Improved surgical procedure using intraoperative navigation for the implantation of the SPG microstimulator in patients with chronic cluster headache

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.

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.

Multicentre, prospective, randomised, controlled, blinded-endpoint study to evaluate the efficacy and safety of pterygopalatine ganglion pulsed radiofrequency treatment for cluster headache: study protocol

INTRODUCTION

Single-centre reports on small groups of patients have shown that pterygopalatine ganglion pulsed radiofrequency treatment in patients with refractory cluster headache (CH) can quickly relieve pain without significant side effects. However, a randomised controlled trial is still necessary to evaluate whether pterygopalatine ganglion pulsed radiofrequency (PRF) treatment is a viable treatment option for patients with CH who are not responding to drug treatment.

METHODS AND ANALYSIS

This investigation is a multicentre, prospective, randomised, controlled, blinded-endpoint study. We will enrol 80 patients with CH who are not responding to medication. The enrolled patients will be randomly divided into two groups: the nerve block (NB) group and the PRF group. All patients will undergo CT-guided pterygopalatine ganglion puncture. A mixture containing steroids and local anaesthetics will be slowly injected into the patients in the NB group. The patients in the PRF group will be treated with PRF at 42°C for 360 s. After treatment, the duration of cluster periods; degree of pain during headache attacks; frequency of headache attacks; duration of each headache attack; dose of auxiliary analgesic drugs; duration of remission; degree of patient satisfaction; effectiveness rates at 1 day, 3 days, 1 week, 2 weeks, 1 month, 3 months, 6 months, and 1 year after the procedure; and intraoperative and postoperative adverse events will be compared between the two groups.

ETHICS AND DISSEMINATION

This study was approved by the institutional ethics committee of the Beijing Tiantan Hospital (approval number: KY 2018-027-02). The results of the study will be published in peer-reviewed journals, and the findings will be presented at scientific meetings.

TRIAL REGISTRATION NUMBER

NCT03567590; Pre-results.

Assessment of tumor margins in head and neck cancer using a 3D-navigation system based on PET/CT image-fusion - A pilot study

OBJECTIVES

Determination of tumor margins in patients with squamous cell carcinoma of the head and neck (SCCHN) is mostly based on preoperative magnetic resonance imaging (MRI) or computed tomography scans (CT). Local recurrence of disease is often correlated with the presence of positive resection margins after surgical treatment. Positron emission tomography/computed tomography (PET/CT) imaging plays a crucial role in the assessment of patients with SCCHN. The purpose of this study was to determine whether PET/CT could predict tumor extension.

METHODS

In 12 patients who underwent surgical treatment of primary SCCHN (Stage III-IV) F18-FDG PET/CT image-fusion was performed on a 3D navigation-system based workstation. Image-guided needle biopsies were obtained from four different, color-coded metabolic areas within the tumor. The histopathological findings were correlated with findings on corresponding PET/CT scans.

RESULTS

81.3% of biopsies from the central area were positive. Specimens taken from the outer metabolic zone were positive in 66.7% of the patients. The highest incidence of positive biopsies was found in the zone adjacent to the outermost area. There was a statistically significant difference in positive tumor histopathology when comparing the various metabolic zones (p = 0.03).

CONCLUSION

Exact determination of tumor is an important research topic, although results remain controversial. The results of this study suggest that in some cases PET scans may overestimate tumor extension.

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.

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.