Abstracts

Rationale: Vagus nerve stimulation (VNS) has been shown in many case series to be a safe and effective intervention in pediatric patients with medically refractory epilepsy. The limits of its indications, particularly in very young patients, have not been fully defined. The role of vagal activity in development during infancy is complex and incompletely understood, particularly in the context of therapeutic stimulation. We report the case of a patient who underwent surgery for VNS at age 6 months due to refractory status epilepticus. A literature search was undertaken to explore the use of VNS in the first year of life.Methods: 41 clinical studies were identified on VNS in the pediatric population, of which 26, including 1174 unique patients, had no subjects under the age of 1 year at surgery. 9 studies did not specify a lower bound on age range. Only 6 studies specified any patients undergoing surgery before 1 year of age.Results: Our index case was delivered at term via C-section. Fever and excessive startles prompted a sepsis workup, EEG, and MRI, all normal. Events resolved with levetiracetam. At age 4 months, a 20 minute tonic clonic seizure was aborted with lorazepam and fosphenytoin. Video EEG captured 23 clinical and subclinical seizures lasting up to 1 hour, arising from the bicentrotemporal regions independently. Exhaustive genetic/metabolic evaluation was negative. Seizure control was never again obtained despite pyridoxine, folinic acid, 7 additional AEDs, and ketogenic diet. Near continuous seizures recurred after 9 days in burst suppression on midazolam. Pentobarbital was initiated. High dose steroids had no impact. At 6 months of age, a vagus nerve stimulator was placed. Output and magnet currents were increased to 2.0 and 2.25 respectively. The magnet had no noticeable effect. At the family s request the patient was transferred to another facility and died one week later. Indications and outcome data for patients under one year of age at surgery were separately reported only in four patients across two studies. Diagnoses included malignant partial epilepsy of infancy in 2 patients, linear nevus sebaceous syndrome, and nonspecific multifocal epilepsy. Surgery was performed at between 7 and 11 months of age. No technical obstacles were identified. 1 patient was seizure free after 21 months but significantly neurologically impaired. The other 3 experienced between 0 and 60% reduction in seizure frequency over 17 to 63 months postoperatively and were all severely neurologically impaired or devastated. Conclusions: Vagus nerve stimulation is rarely employed in the infant age group, and is generally used for severe pathology. Our case represents the youngest patient reported to undergo VNS surgery. No elevated surgical risk profile is evident from the limited data available. Short-term effectiveness has not been very satisfactory, regarding either seizure control or overall neurologic outcome. Only 1 outcome past 2 years has been reported, in a patient neurologically devastated 5 years after surgery. Further prospective study in this age group is indicated.