Migraine is a common neurological disorder that significantly affects quality of life and socio-economic functioning. In patients with headaches resistant to conservative pharmacological treatment, peripheral nerve interventions, particularly greater occipital nerve (GON) block, are frequently used. GON block can reduce the frequency and intensity of migraine attacks and may decrease the need for systemic medications. However, the duration of benefit following GON block with local anesthetics and steroids is often limited to several weeks or months.
To prolong the therapeutic effect of peripheral nerve interventions, pulsed radiofrequency (PRF) has been introduced. PRF modulates pain transmission by generating an electrical field around the targeted nerve without causing structural nerve damage. Greater occipital nerve pulsed radiofrequency (GON PRF) has been reported to be both effective and safe in the treatment of migraine and is widely used in pain management practice.
GON block and GON PRF procedures can be performed using anatomical landmark techniques or under ultrasound guidance. Two ultrasound-guided approaches have been described: a proximal technique targeting the nerve at the C2 vertebral level and a distal technique targeting the superior nuchal line. The proximal (C2) approach has been shown to provide effective results in migraine treatment.
Although the exact mechanism of long-term headache relief following peripheral nerve interventions remains unclear, it is believed to involve central pain modulation. The upper cervical nerve roots are anatomically and functionally connected with trigeminal pathways, converging within the trigeminocervical complex. Neurophysiological findings suggest that unilateral nerve interventions may produce bilateral inhibitory effects through modulation of second-order neuronal transmission.
Retrospective clinical observations indicate that unilateral GON interventions may provide similar reductions in headache frequency, severity, and duration compared to bilateral applications, with potentially fewer side effects. However, there is currently no prospective study directly comparing unilateral and bilateral GON PRF in patients with migraine.
In our clinic, GON PRF is performed under sterile operating room conditions with standard monitoring and intravenous access. For the proximal (C2) approach, patients are positioned prone with slight neck flexion. Under ultrasound guidance, anatomical landmarks including the obliquus capitis inferior and semispinalis capitis muscles are identified. The GON is visualized as an oval hypoechoic structure between these muscles. A 22-gauge RF cannula with a 5 mm active tip is inserted using an in-plane technique. After sensory stimulation confirms appropriate localization, PRF is applied at 45 V, 5 Hz, and 5 ms pulse width for 360 seconds, ensuring that electrode tip temperature does not exceed 42°C. No medications are injected during the PRF procedure. For bilateral treatment, the same procedure is performed contralaterally. Patients are observed for at least one hour post-procedure prior to discharge.
The primary objective of this study is to prospectively compare the clinical efficacy of unilateral and bilateral ultrasound-guided proximal (C2 level) GON PRF treatment in patients with migraine. Secondary objectives include evaluation of migraine-related disability outcomes and assessment of treatment-related adverse events and complications.
