Missed diagnosis of prehospital status epilepticus: Is it serious, doctor?

Pragmatic computerised perfusion diagnostics for non-convulsive status epilepticus: a prospective observational study

BACKGROUND

Non-convulsive status epilepticus (NCSE) is a time-dependent neurological disorder often misdiagnosed in the emergency setting. Electroencephalography (EEG) is often not available on a 24/7 basis, and Salzburg criteria may at times miss the diagnosis. Here, we tested the accuracy of hyperperfusion on CT perfusion imaging (CTP) in the identification of NCSE against Salzburg criteria, to define its potential role in a pragmatic diagnostic workflow.

METHODS

We enrolled consecutive patients with suspected acute seizure or seizure disorder undergoing brain imaging with CTP and EEG from January 2021 to March 2023. EEG recordings, Salzburg criteria and CTP hyperperfusion were rated and adjudicated by two independent experts blinded to patient status. A reference standard including all clinical, lab, imaging, EEG and therapeutic data was used to adjudicate NCSE diagnosis. Sensitivity, specificity, diagnostic accuracy, positive and negative predictive values (NPV) were calculated for CTP hyperperfusion and Salzburg criteria versus NCSE adjudicated according to reference standard.

RESULTS

Seventy-seven patients were enrolled. Among 21 NCSE cases, 17 were adjudicated according to Salzburg criteria (81%) and 4 received NCSE diagnosis according to reference standard. Agreement between EEG and CTP emerged in 16/21 NCSE cases, reaching sublobar level in 37.5% of cases. Receiver operator curve analysis suggested good accuracy for CTP hyperperfusion for the diagnosis of NCSE (AUROC 0.79, 95% CI 0.69 to 0.89). CTP hyperperfusion had a high NPV for NCSE (NPV 0.97, 95% CI 0.86 to 1).

CONCLUSION

CTP hyperperfusion may be implemented in the emergency fast-track to rule out NCSE, given very high NPV. Further validation studies are needed to evaluate CTP application in real-world setting for NCSE codes.

Hyperperfusion Tmax mapping for nonconvulsive status epilepticus in the acute setting: A pilot case-control study

OBJECTIVE

Nonconvulsive status epilepticus (NCSE) is misdiagnosed in >50% of cases in the emergency department. Computed tomographic perfusion (CTP) has been implemented in the hyperacute setting to detect seizure-induced hyperperfusion. However, the diagnostic value of CTP is limited by the lack of thresholds for hyperperfusion and high interrater variability. This pilot case-control study aims at identifying the diagnostic value of reverse Tmax (rTmax) in differentiating NCSE from acute ischemic stroke in the hyperacute setting.

METHODS

We enrolled patients with NCSE (Salzburg criteria-based diagnosis) and stroke cases 1:1 matched for clinical features and time of presentation. CTP standard maps (mean transit time [MTT]-cerebral blood volume-cerebral blood flow [CBF]) and rTmax maps were elaborated and rated by two experts in CTP blinded to the final diagnosis. Hyperperfusion was adjudicated for standard CTP maps as an increase in CBF and a decrease in MTT, and for rTmax as the presence of a black area on 3-, 2-, and 1-s threshold maps. Cronbach alpha was used for interrater agreement; receiver operating curve analysis was run to measure accuracy with area under the curve.

RESULTS

Overall, 34 patients were included (17 NCSE, 17 stroke; time from onset to imaging = 2 h for both groups). People with NCSE were older and more frequently had a history of epilepsy. NCSE patients had hyperperfusion on rTmax maps in 11 of 17 cases versus zero of 17 in stroke. Intra- and interrater reliability was higher for rTmax than for standard CTP maps (κ = 1 vs. κ = .6). rTmax was 82% (95%CI = 67-97%) accurate in predicting NCSE versus stroke in the hyperacute setting. Agreement between neuroimaging and electroencephalography (EEG) was limited at a hemispheric level for standard CTP maps, whereas rTMax had agreement with EEG largely reaching the sublobar level.

SIGNIFICANCE

rTmax mapping might represent a reliable tool to spot NCSE-induced hyperperfusion with a threshold-based reproducible approach. Further studies are needed for validation and implementation in the differential diagnosis of focal neurological deficit in the hyperacute setting.