Effects of Vagus Nerve Stimulation on Sustained Seizure Clusters: A Case Report

Seizure clusters (SCs) are acute repetitive seizures with acute episodes of deterioration during seizure control. SCs can be defined as a series of grouped seizures with short interictal periods. Vagus nerve stimulation (VNS) is a treatment option for drug-resistant epilepsy. We present a case where VNS suppressed epileptic SCs, which had persisted for several months. A 13-year-old boy with congenital cerebral palsy and mental retardation had drug-resistant epilepsy with daily jerking movements and spasms in both sides of his body. The seizures were often clustered, and he experienced two sustained SC episodes that persisted for a few months even with prolonged use of continuous intravenous midazolam (IV-MDZ). The patient underwent VNS device placement at the second sustained SC and rapid induction of VNS. Because the tapering of IV-MDZ did not exacerbate the SC, midazolam was discontinued 4 weeks after VNS initiation. Non-refractory SCs also disappeared 10 months after VNS. The seizure severity was improved, and the frequency of seizures reduced from daily to once every few months. The epileptic activity on electroencephalography (EEG) significantly decreased. This case highlights VNS as an additional treatment option for SC. VNS may be a therapeutic option if SC resists the drugs and sustains. Additional studies are necessary to confirm our findings and to investigate how device implantation and stimulation parameters affect the efficacy of VNS.