Based on the mechanism hypothesis and clinical efficacy of VNS in treating refractory depression, this study will evaluate the safety and efficacy of VNS in treating refractory depression through a small sample of clinical trials

This clinical trial is a prospective, self - controlled clinical validation study. Subjects who met the inclusion criteria and did not meet the exclusion criteria were screened to enter the test. After admission, subjects received vagus nerve stimulation and conventional treatment. Enrolled 10 subjects. Parameter setting and observation were performed 2 weeks after implantation of the vagus nerve stimulation lead and pulse generator, and follow-up evaluation was performed at 3, 6 and 12 months.

Inclusion Criteria:

1. patients with treatment-resistant depression (patients with Hamilton depression scale (HAMD) score reduction rate still less than 50% after adequate treatment with two or more antidepressants)
2. age 18-65; Male or female
3. the patient has a depressive course of 2 years or more or has 2 or more major depressive episodes
4. HAMD-17 score> 17 was at baseline

Exclusion Criteria:

1. pregnant or lactating women, women of childbearing age who plan or have no safe contraceptive measures
2. a patient who is or has been diagnosed with a mental disorder other than depression; Depressive episode with psychotic symptoms
3. patients currently at serious risk of suicide
4. prior 12 months of alcohol or substance dependence, or prior 6 months of substance abuse other than nicotine
5. patients with cardiovascular diseases (myocardial infarction or cardiac arrest) and organic brain diseases (such as cerebral hemorrhage, massive cerebral infarction, encephalitis and epilepsy)
6. accept other clinical trials
7. patients requiring systemic mri after implantation