While not a typical first-line treatment, doctors may also consider a sphenopalatine ganglion (SPG) block. The SPG is a cluster of neurons that sits behind your nose and above your mouth.

We find that, following axotomy, sympathetic neurons in the superior cervical ganglion express vasoactive intestinal peptide (VIP), galanin, and pituitary adenylate cyclase-activating polypeptide, ...

1Department of Medicine, Columbia Center for Human Development, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York. 2Herbert Irving Comprehensive ...