Neuroimaging of the Ictal-Interictal Continuum: Where Do We Stand? A Systematic Review and Meta-Analysis of Current Evidence.

OBJECTIVE:Patterns within the ictal-interictal continuum (IIC) are frequently encountered in critically ill patients undergoing continuous electroencephalographic studies and may reflect ongoing ictal activity or secondary brain injury. Peri-ictal neuroimaging abnormalities (PNA) have been described in association with status epilepticus (SE), but their occurrence in patients with IIC across different neuroimaging modalities remains incompletely characterized. We aimed to assess the occurrence of PNA in adults with IIC across structural and functional neuroimaging techniques. METHODS:We performed a systematic review and meta-analysis following PRISMA 2020 guidelines. PubMed, Embase, and Scopus were searched up to January 2026 for studies reporting PNA in adults with IIC. Eligible modalities included magnetic resonance imaging (MRI), CT perfusion (CTP), and positron emission tomography (PET). Pooled detection rates were estimated using random-effects generalized linear mixed models. RESULTS:Of 8400 records identified, seven studies met the inclusion criteria. Of these, four contributed MRI data (98 patients), two-CTP data (38 patients), and two-PET data (30 patients); no SPECT study was identified. One study contributed data to two modalities. Pooled proportion of PNA was 0.41 (95% CI: 0.30-0.52; I2 = 30.4%) for MRI, 0.34 (95% CI: 0.21-0.50; I2 = 0%) for CTP, and 0.90 (95% CI: 0.73-0.97; I2 = 0%) for PET. SIGNIFICANCE:There are currently a limited number of studies evaluating PNA in IIC. PET showed the highest pooled proportion of PNA, although these findings should be interpreted cautiously. Further studies are required to better define the neuroimaging spectrum within the IIC and to clarify its clinical and diagnostic implications.