Evaluate the long-term clinical effectiveness and safety of the PINS vagus nerve stimulator to patients with refractory epilepsy.

Inclusion Criteria:

1. Age 6-60.
2. Having tried at least two appropriate anti-epileptic drugs (AEDs) tested to tolerance or to blood levels at upper end of the target range of which at least 2 have been tolerated at normal dose.
3. At least 1 seizure per month.
4. In good health except epilepsy.
5. With normal MMSE score
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. The vagus nerve lesion and damage
3. Tumor, cardiopulmonary anomaly, progressive neurological diseases, asthma，mental disease，pepticulcer，diabetes Type 1，bad health etc, and other surgical contraindication
4. Alcohol addiction, smoking, and sleep-related breathing disorders