The LIMIT clinical decision instrument (CDI) was published in 2021 to safely reduce neuroimaging in patients with recurrent seizures. The LIMIT CDI had a sensitivity of 90%, negative predictive value of >99.9%, and reduced neuroimaging by 13.3%. However, the design of the original LIMIT CDI made it cumbersome to use. The goal of this study was to validate the streamlined LIMIT-NeuroImaging (LIMIT-NI) CDI and compare its performance to the original LIMIT CDI.

This was an observational study of patients presenting to three emergency departments with recurrent seizures. The LIMIT-NI CDI was applied to all patients. We calculated the test characteristics of the LIMIT-NI CDI and compared it to unstructured clinical judgement.

3401 patients were screened, and 2125 patients were included in the final analysis. 16 patients (0.75%) had positive CTs; Both the LIMIT-NI CDI and clinician judgement identified all 16 patients with a sensitivity of 100.0% and a negative predictive value of 100.0%. Using unstructured clinical judgement, emergency providers ordered 835 brain CTs, while only 499 brain CTs would have been ordered using the CDI, a reduction of 15.8% (relative reduction 40.2%).

The LIMIT-NI CDI demonstrated greater ease of application and improved test characteristics compared to the original LIMIT CDI. Compared to unstructured clinician judgement, the LIMIT-NI CDI reduced neuroimaging by 15.8% (relative reduction 40.2%) in recurrent seizure patients. The LIMIT-NI CDI can be used by physicians along with clinical judgement to reduce neuroimaging in the recurrent seizure patient.