Abstracts

Rationale: The autonomic nervous system activates during seizures. Objective measures of pupillary reactions indirectly measure the sympathetic and parasympathetic responses. This pilot study evaluated pupillary reactions immediately after epileptic seizures and non-epileptic events to understand the autonomic changes during postictal periods. Methods: This single center study was approved by the local IRB.A handheld device (Neuroptics) measured the pupil changes before and after a seizure. This device, approved by the Food and Drug Administration, records and stores pupil’s reaction to an infrared light stimulus. Three patients admitted for characterization of seizures were enrolled for a total of 4 electrographically confirmed events: 2 right temporal lobe seizures, 2 left frontal with secondarily generalized seizures, and one non-epileptic event. Five baseline pupil measurements were taken for each patient. Post ictal recordings were taken immediately after seizure and up to one hour after seizure. The pupillometer data was time-stamped and analyzed offline. Parameters collected for every pupillary response included: Maximum baseline pupil diameter/area before light stimulus (BPA Max), Minimum baseline pupil diameter/area after light stimulus (BPA Min), Latency (Tlat; Time to start constricting), Constriction percentage (C%; Percentage of constriction: BPA Max-BPA Min/BPA Max X 100) Time to reach BPA Min (Tmin- Excludes Tlat) Constriction Velocity (CV; Velocity at which pupil constricts: BPA Max-BPA Min/Tmin).  Results: Postictally there was a 25 percent decrease in the pupil diameter and constriction velocity from baseline within the first 10 minutes in focal right temporal lobe seizure and first 20 minutes in frontal with secondary generalization seizure. The percentage decrease from baseline measurements is significant compared to normative data from pupillometer validation studies, where there was 8% pupil diameter variation. The miosis slightly predominated on the ipsilateral side. There was no difference from baseline pupil reaction measurements in non-epileptic events.  Conclusions: Pharmacological studies showed that parasympathetic blockade causes increase in BPA Max, and decrease in C% and CV. While, sympathetic blockade decreases BPA Max with no influence on other parameters . Our results suggest that the decrease in BPA Max is due to either sympathetic blockade or increase in parasympathetic activity immediately postictal. The decrease in constriction velocity suggests parasympathetic blockade. Taken together, there might be both sympathetic and parasympathetic blockade with more sympathetic blockade. These results partly support the current pathophysiologic hypothesis of sudden unexpected death in epilepsy (SUDEP) which includes autonomic instability with parasympathetic suppression.To date, no studies have measured quantitative pupillary changes related to seizures. Funding: No funding