Technical and surgical aspects of the sphenopalatine ganglion (SPG) microstimulator insertion procedure

Radiofrequency regulation of the sphenopalatine ganglion in managing herpes zoster ophthalmicus neuralgia: A case series

INTRODUCTION

Trigeminal herpes zoster, which comprises 10% to 20% of cases of herpes zoster, often leads to severe pain in the ophthalmic branches. Current treatments, including drug therapy and minimally invasive interventions, have limitations; accordingly, there is a need to explore alternative approaches. This study aimed to evaluate the efficacy and safety of computerized tomography (CT)-guided pulsed radiofrequency of the sphenopalatine ganglion in patients with intractable trigeminal herpetic pain.

PATIENT CONCERNS

Three patients with intractable trigeminal ophthalmic zoster neuralgia were studied. All patients complained of bursts of headache, which occurred at least 10 times a day, usually in the periorbital and frontal regions. Conventional treatments, including oral medications and radiofrequency therapy targeting the trigeminal-semilunar ganglion and supraorbital nerve, could not sufficiently provide relief.

DIAGNOSIS

Two patients were diagnosed with herpes zoster in the ocular branch of the trigeminal nerve with conjunctivitis, while one patient was diagnosed with postherpetic neuralgia in the ocular branch of the trigeminal nerve.

INTERVENTIONS

This study employed a novel approach that involved CT-guided radiofrequency regulation of the pterygopalatine fossa sphenopalatine ganglion.

OUTCOMES

In all three patients, pain relief was achieved within 1 to 3 days after treatment. During the follow-up, one patient had pain recurrence; however, its severity was ≈ 40% lower than the pretreatment pain severity. The second patient had sustained and effective pain relief. However, the pain of the third patient worsened again after 2 months. The average follow-up duration was 3 months. None of the enrolled patients showed treatment-related adverse reactions or complications.

CONCLUSION

Our findings indicated that CT-guided radiofrequency regulation of the pterygopalatine fossa sphenopalatine ganglion was a safe and effective intervention for pain in patients with trigeminal ophthalmic zoster neuralgia, suggesting that it may be a therapeutic option if other treatments fail.

Continuous positive airway pressure in cluster headache: A randomized, placebo-controlled, triple-blind, crossover study

BACKGROUND

Oxygen inhalation aborts cluster headache attacks, and case reports show the effect of continuous positive airway pressure. The aim of this study was to investigate the prophylactic effect of continuous positive airway pressure in chronic cluster headache.

METHODS

This was a randomized placebo-controlled triple-blind crossover study using active and sham continuous positive airway pressure treatment for chronic cluster headache. Patients entered a one month's baseline period before randomly being assigned to two months' active continuous positive airway pressure treatment followed by a four weeks' washout period and two months' sham continuous positive airway pressure or vice versa. Primary outcome measure was number of cluster headache attacks/week.

RESULTS

Of the 30 included participants (12 males, median age 49.5 years, min-max 20-66 years), 25 completed both treatment/sham cycles (two discontinued, three lost to follow-up). The median number of cluster headache attacks per week was reduced from 8.25 (0.75-89.75) attacks to 6.25 (0-56.00) attacks for active continuous positive airway pressure and to 7.50 (0.50-43.75) attacks for sham continuous positive airway pressure, but there was no difference in active versus sham (p = 0.904). One patient had a serious adverse event during active treatment, none occurred during sham treatment.

CONCLUSIONS

Continuous positive airway pressure treatment did not reduce the number of cluster headache attacks compared to sham treatment in chronic cluster headache patients.

TRIAL REGISTRATION CLINICALTRIALS.GOV

NCT03397563.

Propensity score matching comparing short-term nerve electrical stimulation to pulsed radiofrequency for herpes zoster-associated pain: A retrospective study

BACKGROUND

Zoster-associated pain (ZAP) is notoriously difficult to treat. Pulsed radiofrequency (PRF) and short-term nerve electrical stimulation (st-NES) have been proven effective treatments for ZAP. However, it is still unclear which technique provides improved analgesia in ZAP. This study is based on a large-scale, long-term follow-up to evaluate the efficacy and safety between st-NES and PRF.

MATERIALS AND METHODS

All eligible ZAP patients treated with st-NES or PRF in our department were enrolled. Cohorts were divided into the st-NES group and the PRF group. A 1:1 ratio propensity score matching (PSM) was used to balance the baseline characteristics. The PS-matched cohort was adopted to investigate the efficacy and safety of the two treatments. The ordinal regression analysis was performed to determine the variables affecting the treatment effect of ZAP.

RESULTS

A total of 226 patients were included after PSM. The numerical rating scale (NRS) scores in st-NES and PRF groups considerably reduced compared to baseline levels after treatment. The NRS scores in the st-NES group were obviously lower than those in the PRF group at discharge, 1, 3, 6, 12, and 24 months. During the follow-up period, the NRS reduction rate remained higher in the st-NES group than in the PRF group (P < 0.01). The dosage of medication, Pittsburgh Sleep Quality Index (PSQI) score, and the number of patients with aggravated pain after discharge in the st-NES group were significantly less than in the PRF group after treatment.

CONCLUSION

Short-term nerve electrical stimulation has been shown to be more advantageous than PRF for pain relief and quality of life improvement for ZAP patients.

Transnasal endoscopy-guided percutaneous access to the sphenopalatine ganglion for neurostimulation in the treatment of primary headache: operative technique and feasibility

OBJECTIVES

Cluster headache is considered a trigeminal autonomic cephalalgia and may present with characteristic symptoms of sympathetic/parasympathetic activation on the affected side of the face, such as nasal discharge, tearing, and conjunctival injection. Invasive therapies targeting the sphenopalatine ganglion have been performed in these headache syndromes and can have a medication-sparing effect, especially in refractory, difficult-to-manage cases. The gate control theory of pain suggests that electric pulses delivered to nerve tissues can modulate neuronal activity, thus aiding in management of nociceptive or neuropathic pain, and studies have demonstrated the efficacy and safety of sphenopalatine ganglion neurostimulation. Within this context, we sought to assess the feasibility of a new surgical technique for neurostimulation of the sphenopalatine ganglion in a cadaver dissection model.

METHODS

The technique was developed through dissection of two cadaver heads. We divided the procedure into two stages: an endonasal endoscopic approach to expose the sphenopalatine ganglion and confirm electrode placement, and a cervicofacial approach to introduce the electrode array and position the internal pulse-generator unit. Computed tomography was performed to confirm implant placement at the end of the procedure.

RESULTS

The pulse-generator unit was successfully placed through a retroauricular incision, as is already standard for cochlear implant placement. This should reduce the incidence of perioperative sequelae, especially pain and swelling in the oral region, which are a common complication of previous approaches used for this purpose. Control imaging confirmed proper electrode placement. The device used in this study allows the patient to modulate the intensity of the stimulus, reducing or even obviating the need for drug therapy.

CONCLUSION

The novel technique described herein, based on percutaneous access guided by transmaxillary endoscopy, can provide great precision in electrode array positioning and decreased perioperative morbidity, combining the advantages of endoscopic approaches with those of the retroauricular route.

LEVEL OF EVIDENCE: 3

Neuromodulation in headache and craniofacial neuralgia: guidelines from the Spanish Society of Neurology and the Spanish Society of Neurosurgery

INTRODUCTION

Numerous invasive and non-invasive neuromodulation devices have been developed and applied to patients with headache and neuralgia in recent years. However, no updated review addresses their safety and efficacy, and no healthcare institution has issued specific recommendations on their use for these 2 conditions.

METHODS

Neurologists from the Spanish Society of Neurology's (SEN) Headache Study Group and neurosurgeons specialising in functional neurosurgery, selected by the Spanish Society of Neurosurgery (SENEC), performed a comprehensive review of articles on the MEDLINE database addressing the use of the technique in patients with headache and neuralgia.

RESULTS

We present an updated review and establish the first set of consensus recommendations of the SEN and SENC on the use of neuromodulation to treat headache and neuralgia, analysing the current levels of evidence on its effectiveness for each specific condition.

CONCLUSIONS

Current evidence supports the indication of neuromodulation techniques for patients with refractory headache and neuralgia (especially migraine, cluster headache, and trigeminal neuralgia) selected by neurologists and headache specialists, after pharmacological treatment options are exhausted. Furthermore, we recommend that invasive neuromodulation be debated by multidisciplinary committees, and that the procedure be performed by teams of neurosurgeons specialising in functional neurosurgery, with acceptable rates of morbidity and mortality.

Localization of the Sphenopalatine Ganglion Within the Pterygopalatine Fossa on Computed Tomography Angiography-A Potential Role in the Setting of Sphenopalatine Ganglion Microstimulator Implantation

OBJECTIVES

A recent approach to treatment of cluster headaches (CH) employs a microstimulator device for on-demand neuromodulation of the sphenopalatine ganglion (SPG) during an acute CH attack. A precise anatomical localization of the SPG within the pterygopalatine fossa (PPF) is optimal in order to position the SPG electrode array. This study aims to investigate a novel approach for SPG localization using computed tomography angiographic studies (CTA).

MATERIALS AND METHODS

Two independent observers identified the location of the SPG on 54 computed tomography angiographic studies (CTA) and measured its position relative to the vidian canal (VC). The qualitative confidence of identification, morphology, position within the PPF and its relation to vascular structures were also recorded.

RESULTS

The SPG was detectable in 88% of cases with a variable position. The most frequent positions were superior (56%) and lateral (99%) relative to the VC with a mean (±SD) craniocaudal distance of 0.34 mm (±1.38) and a mean mediolateral distance of 3.04 mm (±1.2). However, in a considerable proportion of cases, the SPG was identified inferiorly to the VC (33%). Interobserver and intraobserver agreement for SPG location were moderate and strong respectively.

CONCLUSIONS

Since localization of SPG on CTAs is feasible and reproducible, it has future clinical potential to aid placement, optimal positioning and individualized programming of the electrode array.

An Anatomical Study of the Foramen Ovale for Neuromodulation of Trigeminal Neuropathic Pain

OBJECTIVE

Neuromodulation for trigeminal pain syndromes such as trigeminal neuropathic pain (TNP) necessitates accurate localization of foramen ovale (FO). The Härtel-type approach is very well-established and safe, ideal for temporary cannulation of the FO for ablative procedures such as balloon microcompression. A key shortcoming of the Hartel approach for placement of neuromodulation leads is the limited opportunity for secure anchoring. The aim of this study is to introduce a novel surgical approach for the treatment of TNP by investigating key osseous landmarks and their spatial relationships to the FO.

MATERIALS AND METHODS

Sixteen sides of cadaver heads were dissected to investigate a surgical route of the FO via transoral gingival buccal approach. Alveolar arch of the maxilla and zygomaticomaxillary suture were selected to serve as an osseous landmark for the surgical guidance to the FO. Through the intraoral route, a needle simulating electrode was traversed to aim the FO from the inferior lateral to the superior medial direction to target specific fibers of the aimed division of the nerve.

RESULTS

Visual identification and access to the trigeminal nerve at the external opening of FO was successful in all 16 hemifacial cadavers. A needle successfully targeted different regions of the trigeminal nerve by changing the angle of the trajectory allowing the needle to reach a specific division of the trigeminal nerve.

CONCLUSIONS

This study provides a novel means of approaching the FO via transoral gingival buccal access.

Device review: Pulsante™ sphenopalatine ganglion microstimulator

Cluster headache (CH) is a primary headache disorder. The use of neuromodulation in treatment of CH is well documented. The sphenopalatine ganglion (SPG) has long been a target for management of CH. Intervention at the level of the SPG can interrupt the trigemino-autonomic reflex, which mediates CH pain. The Pulsante system is the only device on the market created for SPG stimulation. The Pulsante device consists of the device body, a lead with six stimulating electrodes placed in the pterygopalatine fossa, and a fixation plate to allow anchoring of the device to the maxilla. Stimulation is administered via a patient-controlled handheld remote control held over the cheek. SPG stimulation is an important treatment option for CH patients.

Analysis of the Pterygomaxillary Fissure for Surgical Approach to Sphenopalatine Ganglion by Radiological Examination of Cone Beam Computed Tomography

The pterygopalatine fossa (PPF) is a complex and paired anatomical structure located at the skull base. A clinically and surgically relevant structure located in the pterygopalatine fossa is the sphenopalatine ganglion. Electrical stimulation of the sphenopalatine ganglion is one possible method of treating cluster headache. The pterygomaxillary fissure (PMF) defines the pterygopalatine fossa laterally and determines the surgical approach. As part of preoperative surgical planning, each patient undergoes a preoperative head computed tomography or a cone beam computed tomography. In our study cone beam computed tomography images of 90 male and 110 female PMF were analyzed. Generally, males have a wider fissure than females. Moreover, a significant inter-subject difference could be shown between males and females. The analysis of the right and left PMF according to gender and age does not show any significant intra-subject differences. Following an established protocol for high-resolution CT images the measurements were classified into four fissure types and also analyzed according to gender and age. Fissure type I is significantly more often present in males, whereas the smaller fissure types (II, III, and IV) are significantly more often found in females. Older patients presented statistically significant more often with type I, whereas the younger patients showed more often the narrower types II and IV. Due to the fact that narrow fissures smaller than 2 mm could limit the insertion of neurostimulator implants in the PPF, special attention should be paid to females and younger patients during preoperative planning.

Neurostimulation methods in the treatment of chronic pain

The goal of this narrative review was to give an up-to-date overview of the peripheral and central neurostimulation methods that can be used to treat chronic pain. Special focus has been given to three pain conditions: neuropathic pain, nociplastic pain and primary headaches. Both non-invasive and invasive techniques are briefly presented together with their pain relief potentials. For non-invasive stimulation techniques, data concerning transcutaneous electrical nerve stimulation (TENS), transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), remote electrical neuromodulation (REN) and vagus nerve stimulation (VNS) are provided. Concerning invasive stimulation techniques, occipital nerve stimulation (ONS), vagus nerve stimulation (VNS), epidural motor cortex stimulation (EMCS), spinal cord stimulation (SCS) and deep brain stimulation (DBS) are presented. The action mode of all these techniques is only partly understood but can be very different from one technique to the other. Patients' selection is still a challenge. Recent consensus-based guidelines for clinical practice are presented when available. The development of closed-loop devices could be of interest in the future, although the clinical benefit over open loop is not proven yet.

Systematic review of the safety and effectiveness of peripheral neurostimulation of the sphenopalatine ganglion for the treatment of refractory chronic cluster headache

INTRODUCTION

This study aimed to assess the safety and effectiveness of peripheral neurostimulation of the sphenopalatine ganglion (SPG) in the treatment of refractory chronic cluster headache.

DEVELOPMENT

Various medical databases were used to perform a systematic review of the scientific literature. The search for articles continued until 31 October 2016, and included clinical trials, systematic reviews and/or meta-analyses, health technology assessment reports, and clinical practice guidelines that included measurements of efficiency/effectiveness or adverse effects associated with the treatment. The review excluded cohort studies, case-control studies, case series, literature reviews, letters to the editor, opinion pieces, editorials, and studies that had been duplicated or outdated by later publications from the same institution. Regarding effectiveness, we found that SPG stimulation had positive results for pain relief, attack frequency, medication use, and patients' quality of life. In the results regarding safety, we found a significant number of adverse events in the first 30 days following the intervention. Removal of the device was necessary in some patients. Little follow-up data, and no long-term data, is available.

CONCLUSIONS

These results are promising, despite the limited evidence available. We consider it essential for research to continue into the safety and efficacy of SPG stimulation for patients with refractory chronic cluster headache. In cases where this intervention may be indicated, treatment should be closely monitored.

Vidian Neurectomy for Management of Chronic Cluster Headache

BACKGROUND

Management of chronic cluster headache (CCH) remains a challenging endeavor, and the optimal surgical approach for medically refractory CCH remains controversial.

OBJECTIVE

To conduct a preliminary evaluation of the efficacy and safety of vidian neurectomy (VN) in patients with medically refractory CCH.

METHODS

Between March 2013 and December 2015, 9 CCH patients, all of whom had failed to respond to conservative therapy, underwent VN with a precise nerve cut and maximal preservation of the sphenopalatine ganglion. Data included demographic variables, cluster headache onset and duration, mean attack frequency, mean attack intensity, and pain disability index measures pre- and through 12-mo postsurgery.

RESULTS

Seven of the 9 cases (77.8%) showed immediate improvement. Improvement was delayed by 1 mo in 1 patient, after which the surgical effects of pain relief were maintained throughout the follow-up period. One patient (11.1%) did not improve after surgery. One year after VN, patients' mean attack frequency, mean attack intensity, and pain disability index decreased by 54.5%, 52.9%, and 56.4%, respectively. No patient experienced treatment-related side effects or complications.

CONCLUSION

VN is an effective treatment method for CCH patients. Precise Vidian nerve identification and maximal preservation of the sphenopalatine ganglion may achieve good surgical outcomes and dramatically improve quality of life among patients, without significant adverse events.

Prediction of the sphenopalatine ganglion localization in computerized tomography images

Background:

The sphenopalatine ganglion (SPG) is a target for several headache syndromes. Most of the groups targeting the SPG do not localize it directly, and this might account for some therapeutic failures. As the SPG cannot be seen on computerized tomography (CT) scans, magnetic resonance image (MRI) must be used to visualize the ganglion. It would be advantageous to be able to predict the location of the SPG on CT scans for those using fluoroscopy or CT-guided injections and for those in whom MRI is not accessible or contraindicated.

Methods:

We localized the SPG in 21 Caucasian patients (21 right and 17 left ganglia; total 38) in 3 tesla MR images subsequently fused with CT scans. We measured the distance from the SPG to two bony landmarks identified on CT scans. We then applied the average distances to find an estimated position of the SPG. The first landmark was the center of the anterior opening of the vidian canal (VC). The second landmark was a point on the sphenoidal bone, defined in an axial plane at the level of the center of the VC (S-point). The predicted position of the SPG measured from the VC and the sphenoidal bone were referred to as, respectively, vcSPG and sSPG. Finally, the distances between the SPG, as seen on MRI, and predicted vcSPG/sSPG were calculated.

Results:

The average distance between SPG as seen on the MRI images and the estimated position based on CT images were 1.82 mm (SD 0.83, range 0.22–3.57 mm) for vcSPG and 2.09 mm (SD 0.99, range 0.71–4.79 mm) for sSPG.

Conclusions:

The localization of the SPG can be predicted on CT images using bony landmarks. Localization of the SPG may be important in achieving successful therapeutic outcomes for treatments that are directed toward the SPG.

Location and Volume of MRI Artifacts in Patients With Implanted Sphenopalatine Ganglion Neurostimulators for Treatment of Chronic Cluster Headache

INTRODUCTION

Sphenopalatine ganglion stimulation (SPG-S) is an invasive form of neuromodulation by which a neurostimulator is implanted into the pterygopalatine fossa to treat refractory chronic cluster headache. The implant is MRI conditional, up to 3 T, however there is no clinical data on the shape, size, and location of the artifact produced by the implant.

MATERIALS AND METHODS

Records of patients with SPG-S were analyzed for postoperative cranial MRI scans. MRI and intraoperative CT scans for visualization of the implant were fused and volumetry was performed for both the implant and the MRI artifact in different MRI sequences.

RESULTS

In total, n = 3 patients with postoperative MRI scans were identified. The mean CT artifact volume was 0.73 cm³ (±0.15 cm³ ). MRI artifact volume differed between sequences (range: 25.2-220.7 cm³ ). The intracranial space was largely unaffected besides the pole of the ipsilateral temporal lobe and the basal frontal gyrus. MRI artifacts affected the extracranial space (orbit, maxillary and ethmoid sinuses, and parts of the parotid gland). No adverse events occurred during or after MRI scans.

CONCLUSIONS

Cranial MRI scans with SPG-S implants were safely performed in three patients following the manufacturer's MRI conditions. MRI artifacts were mostly located in the extracranial space. Brain MRI imaging is largely unaffected.

CONFLICT OF INTEREST

The authors declare no potential conflicts of interest with respect to research, authorship, and/or publication of this article.

Changes in medication cost observed in chronic cluster headache patients treated with sphenopalatine ganglion (SPG) stimulation: Analysis based on 1-year data from the Pathway R-1 Registry

Background On-demand stimulation of the sphenopalatine ganglion (SPG) by means of an implantable neurostimulation system has been shown to be a safe and effective therapy for treatment-refractory cluster headache patients. Our objective was to estimate changes in cluster headache medication cost observed in SPG-treated chronic patients. Methods Detailed patient-level data of 71 chronic patients treated with the Pulsante® SPG Microstimulator System were available from the Pathway R-1 Registry through 12 months' follow-up. We used utilization data of preventive and acute medications reported at baseline, 3, 6, 9, and 12 months to estimate annualized drug costs for SPG-treated patients and compared it to baseline. Cost estimates for all drug/dosage combinations were developed based on German medication prices for 2016. Results In the base case analysis, mean annual acute and preventive medication costs decreased from €14,178 to €6924 (-€7254; -51%), and €559 to €328 (-€231; -41%), respectively, leading to total estimated annual drug cost savings of €7484, 97% of which were attributable to acute medications. Conclusions Our analysis suggests that SPG stimulation for the treatment of chronic cluster headache is associated with pronounced reductions in cluster headache medication usage that might lead to sizable annual savings in medication costs.

Managing cluster headache with sphenopalatine ganglion stimulation: a review

Cluster headache (CH) is a primary headache and considered as one of the worst pains known to man. The sphenopalatine ganglion (SPG) plays a pivotal role in cranial autonomic symptoms associated with pain. Lesioning procedures involving the SPG and experimental acute SPG stimulation have shown some degree of efficacy with regard to CH. A neuromodulation device, chronically implanted in the pterygopalatine fossa, has been specifically designed for acute on-demand SPG stimulation. In a pilot placebo-controlled study in 28 patients suffering from refractory chronic CH, alleviation of pain was achieved in 67.1% of full stimulation-treated attacks compared to 7% of sham stimulation-treated attacks (p<0.0001). Long-term results (24 months; 33 patients) confirmed the efficacy of SPG stimulation as an abortive treatment for CH attacks. Moreover, 35% of the patients observed a >50% reduction in attack frequency, suggesting that repeated use of SPG stimulation might act as a CH-preventive treatment. Globally, 61% of the patients were acute responders, frequency responders, or both, and 39% did not respond to SPG stimulation. The safety of SPG microstimulator implantation procedure was evaluated in a cohort of 99 patients; facial sensory disturbances were observed in 67% of the patients (46% of them being transient), transient allodynia in 3%, and infection in 5%. SPG stimulation appears as a promising innovative, efficient, and safe therapeutic solution for patients suffering from severe CH. It has shown its efficacy in aborting CH attacks compared to placebo stimulation, suggesting that it is particularly adapted for CH patients who are not sufficiently improved by abortive treatments such as sumatriptan and oxygen. However, further studies comparing SPG stimulation with standard abortive and/or preventive CH treatments will be necessary to define more precisely its place within the management of severe chronic and/or episodic CH.

Sphenopalatine ganglion stimulation for cluster headache, results from a large, open-label European registry

Background

Cluster headache (CH) is a disabling primary headache disorder characterized by severe periorbital pain. A subset of patients does not respond to established pharmacological therapy. This study examines outcomes of a cohort of mainly chronic CH patients treated with sphenopalatine ganglion (SPG) stimulation.

Methods

Patients were followed in an open-label prospective study for 12 months. Ninety-seven CH patients (88 chronic, 9 episodic) underwent trans-oral insertion of a microstimulator targeting the SPG. Patients recorded stimulation effect prospectively for individual attacks. Frequency, use of preventive and acute medications, headache impact (HIT-6) and quality of life measures (SF-36v2) were monitored at clinic visits. Per protocol, frequency responders experienced ≥ 50% reduction in attack frequency and acute responders treated ≥ 50% of attacks. HIT-6 responders experienced an improvement ≥ 2.3 units and SF-36 responders ≥ 4 units vs. baseline.

Results

Eighty-five patients (78 chronic, 7 episodic) remained implanted and were evaluated for effectiveness at 12 months. In total, 68% of all patients were responders, 55% of chronic patients were frequency responders and 32% of all patients were acute responders. 67% of patients using acute treatments were able to reduce the use of these by 52% and 74% of chronic patients were able to stop, reduce or remain off all preventive medications. 59% of all patients were HIT-6 responders, 67% were SF-36 responders.

Conclusions

This open-label registry corroborates that SPG stimulation is an effective therapy for CH patients providing therapeutic benefits and improvements in use of medication as well as headache impact and quality of life.

Electronic supplementary material

The online version of this article (10.1186/s10194-017-0828-9) contains supplementary material, which is available to authorized users.

Systematic review of the safety and effectiveness of peripheral neurostimulation of the sphenopalatine ganglion for the treatment of refractory chronic cluster headache

INTRODUCTION

This study aimed to assess the safety and effectiveness of peripheral neurostimulation of the sphenopalatine ganglion (SPG) in the treatment of refractory chronic cluster headache.

DEVELOPMENT

Various medical databases were used to perform a systematic review of the scientific literature. The search for articles continued until 31 October 2016, and included clinical trials, systematic reviews and/or meta-analyses, health technology assessment reports, and clinical practice guidelines that included measurements of efficiency/effectiveness or adverse effects associated with the treatment. The review excluded cohort studies, case-control studies, case series, literature reviews, letters to the editor, opinion pieces, editorials, and studies that had been duplicated or outdated by later publications from the same institution. Regarding effectiveness, we found that SPG stimulation had positive results for pain relief, attack frequency, medication use, and patients' quality of life. In the results regarding safety, we found a significant number of adverse events in the first 30 days following the intervention. Removal of the device was necessary in some patients. Little follow-up data, and no long-term data, is available.

CONCLUSIONS

These results are promising, despite the limited evidence available. We consider it essential for research to continue into the safety and efficacy of SPG stimulation for patients with refractory chronic cluster headache. In cases where this intervention may be indicated, treatment should be closely monitored.

Radiological anatomy assessment of the fissura pterygomaxillaris for a surgical approach to ganglion pterygopalatinum

The ganglion pterygopalatinum has become a therapeutic target to treat various pain syndromes in recent years. It is located in the fossa pterygopalatina, and the fissura pterygomaxillaris is the main access to surgically approach this structure. Recently, the neuromodulation of the ganglion pterygopalatinum by microstimulator implantation has become the first therapeutic line in refractory cluster headache treatment. This invasive technique is performed transorally through the fissura pterygomaxillaris, and is limited by the size of the implantation device, which requires an opening of at least 2 mm. Therefore, extensive knowledge about the anatomy of the fissura pterygomaxillaris prior to surgery is necessary to predict the success of both the approach and intervention. Likewise, establishing a morphological typology of the different fissura pterygomaxillaris variations would be a valuable predictive tool in the clinical practice. In this work, an anatomical analysis was performed of the morphological characteristics of the 242 fissurae pterygomaxillares, which corresponded to 121 adult patients, 58 males and 63 females, aged between 18 and 87 years. For each subject, right and left fissures were studied with radiological computed tomography images. Aperture fissura pterygomaxillaris measurements were taken in an upper (Measure A), middle (Measure B) and lower craneo-caudal third (Measure C). Intra-subject differences were studied between the measurements taken of each patient's right and left fissures, and the inter-subject measures in which fissures were compared according to patients' age and gender. The obtained results showed no significant differences between each patient's right and left fissures in any three measurements taken. Intra-subject differences were not significant for gender or age. No statistically significant differences were found for the inter-subject measures between the measures of fissures according to patients' age. However, our data revealed that males' fissurae pterygomaxillares were significantly larger than those of females in all three measures. Having analysed fissures, a typological classification was made according to the morphological patterns found. A 2-mm limiting measure was considered, and Measures A, B and C of each fissure were classified depending on whether they had a value above or equal to 2 mm, or below 2 mm. With this classification criterion, four fissurae pterygomaxillares types were obtained. Type I and II fissure values (with a higher prevalence) were equal to or were greater than 2 mm in all three measures, or in two measures. Type III fissure values were only greater than or equal to 2 mm in Measure A, whereas all the Type IV fissure values were below 2 mm. Future studies are necessary to correlate the fissure types successfully proposed in the surgical ganglion pterygopalatinum approach.

Sphenopalatine Ganglion (SPG): Stimulation Mechanism, Safety, and Efficacy

OBJECTIVE

To describe the history of and available data on sphenopalatine ganglion (SPG) neuromodulation in the treatment of headache up to the present.

BACKGROUND

The SPG has been a therapeutic target to treat primary headache disorders for over 100 years. Multiple destructive lesions have also been tried with variable rate and duration of success. Neurostimulation of the SPG for cluster headache was first described in 2007.

METHODS

This is not a systematic review. The authors review the anatomy and pathophysiology of the SPG and cluster headache and the important clinical trials, relating a history of how SPG neuromodulation reached the current state of approval in the European Union (EU) and pivotal registration study for cluster headache in the US.

RESULTS

The EU approved SPG stimulation for cluster headache with a CE Mark in February of 2012. Since then, several EU countries have elected to reimburse implantation for cluster headache, and over 300 patients have been implanted worldwide.

CONCLUSIONS

Success rates for implanted SPG neuromodulation in the experimental phase of the European randomized controlled trial, in the open label extension trial, and in the registry of patients implanted outside of the trial remain at about two-thirds of patients implanted being responders, defined as being able to terminate at least 50% of attacks or having at least a 50% decrease in attack frequency or both. A US pivotal registration study is underway to confirm these results and obtain FDA approval for this treatment for cluster headache patients. Further studies in migraine are also underway.

Cluster headache attack remission with sphenopalatine ganglion stimulation: experiences in chronic cluster headache patients through 24 months

Background

Cluster headache (CH) is a debilitating headache disorder with severe consequences for patient quality of life. On-demand neuromodulation targeting the sphenopalatine ganglion (SPG) is effective in treating the acute pain and a subgroup of patients experience a decreased frequency of CH attacks.

Methods

We monitored self-reported attack frequency, headache disability, and medication intake in 33 patients with medically refractory, chronic CH (CCH) in an open label follow-up study of the original Pathway CH-1 study. Patients were followed for at least 24 months (average 750 ± 34 days, range 699-847) after insertion of an SPG microstimulator. Remission periods (attack-free periods exceeding one month, per the ICHD 3 (beta) definition) occurring during the 24-month study period were characterized. Attack frequency, acute effectiveness, medication usage, and questionnaire data were collected at regular clinic visits. The time point “after remission” was defined as the first visit after the end of the remission period.

Results

Thirty percent (10/33) of enrolled patients experienced at least one period of complete attack remission. All remission periods followed the start of SPG stimulation, with the first period beginning 134 ± 86 (range 21-272) days after initiation of stimulation. On average, each patient’s longest remission period lasted 149 ± 97 (range 62-322) days. The ability to treat acute attacks before and after remission was similar (37 % ± 25 % before, 49 % ± 32 % after; p = 0.2188). Post-remission headache disability (HIT-6) was significantly improved versus baseline (67.7 ± 6.0 before, 55.2 ± 11.4 after; p = 0.0118). Six of the 10 remission patients experienced clinical improvements in their preventive medication use. At 24 months post insertion headache disability improvements remained and patient satisfaction measures were positive in 100 % (10/10).

Conclusions

In this population of 33 refractory CCH patients, in addition to providing the ability to treat acute attacks, neuromodulation of the SPG induced periods of remission from cluster attacks in a subset of these. Some patients experiencing remission were also able to reduce or stop their preventive medication and remissions were accompanied by an improvement in headache disability.

Long-term effectiveness of sphenopalatine ganglion stimulation for cluster headache

Objectives

The sphenopalatine ganglion (SPG) plays a pivotal role in cluster headache (CH) pathophysiology as the major efferent parasympathetic relay. We evaluated the long-term effectiveness of SPG stimulation in medically refractory, chronic CH patients.

Methods

Thirty-three patients were enrolled in an open-label follow-up study of the original Pathway CH-1 study, and participated through 24 months post-insertion of a microstimulator. Response to therapy was defined as acute effectiveness in ≥ 50% of attacks or a ≥ 50% reduction in attack frequency versus baseline.

Results

In total, 5956 attacks (180.5 ± 344.8, range 2–1581 per patient) were evaluated. At 24 months, 45% (n = 15) of patients were acute responders. Among acute responders, a total of 4340 attacks had been treated, and in 78% of these, effective therapy was achieved using only SPG stimulation (relief from moderate or greater pain or freedom from mild pain or greater). A frequency response was observed in 33% (n = 11) of patients with a mean reduction of attack frequency of 83% versus baseline. In total, 61% (20/33) of all patients were either acute or frequency responders or both. The majority maintained their therapeutic response through the 24-month evaluation.

Conclusions

In the population of disabled, medically refractory chronic CH patients treated in this study, SPG stimulation is an effective acute therapy in 45% of patients, offering sustained effectiveness over 24 months of observation. In addition, a maintained, clinically relevant reduction of attack frequency was observed in a third of patients. These long-term data provide support for the use of SPG stimulation for disabled patients and should be considered after medical treatments fail, are not tolerated or are inconvenient for the patients.