Non-invasive electroencephalography-based technique for rapid diagnostics of absence epilepsy in rats

Electroencephalography (EEG) is a crucial tool for diagnosing absence epilepsy, a type of generalized epilepsy characterized by brief lapses of consciousness. Here, we used a Wistar Albino Glaxo from Rijswijk (WAG/Rij) rat genetic model of absence epilepsy, in which spike-wave discharges (SWDs) manifested spontaneously and were linked to absence-like behavior. Conventionally, invasive electrocorticography (ECoG) with surgically implanted chronic electrodes has been used to confirm the absence epilepsy by the presence of SWDs in rats. However, this restricts the utilization of the same rat subject in multiple experiments. Therefore, there is a need for non-invasive EEG-based diagnostic tools in rats. This study introduces a novel, non-invasive EEG-based technique designed specifically for the rapid diagnosis of absence epilepsy. This approach is based on the sedative effect of xylazine and its unique capacity to induce SWDs. This approach was evaluated in a well-accepted genetic WAG/Rij rat model of absence epilepsy, including adult subjects of both sexes. Non-invasive EEG recording lasted 6 – 9 min. During the 6-min post-injection period, xylazine-induced SWDs closely resembled spontaneous SWDs in terms of the spike-wave morphology and frequency. The proposed non-invasive EEG-based technique is rapid, safe, inexpensive, and yields consistent results. Importantly, it can be repeated throughout a rat’s lifespan to assess the age-related progression of absence epilepsy.