Classification and comparative analysis of psychogenic nonepileptic seizures (PNES) semiology based on video-electroencephalography (VEEG)

Functional seizures: Are they consistent over time?

BACKGROUND

Our previous study showed that functional seizures (FS) are consistent in the same patient during a single video EEG monitoring (VEEG). This study aimed to check whether FS remains consistent across VEEG sessions even after several years.

METHODS

The study evaluated the consistency of FS across different VEEG sessions using five criteria: FS type, the main anatomical region involved (specifically, the body part most affected during the seizure), other involved anatomical regions, frequency of movements, and duration of FS. Consistency levels were categorized as low (one consistent axis), moderate (two consistent axes), and high (three or more consistent axes).

RESULTS

Fourteen patients were included in the final analysis. The mean time between monitoring was 3.8 ± 2.5 years (0.5-8 year). In 13 of 14 patients, the first and second monitoring events were classified into the same FS category. There was consistency in the main anatomical region involved in 9 out of 12 patients with motor FS. In 9 out of 12 patients with motor FS, the other anatomical regions involved were consistent in both sessions. The mean duration of the FS between sessions was inconsistent in most of the patients. Ten patients were classified with high consistency, one patient with moderate consistency, two patients with low consistency, and in one patient, the events were classified as inconsistent.

CONCLUSIONS

Our results show that FS tends to remain consistent in a single patient even after several years, and there is probably no correlation between the degree of consistency and the time between VEEG sessions. These findings have implications for supporting the concept of FS as a consistent phenomenon. Additionally, they may suggest potential avenues for future research to elucidate the origins of FS. Subsequent studies are essential to validate and expand upon these preliminary observations.

Heart rate and autonomic biomarkers distinguish convulsive epileptic vs. functional or dissociative seizures

OBJECTIVE

20-40% of individuals whose seizures are not controlled by anti-seizure medications exhibit manifestations comparable to epileptic seizures (ES), but there are no EEG correlates. These events are called functional or dissociative seizures (FDS). Due to limited access to EEG-monitoring and inconclusive results, we aimed to develop an alternative diagnostic tool that distinguishes ES vs. FDS. We evaluated the temporal evolution of ECG-based measures of autonomic function (heart rate variability, HRV) to determine whether they distinguish ES vs. FDS.

METHODS

The prospective study includes patients admitted to the University of Rochester Epilepsy Monitoring Unit. Participants are 18-65 years old, without therapies or co-morbidities associated with altered autonomics. A habitual ES or FDS is recorded during admission. HRV analysis is performed to evaluate the temporal changes in autonomic function during the peri‑ictal period (150-minutes each pre-/post-ictal). We determined if autonomic measures distinguish ES vs. FDS.

RESULTS

The study includes 53 ES and 46 FDS. Temporal evolution of HR and autonomics significantly differ surrounding ES vs. FDS. The pre-to-post-ictal change (delta) in HR differs surrounding ES vs. FDS, stratified for convulsive and non-convulsive events. Post-ictal HR, total autonomic (SDNN & Total Power), vagal (RMSSD & HF), and baroreflex (LF) function differ for convulsive ES vs. convulsive FDS. HR distinguishes non-convulsive ES vs. non-convulsive FDS with ROC>0.7, sensitivity>70%, but specificity<50%. HR-delta and post-ictal HR, SDNN, RMSSD, LF, HF, and Total Power each distinguish convulsive ES vs. convulsive FDS (ROC, 0.83-0.98). Models with HR-delta and post-ictal HR provide the highest diagnostic accuracy for convulsive ES vs. convulsive FDS: 92% sensitivity, 94% specificity, ROC 0.99).

SIGNIFICANCE

HR and HRV measures accurately distinguish convulsive, but not non-convulsive, events (ES vs. FDS). Results establish the framework for future studies to apply this diagnostic tool to more heterogeneous populations, and on out-of-hospital recordings, particularly for populations without access to epilepsy monitoring units.

Non-1st seizure was less severe than 1st seizure with non-urgent level among suspected seizures transferred by ambulance

BACKGROUND

To prioritize emergency medical calls for ambulance transport for patients with suspected seizures, information about whether the event is their 1st or non-1st seizure is important. However, little is known about the difference between 1st and non-1st seizures in terms of severity. We hypothesized that patients transferred multiple times (≥2 times) would represent a milder scenario than patients on their first transfer. The purpose of this study was to compare patients with suspected seizures on 1st transfer by ambulance and patients who had been transferred ≥2 times.

METHODS

We statistically compared severity of suspected seizures between two groups of patients with suspected seizures transferred between December 2014 and November 2019 (before the coronavirus disease 2019 pandemic) to our facility by ambulance for either the first time (1st Group) or at least the second time (Non-1st Group). Severity categories were defined as: Level 1 = life-threatening; Level 2 = emergent, needing admission to the intensive care unit; Level 3 = urgent, needing admission to a hospital general ward; Level 4 = less urgent, needing intervention but not hospitalization; and Level 5 = non-urgent, not needing intervention.

RESULTS

Among 5996 patients with suspected seizures conveyed to the emergency department by ambulance a total of 14,263 times during the study period, 1222 times (8.6%) and 636 patients (11%) met the criteria. Severity grade of suspected seizures ranged from 1 to 5 (median, 4; interquartile range, 3-4) for the 1st Group and from 1 to 5 (median, 5; interquartile range, 4-5) for the Non-1st Group. Most severe grade ranged from 1 to 5 (median, 4; interquartile range, 4-5) for the Non-1st Group. Severity grade differed significantly between groups (p < 0.001, Mann-Whitney U-test). Uni- and multivariate logistic regression tests also suggested a significant difference (p < 0.001) in severity grades.

CONCLUSION

In direct comparisons, grade of suspected seizure severity was lower in the Non-1st Group than in the 1st Group.