Abstracts

Rationale: Hot water epilepsy (HWE) is a reflex epilepsy precipitated by hot water bath. This study aims to examine the changes in resting state networks in patients with hot water epilepsy.  Methods: Five patients (M:F- 3:2, age at onset, 9.68±10.27 years, age at evaluation – 24.4±13.27 years) with refractory reflex hot water and unprovoked epilepsy underwent MEG as a part of their routine pre-surgical evaluation (including MRI, Video-EEG, neuropsychological assessment and routine EEG) and 5 age and gender matched healthy controls were included in this study (MRI findings: 3 patients-Normal MRI, 2 patients-right supra-sylvian calcification, and left occipital gliosis). Resting record of MEG was obtained in an Elekta Neuromag Triux 306 channel system and pre-processed with Maxfilter. Cardiac artifacts were removed by ICA. Patient MRI was used as a forward model and source space mapping was performed using beamformer (LCMV) for 0.5-150Hz band filtered data. Phase Lag Index (PLI) was calculated for the parcellated (68 regions) source space time series and compared with PLI values of the healthy controls using Wilcoxon signed rank sum test with FDR correction.  Results: Patients had both reflex hot water and spontaneous unprovoked seizures which were uncontrolled with >=2 AEDs. Examination of connectivity with PLI showed decrease in connectivity in bilateral superior temporal sulcus banks (STSB), right orbitofrontal, left lingual and right paracentral areas of the cortex (p<0.0113). No significant differences were seen in specific bands.  Conclusions: Animal models have shown the involvement of STSB in multimodal sensory processing including auditory, visual and somato-sensory information. The orbitofrontal cortex has extensive connections with the sensory areas and the limbic cortex. Involvement of these sensory hubs might contribute to the reflex component of HWE and the proximity to the limbic cortex might be responsible for the typical hypomotor seizures seen in HWE. Further studies examining the role of subcortical regions in HWE would provide greater understanding in the network changes associated with it.  Funding: No funding