Abstracts

Rationale: Daily seizure diaries are essential for epilepsy trials. As disease-modifying and device therapies emerge, longer trials will be needed. However, it is unclear whether patients or caregivers can maintain accurate diaries beyond 12 months, especially in developmental and epileptic encephalopathies (DEEs), where seizure and caregiver burdens are high. We evaluated diary adherence in a prospective feasibility trial of neurostimulation in Lennox-Gastaut Syndrome (LGS).

Methods: Twenty patients (≥12 years) with LGS were enrolled in a single-blind crossover study of bilateral thalamocortical responsive neurostimulation (RNS^® System; NCT05339126). The 13-month trial included a 1-month baseline, a 3-month post-implant period, and three 3-month treatment blocks. Caregivers maintained daily paper seizure diaries, noting seizure-free days and rescue medication use. They were also instructed to interrogate both RNS System devices daily using a tablet, wand, and internet connection. We assessed diary adherence by comparing expected vs. actual diary entries across trial periods and individuals. Device interrogation adherence was similarly assessed.

Results: Overall, ~19% of seizure diary data was missing. Diary adherence ranged from 78-95%, with 5–22% of days missing across study periods. Adherence was highest during baseline (5% missing) and lowest during open label (22% missing). By subject, missing data ranged from 0 to 148 days (n=20). (Figure 1 and Figure 2)
Device interrogation adherence ranged from 54–67%. Adherence was highest post-implant (67%) and lowest in treatment blocks 2–3 (54–55%). These trends highlight the challenge of sustaining engagement, even in motivated participants. Data collection and monitoring are ongoing, and data may change. (Figure 2)

Conclusions: Diary adherence declined over time, underscoring the difficulty of maintaining consistent reporting in long-term trials. These findings emphasize the need for lower-burden alternatives to ensure reliable outcome measurement, especially for non-seizure endpoints. Future trials, particularly those assessing durable or delayed effects, must address diary fatigue and validate alternative tracking strategies.

Funding: Research reported in this publication was supported by the National Institute Of Neurological Disorders And Stroke of the National Institutes of Health under Award Number UH3NS109557. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.