Trial to Assess Vagus Nerve Stimulation Therapy in Children With Lennox-Gastaut Syndrome

Inclusion Criteria: 1. Age 3-14 year 2. Lennox - Gastaut syndrome diagnostic standard 3. Regular drug treatment is invalid 4. Antiepileptic drug stability in recent 3 months 5. Good health except epilepsy 6. Patients or his(her) familyscould understand this method and sign the informed consent 7. Patients with good compliance and could complete postoperative follow-up. Exclusion Criteria: 1. Results of MRI remind epilepsy caused by intracranial space-occupying lesions 2. Had epileptic foci excision surgery or corpus callosum 3. The vagus nerve lesion and damage 4. Tumor, cardiopulmonary anomaly, progressive neurological diseases, asthma， mental disease，peptic ulcer，diabetes Type 1，bad health etc, and other surgical contraindication 5. Participated in other clinical drug test subjects within three months 6. The researchers think that is not suitable for participants'