Comparing Unilateral and Bilateral Proximal GONPRF in Migraine Treatment

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.

Inclusion criteria

• Age between 18 and 65 years
• Followed at the Algology outpatient clinic of Ankara Bilkent City Hospital
• Diagnosis of episodic migraine (≥5 attacks per month) or chronic migraine according to ICHD-3 criteria
• Inadequate response to migraine preventive medications
• Not currently using preventive migraine medication OR no change in medication and/or dosage within the last 3 months
• No bleeding or coagulation disorders
• No active infection
• Not pregnant and not suspected of pregnancy
• No history of craniocervical surgery affecting the intervention area
• Able to understand the study and provide written informed consent
• Able to comply with study procedures and follow-up

Exclusion criteria

• Diagnosis of primary headache other than migraine according to ICHD-3 criteria
• Fewer than 5 migraine attacks per month
• Headache secondary to comorbid conditions (e.g., uncontrolled hypertension, intracranial lesions)
• Interventional migraine treatment within 3 months prior to GON-PRF
• Botulinum toxin injection within 3 months prior to GON-PRF
• Non-pharmacological migraine treatment (e.g., acupuncture, physical therapy, ozone therapy, cognitive behavioral therapy) within 3 months prior to GON-PRF
• Withdrawal of consent at any stage of the study
• Failure to attend follow-up visits
• Development of any condition that meets exclusion criteria during the study