Clinical Outcomes of Ultrasound-Guided Stellate Ganglion Block in Highly Treatment-Resistant Chronic Migraine: A 6-Month Prospective Single-Group Interventional Study

Background and Objectives: Chronic migraine (CM) remains a major cause of neurological disability, and a subset of patients remains highly treatment-resistant despite previous preventive and interventional treatments. Stellate ganglion block (SGB) has been proposed as a sympathetic neuromodulatory intervention, but evidence in this population remains limited. This study evaluated 6-month clinical outcomes and tolerability after a structured ultrasound-guided SGB protocol. Materials and Methods: This prospective, single-center, uncontrolled, single-group interventional study enrolled 42 adults with CM who had experienced insufficient benefit from prior preventive migraine treatment and previous interventional headache procedures. After an initial ultrasound-guided SGB to assess anatomical suitability and procedural tolerability, all participants proceeded to four additional weekly ultrasound-guided SGB sessions using 5 mL of 1% lidocaine, for five protocol-defined sessions in total. The primary outcome was the change in monthly headache days (MHD) from baseline to 6 months. Results: All 42 participants (mean age: 44.4 ± 7.4 years) completed the 6-month follow-up. Median MHD decreased from 29.0 days at baseline to 6.0 days at 6 months (Kendall’s W = 0.643, p < 0.001), corresponding to a median within-participant reduction of 17.0 days (BCa 95% CI: 13.0–19.0). A ≥50% reduction in MHD was achieved by 73.8% of participants (95% CI: 58.9–84.7) at 6 months, whereas 14.3% (95% CI: 6.7–27.8) achieved a ≥50% reduction in mean pain intensity. HIT-6 and MIDAS scores also improved significantly (p < 0.001). Six participants (14.3%) reported mild, self-limited adverse effects; no serious adverse events were documented. Conclusions: Ultrasound-guided SGB was associated with sustained reductions in headache frequency, analgesic use, and migraine-related disability over 6 months. Because this was an uncontrolled single-group study, the findings should be considered preliminary and hypothesis-generating. The frequency-dominant pattern of improvement and favorable tolerability support further controlled evaluation of SGB as a potential adjunctive neuromodulatory strategy in highly treatment-resistant CM.