Value of intra- and post-operative cone beam computed tomography (CBCT) for positioning control of a sphenopalatine ganglion neurostimulator in patients with chronic cluster headache

https://doi.org/10.1016/j.jcms.2014.12.017Get rights and content

Abstract

Introduction

The objective of this study was to determine whether postoperative control of the neurostimulator placement within the pterygopalatine fossa (PPF) by means of 3-dimensional (3D) cone beam computed tomography (CBCT) was of therapeutic relevance compared to intraoperative CBCT imaging alone.

Material and methods

Immediately after implantation of the sphenopalatine ganglion (SPG) neurostimulator, intraoperative CBCT datasets were generated in order to visualize the position of the probe within the PPF. Postoperatively, all patients received a CBCT for comparison with intraoperatively acquired radiographs.

Results

Twenty-four patients with cluster headache (CH) received an SPG neurostimulator. In 4 patients, postoperative CBCT images detected misplacement not found in intraoperative CBCT. In 3 cases, electrode tips were misplaced into the maxillary sinus and in 1 case into the apex of the PPF superior to the suspected location of the SPG. Immediate revision with successful repositioning within 3 days was done in 2 patients and a deferred reimplantation in 1 patient within 6 months. One patient declined revision.

Conclusion

We were able to demonstrate the clinical value of postoperative dental CBCT imaging with a wide region of interest (ROI) due to a superior image quality compared with that achieved with intraoperative medical CBCT. Although intraoperative 3D CBCT imaging of electrode placement is helpful in the acute surgical setting, resolution is, at present, too low to safely exclude misplacement, especially in the maxillary sinus. High-resolution postoperative dental CBCT allows rapid detection and revision of electrode misplacement, thereby avoiding readmission and recurrent tissue trauma.

Introduction

Cluster headache (CH) belongs to a group of primary headaches that are extremely painful and debilitating and hence are also named ‘suicide headaches’. Especially the chronic subtype (cCH) leads to severe physical impairment (Jürgens et al., 2011). CH is characterized by excruciating unilateral headache attacks lasting 15–180 min with co-activation of the cranial autonomic system ipsilateral to the side of headache (International Headache Society, 2013, Schoenen et al., 2013). The complex pathophysiology of CH involves cross-talk between afferent trigeminal fibres and the cranial parasympathetic efferents from the superior salivary nucleus—mediated primarily through the sphenopalatine ganglion (SPG) located in the pterygopalatine fossa (PPF) (Goadsby, 2002, May, 2005). Postganglionic fibres from SPG innervate facial structures such as the lacrimal gland, the conjunctiva and the nasopharyngeal mucosa. This anatomic relationship explains autonomic symptoms, such as lacrimation and rhinorrhea, during a typical CH attack. Furthermore, these nerve fibres innervate cerebral and meningeal blood vessels (Schoenen et al., 2013, Nozaki et al., 1993, Ruskell, 2003). It has been hypothesized that a centrally driven activation of the peripheral parasympathetic system induces a release of nociceptive neurotransmitters and vasodilators, causing a painful neurogenic inflammation around the meningeal vessels activating afferent nociceptive fibers of the trigeminal nerve. Due to the trigemino-parasympathetic reflex, increased afferent trigeminal input further induces an increase in parasympathetic outflow, creating a centrally driven vicious circle (Schoenen et al., 2013, May and Goadsby, 1999).

Alongside conservative treatment options, such as subcutaneous sumatriptan injections or oxygen inhalation to abort acute attacks (Schoenen et al., 2013, May et al., 2006, Cohen et al., 2009, Ekbom et al., 1993), several interventional approaches targeting the SPG as the relevant peripheral structure have been suggested for interrupting the above vicious circle. Transnasal injection of local anaesthetics and corticosteroids or alcohol injections into the PPF and pulsed radiofrequency ablations of the SPG were tried with only moderate or temporary relief (Schoenen et al., 2013, Devoghel, 1981, Felisati et al., 2006). Recently, on-demand neuromodulation of the SPG during an acute CH attack has been introduced by means of an implantable microstimulator (Fig. 1). In a randomized controlled study, acute attacks were effectively aborted or substantially relieved after 15 min of active stimulation compared to sham stimulation (Schoenen et al., 2013). The microstimulator consists of a bone plate for fixation, a stimulator body (with a radiofrequency-based communication module and the processor) and the electrode lead with 7 electrode contacts to be placed in the PPF close to the putative location of the SPG in close proximity to the Vidian canal (Canalis pterygoideus). During a minimally invasive surgical intervention, the neurostimulator body is anchored to the maxillary buttress with an electrode tip extending into the PPF close to the SPG.

When surgical positioning of the SPG neurostimulator was deemed to be ideal by fluoroscopy, an intraoperative 3D CBCT was performed, as other procedures (such as test stimulation to induce autonomic activation) have not been shown to reliably ascertain the correct placement. Due to metallic artefacts caused by the neurostimulator, crowns or dental implants, intraoperative verification by CBCT was difficult to interpret in some cases. However, the implantation was not finished before correct positioning was assumed on CBCT. Our aim was to verify whether additional postoperative CBCT scans routinely acquired afterwards were helpful in detecting misplacement not noticed on intraoperative images.

Section snippets

Patients

We conducted a retrospective review of study data available for all patients who received an implantable SPG neurostimulator between June 2011 and November 2013 as part of a clinical study on an implantable medical device, the ATI neurostimulator. A total of 24 patients were included in this study, 21 males (87.5%) and 3 females (12.5%). Mean age was 45.2 years, (range, 20–73 years). Mean duration of CH at time of implantation was 11.3 years (range, 2–35 years). Five patients (21%) received a

Results

In 3 patients (12.5%), dislocation of the integral electrode lead into the left maxillary sinus was not clearly detectable on the intraoperative CBCT (Fig. 2), but became apparent on postoperative dental CBCT (Fig. 3, Fig. 4). An iatrogenic fracture of the posterior wall was considered causal in 3 patients. In 2 of those patients (CH-17 and CH-18), an osteoporotic bone structure due to systemic corticosteroid therapy over a period of more than 10 years (as frequently given to patients with

Discussion

In this retrospective analysis, all 24 patients had intraoperative CBCT scans suggesting correct positioning of the SPG neurostimulator within the PPF. However, postoperative CBCT scans revealed misplacement in 4 patients, 2 of whom had pre-existing osteoporosis. Postoperative CBCTs were helpful in detecting these misplacements and allowed successful repositioning in 3 patients (all patients with dislocation to the maxillary sinus). As postoperative CBCT scans were done within the next 24 h,

Conclusion

Intraoperative 3D analysis of SPG neurostimulator placement into the PPF is an effective tool to facilitate the surgical setting. However, thin bone walls, metal artefacts and image quality of intraoperative CBCT may interfere with the accuracy of visualization. We could demonstrate the clinical value of dental CBCT imaging having a wide region of interest (ROI) due to the quite different image quality of intraoperative CBCT and postoperative dental CBCT. Therefore, we recommend an immediate

Conflicts of interest

A.T.A., J.C.K., M.B., C.K., P.P., A.M. and TPJ have been consultants for ATI since 2010 or 2011 and have received payment for services not related to the conduct of the Pathway CH-1 study. A.M. is one of the steering committee members for the Pathway CH-1 trial. All costs associated with patient care during the Pathway CH-1 trial were reimbursed to all enrolling institutions.

References (28)

  • K. Ekbom et al.

    Subcutaneous sumatriptan in the acute treatment of cluster headache: a dose comparison study. The Sumatriptan Cluster Headache Study Group

    Acta Neurol Scand

    (1993)
  • G. Felisati et al.

    Sphenopalatine endoscopic ganglion block: a revision of a traditional technique for cluster headache

    Laryngoscope

    (2006)
  • P.J. Goadsby et al.

    Towards a definition of intractable headache for use in clinical practice and trials

    Cephalalgia

    (2006)
  • Headache Classification Committee of the International Headache Society (IHS)

    The International Classification of Headache Disorders, 3rd edition (beta version)

    Cephalagia

    (2013 Jul)
  • Cited by (0)

    1

    The first two authors contributed equally to this work.

    View full text