How accurate are witnesses of first suspected seizures in recalling semiology at clinically relevant timepoints? A UK experimental study with a pilot intervention.

Objective: A key diagnostic challenge at "first seizure" clinic appointments is determining whether the reported event was epileptic. Witness accounts are often critical, yet such appointments typically occur weeks after the event. Guidelines recommend review within 2 weeks. Wait times are however often longer, with a median of 7 weeks in countries such as the UK. The accuracy of witness recall at these clinically relevant intervals and whether their confidence predicts accuracy have never been determined. This study addressed these fundamental questions. It also piloted a potential intervention: whether asking witnesses a set of systematic questions immediately after viewing a suspected seizure improves recall at follow-up, compared to the usual free recall approach used by first responders.

Methods: In this UK-based experimental study, adults (≥18 years old) viewed a video of an epileptic seizure and were randomized into four conditions: A (immediate free recall + 2-week follow-up), B (immediate free recall + 7-week follow-up), C (immediate systematic questions + 2-week follow-up), and D (immediate systematic questions + 7-week follow-up). The primary outcome was accuracy on 15 standardized questions addressing key semiological features, scored against consensus ratings from five neurologists.

Results: Of a representative sample of 304 participants, 295 (97%) fully viewed the video, and 94.7% completed follow-up. At 2 weeks, participants answered 54.4% of questions correctly-only 3.9% (95% confidence interval [CI] = .52-7.3) more than those at 7 weeks. Confidence was poorly correlated with accuracy. Immediate systematic questioning improved later recall by 6.7% (95% CI = 3.3-10.0). A definitive trial of this intervention would require 926 participants.

Significance: This is the first evidence on the accuracy of witness recall at clinically relevant intervals. Recall is modest even within recommended timeframes and declines only slightly by 7 weeks. Witness confidence does not predict accuracy. Immediate structured questioning may enhance later recall and thus support seizure diagnoses.