DISCUSSION
Peripheral nerve blocks have recently become a preferable treatment option for primary headaches’ acute and preventive treatments. Numerous randomized, controlled studies have shown that the GON block was effective [4, 8, 9]. Its contributions to patient satisfaction, daily activities, and treatment costs are too significant to be ignored, mainly due to improvements in migraine treatments. There were statistically significant reductions in our study when the first and third-month values were compared to the pre-treatment values regarding the days with pain, analgesic use, VAS, and MIDAS scores in 120 patients in whom we had performed a GON block (Figures 1 and 2).
In many studies, it has been shown that significant improvements occurred with a GON block, injecting a local anesthetic substance, and steroids in migraines of resistant patients who were unresponsive to prophylactic treatment [4-8]. Caputi et al. performed GON and supraorbital blocks using bupivacaine and determined decreasing headache severity in 85% of their patients. This study determined significant pain severity reductions when we compared the periods before and after the treatment.
The American Headache Society made practical recommendations regarding peripheral nerve and GON blocks in 2013; however, they stated that a consensus had not been reached on the amount to be administered and the repetition frequency since there were not enough randomized, controlled studies [10]. Numerous studies have been conducted on the effectiveness and use of the GON block in primary headaches to clarify such issues and determine the boundaries; however, standardization has not been yet achieved, and in most studies, different options were preferred regarding the administration technique, drug preference, and dosage [9, 11, 12].
Lidocaine and bupivacaine are commonly preferred in peripheral nerve blocks. We preferred lidocaine in our patients because of its shorter half-life when compared to bupivacaine. Local anesthetics create a reversible blockade in sodium channels of nerve fibers and provide efficient control by causing depolarization in demyelinated C-fibers and myelinated A-fibers, which play roles in pain signal transmission. Since pain control’s duration is longer than the administered local anesthetic agent’s half-life, pain control has been considered to be associated with central modulation. Corticosteroids may be preferred for treatment from time to time to prolong the block duration. Even though less common in chronic migraine patients, corticosteroids have been preferred particularly for the treatment of cluster headaches, and they were determined to be more efficacious [13]. The corticosteroids’ long-term effects are unknown. Corticosteroids are known to inhibit pro-inflammatory cytokines’ synthesis and release and suppress inflammation. Moreover, they provide efficient pain control through membrane stabilization, reversible inhibition of nociceptive C-fibers, and modulation of nociceptive input to the substantia gelatinosa [5, 14].
Numerous studies have been conducted on local anesthetics’ effectiveness, superiorities to each other, and combination treatments with steroids. Gül et al. compared bupivacaine and saline and determined that the 2-month and 3-month VAS scores were significantly superior to those of the placebo group [15]. When 0.25 ml of lidocaine 0.5% was compared to 2.5 ml of bupivacaine 0.5% and methylprednisolone, it was determined that their efficacies were not superior to each other. Studies on steroids’ addition to treatment have shown that steroids did not contribute [12, 16, 17].
There is no standardization regarding unilateral or bilateral GON block applications, and the block is performed on an optional basis. The study comparing unilateral and bilateral GON blocks’ efficacies reported no difference between them [18]. We preferred to perform bilateral GON blocks and additionally the supraorbital nerve block in our method.
Single block or repeated nerve blocks? Numerous studies have reported that repeated nerve blocks were more effective than single blocks [16, 18-21]. In our clinic, we preferred to perform six sessions of blocks in total, once a week in the first month and once a month in the second and third months. The treatment responses of patients in whom a GON block was performed together with prophylaxis were compared to those in whom only a GON block was performed, and no significant differences were determined between the two groups regarding the headache duration and attacks. Most of our patients had been receiving prophylactic treatment, and some of them stated that their requirement for prophylactic treatment had decreased in later treatment stages, and they had quit their medications. We determined significant reductions in patients’ analgesic requirements in the course of treatment (Figure 3). The GON block is reliable for patients; however, vasovagal syncope, temporary numbness at the injection site, and particularly when combined with steroids, alopecia, and cutaneous atrophy were reported [9]. No significant side effects were observed during and after the GON block in our study.
Our study had various limitations. Since the study data were collected through retrospective chart review, we could not reach some data, and our study’s data were confined to the records only. Our study’s shortcomings were its small sample size, absence of a control group, and our inability to follow up the patients for a longer duration. Prospective, randomized, and placebo-controlled future studies with longer duration and larger sample sizes are required.