Is β endorphin related to migraine headache and its relief?

Abstract

Background Low β endorphin level in serum and cerebrospinal fluid (CSF) has been reported in migraine. The basis of pain relief in migraine by repetitive transcranial magnetic stimulation (rTMS) may be related to β endorphin (BE), which has not been evaluated. It is proposed to measure plasma β endorphin level in migraine patients and the change in β endorphin level following rTMS, and to correlate these changes with migraine relief. Methods Twenty-five patients with migraine diagnosed as per International Headache Society criteria and 20 gender- and age-matched controls were included. Their clinical characteristics including duration of migraine, its frequency, severity and functional disability, triggers, allodynia and number of analgesic used were noted. Plasma β endorphin level was estimated before and after the third rTMS session. rTMS was delivered on the hot spot of right abductor digiti minimi on alternate days for 3 days and each session consisted of 600 pulses at 10 Hz. The clinical response was noted weekly for 1 month and correlated with β endorphin level. Results The median age of the patients was 35 (20–50) years and 19 were females. Eight patients had episodic and 17 chronic migraine. β endorphin level was significantly lower in migraine (4.35 ± 2.29 ng/ml) compared to controls (6.68 ± 2.93 ng/ml). β endorphin level was lower in chronic compared to episodic migraine (3.74 ± 2.20 versus 5.65 ± 2.02 ng/ml). Following rTMS, the headache frequency, severity, functional disability and analgesic intake significantly reduced on the seventh day of rTMS and remained significant until the fourth week compared to the baseline. The clinical improvement was associated with increase in β endorphin level (4.35 ± 2.29 versus 6.58 ± 3.33 ng/ml). Conclusion It can be concluded from this study that the basal plasma β endorphin level was low in migraine patients, especially in chronic migraine. The improvement in migraine after rTMS was associated with increase in β endorphin level.