Human neocortical interictal epileptiform discharges are initiated by a low-voltage negative polarity wave.

In between seizures, the brain of a patient with epilepsy will generate isolated, sporadic discharges (interictal epileptiform discharges [IEDs]). IED identification enables clinicians to diagnose epilepsy, and an understanding of IED waveforms may yield new insights into basic epilepsy mechanisms. I show that intracranial EEGs disclose a previously unreported negative polarity, low-voltage pre-potential at IED onset (i.e., a negative wave [n-wave]). I describe the features of n-waves and propose a plausible mechanism of their generation. In intracranial EEGs of the human neocortex, I assessed n-waves' occurrence, anatomical location, amplitude, kinetics, and association with the subsequent positive pre-potential. I computed a model simulation of IED onset to identify plausible mechanisms behind n-wave generation. N-waves manifested in 40% of patients, in zones with and without seizures, and without a statistically significant prevalence in their anatomical location. These waveforms exhibited voltages of 140+42 μV and durations of 39.9+12.2 msec and were coupled with a positive pre-potential. In simulations of IED onset, n-waves can be generated by sequential recruitment of distinct microfoci over superficial cortical laminae. N-waves represent an overlooked component of IED waveforms. They prolong the duration of IED onset and can facilitate synaptic hypersynchrony. They may also be associated with chronic epilepsy. Copyright © 2019. Published by Elsevier Ltd.

Citation

Ruggero Serafini. Human neocortical interictal epileptiform discharges are initiated by a low-voltage negative polarity wave. Seizure. 2020 May;78:150-158

Mesh Tags

PMID: 31629613

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