Deep Brain Stimulation of Nucleus Accumbens to Treat Severe Anorexia Nervosa

Inclusion Criteria: 1. Age between 18 and 65 years of age, male or female patients. 2. Diagnosis is Anorexia Nervosa(AN) by the DSMIV(Diagnostic and Statistical Manual of Mental Disorders Fourth Edition). 3. BMI\<16. 4. Long-term pharmacotherapy resistance. 5. Written informed consent. 6. normal intelligence and compliance Exclusion Criteria: 1. Surgical contradiction（implanted artificial cochlea、cardiac pacemaker、cardiac defibrillator、stereotactic ablative surgery、DBS）or receive other surgery which may influence this time of surgery in half year, or other neurosurgical contradictions； History of brain trauma； 2. History of severe neuropsychiatric disease； 3. Epilepsy； 4. severe liver、kidney、heart and lung disease, severe hypertension and severe orthostatic hypotension； 5. Severe diabetes ,severe cardiovascular and cerebrovascular disease； 6. Malignant tumor； 7. Being using anticoagulant or showing clinical hemorrhagic tendency； Pregnant female； 8. Patients are taking part in other clinical trials in recent 3months； Being deem as unfit for the trials by researcher