Ictal-interictal continuum following coil embolization of cerebral aneurysms

Purpose

The ictal-interictal continuum (IIC) has been reported in various clinical conditions, but its relationship with intravascular treatments remains poorly understood. This study reports three cases of IIC following coil embolization (CE) of cerebral aneurysms and evaluates associated outcomes.

Methods

A retrospective review of medical records from May 2018 to May 2024 was conducted, focusing on patients with reduced consciousness after CE. IIC was diagnosed based on EEG patterns following the guidelines of the American Clinical Neurophysiology Society. Factors related to outcomes, including IIC development, were analyzed using a multivariable linear regression model with robust standard errors.

Results

Of 30 patients who underwent continuous (3-hour) EEG monitoring post-coiling, three exhibited IIC patterns characterized by lateralized epileptic activity ipsilateral to the coiling site. One patient also displayed repeated electrographic seizures associated with subtle motor phenomena. EEG abnormalities resolved immediately after intravenous benzodiazepines, but coma persisted. Full recovery of consciousness occurred approximately one week after benzodiazepines withdrawal. Adjusting for other risk factors, patients with IIC had a mean Glasgow Coma Scale score 3.13 points higher at 14 days compared to those without IIC (95 % CI, 0.43∼5.84; p = 0.025). Durations of ICU stay (95 %CI, -6.30–8.27; p = 0.782) and total hospital stay (95 %CI, -43.15∼20.79; p = 0.477) were comparable between groups.

Conclusions

This study highlights IIC as a potential complication of CE. The development of postoperative IIC does not necessarily correlate with worse outcomes.