Abstracts

Rationale: Rapid reduced montage EEG (RRME) is valuable in evaluating patients emergently to rule out nonconvulsive status epilepticus (NCSE) related to periodic/rhythmic EEG patterns. However, capturing epileptiform and periodic waveforms (EPWs) on emergent EEG is also important in considering use of antiseizure medication (ASM) and need for standard EEG and continuous EEG monitoring. Considering spatial limitations of RRME, sporadic epileptiform discharges with restricted fields could elude detection. In this study, we evaluated patients who underwent both urgent RRME and standard EEG afterward to determine the sensitivity of RRME in capturing EPWs.


Methods: The Ceribell^© database at Mayo Clinic Florida was retrospectively reviewed. Studies were performed between September 2019 and May 2024 to evaluate for NCSE. A neurocritical care fellow (MT) reviewed the EEG and RRME, and a board certified clinical neurophysiologist (BF) reviewed the RRME while blinded to standard EEG studies. Covariates were compared with Student’s t-tests for normally distributed continuous variables, Mann Whitney U-tests for non-normally distributed continuous variables and Fisher exact test for categorical variables. A p-value < 0.05 was significant.


Results: 116 RRME were performed, all followed by standard EEG, and 31 standard EEGs demonstrated EPWs, with 1 excluded due to < 1 minute of RRME recorded. 19/30 had EPWs detected on RRME correlated with the same finding on standard EEG. The frequency of discharges being rare, occasional, or frequent (p=0.003) on standard EEG predicted a lower likelihood of capture on RRME as compared to those seen abundantly or periodically. The time to standard EEG following RRME was not significantly different between those with and without EPWs on standard EEG (p=0.382). Those with EPWs on RRME underwent longer duration RRME (p < 0.025). EPWs were more likely to be detected when in the temporal, frontopolar, and/or occipital regions on standard EEG (p=0.047). There was a wider spatial field of distribution on standard EEG predicting capture of EPWs on RRME (p=0.047); discharges involving > 10 derivations on standard EEG were more likely to be recorded on RRME (p=0.052). Of 3 with parasagittal focal discharges on standard EEG, RRME detected them in 1 case (bilateral field), and most triphasic waves (7/10) on standard EEG were also captured on RRME.

Conclusions: In this study, we demonstrate RRME is sensitive in detecting abundant/periodic discharges, as well as discharges in the temporal, frontopolar, and occipital regions and those with a wider spatial field of distribution on standard EEG. Less frequent sporadic discharges may elude detection on RRME. Though parasagittal discharges could be missed with RRME, a bilateral and multi-derivation field of distribution increases the likelihood of capture. Shorter duration RRME may affect detection of interictal epileptiform activity. Further studies are needed to better understand the utility and limitations of RRME regarding triage for continuous EEG monitoring and consideration of antiseizure medication initiation with EEG outside of the IIC, as well as determining when emergent standard EEG is still warranted following RRME.


Funding: N/A