Stellate Ganglion Blockade for Refractory Chronic Migraine

Migraine is a common neurological disorder, and approximately 8% of patients develop chronic migraine (CM), defined as headache occurring on 15 or more days per month for more than three months, with at least 8 days fulfilling migraine criteria. Chronic migraine is associated with substantial disability and reduced quality of life. In patients who do not respond adequately to preventive pharmacological therapies, interventional procedures such as greater occipital nerve blocks, sphenopalatine ganglion blocks, pulsed radiofrequency procedures, and botulinum toxin injections may be considered. However, a subset of patients continues to experience persistent and disabling symptoms despite these interventions. The stellate ganglion is formed by the fusion of the inferior cervical and first thoracic sympathetic ganglia and plays a key role in cervical sympathetic outflow. Stellate ganglion block (SGB) involves the injection of local anesthetic around the stellate ganglion to temporarily inhibit sympathetic activity. Ultrasound guidance allows real-time visualization of anatomical structures, reduces the risk of vascular injury, and avoids radiation exposure. In this study, SGB is performed under sterile conditions with continuous monitoring and real-time ultrasound guidance. A linear ultrasound probe is positioned at the level of the sixth cervical vertebra to identify relevant anatomical structures. A 22-gauge, 90-mm needle is advanced using an in-plane technique, and 5 mL of 1% lidocaine is administered after confirming correct placement. For participants with bilateral headache distribution, bilateral blocks were performed sequentially with a minimum 60-minute interval between sides. The primary aim of the study is to evaluate 6-month clinical outcomes following ultrasound-guided SGB in patients with treatment-resistant chronic migraine. Secondary aims include evaluation of pain intensity, headache-related disability, analgesic use, patient-reported global improvement, and tolerability outcomes. The original study protocol was approved on 6 March 2024 (TABED 2-24-33) and initially specified follow-up through 3 months. The study was retrospectively registered at ClinicalTrials.gov (NCT06891118); the initial registration was submitted on 6 March 2025 and first posted on 24 March 2025. A formal protocol amendment was submitted on 30 October 2025, while follow-up data collection was ongoing and before statistical analysis, to extend follow-up from 3 to 6 months and to define the final assessment time points as months 1, 3, and 6. The amendment was approved by the institutional ethics committee on 26 November 2025 (TABED 2-25-1653). The ClinicalTrials.gov record was subsequently updated to reflect the approved 6-month follow-up and the primary outcome, defined as change in Monthly Headache Days from baseline to 6 months.