A superficial dissection approach to the sphenopalatine (pterygopalatine) ganglion to emphasize osteopathic clinical relevance.

The sphenopalatine (pterygopalatine) ganglion (SPG) is the most superficial ganglia to manipulate from the oral cavity. It has parasympathetic and sensory fibers directly affecting the paranasal sinuses as well as the palatine, nasal, pharyngeal, and lacrimal glands. The SPG can be manipulated intraorally by students and physicians utilizing osteopathic manipulative treatment (OMT) to relieve congestion associated with sinusitis, allergies, headaches, and upper respiratory infections. Within osteopathic medical education programs, students have anecdotally had difficulty identifying this ganglion due to its deep anatomic location and lack of direct visualization. In this article, we discuss that cadaveric dissection with a superficial to deep approach to the SPG has the ability to allow medical students and physicians to better understand the three-dimensional location and osteopathic clinical relevance of this ganglion.

Neuromodulation for the Sphenopalatine Ganglion-a Narrative Review.

PURPOSE OF REVIEW: To provide an integrated overview of the current state of knowledge of neuromodulation for the sphenopalatine ganglion (SPG) by reviewing relevant and significant literature. RECENT FINDINGS: There are several case reports and clinical trials evaluating neuromodulation for the SPG. We identified two blinded, randomized clinical trials for patients with chronic cluster headache. The randomized trials and additional studies demonstrated the long-term safety, efficacy, and cost-effectiveness of neuromodulation for the SPG. Recent studies in Europe and the USA suggest that SPG neuromodulation is a novel modality with clinical importance for treating acute cluster headaches and reducing the frequency of attacks.

Sphenopalatine ganglion volumetry in episodic cluster headache: from symptom laterality to cranial autonomic symptoms.

BACKGROUND: Sphenopalatine ganglion (SPG) is a peripheral structure that plays an important role in cluster headache (CH). Hence, a reliable method to measure the volume of SPG is crucial for studying the peripheral mechanism of CH. Additionally, the association between the clinical profiles and the morphology of the SPG in CH remains undetermined. This study aims to use the manual measurement of SPG volume to investigate its associations with CH, including headache laterality, cranial autonomic symptoms (CASs), presence of restlessness or agitation, and other clinical profiles. METHODS: We prospectively recruited consecutive CH patients at a tertiary medical center between April 2020 and April 2022. A total of eighty side-locked, in-bout, episodic CH patients and 40 non-headache healthy controls received 1.5 T brain MRI focusing on structural neuroimaging of the SPG. The manual measurement process for SPG was under axial and sagittal FIESTA imaging, with reference T2 weight images (sagittal and axial) for localization. The inter-observer agreement of the SPG volume (both sides of the SPG from CH patients and controls) between the two observers was calculated. In CH patients, clinical profiles and the number of CASs (range 0-5) were recorded to analyze their association with SPG volume. RESULTS: The inter-observer agreement between the two raters was excellent for the new SPG volumetry method at 0.88 (95% CI: 0.84-0.90, p < 0.001). The mean [SD] SPG volume was larger in CH patients than in non-headache controls (35.89 [12.94] vs. 26.13 [8.62] µL, p < 0.001). In CH patients, the SPG volume was larger on the pain side than on the non-pain side (38.87 [14.71] vs. 32.91 [12.70] µL, p < 0.001). The number of CASs was positively moderately correlated with the pain-side SPG volume (Pearson r = 0.320, p = 0.004) but not the non-pain side SPG volume (Pearson r = 0.207, p = 0.066). CONCLUSIONS: This proof-of-concept study successfully measured the SPG volume and demonstrated its associations with symptomatology in patients with episodic CH. The direct measurement of SPG provide insights into studies on peripheral mechanism of CH.

[Sphenopalatine ganglion stimulation in the treatment of chronic refractory cluster headache. A preliminary multicenter study in Russia]. / Stimulyatsiya krylonebnogo gangliya v lechenii khronicheskoi klasternoi golovnoi boli. Rezul'taty pervogo mul'titsentrovogo opyta v Rossii.

OBJECTIVE: To analyze the results of sphenopalatine ganglion stimulation in treatment of chronic headache. MATERIALS AND METHODS: Medical histories of patients who underwent sphenopalatine ganglion stimulation in 4 clinical centers have been analyzed. The analysis included the type of pain and its characteristics, methods of surgery, CT, MRI, radiography before and after surgery. The follow-up data of patients with implanted pulse generators was collected in an outpatient clinic or by telephone review. RESULTS: The study included 15 patients with chronic refractory headache, including 14 with cluster headache and one female patient with features of trigeminal autonomic cephalgia without a clear definition of the type of pain. Trial stimulation was performed in 10 patients to determine analgesic effect. Among them stimulation was favorable in 7 cases, and 6 of them underwent pulse generator implantation. In total, 11 (73%) patients underwent implantation with a follow-up from 1 to 60 months. Among them only 6 (54%) patients use stimulation, the remaining 5 (46%) cases had device-related complications (migration, infection of system). Cluster headache has a significant improvement in long-term follow-up. CONCLUSIONS: Sphenopalatine ganglion stimulation may have high potential in the treatment of chronic drug-resistant cluster headache. The complication rate demonstrates that operative technique should be improved.

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.

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.

Accuracy of Electrode Position in Sphenopalatine Ganglion Stimulation in Correlation With Clinical Efficacy.

INTRODUCTION: Sphenopalatine ganglion (SPG) stimulation is an efficient treatment for cluster headache. The target for the SPG microstimulator in the pterygopalatine fossa lies between the vidian canal and foramen rotundum, ideally two contacts should be placed in this area. However, placement according to the manufacturers recommendations is frequently not possible. It is not known whether a suboptimal electrode placement interferes with postoperative outcomes. MATERIALS AND METHODS: SPG stimulation was performed in 13 patients between 2015 and 2018 in a single center. Lead location was determined by intraoperative computed tomography scan and correlated with the planned lead position as well as clinical data and stimulation parameters. Patients with a reduction of 50% or more in pain intensity or frequency were considered responsive. RESULTS: Eleven patients (84.6%) responded to SPG stimulation with eight being frequency responders (61.5%). In seven cases, there were less than two electrodes between vidian canal and foramen rotundum, there was no significant correlation with negative stimulation results (p = 0.91). The mean distance of lead location between pre- and postoperative images did not correlate with clinical outcomes (p = 0.84) and was even bigger in responders (4.91 mm vs. 4.53 mm). The closest electrode contact to the vidian canal was in the stimulation area in all but one patient, regardless of its overall distance to canal. The distance of the closest electrode to the vidian canal was, however, not significantly correlated to the percentage of frequency (p = 0.68) or intensity reduction (p = 0.61). CONCLUSION: There was no significant correlation regarding aberrations of lead position from the planned position with clinical outcome. However, this study might be underpowered to detect such a correlation. The closest electrode contact to the vidian canal was in the stimulation area in all but one patient in the final programming. This indicates that, overall, the lead location does play a crucial role in SPG stimulation for cluster headache.

Occipital Nerve Stimulation and Sphenopalatine Ganglion Stimulation for Treatment of Intractable Headache Syndromes.

Headaches are an increasing cause of disability in the world. Intractable headache syndromes affect all age groups but predominantly the middle-aged, working population. Occipital neuralgia is a frequent comorbidity with intractable migraine headaches. Occipital nerve stimulation at the level of nuchal ridge is a reasonable option for these refractory patients. Ultrasound guidance of occipital nerve stimulation can optimize depth placement of leads. Revision surgeries of occipital nerve stimulation are usually performed using surgical leads. Cluster headaches and trigeminal autonomic cephalagias (TACs) are refractory headache conditions that are mediated by sphenopalatine ganglion. Sphenopalatine ganglion stimulation with infrazygomatic approach and fluoroscopic guidance of percutaneous leads can help alleviate pain from cluster headaches and TACs. Innovation in neurostimulation technologies have brought new optimism to these refractory conditions. Efficient and optimal delivery of neurostimulation for intractable headache syndromes requires a multidisciplinary team-based approach for long term compliance and efficacy.

Sphenopalatine Ganglion Stimulation for Chronic Headache Syndromes.

Neuropathic facial pain is notoriously difficult to treat, regardless of its origin and duration. Since the first reported sphenopalatine ganglion blockade by Sluder in 1908, this ganglion has assumed an important role among the structures targeted for the treatment of facial pain. Recent years have witnessed the rise of neuromodulation over ablative procedures, including the development of an implantable stimulation device specially designed for use in the pterygopalatine fossa. Sphenopalatine ganglion stimulation has been demonstrated as effective and safe for refractory cluster headache, today the major indication for this therapy, but increasing evidence shows that the effect on the autonomic system and cerebral circulation could justify an even wider use of sphenopalatine ganglion stimulation for other chronic headache syndromes and vascular diseases.

Low frequency activation of the sphenopalatine ganglion does not induce migraine-like attacks in migraine patients.

INTRODUCTION: Cephalic autonomic symptoms occur in 27‒73% of migraine patients during attacks. The role of parasympathetic activation in migraine attack initiation remains elusive. Low frequency stimulation of the sphenopalatine ganglion increases parasympathetic outflow. In this study, we hypothesized that low frequency stimulation of the sphenopalatine ganglion would provoke migraine-like attacks in migraine patients. METHODS: In a double-blind randomized sham-controlled crossover study, 12 migraine patients with a sphenopalatine ganglion neurostimulator received low frequency or sham stimulation for 30 min on two separate days. We recorded headache characteristics, cephalic autonomic symptoms, ipsilateral mechanical perception and pain thresholds, mean blood flow velocity in the middle cerebral artery (VMCA) and diameter of the superficial temporal artery during and after stimulation. RESULTS: Five patients (42%) reported a migraine-like attack after low frequency stimulation compared to six patients (50%) after sham (p = 1.000). We found a significant increase in mechanical detection thresholds during low frequency stimulation compared to baseline (p = 0.007). Occurrence of cephalic autonomic symptoms and changes in mechanical perception thresholds, VMCA and diameter of the superficial temporal artery showed no difference between low frequency stimulation compared to sham (p = 0.533). CONCLUSION: Low frequency stimulation of the sphenopalatine ganglion did not induce migraine-like attacks or autonomic symptoms in migraine patients. These data suggest that increased parasympathetic outflow by the sphenopalatine ganglion neurostimulator does not initiate migraine-like attacks.Study protocol: ClinicalTrials.gov registration number NCT02510742.

Effect of pterygopalatine blockade on perioperative stress and inflammatory outcomes following paediatric cataract surgery.

BACKGROUND: General anesthesia is required to perform pediatric cataract surgery. To reduce severity of surgical intervention and postoperative complications, regional techniques have been concomitantly used. The traditional regional ophthalmic techniques are retrobulbar, peribulbar and sub-Tenon blocks, which present some technical difficulties and associated complication risks. The pterygopalatine blockade has been exempt of many of these concerns as it is performed out of the orbit. The purpose of this study was to compare the analgesic and anti-inflammatory effects of the pterygopalatine blockade with retrobulbar block in children undergoing elective congenital cataract surgery. METHODS: After approval of ethics committee and informed consents, patients were enrolled to the study to have either ultrasound-guided pterygopalatine block (group P) or retrobulbar block (group R), with 2 mL lidocaine 2% and 1 mL ropivacaine 0.5%. Hemodynamic monitoring was recorded throughout the perioperative period. Cortisol level and oxidation-reduction status were assessed before and after surgery. Pain and inflammatory response (Tyndall effect, corneal syndrome and edema) were assessed on the first postoperative day. RESULTS: Comparative analysis demonstrated a decrease in cortisol of 123.24% (p˂0.05) and an increase in the redox coefficient of 37.7% (p˂0.05) in group P. Pain intensity was significantly higher in group R until the 16th postoperative hour. The corneal syndrome in patients in group P and group R was noted by 7.6% and in 32.1%, respectively (p˂0.05). CONCLUSION: The use of the pterygopalatine blockade as a component of anesthesia in pediatric cataract surgery allows reduction of the severity of surgical stress during surgical intervention, providing intraoperative hemodynamic stability and prolonged analgesia.

Refined Sphenopalatine Ganglion Stimulator Placement and Intensity Setting to Augment Blood Flow and Neurologic Function.

Background and Purpose- Two large, randomized trials indicated that sphenopalatine ganglion (SPG) stimulation improves final disability outcome in acute anterior circulation patients with ischemic stroke with confirmed cortical involvement. This study evaluated 2 refinements in SPG stimulation treatment technique: (1) SPG electrode placement with real-time optical tracking guidance; and (2) stimulation intensity comfortable tolerance level selection using non-noxious facial physiological markers. Methods- This study was a single, active arm trial at 4 centers, enrolling patients with anterior circulation ischemic stroke, National Institutes of Health Stroke Scale 1 to 6 including arm weakness subitem score ≥1, not receiving recanalization therapies, and within 24 hours of onset. Stimulation level was set based on ipsilateral facial tingling sensation or lacrimation. SPG stimulation effects were assessed by measuring volumetric blood flow in the ipsilateral common carotid artery by ultrasound and grasp and pinch strength in the affected hand before and during stimulation, and by change in National Institutes of Health Stroke Scale from day 1 to 7. Results- Among 50 enrolled patients, age was median 66 years (interquartile range, 60-74), 44% were female, National Institutes of Health Stroke Scale median was 5 (interquartile range, 4-5), and median onset-to-screening time was 18 hours (interquartile range, 9-20). Median implantation skin-to-skin time was 4 minutes (interquartile range, 3-7), and all 50 implants were placed correctly. Comfortable tolerance level was found based on physiological biomarkers in 96% of patients, including 86% in the optimal, low-medium intensity range. SPG stimulation significantly increased common carotid artery peak systolic and end-diastolic blood flow (44%, P<0.0001; and 52%, P<0.0001) and improved pinch strength (42%, P<0.0001) and grasp strength (26%, P<0.0001). Degree of National Institutes of Health Stroke Scale recovery by day 7 was greater than in matched historic controls, median 75% versus 50%, P=0.0003. Conclusions- SPG stimulator placement with real-time optical tracking guidance was fast and accurate, and selection of stimulation intensity levels based on non-noxious facial tingling and lacrimation was feasible in nearly all patients. SPG stimulation led to cervico-cranial blood flow augmentation and improved hand motor function. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT03551093.

Implant for Augmentation of Cerebral Blood Flow Trial-1 (ImpACT-1). A single-arm feasibility study evaluating the safety and potential benefit of the Ischemic Stroke System for treatment of acute ischemic stroke.

BACKGROUND: The Ischemic Stroke System is a novel device designed to deliver stimulation to the sphenopalatine ganglion(SPG).The SPG sends parasympathetic innervations to the anterior cerebral circulation. In rat stroke models, SPG stimulation results in increased cerebral blood flow, reduced infarct volume, protects the blood brain barrier, and improved neurological outcome. We present here the results of a prospective, multinational, single-arm, feasibility study designed to assess the safety, tolerability, and potential benefit of SPG stimulation inpatients with acute ischemic stroke(AIS). METHODS: Patients with anterior AIS, baseline NIHSS 7-20 and ability to initiate treatment within 24h from stroke onset, were implanted and treated with the SPG stimulation. Patients were followed up for 90 days. Effect was assessed by comparing the patient outcome to a matched population from the NINDS rt-PA trial placebo patients. RESULTS: Ninety-eight patients were enrolled (mean age 57years, mean baseline NIHSS 12 and mean treatment time from stroke onset 19h). The observed mortality rate(12.2%), serious adverse events (SAE)incidence(23.5%) and nature of SAE were within the expected range for the population. The modified intention to treat cohort consisted of 84 patients who were compared to matched patients from the NINDS placebo arm. Patients treated with SPG stimulation had an average mRS lower by 0.76 than the historical controls(CMH test p = 0.001). CONCLUSION: The implantation procedure and the SPG stimulation, initiated within 24hr from stroke onset, are feasible, safe, and tolerable. The results call for a follow-up randomized trial (funded by BrainsGate; clinicaltrials.gov number, NCT03733236).

An injectable implant to stimulate the sphenopalatine ganglion for treatment of acute ischaemic stroke up to 24 h from onset (ImpACT-24B): an international, randomised, double-blind, sham-controlled, pivotal trial.

BACKGROUND: Sphenopalatine ganglion stimulation increased cerebral collateral blood flow, stabilised the blood-brain barrier, and reduced infarct size, in preclinical models of acute ischaemic stroke, and showed potential benefit in a pilot randomised trial in humans. The pivotal ImpACT-24B trial aimed to determine whether sphenopalatine ganglion stimulation 8-24 h after acute ischaemic stroke improved functional outcome. METHODS: ImpACT-24B is a randomised, double-blind, sham-controlled, pivotal trial done at 73 centres in 18 countries. It included patients (men aged 40-80 years and women aged 40-85 years) with anterior-circulation acute ischaemic stroke, not undergoing reperfusion therapy. Enrolled patients were randomly assigned via web-based randomisation to receive active sphenopalatine ganglion stimulation (intervention group) or sham stimulation (sham-control group) 8-24 h after stroke onset. Patients, clinical care providers, and all outcome assessors were masked to treatment allocation. The primary efficacy endpoint was the difference between active and sham groups in the proportion of patients whose 3-month level of disability improved above expectations. This endpoint was evaluated in the modified intention-to-treat (mITT) population (defined as all patients who received one active or sham treatment session) and the population with confirmed cortical involvement (CCI) and was analysed using the Hochberg multi-step procedure (significance in both populations if p<0·05 in both, and in one population if p<0·025 in that one). Safety endpoints at 3 months were all serious adverse events (SAEs), SAEs related to implant placement or removal, SAEs related to stimulation, neurological deterioration, and mortality. All patients who underwent an attempted sphenopalatine ganglion stimulator or sham stimulator placement procedure were included in the safety analysis. This trial is registered with ClinicalTrials.gov, number NCT00826059. FINDINGS: Between June 10, 2011, and March 7, 2018, 1078 patients were enrolled and randomly assigned to either the intervention or the sham-control group. 1000 patients received at least one session of sphenopalatine ganglion stimulation or sham stimulation and entered the mITT population (481 [48%] received sphenopalatine ganglion stimulation, 519 [52%] were sham controls), among whom 520 (52%) patients had CCI on imaging. The proportion of patients in the mITT population whose 3-month disability level was better than expected was 49% (234/481) in the intervention group versus 45% (236/519) in the sham-control group (odds ratio 1·14, 95% CI 0·89-1·46; p=0·31). In the CCI population, the proportion was 50% (121/244) in the intervention group versus 40% (110/276) in the sham-control group (1·48, 1·05-2·10; p=0·0258). There was an inverse U-shaped dose-response relationship between attained sphenopalatine ganglion stimulation intensity and the primary outcome in the CCI population: the proportion with favourable outcome increased from 40% to 70% at low-midrange intensity and decreased back to 40% at high intensity stimulation (p=0·0034). There were no differences in mortality or SAEs between the intervention group (n=536) and the sham-control group (n=519) in the safety population. INTERPRETATION: Sphenopalatine ganglion stimulation is safe for patients with acute ischaemic stroke 8-24 h after onset, who are ineligible for thrombolytic therapy. Although not reaching significance, the trial's results support that, among patients with imaging evidence of cortical involvement at presentation, sphenopalatine ganglion stimulation is likely to improve functional outcome. FUNDING: BrainsGate Ltd.

Cluster headache: crosspoint between otologists and neurologists-treatment of the sphenopalatine ganglion and systematic review.

Among cephalgias, cluster headache (CH) is the rarest and the most disabling, explaining the appellation of "suicide headache." Up to 20% of chronic CH reveals to be resistant to pharmacological treatments, in which case interventional procedures should be considered. Many reports evaluated invasive approaches and a wide strand of research is dedicated to the sphenopalatine ganglion. Our paper will now be focused on providing an overview on modern applications on the sphenopalatine ganglion (SPG), their outcomes, and their feasibility in terms of risks and benefits. The group reviewed the international literature systematically for procedures targeting the sphenopalatine ganglion and its branches for episodic and chronic CH, including block, stimulation, radiofrequency, stereotactic radiosurgery, and vidian neurectomy. Seventeen articles fixed our inclusion criteria. Comparing the outcomes that have been analyzed, it is possible to notice how the most successful procedure for the treatment of refractory chronic and episodic CH is the SPG block, which reaches respectively 76.5% and 87% of efficacy. Radiofrequency has a wide range of outcomes, from 33 to 70.3% in CCH. Stimulation of SPG only achieved up to 55% of outcomes in significant reduction in attack frequency in CCH and 71% in ECH. Radiosurgery and vidian neurectomy on SPG have also been analyzed. Generally, ECH patients show better response to standard medical therapies; nevertheless, even this more manageable condition may sometimes benefit from interventional therapies mostly reserved for CCH. First results seem promising and considering the low frequency of side effects or complications, we should think of expanding the indications of the procedures also to those conditions. Outcomes certainly suggest that further studies are necessary in order to understand which method is the most effective and with less side effects. Placebo-controlled studies would be pivotal, and tight collaboration between neurologists and otorhinolaryngologists should also be central in order to give correct indications, which allow us to expect procedures on the SPG to be an effective and mostly safe method to control either refractory ECH or CCH.

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.

Novel Interventional Nonopioid Therapies in Headache Management.

PURPOSE OF REVIEW: Headaches encompass a broad-based category of a symptom of pain in the region of the head or neck. For those patients who unfortunately do not obtain relief from conservative treatment, interventional techniques have been developed and are continuing to be refined in an attempt to treat this subset of patients with the goal of return of daily activities. This investigation reviews various categories of headaches, their pathophysiology, and types of interventional treatments currently available. RECENT FINDINGS: Injection of botulinum toxin has been shown to increase the number of headache free days for patients suffering from chronic tension-type headaches. Suboccipital steroid injection has been demonstrated as a successful treatment option for patients suffering from cluster headache. Occipital nerve stimulation (ONS) has been described as a treatment for all types of trigeminal autonomic cephalgias. Percutaneous ONS is a minimally invasive and reversible approach to manage occipital neuralgia performed utilizing subcutaneous electrodes placed superficial to the cervical muscular fascia in the suboccipital area. Radiofrequency lesioning is another commonly used treatment in the management of chronic pain syndromes of the head and neck. If a diagnostic sphenopalatine ganglion block successfully resolves the patient's symptoms, neurolysis can be employed as a more permanent solution. Although many patients who suffer from headaches can be treated with conservative, less-invasive treatments, there still remains at present an ever-increasing need for those patients who are refractory to conservative measures and thus require interventional treatments. These procedures are continually evolving to become safer, more precise, and more readily available for clinicians to provide to their patients.