Continuous Electroencephalographic Characterization of Late Seizures in Traumatic Brain Injury With a Biphasic Clinical Course and Late Reduced Diffusion: A Case Series.

BACKGROUND: This study aimed to characterize late seizures in infants with traumatic brain injury with a biphasic clinical course and late reduced diffusion (TBIRD) using continuous electroencephalography (cEEG). METHODS: The present, single-center, retrospective case series was conducted at a single center between 2020 and 2025. TBIRD was defined as early post-traumatic seizures or impaired consciousness, seizure onset 3-6 days after injury, and the late appearance of high signal intensity areas in the subcortical white matter on diffusion-weighted magnetic resonance imaging. cEEG recordings and clinical and imaging data were reviewed by pediatric neurologists using standardized critical care electroencephalography terminology. RESULTS: Seven infants aged 3-9 months (median age: 5 months) presenting with early convulsive status epilepticus, acute subdural hematoma, and a high Tada score (≥4) met the inclusion criteria. The seizures emerged 3-5 days after injury and initially occurred as electrographic seizures without clinical correlates, clustered in all the patients, and evolved into electrographic status epilepticus in five patients. The seizures typically arose from lateralized periodic discharges or lateralized rhythmic delta activity, most often in the occipital region or in the areas adjacent to the hematoma. CONCLUSIONS: These findings indicated that late seizures in infantile TBIRD are frequently occult at the bedside and may be overlooked without cEEG. cEEG monitoring may facilitate earlier recognition of late seizures and enable timely diagnosis and management of TBIRD.