The goal of this interventional study is to evaluate whether fluoxetine, a selective serotonin reuptake inhibitor (SSRI), can alleviate core symptoms and reduce the need for surgical intervention in patients with refractory superior mesenteric artery syndrome (SMAS) who meet diagnostic criteria for somatic symptom disorder (SSD). The main questions it aims to answer are:

Can fluoxetine improve abdominal symptoms and nutritional status in patients with SMAS and comorbid SSD?

Can psychiatric intervention targeting SSD reduce the likelihood of requiring duodenojejunostomy in refractory SMAS?

Participants will:

Receive oral fluoxetine therapy for a planned treatment duration of 6 months.

Undergo baseline and follow-up assessments including symptom scoring (pain, nausea, dietary intake), body weight/BMI monitoring, and psychiatric evaluation.

Complete psychological questionnaires (PHQ-15, GAD-7, PHQ-9) and resting-state fMRI at baseline and study endpoint.

Inclusion Criteria:

1. SMAS was confirmed by two key indicators using imaging or angiographic criteria: aortomesenteric angle of less than 22° or aortomesenteric distance of less than 8 mm;
2. refractory SMAS was defined as failure of conservative treatments, including gastrointestinal decompression, enteral nutrition and parenteral nutrition;
3. accompanied by one or more following characteristics: Severe upper gastrointestinal symptoms (nausea, vomiting, bloating, pain), usually occurring more than once a week; body mass index (BMI)<18.5 kg/m2 related to feeding difficulties;
4. meets the aforementioned criteria for SSD;
5. voluntarily provided informed consent prior to enrollment.

Exclusion Criteria:

1. secondary SMAS due to identifiable causes such as tuberculosis or liver cirrhosis;
2. pregnant or lactating women;
3. patients with malignant tumors or autoimmune diseases;
4. individuals with cardiovascular diseases, organ failure, cognitive impairments, aphasia, or other chronic conditions which interfere with examinations and treatment;
5. psychotropic agents' allergic patients.

Access to trial IPD can be requested by qualified researchers engaging in independent scientific research, and will be provided following review and approval of a research proposal and Statistical Analysis Plan (SAP) and execution of a Data Sharing Agreement (DSA). For more information or to submit a request, please contact zhaozhifeng@outlook.com.

Data requests can be submitted starting 9 months after article publication and the data will be made accessible for up to 24 months. Extensions will be considered on a case-by-case basis.

For more information or to submit a request, please contact zhaozhifeng@outlook.com.