Comparing Unilateral and Bilateral Proximal GONPRF in Migraine Treatment

This study is designed to compare the clinical effectiveness of unilateral and bilateral Greater Occipital Nerve Pulsed Radiofrequency (GON-PRF) treatment at the C2 level in patients with migraine. The procedure will be guided by ultrasound and will focus on evaluating how each technique affects migraine symptoms.

The main goal of this study is to assess the impact of both unilateral and bilateral GON-PRF treatments on migraine relief. Additionally, the secondary objectives of this study include evaluating the effects of these treatments on migraine-related disability and comparing any potential side effects or complications that may occur during the treatments.

This research will help us understand which technique may be more effective and provide more information on the safety of these treatments.

Migraine is a common neurological disorder that can affect patients' quality of life and socio-economic functionality. In cases of resistant headaches that do not respond to conservative pharmacological treatment, peripheral nerve blocks, particularly greater occipital nerve (GON) block, can be applied. GON block (GONB) can help reduce the frequency and intensity of attacks, as well as the systemic side effects of pharmacological treatment. However, the literature reports that the effectiveness of GON block with local anesthetics and steroids for the treatment of various headache disorders is limited to a few weeks to several months .

To prolong the effect of peripheral nerve blocks, pulsed radiofrequency (PRF) is used. PRF modulates pain transmission without damaging the nerve or surrounding sensitive structures by creating an electrical field in the targeted nerves. Greater occipital nerve pulsed radiofrequency (GON PRF) has been found to be effective and safe in the treatment of migraine . In the treatment of migraine resistant to conservative treatment, GON block and GON PRF, both proven to be effective and safe, are widely used in pain management practice and in our clinic.

GON block and GON PRF can be performed using anatomical landmark technique or under ultrasound guidance (USG). Currently, two different techniques for ultrasound-guided GON block are described. These are the proximal technique targeting the GON at the second cervical vertebra (C2) level and the distal technique targeting the superior nuchal line level. It has been reported that GON block and GON PRF applied with the proximal technique under ultrasound guidance are effective. In our clinic, we apply GON block and GON PRF treatments using ultrasound guidance with either the proximal or distal technique.

Although the exact mechanism of long-term headache relief following peripheral nerve blocks is unknown, it is thought to be related to central pain modulation. The upper cervical nerve roots are anatomically and functionally connected to the trigeminal pathways, and they converge in the trigeminal cervical complex. In a neurophysiological study conducted by Busch et al. on fifteen healthy volunteers without headaches, it was found that unilateral nerve block causes bilateral inhibition, and this inhibitory effect is thought to be due to modulation of the heterosynaptic convergence transmission of second-order neurons or interneurons extending from the caudal trigeminal nucleus to the upper cervical segments. In a retrospective study conducted on chronic migraine patients, it was reported that unilateral GONB was as effective as bilateral GONB in terms of the frequency, severity, and duration of headaches, with the added benefit of a lower frequency of side effects with unilateral GONB. Another retrospective study compared unilateral and bilateral proximal GON block in the treatment of chronic migraine. It was found that proximal GON block at the C2 level was effective in the treatment of chronic migraine, and bilateral application was not superior to unilateral application, with patients tolerating unilateral blocks better.

In our clinic, GON PRF treatment is performed under sterile conditions in an operating room, with patients monitored during the procedure and intravenous access established. For the proximal (C2) level, patients are positioned in a prone position with neck flexion. Anatomical landmarks include the obliquus capitis inferior (OCI) muscle and the bifid spinous process of C2. After sterilizing the application area, a linear ultrasound probe is placed transversely on the occipital protuberance, and it is moved caudally in the sagittal plane to first visualize C1 with a single spinous process, and then, when moving further caudally, C2 with two spinous processes. The probe is then moved laterally to visualize the OCI and semispinalis capitis (SSC) muscles, and it is slightly directed cephalad. The GON appears as an oval, hypoechoic structure between the OCI and SSC muscles at this level and is selected as the target. A catheter needle (22 gauge 5 cm 5 mm active tip RF cannula) and RF electrode are placed using an in-plane technique, from lateral to medial, near the target area (right or left GON). Following this, a sensory stimulation test is performed using the RF generator. After reporting dysesthesia and tingling sensations in the occipital region below 0.2 V by the patient, PRF treatment is applied at 45 V, 5 Hz, and 5 ms pulse width for 360 seconds, ensuring that the electrode tips do not exceed 42°C. For bilateral GON PRF, the same procedure is applied to the other side. No drug injections are administered during the GON PRF treatment. After the procedure, patients are observed in the recovery room for at least one hour and are discharged following a general and neurological evaluation.

According to current knowledge, there is no study comparing the effectiveness of unilateral and bilateral GON PRF in the treatment of migraine. Therefore, our study primarily aims to prospectively compare the clinical efficacy of unilateral and bilateral GON PRF treatment performed at the C2 level using a proximal technique under ultrasound guidance in migraine patients. Additionally, secondary objectives of this study include evaluating the effects of unilateral and bilateral GON PRF treatments on migraine-related disability and comparing any potential side effects and complications associated with the treatment.

Eligibility Criteria:
Inclusion Criteria:Volunteers who are followed up at the Algology polyclinic of Ankara Bilkent City Hospital, between the ages of 18-65, who meet the diagnosis criteria for episodic (≥5 attacks/month) or chronic migraine according to ICHD-3 criteria, who do not benefit sufficiently from the migraine prevention medications used, who are not currently using migraine prevention medications or who have not changed their medication and/or dosage in the last 3 months, who do not have bleeding-clotting disorders and active infection in laboratory tests, who are not pregnant or suspected of being pregnant, who do not have a history of craniocervical surgery that may disrupt the anatomical structure in the intervention area, who can understand and approve the treatment and the informed consent form and who can comply with the treatment will be included in this study. Exclusion criteria for files/records/materials to be included in the study: Patients with a history of primary headache other than migraine according to ICHD-3 criteria, \<5 attacks per month, comorbid diseases that may cause headaches (such as uncontrolled hypertension, intracranial lesions), and those who have received interventional treatment, botulinum toxin injection and/or non-pharmacological treatment (acupuncture, physical therapy, ozone, cognitive behavioral therapy, etc.) for migraine within 3 months prior to GON-PRF treatment will not be included in the study.

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Exclusion Criteria:The voluntary participants' request to withdraw for any reason at any stage of the study, the volunteer/legal representative's withdrawal of consent to participate in the study, failure to attend follow-up, and the emergence of any of the following criteria for not being included in the study.

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