Lesion focused stereotactic thermo-coagulation of focal cortical dysplasia IIB: a new approach to epilepsy surgery?

PURPOSE: Over the last few decades, preferred epilepsy surgical approaches have developed from standard lobectomies to individually tailored resections. Yet, it remains uncertain how small surgical interventions can be without compromising the success of the surgery. Particularly in patients with epileptogenic lesions identified by magnetic resonance imaging (MRI), it is unresolved whether resection or destruction of the lesion suffices to eliminate the epileptogenic zone. We present a minimally invasive surgical approach that may provide insight into this issue.
METHODS: Two patients with pharmacoresistant epilepsy due to focal cortical dysplasia type IIB demonstrated by 3 Tesla MRI were treated with lesion-focused stereotactic radio-frequency thermo-coagulation. In both patients, pathognomonic epileptic discharges were recorded from the lesion via a stimulation device prior to coagulation. In one patient, the suspected proximity of the lesion to the pyramidal tract was verified by eliciting motor evoked potentials from the depths of the lesion.
RESULTS: Following complete and near complete lesion destruction, seizures (several per day or per week, respectively) ceased in patients A and B, with no seizures for 12 months and 5 months, respectively, at the time of this publication. Neither patient acquired persistent postoperative neurological deficits.
CONCLUSION: The fact that seizure activity stopped after destruction of small bottom-of-sulcus dysplasias implies that in these cases, the epileptogenic zone and the epileptogenic lesion may overlap. If future studies can replicate this finding, focused lesion destruction could be a further development of individually tailored epilepsy surgery. The technique described here is especially suited for high-precision surgery close to eloquent brain structures.