Reflex “toothbrushing” epilepsy: Seizure freedom after focal ablation assisted by ictal <scp>fMRI</scp>

A 22-year-old female presented with drug-resistant focal motor seizures with onset at age 14. This manifested as daily episodes of right facial dystonia triggered by toothbrushing, but also by eating, talking, and strenuous exercise. On ictal scalp EEG, there was low-voltage fast activity over the left pericentral area. Structural MRI did not identify a definite lesion. Functional MRI (fMRI) of a reflex seizure, as well as task-based fMRI during toothbrushing, both demonstrated focal activation at the left low pericentral cortex. Stereoelectroencephalography (sEEG) showed recurrent ictal trains of focal spiking concordant with the fMRI activation. Radiofrequency (RF) thermocoagulation was applied at the posterior bank of the left low pre-central gyrus, with post-operative MRI confirming small ablative lesions immediately deep to the ictal fMRI activation, and the patient remains seizure-free more than 3 years after this treatment. Toothbrushing epilepsy is a rare form of reflex epilepsy where seizures are induced by toothbrushing. In this unique case, ictal fMRI assisted targeting of the sEEG implantation, to confirm seizure onset and enable minimally invasive treatment via RF thermocoagulation, resulting in seizure freedom.