Do witnesses of functional/dissociative seizures recall them accurately? A UK experimental study of semiology recall at clinically relevant time points with a pilot intervention

Objective Different causes of transient loss of consciousness (TLOC) carry distinct risks and require different management. Early accurate diagnosis is essential to guide counseling, investigation, and referral. In routine practice, frontline clinicians and specialists often rely on eyewitness accounts, yet the reliability of witness testimony for functional/dissociative seizures (FDSs) is unknown. We, for the first time, evaluated eyewitness recall of a single FDS immediately and after clinically relevant delays of 2 and 7 weeks, reflecting waiting times for specialist assessment in the United Kingdom (UK) and elsewhere. We also examined the relationship between confidence and accuracy, and whether early structured questioning improves later recall. Methods In this UK‐based experimental study, general population adults (≥18) viewed a video of an FDS and were randomized to four conditions: A (immediate free recall + 2‐week follow‐up), B (immediate free recall + 7‐week follow‐up), C (immediate systematic questioning + 2‐week follow‐up), and D (immediate systematic questioning + 7‐week follow‐up). The primary outcome was accuracy on 15 standardized semiology questions, scored against consensus ratings from five neurologists. Results Of 300 participants, 286 (95.3%) viewed the video in full; 90% completed follow‐up. Immediately afterward, participants answered only 67.0% of questions correctly. Accuracy declined to 58.8% at 2 weeks and was a further 5.4% lower at 7 weeks (95% confidence interval [CI] = 2.07–8.73). Features sometimes considered diagnostically informative—asynchronous limb movements, head movements, ictal eye closure—were prone to decay. Confidence was weakly associated with accuracy. Immediate systematic questioning did not improve follow‐up recall compared with free recall (−2.9, 95% CI = −6.3 to .5). Significance Eyewitness recall of FDSs is modest and declines over clinically relevant intervals, and confidence poorly reflects accuracy. Early structured questioning did not improve retention. These findings highlight a key constraint on diagnostic accuracy in TLOC. Strategies to support differentiation in routine care are needed.