intracranial haemorrhage with immediate versus delayed electrode removal following RF-TC.

217 SEEG electrodes from 16 consecutive patients were retrospectively reviewed for haemorrhage. 3D T1-weighted (T1w) and Susceptibility Weighted (SWI) imaging were reviewed for haemorrhage along the electrode tract and at the site of RF-TC. The primary outcome measure was the per-electrode volume of T1w detectable haemorrhage at the site of RF-TC in electrodes removed immediately after RF-TC, compared to electrodes removed 3-days after RF-TC. Secondary outcomes compared the incidence and volume of T1w haemorrhage along the electrode tract in thermocoagulated versus non-thermocoagulated electrodes, presumed due to reflect haemorrhage from electrode insertion/removal. We also describe the temporal evolution of the MRI appearance of haemorrhage following SEEG-guided RF-TC.

No clinically significant haemorrhages occurred. At the site of RF-TC a small amount of blood product is universally present but there was no significant difference in per-electrode haemorrhage volume following delayed (93.8 ± 39.8 mm³; ~diameter 5.6 mm) and immediate (80.0 ± 37.5 mm³; ~ diameter 5.3 mm) removal of electrodes (Mann-Whitney U test, p = 0.10). At the cortical surface there was no significant difference in the rate of T1w haemorrhage between thermocoagulated and non-thermocoagulated electrodes (63.1% vs 52.5%, p = 0.12, chi-squared).

Delayed removal of electrodes post-RF-TC allows assessment of response to RFA and the opportunity for further thermocoagulation if necessary. This exploratory study found no significant increase in haemorrhage volume with delayed electrode removal following RF-TC but a larger study would be required to definitively estimate haemorrhage risk.