Clinical profiles and prognostic factors in reflex epilepsy: Insights from a Taiwanese cohort

Purpose: To investigate the clinical characteristics, treatment, and prognosis of patients with reflex epilepsies in Taiwan.

Methods: Patients with reflex epilepsies (RE) induced by specific trigger factors from July 2000 to May 2024, were recruited at Chang Gung Memorial Hospital, Linkou, Taiwan. All patients had at least 12 months of follow-up. Demographic data, antiseizure medication (ASM) treatment, stimulus avoidance, and seizure outcome were analyzed. We further divided the patients into extrinsic and intrinsic RE groups based on the nature of stimuli. We also categorized them into ongoing seizure and seizure-free groups based on their seizure control. Fisher's exact test and Independent-Samples Mann-Whitney U Test were used to evaluate associations between clinical factors and prognosis. Multivariate logistic regression analysis was further carried out to determine the predictors of seizure outcomes.

Results: In this study, 81 patients with reflex epilepsies (RE) were analyzed, focusing on those with extrinsic (photosensitive) and intrinsic (Mah-Jong-related) seizure triggers. Patients with extrinsic RE were significantly younger (mean age 40.4 years) than those with intrinsic RE (mean age 64.4 years, p < 0.001) and had a notably earlier onset of reflex seizures (21.9 years vs. 49.7 years, p < 0.001). A higher proportion of extrinsic RE patients experienced spontaneous seizures (98 %) compared to intrinsic RE (40 %). Abnormal EEG findings were more prevalent in the extrinsic group (94.1 %) than in the intrinsic group (66.7 %). Ninety-eight percent of patients with extrinsic RE were treated with antiseizure medications (ASMs), with an average of 2.2 ASMs per patient, compared to 73.3 % and 1.2 ASMs in patients with intrinsic RE. Furthermore, the rate of stimulus avoidance was significantly higher among those with intrinsic RE, at 43.3 % compared to 3.9 % in the extrinsic group (p < 0.001). Both groups achieved similar seizure-free outcomes (68.6 % in extrinsic vs. 63.3 % in intrinsic RE), but stimulus avoidance is independently associated with a reduced likelihood of ongoing seizures (p = 0.038), with an odds ratio (OR) of 0.110.

Conclusion: Intrinsic RE exhibited a later onset of spontaneous and reflex seizures than extrinsic RE. Avoidance of seizure triggers was more frequent in intrinsic RE and among seizure-free patients, suggesting that stimulus avoidance is crucial for better seizure control and prognosis. On the other hand, patients with extrinsic RE had a lower rate of trigger avoidance but were more likely to receive ASM treatment, suggesting ASM is crucial for managing seizures due to challenges in avoiding environmental triggers. Despite these differences, both groups achieved similar seizure-free outcomes, underscoring the necessity for tailored management strategies based on the type of reflex seizures.