Sphanopalatine Ganglion Stimulation

Abstract

Interventions directed at the sphenopalatine ganglion (SPG, also called the pterygopalatine ganglion) with the intention of treating headache dates back over 100 years to work done by Dr. Sluder [1]. In the time since, a number of treatments targeting the SPG have been applied in headaches resistant to standard therapy. These include complete ganglionectomy [2], radiofrequency lesioning [3], injections using alcohol, corticosteroids, lidocaine, cocaine, or botulinum toxin injections to the SPG [4–8]. While some of these interventions provided relief, this was often fleeting, requiring multiple procedures, or they were accompanied by unacceptable side effects. A subset of cluster headache (CH) patients are treatment refractory [9], and especially in the chronic subform (cCH), with a high headache burden, this combination presents a considerable clinical challenge. Due to abortive medications also including oxygen inhalation or injections with sumatriptan, motivation to develop new treatment strategies is high. Especially preventive medications including verapamil, corticosteroids, methysergide, divalproex sodium (valproate), or lithium carbonate show very significant side effects in many cases and not all patients have relief. These side effects can be very incisive, including bradycardia, AV block, myocardial infarction, nausea, and fatigue to hypotension [10]. A new treatment option for refractory CH is the sphenopalatine ganglion stimulation via an inserted miniaturized microstimulator (Pulsante™ Microstimulator System, previously referred to as the ATI Neurostimulation System) has been made available as both an acute and preventive therapeutic option [10]. After a proof-of-concept case study was published in 2007 [11], in two small series of CH and migraine patients, electrical stimulation was initially tested in an experimental setting [12, 13]. A few years later, the first randomized controlled study of the Pulsante™ system, developed by Autonomic Technologies Inc., was published [14]. Today, we have long-term data available for CH and guidelines on patient selection and technical aspects available [10]. The majority of the evidence is for SPG stimulation (SPGS) in CH patients (episodic (eCH) and chronic), and this will be reflected below. This chapter gives an overview of the surgical and technical aspects as well as the evidence available for SPG stimulation.