Introduction: The two dominant treatments for refractory atonic seizures are corpus callosotomy (CC) and vagus nerve stimulation (VNS). Several studies examining the efficacy these treatments individually exist, but to date there have been no systematic comparisons.
Methods: PubMed was queried using the following Boolean terms for CC—“callosotomy” AND (seizure OR seizures OR epilepsy) AND (atonic OR “drop attack”)—and for VNS: (vagus OR vagal) AND (stimulation OR stimulator) AND (seizure OR seizures OR epilepsy) AND (atonic OR “drop attack”). Only those articles with outcome data specific for atonic seizures were included.
Results: Thirteen articles were identified for VNS and 56 for CC. Of these, 16 articles on CC and 6 on VNS met inclusion criteria, corresponding to 257 patients undergoing CC and 33 undergoing VNS. Median follow up was 2 years for CC patients and 1 year for VNS. Significantly more patients were seizure free after undergoing CC (163 patients, 63.4%) than VNS (8 patients, 24.2%), with a risk ratio (RR) of 2.6 (95% CI 1.4, 4.7). CC was also more effective when looking at patients with >50% reduction in seizures: 233 CC patients (90.7%) vs. 19 VNS (57.6%; RR 1.5, 95% CI 1.1, 2.1). Adverse events were far more common with VNS (e.g., 22% hoarseness and voice changes), but were generally less severe than those of CC (e.g., 0.9% epidural hematomas requiring surgical intervention).
Conclusions: Far more patients achieved freedom from atonic seizures after CC than VNS. Moreover, VNS generated far more adverse events, though the complications of CC were more serious. Ultimately, further studies are needed to determine whether the weaker seizure control of VNS is counterbalanced by its relatively benign (though frequent) side effects.
Patient Care: Understanding the potential surgical treatments for atonic seizures and their relative merits is important for surgeons taking care of these patients.
Learning Objectives: By the end of this session, participants should understand: 1) the surgical treatments for atonic seizures, 2) the efficacy of vagus nerve stimulation (VNS) and corpus callosotomy (CC) for atonic seizures, 3) the frequency and type of complications for both VNS and CC.