Sphenopalatine ganglion stimulation in neurovascular headaches

Abstract
The interest for the sphenopalatine ganglion (SPG) in neurovascular headaches dates back to 1908 when Sluder presented his work on the role of the sphenopalatine ganglion in «nasal headaches» that are now part of the trigeminal autonomic cephalalgias and cluster headache (ICHD-III beta). Since then various interventions with blocking or lesional properties have targeted the SPG (transnasal injection of lidocaine and other agents, alcohol or steroid injections, radiofrequency lesions or even ganglionectomy); sucess rates varied, but benefit was usually transient. Here we briefly review some anatomo-physiological characteristics of the SPG and hypotheses about its pathophysiological role in neurovascular headaches before describing recent therapeutic results obtained with electrical stimulation of the SPG.
Based on results of a prospective randomized controlled study, SPG stimulation appears to be an effective treatment option for patients with chronic cluster headaches; efficacy data indicate that acute electrical stimulation of the SPG provided significant attack pain relief and in many cases pain freedom compared to sham stimulation. Moreover, in some patients SPG stimulation was associated with a significant and clinically meaningful reduction in cluster headache attack frequency; this preventive effect of SPG stimulation warrants further investigation.
For migraine attacks, the outcome of the proof-of-concept study using a temporary electrode implanted in the pterygopalatine fossa was less encouraging – but an ongoing multi-center trial evaluates the efficacy of long-term SPG stimulation against sham stimulation for acute and preventive treatment in patients with frequent migraine.