* PRF performed on the sphenopalatine ganglion level under ultrasound guidance. * Standard voltage PRF parameters: 45 V, 5 Hz frequency, 5 ms pulse width, 360 seconds duration, electrode temperature ≤42°C. * Supravoltage PRF parameters: Higher voltage than standard (e.g., 60-70 V), with same frequency, pulse width, and duration, maintaining temperature ≤42°C to avoid nerve damage.
Diagnosis of chronic migraine according to International Classification of Headache Disorders criteria (≥15 headache days/month for >3 months, including ≥8 migraine days/month) documented by Completion of 4-week prospective baseline headache diary immediately preceding randomization
Failure of ≥2 classes of preventive pharmacological migraine medications (e.g., beta-blockers, antiepileptics, antidepressants...) to get clinically meaningful response ( defined as ≥50% reduction in monthly migraine days), at standard therapeutic doses (Beta-blockers (e.g., propranolol ≥160 mg/day, metoprolol ≥100 mg/day, Antiepileptics (e.g., topiramate ≥100 mg/day, valproate ≥500 mg/day, Tricyclic antidepressants (e.g., amitriptyline ≥50 mg/day, SNRIs (e.g., venlafaxine ≥150 mg/day ) for at least 8 weeks or ≥12 weeks in case of CGRP ).
Stable preventive migraine therapy for at least 4 weeks prior to enrollment.
MIDAS score ≥11 indicating moderate to severe disability.
Medication Overuse Headache per ICHD-3: Simple analgesics (acetaminophen, NSAIDs, non-opioid analgesics) used on ≥15 days per month for >3 months, OR Triptans, ergot derivatives, opioids, or combination analgesics used on ≥10 days per month for >3 months.
Any secondary headache disorder ( cluster headache, hemiplegic migraine, migraine with brainstem aura (distinct pathophysiology); chronic tension-type headache >10 days/month.
Any prior SPG block, PRF, radiofrequency thermocoagulation, chemical neurolysis, or neurostimulation of SPG/trigeminal system within 6 month.
No prior occipital or supra-orbital nerve radiofrequency, cryotherapy, or chemical neurolysis within 3 months