Ultrasound-Guided Stellate Ganglion Block in Fibromyalgia

Inclusion Criteria: * Diagnosis of Fibromyalgia Syndrome (FMS) according to the 2016 American College of Rheumatology criteria. * Followed for at least 1 year with insufficient benefit from previous pharmacological and/or non-pharmacological treatments. * Receiving a stable dose of duloxetine 60 mg once daily for at least 4 weeks prior to inclusion. * Willingness to continue the fixed dose of duloxetine throughout the study. * Aged between 18 and 65 years. Exclusion Criteria: * Non-pharmacological treatments within the previous 6 months (e.g., acupuncture, ozone therapy, cognitive behavioral therapy). * Local infection at the injection site. * Pregnancy or suspected pregnancy. * Known allergy to local anesthetics. * History of malignancy. * Bleeding or coagulation disorders or use of oral anticoagulants. * Uncontrolled hypertension, diabetes mellitus, asthma, chronic obstructive pulmonary disease, or heart failure. * Psychiatric or cognitive disorders that could interfere with treatment compliance (e.g., severe psychiatric illness, dementia). * Refusal of interventional treatment.