Main objective:~To selectively target for neuromodulation the key structures known to be involved in the motivational aspect of food intake, i.e. the nucleus accumbens, while evaluating safety and tolerance in the specific setting of AN patients (monitoring of serious adverse events [SAE])~Secondary objectives:~Evaluation of patient's acceptance,~Effect of DBS on weight stabilization (maintenance of patients' BMI above 14kg/m2),~Effect of DBS on pupillometry in patients with severe and resistant AN,~Effect of DBS on intermediate clinical variables such as loss of cognitive flexibility, overestimation of delayed rewards, and central coherence defect,~Effect of DBS on psychiatric comorbidities of patients suffering from severe and resistant AN.~Prospective multicenter study: interventional cohort~Practical conduct:~A. If all the inclusion criteria are met, proposal to participate in the study allowing a time window of 2 weeks of reflection before giving consent, B. Joint neurosurgeon/psychiatrist information consultation with delivery of a consent form, C. Preoperative assessment carried out after a delay of at least 2 weeks (anaesthesia consultation, brain MRI and neurocognitive assessment), D. Admisison in neurosurgery for one week to perform the DBS procedure. Post-operative CT Scan. The stimulation is turned on for all patients upon discharge from the hospital , E. Joint follow-up visit with the referring physician (once a month) and the neurosurgeon (once every 2 months) for 12 months F. Two neurocognitive assessments during follow-up visit : one early and one late postoperative (respectively at 5 and 11 months)~Inclusion period: 24 months Duration of preoperative assessment and reflection phase: 3 months Duration of participation (treatment + follow-up): 12 months Total duration: 40 months~Statistical analyses:~Descriptive results are presented as means ± standard deviations for continuous data and as percentages for categorical data.~The unpaired and paired t-test because of repeated measures in the same subjects, the Fisher's exact test will be use. A p<0.05 will be considered as statistically significant. A binomial sequence test is performed after each patient inclusion to check that the rate of SAE remains inferior to 25%.
The somatic complications as well as the suicidal risk make Anorexia Nervosa (AN) the psychiatric disease with the highest mortality rate: the standardized mortality ratio is higher than 4 and 1 in 5 patients with AN who dies has committed suicide. Approximately 20% of patients suffering from AN evolves into a chronic form without prolonged remission. These patients are at high risk of serious complications (somatic and psychiatric). The peak incidence of AN lies between 15 and 19 years: patients suffering from severe and resistant AN are therefore mostly young people. At present, there is no treatment for severe and resistant AN. New insights in AN pathophysiology revealed that AN patients develop a kind of addiction to thinness which contributes to weight loss despite negative consequences. In parallel, Deep Brain Simulation (DBS) is now widely performed for movements disorders with good results and low morbidity. DBS is also currently under investigations for other indications such as obsessional compulsive disorder or pharmacoresistant epilepsy. Some case series reported promising results of DBS for severe and resistant AN. The aim of this study is to investigate the safety of nucleus accumbens chronic stimulation for patients enduring severe and resistant AN. Secondary objective is to evaluate patient's acceptance of this new treatment.