Markus Reuber

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.

Objective: Several studies have found that people with functional seizures (FS) have increased mortality, approaching that of epilepsy (epileptic seizures [ES]). The small numbers of deaths in these studies make it unclear whether they can be attributed to comorbidities. We used a very large electronic health database to compare mortality in FS and ES, controlling for comorbidity. Methods: We searched the TriNetX database for people with FS and no ES, people with ES and no FS, and people with neither FS nor ES (NS). We compared mortality while controlling for demographics and comorbid conditions. Results: We identified 1 916 787 people with ES, 32 854 people with FS, and 21 053 667 healthy controls. FS had rates of mental and physical comorbidities that were higher than NS and, for most categories, higher than ES. The risk of death (hazard ratio [HR]) in ES compared to FS was 2.99 (95% confidence interval [CI] = 2.81–3.18), which was reduced to 2.07 (95% CI = 1.92–2.24) when matched for 31 demographic and health factors. The risk of death in NS compared to FS was .56 (95% CI = .53–.59); after matching for demographics and mood disorders, this was .48 (95% CI = .44–.53). Matched sensitivity analyses suggest this was particularly pronounced in the year following diagnosis (HR = .39, 95% CI = .33–.47) and in the 5th decade of life (HR = .38, 95% CI = .27–.52). Significance: FS confers approximately doubled mortality over that conferred by its comorbidities, although still only half of that conferred by ES, most prominently after diagnosis and in early middle age.