gms | German Medical Science

Objective: Modern imaging and improvements in invasive diagnostic of epilepsies allow detection of small epileptogenic lesions, also deep seated or eloquent. Surgical removal of them, even if providing good seizure outcome, can be problematic and risky. Stereotactic radiofrequency thermocoagulation (SRT) allows targeted destruction of small deep or eloquent seated lesions with minimal collateral damage to brain tissue. We report results of SRT in 8 patients.

Method: 8 patients, treated with SRT since 2011 (6 patients with focal cortical dysplasia, 1 patient with histologically unclear lesion and 1 patient with hypothalamic hamartoma (HH)) received multifocal MR- based and SEEG-tailored SRT. In three cases we predicted two independent active irritative zones, in these we decided to perform SRT in SEEG-verified seizure onset zone. SRT was done using multifokal radiofrequency destruction through stereotactic 2,1 mm lesioning electrode. Resulting lesion was consisting of multiple (up to 7) trajectories with several lesions on each, summary SRT volume covered MRI-defined volume of lesion. We recorded SEEG from each lesioning point and from locations, surrounding defined lesion volume on planed trajectories. In several cases we detected specific epileptogenic activity outside of predefined treatment volume and we expended lesions to include these highly active spots.

Results: Complete seizure freedom was archived in 3 patients with focal cortical dysplasia. In 2 Patients with highly active irritative zones in basal temporal lobe and lesions in lingual gyrus we archived >90% seizure reduction. In one patient with complex insular focal dysplasia due to incomplete lesion was no seizure reduction observed. In 2 Patients (eloquent FCD and HH) due to short postoperative follow-up no seizure outcome yet available. One patient developed permanent incomplete expressive aphasia after treatment. No further permanent morbidity or complications observed.

Conclusions: Seizure freedom can be achieved using SRT lesioning in patients with lesional epilepsy. In patients with multiple independent epileptogenic zones it is possible to use SRT as low risk technique resulting in seizure reduction or even seizure freedom also as palliative treatment. Further evaluations of required lesioning volume extension in relation to MRI target volume and SEEG profile are needed. To predict exact lesioning result of multifocal SRT further research of radiofrequency lesion pathophysiology and physics in brain tissue necessary.