SUMMARYReading epilepsy (RE) is an idiopathic reflex epilepsy syndrome characterized by perioral myoclonic jerks (PMJs) during reading associated with left-dominant frontotemporal spike-wave discharges (SWDs). To better understand the pathophysiology of this syndrome, we studied a 45-year-old patient using magnetic source imaging (MSI). The patient underwent two whole-head magnetoencephalography (MEG) recordings (Elekta Neuromag Oy) within 2 months while reading aloud. Forty-two SWDs associated with PMJs were recorded and averaged with respect to SWDs peak power. Epileptic discharges were then reconstructed using conventional equivalent current dipoles (ECDs) modeling, distributed sources sLORETA modeling, and beamformer approach. These methods identified two brain sources located in the left supplementary motor cortex (SMC) and the left primary sensorimotor face area (PSMFA). The spatiotemporal pattern of the sources was characterized by a cross-talk between these two brain regions, with an initial source in the left SMC. This MSI investigation suggests that RE-PMJs are associated with reading-induced activation of hyperexcitable neurons in the left SMC, followed by secondary propagation to the left PSMFA producing the myoclonus. KEY WORDS: Reading epilepsy, Reflex epilepsy, Magnetoencephalography, Magnetic source imaging, Supplementary motor cortex.Reading epilepsy (RE) is a rare idiopathic partial reflex epileptic syndrome characterized by two types of readinginduced seizures (Koutroumanidis et al., 1998;Gavaret et al., 2010;Koepp 2010;Maillard et al., 2010;Miller et al., 2010). The most common seizure type associates perioral myoclonic jerks (PMJs) with left-dominant frontotemporal spike-wave discharges (SWDs). The second seizure type associates visual symptoms and alexia or dyslexia with leftdominant temporooccipital SWDs.The pathophysiology of RE characterized by PMJs remains unclear. Combined electroencephalgraphy (EEG) and functional magnetic resonance imaging (EEG-fMRI) studies have found left-dominant activations of motor and premotor cortical areas, together with some subcortical structures, during reading-induced PMJs (Archer et al., 2003;Salek-Haddadi et al., 2009). Due to the relatively low temporal resolution of EEG-fMRI, these studies did not inform on the neuronal recruitment chronology within the identified network.To tackle this temporal dimension, we report a case of RE with PMJ studied with magnetic source imaging (MSI). MSI localizes noninvasively neuronal sources contributing to signals detected by magnetoencephalography (MEG), with a temporal resolution in the millisecond range and a spatial resolution of a few millimeters (Hämäläinen et al., 1993)
Material and Methods
Clinical dataA right-handed and Dutch-speaking 45-year-old woman, diagnosed with catatonic schizophrenia, was treated with quetiapine, an oral antipsychotic drug. A few months after quetiapine was started, right PMJs appeared while she was reading and led to two episodes of secondary tonic-clonic generalized seizures. Vide...