Epilepsy Journal

Voltage Dependent Sodium Channels (VDSC) is fundamental for neuronal excitability and action potential propagation. There is a differential expression of the VDSC isoforms in different regions within the Central (CNS) and Peripheral Nervous System (PNS). The different isoforms (Nav1.1–Nav1.9) are widely expressed within the nervous system during specific developmental stages; however, the precise subcellular distribution for some isoforms is still incomplete. VDSC are important therapeutic targets for a wide variety of pathophysiological conditions, including chronic pain, cardiac arrhythmia, and epilepsy. Studies on the genetic basis underlying several striking human phenotypes have revealed the importance of NaV1.7 in pain signalling pathways and as a therapeutic target for treatment of chronic pain. Given that NaV1.7 expression in CNS has not been precisely addressed, and that the determination of its precise location is important to understand its function within neurons, we attempted to study the NaV1.7 subcellular localization in hippocampal neurons in culture by immunofluorescence. On the other hand, we studied the NaV1.2 subcellular localization and compared its expression pattern with NaV1.7. NaV1.2 is a Tetrodotoxin (TTX)-sensitive channel, predominantly expressed in the central nervous system and its subcellular distribution has been widely studied in central neurons. When we compared NaV1.2 and NaV1.7 we observed a distinctive subcellular localization for these two isoforms. Additionally, using a PanNaV antibody, which recognizes all sodium channel isoforms, we observed that PanNaV signal overlapped NaV1.2 and NaV1.7 specific signals. PanNaV labeled the Axon Initial Segment (AIS), cell bodies and neurites. NaV1.2 specific signal was mainly observed in the AIS, soma, dendrites and Golgi apparatus; while NaV1.7 mainly was present in soma, axons and growth cones. Our findings describing Nav1.7 in growth cones represent a new subcellular localization for this isoform and provide new evidences that suggest additional roles in neuronal functioning within the CNS.

Muscle-Eye-Brain Disease (MEB) constitutes part of a spectrum of closely overlapping Congenital Muscular Dystrophies (CMD) and neuronal migration disorders. Here, we present a child with MEB presenting with refractory epilepsy, a rare disease and all the more, a rare presenting manifestation. We hereby highlight the rarity of the syndrome per say, its presentation as refractory seizures to an Epileptologist and the radiological characteristics which help diagnosing MEB accurately obviating the need for an invasive procedure like muscle biopsy and molecular genetic studies in centres with limited infrastructure.

Introduction: Hyper Motor Seizures [HMS] are characterized by complex high amplitude movements involving proximal segments of the body resulting violent and inappropriate to the context.

Objective: To review the possible ictal onset zones related to HMS and the cortical areas that would be covered if invasive recording are needed.

Development: Semiology can predict the localization of ictal onset zone. Two subtypes of HMS [type 1 and 2] have been described. HMS1 is associated with an epileptogenic zone on the ventromedial frontal cortex and HMS2 has been associated with a more dorsal epileptogenic zone than those resulting in HSM1. However, HMS can also be originated in temporal lobe [mesial, neocortical or in the pole], in insular cortex or even in parietal lobe. The origin of HMS can be suspected by the associated signs. Thus, HMS originating in the insula–operculum regions can be associated with various somatosensory auras; in parietal seizures, propioceptive sensations may precede hyper motor behavior [HM], whereas autonomic and emotional auras prompt to think in the temporal lobe origin.

Conclusion: Except in cases of lesional temporal lobe epilepsy with concordant prersurgical results, all patients with HMS should be evaluated through intracranial recordings. The auras, the HMS subtype, the hypometabolic areas showed by PET study, and the localization and lesion type seeing on MRI can help to decide what structures should be covered with depth electrodes during invasive recordings.