Abstracts

Rationale: To investigate if glucose levels influence seizure patterns. Methods: In a patient drug-resistant temporal lobe epilepsy and an RNS with bilateral hippocampi electrodes and type I diabetes mellitus, data from her continuous glucose monitoring system (CGM) and her RNS devices were studied for relationships between left focal seizures (LFS) or right focal seizures (RFS) by outcomes time of seizure and glucose. Consecutive RNS long events were reviewed by a board certified Epileptologist and verified as seizure. Seizures were not studied unless glucose data was available at the time of seizure, only one seizure per day, the first, was used. The closest CGM reading prior to seizure onset was studied (tissue glucose is typically recorded every five minutes). Ultradian trends in glucose were also studied immediately after seizure and in the hours prior and post seizure.A control group was set up based on random date generations during the study period at the exact time of left or right focal seizures. Two controls were studied, one based only on glucoses from seizure-free times matched to LFS or RFS seizure times, and a second based on glucose from seizure-free times matched to any seizure. Two-tailed T-tests were run with variables including tissue glucose by side of seizure onset and control. Trends in tissue glucose in the hour prior to and post event were studied with Chi square. Results: Over 19 consecutive months, A total of 45 seizures were recorded from the hippocampal electrodes, 22 LFS and 23 RFS. Seizures showed no seasonal or monthly trends apparent in frequency or onset location. Seizures were least likely between 6 AM to 4PM, a time in which glucose in general was normal or hyperglycemic. The average glucose closest to time of seizure was 150 mg/dL, those levels were measured on average 2.3 minutes prior to seizure onset. The average glucose at the next CGM reading post seizure was 149 mg/dL and occurred on average 3.27 minutes post seizure. Glucose levels for LFS showed a mean of 169 mg/dL (SD = 66.3), for RFS 131 mg/dL (SD 41.5, t = 2.29 p = 0.03). With comparison to control groups, only the right side showed significance. The mean time of seizure for LFS was 17:02 and for RFS was 4:23, though time plots suggest acrophasic clusterings of seizures different to the mean levels, i.e. LFS in the evening, RFS from midnight until 4 AM.  LFS were of greater intensity, 19 of 22 events spread from left to right hippocampi, while most RFS remained unilateral, with only 2 of 23 spreading to the left side. Conclusions: In a convenience sample of one patient, seizure onset laterality and spread varies with glucose levels AND time of seizure; this finding was most significant for right temporal seizure onsets. Funding: No funding