The SPG Nerve Bundle

What is the sphenopalatine ganglion?

While the cause of cluster headache remains unknown, scientists and physicians seeking to treat this debilitating disease have targeted a small yet critical piece of anatomy for over a hundred years1:  the sphenopalatine ganglion.

The sphenopalatine ganglion (SPG) is a group of nerve cells located deep in the face, behind the nose. It consists of the largest collection of neurons in the head outside of the brain.2

The SPG resembles an intricate “highway crossing” on the pain pathway with many nerve “on-ramps” and “exits” carrying pain signals between the brain and nerves of the face.2 The nerve “exits” from the SPG supply nerve fibers to the sinus, roof of mouth, the eye, cerebral blood vessels and vessels covering the brain.3-5 

During a cluster headache attack, often there is pain around or behind one eye as well as the temple. Many patients experience symptoms such as nasal congestion and tearing of the eyes. 6 

Given its central role in the peripheral nervous system, many physicians call the SPG the last “switching station” in the headache pathway.


References:

  1. Sluder G. The anatomical and clinical relations of the sphenopalatine ganglion to the nose. NY State J Med. 1908;90:293–298.
  2. Robbins, et al. The Sphenopalatine Ganglion: Anatomy, Pathophysiology, and Therapeutic Targeting in Headache. Headache. 2016 Feb;56(2):240-58.
  3. Ruskell GL. The orbital branches of the pterygopalatine ganglion and their relationship with internal carotid nerve branches in primates. J Anat. 1970;106:323-339.
  4. Suzuki, et al. The cerebrovascular parasympathetic innervation. Cerebrovasc Brain Metab Rev. 1993;5:33-46.
  5. Ruskell, et al Orbital passage of pterygopalatine ganglion efferents to paranasal sinuses and nasal mucosa in man. Cells Tissues Organs. 2003;175:223-228.
  6. Tepper, et al. Sphenopalatine Ganglion (SPG): Stimulation Mechanism, Safety, and Efficacy. Headache 2017;57:14-28.