A pilot study on the use of transcutaneous auricular vagus nerve stimulation to relieve dysmenorrhea in patients with adenomyosis and endometriosis.

Adenomyosis and endometriosis are two sister diseases that cause menstrual pain and other symptoms. We have previously reported that patients with these conditions have a less active 'calm-and-rest' system and a more active 'stress-and-alert' system. Other studies have shown that a gentle, non-invasive treatment called transcutaneous auricular vagus nerve stimulation (taVNS) can safely and effectively boost the 'calm-and-rest' system in many disorders. So we wanted to see if taVNS could also help with menstrual pain caused by endometriosis and adenomyosis. We tried it in a small pilot study with four patients with adenomyosis and two patients with endometriosis. They received taVNS for six months. We found that taVNS was well tolerated and relieved their pain three and six months after taVNS. These early results are encouraging, but because the study was small, we need larger, more rigorous studies to fully know how well taVNS works for this kind of pain.