Migraine is counted among the most prevalent primary headache worldwide. Around 2% of the world population is known to suffer from chronic migraine problem. Various treatments are used to treat these chronic primary headaches. One of such is greater occipital nerve (GON) block treatment. However, its unilateral and bilateral block application in a chronic migraine is not well studied. Therefore, scientists conducted a study to evaluate this treatment effectiveness among migraine patients and whether there is any difference in bilateral and unilateral nerve block or not.

A total of 41 patients involved in the study, out of which 18 received bilateral nerve block treatment, and another left 23 patients received unilateral block treatment. These patients went through one block for the first month and after that one block per month according to GON block protocol. During the study, patient number underwent GON block treatment, mean days of pain per month before and after surgery, mean Visual Analog Scale (VAS) in the attack, mean duration (in hours) of pain during attacks and pain severity were checked out. 

Both groups in 2 and three months showed a decrease in the number of days with a migraine significantly as compared to pre-block treatment (P<0.001). The patients who went under the bilateral block showed a significant decrease in the mean duration of a headache whereas another group exhibited a reduction but did not differ significantly. On the other hand, patients with unilateral block treatment showed a significant reduction in mean severity during 2 and three months as compared to pre-block therapy. However, no difference was seen during the 3-month treatment period in regards to headache duration, frequency and severity. This whole study reflected the results that GON block manage a chronic condition of a migraine very efficiently and unilateral block treatment is superior to bilateral treatment.