Nonconvulsive status epilepticus featuring ictal paresis mimicking a stroke.

PURPOSE: Wilson (1928) and Lennox (1960) described ictal paresis (IP) occurring during prolonged seizures that correspond to the modern definition of nonconvulsive status epilepticus (NCSE). This study aims to characterize this NCSE variant and clearly distinguish it from an acute stroke. METHODS: Three male and three female patients were evaluated from 2015 to 2023. Analysis was restricted to the ictal phase by including only those with neurological deficits at the time of MRI/CT perfusion. RESULTS: Among the six patients, four had hemicorporeal deficits and two had isolated arm deficits. Other manifestations included sensory disturbances in three cases, mutism in five cases, and hemianopia in four cases. Two patients displayed perioral paresthesia. EEG showed ictal-interictal continuum patterns in three cases and focal/regional slowing in the other three. In contrast, MRI supported the diagnosis in all six patients. ASL proved diagnostic in each of the three patients who underwent this sequence, including two individuals with normal DWI and FLAIR results. Three patients underwent CT perfusion, which revealed focal hyperperfusion consistent with ongoing SE in one case. The median NCSE duration was 7.5 days (range 3-28). One patient had a brain atrophy sequela, which was the only patient with caudate nucleus and putamen involvement on MRI during NCSE. CONCLUSION: IP represents an under-recognized manifestation of NCSE. This study shows that perfusion-based neuroimaging is more sensitive than EEG for detecting ictal activity in this setting. We advocate for the routine inclusion of ASL sequences in the neuroimaging evaluation of patients with a suspected stroke and negative DWI findings.