Stereo-EEG Evaluation and Surgical Treatment in Patients With Drug-Resistant Focal Epilepsy Associated With Nodular Heterotopia

Abstract

Purpose: Nodular heterotopia (NH) is a common cause of drugresistant epilepsy. Only limited studies detail the treatment of NH with laser interstitial thermal therapy and none analyze the relation between epileptogenicity and NH location.Methods: We retrospectively studied nine patients with drugresistant epilepsy and NH who underwent stereoelectroencephalography and subsequent epilepsy surgery. Nodular heterotopia in the frontal lobes or along the bodies of the lateral ventricles was classified as anterior NH. Nodular heterotopia in the trigones, temporal or occipital horns, or temporal lobes was classified as posterior NH. Nodular heterotopia in both anterior and posterior locations was classified as diffuse NH. Interictal and ictal stereoelectroencephalography were analyzed, and patients were followed postoperatively to assess outcomes.Results: Of the six patients who underwent nine laser interstitial thermal therapy procedures either in isolation or in combination with other surgical therapies, four patients were Engel Ia, one was Engel IIb, and one was Engel IIIa, with an average follow-up of 22.8 months. All patients with posterior NH had interictal epileptiform abnormalities and seizures originating from the posterior NH. None of the patients with anterior NH had epileptiform activity recorded from their NH. Conclusion:Laser interstitial thermal therapy alone or in combination with other surgical therapies is an effective treatment in those with drug-resistant epilepsy because of NH, even in those with extensive NH and broad seizure onset. We observed a trend suggesting that posterior NH are more likely to be epileptogenic compared with anterior NH and recommend that in patients with anterior NH, alternative epilepsy etiologies and stereoelectroencephalography implantation strategies be considered.

Stereo‐EEG–based ictal functional connectivity in patients with periventricular nodular heterotopia–related epilepsy

“…Indeed, several surgical approaches have been proposed: resective surgery, radiofrequency thermocoagulation (or RF-TC), laser interstitial thermal therapy, responsive neurostimulation, and deep brain stimulation, with various outcomes. [18][19][20][21][22][23][24] NHs are deeply rooted, making resection surgery difficult. Good, albeit, inconsistent results with RF-TC have been reported.…”

“…Identifying seizure leader in cases of NH‐related drug‐resistant epilepsy is of particular importance. Indeed, several surgical approaches have been proposed: resective surgery, radiofrequency thermocoagulation (or RF‐TC), laser interstitial thermal therapy, responsive neurostimulation, and deep brain stimulation, with various outcomes 18–24 . NHs are deeply rooted, making resection surgery difficult.…”

Stereo-electroencephalographic seizure localization in patients with mesial temporal sclerosis: A single center experience

“…SEEG implantation was performed as previously described. ( Durica et al, 2023 ) Postoperatively, all SEEG segments were analyzed by two epileptologists, who determined the location of ictal onset. The ictal onset was defined as repetitive spike discharges, or rhythmic fast waves.…”

Epileptogenicity of incomplete hippocampal inversion and hippocampal sclerosis in a case with periventricular nodular heterotopias

“…Although the left atrium nodule was not an epileptogenic focus itself in this case, it possessed not only physiological visual functions but also extensive direct and indirect connections with the epileptogenic area through the surrounding white matter. The posterior nodules played a complex role alongside the ipsilateral hippocampus within the epileptic network of temporal lobe epilepsy 2,9 . Additionally, an increased complexity of the parahippocampal cortex was found to correlate with hippocampal malrotation indices 6 .…”

“…In this case, the identified epileptogenic zone encompassed the caudal hippocampus and amygdala, with the left atrium nodule exhibiting close connections to the epileptogenic zone. These regions were selected as targets for radiofrequency thermocoagulation (RFTC), 2,3 resulting seizure free for 10 months.…”