Peripheral neurostimulation for control of intractable occipital neuralgia

Peripheral nerve stimulation: a percutaneous minimally invasive approach

We report on the use of a new percutaneous technique for peripheral nerve stimulation (PNS) treatment of chronic pain. A 56-year-old woman was diagnosed with algodystrophic syndrome, now called Complex Regional Pain Syndrome, type 2 (CRPS2), due to a lesion of the right medial nerve despite surgical revascularization, angioplasty and stent insertion. After a successful 10-day trial of PNS via a percutaneous quadripolar lead in the interscaline space, an implantable pulse generator was implanted in the abdominal subcutaneous tissue and connected to the subcutaneous lead via an extension. After one year of follow-up, the patient was still experiencing good pain relief. We conclude that this novel percutaneous PNS technique offers the advantage of being a minimally invasive approach that can be easily adopted for the management of chronic pain.

Occipital nerve stimulation for the treatment of occipital neuralgia-eight case studies

Objective.  The aim of this study was to examine the hypothesis that subcutaneous occipital stimulation influences pain due to occipital neuralgia. Materials and Methods.  Between 2001 and 2004 eight patients with intractable occipital neuralgia were referred to our center. Their records were reviewed. Each patient was interviewed over the telephone. They were all offered a trial of stimulation using a percutaneous lead over 1 week. If they achieved 50% pain reduction a permanent lead was implanted. The impact of occipital stimulation was measured by pain score, analgesic requirements, and employment status. Results.  Seven proceeded to a permanent stimulator. There was a reduction in the visual analog score postimplantation in five of the seven patients. The total quantity of opiates taken after implantation showed a marked reduction. Of the seven who had a permanent implant two acquired full-time employment. Conclusion.  Occipital neuralgia is a useful and reversible treatment for intractable occipital neuralgia.

Perineuromal stimulation in the treatment of occipital neuralgia: a case study

This case study is presented to exemplify the application of a perineuromal approach in the treatment of recalcitrant occipital neuralgia. The patient was a 49-year-old female with severe and disabling occipital neuralgia. The pain persisted despite several surgical procedures, injections in the affected area, and medications. Threading the electrode into the cervical epidural space and attempts at peripheral stimulation using the Weiner and Reed approach were unsuccessful. Immediate benefit was derived when the electrode was advanced subcutaneously and positioned underneath the neuroma apparently created by a C2 nerve transection. A Medtronic Octad (model #3898) was utilized. The patient was contacted at seven and nine months post implantation. She reported 90% improvement in her pain. The improvements were also noted in numerical pain ratings, Beck Depression Inventory, and Oswestry Disability Scale. These improvements were corroborated by her husband. The Minnesota Multiphasic Personality Inventory (MMPI) remained relatively unchanged. This case illustrates the possible utilization of perineuromal stimulation in the treatment of occipital neuralgia. The specific mechanism of action remains unclear. Replication and controlled studies are required to determine the general applicability of this approach.

Peripheral nerve field stimulation: is age an indicator of outcome?

Objective.  This study aims to assess peripheral nerve field stimulation as a treatment option for chronic pain and test for indicators of outcome. Materials and Methods.  We reviewed all patients permanently implanted with peripheral nerve field stimulators over the past 24 months. A questionnaire was used to assess outcomes. Results.  Twenty-seven questionnaires were sent out and 23/27 responded. A significant average decrease of 4.02 visual analog scale points was observed. The average pain decrease for the low back was 3.77 points and 5.9 for occipital implants. An age effect was detected; younger patients (<60 years) reported an average pain relief of 4.79 points while older patients (>61 years) reported an average pain relief decrement of only 2.83 points. Most patients reported decreases in analgesic use after treatment. Pain relief was significantly and highly correlated with reduced analgesic intake and patient satisfaction. Conclusion.  Peripheral nerve field stimulation is a safe, reversible, and effective treatment option for patients with chronic pain, particularly those under 60 years.

Neurostimulation therapies for primary headache disorders: present and future

PURPOSE OF REVIEW

Most pharmacological treatments of primary headache disorders are partially effective and have cumbersome side effects. Therapies with better efficacy and tolerance are needed. Neurostimulation techniques may have this potential. This is an attempt to summarize the latest clinical trial results published in the field.

RECENT FINDINGS

Hypothalamic deep brain stimulation is effective in drug-resistant chronic cluster headache (drCCH) but not riskless. Recent anatomical MRI studies indicate that the effective stimulation sites are rather widespread. Occipital nerve stimulation (ONS) seems to be effective in up to 76% of drCCH patients and its benefit long-lasting. A minority of patients are able to abandon preventive drugs. Its mechanism of action appears nonspecific. In chronic migraine, randomized controlled trials of ONS showed recently encouraging results, but long-term studies are missing. An ongoing sham-controlled trial suggests sphenopalatine ganglion neurostimulation (SPGS) efficacy in drCCH acute treatment, but possibly also in preventive therapy. Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) modulate cortical excitability and connectivity. TMS could prevent headache when applied over the occipital cortex during the migraine aura. Repetitive TMS and tDCS have provided mixed results in a few small studies and warrant further trials.

SUMMARY

Neurostimulation therapies inaugurate a new era in headache management and offer a promising alternative to medications. Future studies are necessary to provide evidence-based efficacy data, knowledge on their mode of action and information about their pharmaco-economic advantages.

Occipital nerve stimulation in primary headache syndromes

Chronic daily headache is a major worldwide health problem that affects 3-5% of the population and results in substantial disability. Advances in the management of headache disorders have meant that a substantial proportion of patients can be effectively treated with medical treatments. However, a significant minority of these patients are intractable to conventional medical treatments. Occipital nerve stimulation (ONS) is emerging as a promising treatment for patients with medically intractable, highly disabling chronic headache disorders, including migraine, cluster headache and other less common headache syndromes. Open-label studies have suggested that this treatment modality is effective and recent controlled trial data are also encouraging. The procedure is performed using several technical variations that have been reviewed along with the complications, which are usually minor and tolerable. The mechanism of action is poorly understood, though recent data suggest that ONS could restore the balance within the impaired central pain system through slow neuromodulatory processes in the pain neuromatrix. While the available data are very encouraging, the ultimate confirmation of the utility of a new therapeutic modality should come from controlled trials before widespread use can be advocated; more controlled data are still needed to properly assess the role of ONS in the management of medically intractable headache disorders. Future studies also need to address the variables that are predictors of response, including clinical phenotypes, surgical techniques and stimulation parameters.

Long-term outcome in occipital nerve stimulation patients with medically intractable primary headache disorders

INTRODUCTION

€‚ Occipital nerve stimulation (ONS) may provide relief for refractory headache disorders. However, scant data exist regarding long-€term ONS outcomes.

METHODS

€‚ The methods used were retrospective review of the medical records of all (nonindustry study) patients who were trialed and implanted with occipital nerve stimulator systems at our institution, followed by a phone interview. Up to three attempts were made to contact each patient, and those who were contacted were given the opportunity to participate in a brief phone interview regarding their ONS experience. Data for analysis were gleaned from both the phone interview and the patient's medical records.

RESULTS

€‚ Twenty-nine patients underwent a trial of ONS during the 8.5-€year study period. Three patients did not go on to permanent implant, 12 could not be contacted, and 14 participated in the phone interview. Based upon the phone interview (if the patient was contacted) or chart review, ONS was deemed successful in five of the 12 migraine, four of the five cluster headache, and five of the eight miscellaneous headache patients, and therapy was documented as long as 102 months. In one of the 26 patients, success of ONS could not be determined. Among patients deemed to have successful outcomes, headache frequency decreased by 18%, severity by 27%, and migraine disability score by 50%. Fifty-€eight percent of patients required at least one lead revision.

DISCUSSION

€‚ These results, although limited by their retrospective nature, suggest that ONS can be effective long term despite technical challenges. The number of patients within each headache subtype was insufficient to draw conclusions regarding the differential effect of ONS.

CONCLUSIONS

€‚ Randomized controlled long-€term studies in specific, intractable, primary headache disorders are indicated.

Resilience in migraine brains: decrease of coherence after photic stimulation

Background: During migraine attacks, patients generally have photophobia and phonophobia and seek for environments with less sensorial stimulation. Present work aimed to quantify cortical partial directed coherence (PDC) of electroencephalographic (EEG) recordings from migraine patients and controls in occipital, parietal, and frontal areas with or without photic stimulation. Our hypothesis is that migraine patients with visual aura might have neuronal networks with higher coherence than controls even in interictal periods due to a predisposition in sensory cortical processing. Methods: Eleven adult women with migraine with visual aura (at least 48 h without previous attacks) and seven healthy adult woman were submitted to EEG recording in basal state and during photic stimulation. Results: When compared to healthy volunteers, migraine patients show different coherence profiles. Migraine patients had greater coherence than controls during the basal period (without photic stimulation), showing predisposition for sensory processing in many frequency ranges. After photic stimulation, patients showed a decrease in cortical coherence while controls had an increase. Conclusions: When compared to healty subjects, migraineurs show increased cortical coherence before photic stimulation, but a decrease when stimulation starts. This may be the expression of a resilience mechanism that allows migraineurs the interictal period. The PDC analysis permits to address a patient coherence profile, or “coherence map,” that can be utilized for management of the headache disorder or following up treatments.

Occipital Nerve Stimulation for Refractory Headache in the Chiari Malformation Population

BACKGROUND:

Chronic occipital and suboccipital headache is a common symptom in patients with Chiari I malformation. These headaches may persist despite appropriate surgical treatment of the underlying pathology via suboccipital decompression, duraplasty, and cerebrospinal fluid diversion. Occipital nerve stimulation has been shown to be effective in the treatment of a variety of occipital headache/pain syndromes.

OBJECTIVE:

To review retrospectively our experience with occipital nerve stimulation in patients with a primary diagnosis of Chiari malformation and a history of chronic occipital pain intractable to medical and surgical therapies.

METHODS:

We present a retrospective analysis of our series of 22 patients with Chiari malformation and persistent occipital headaches who underwent occipital neurostimulator trials and, after successful trials, permanent stimulator placement. A trial was considered successful with &gt; 50% pain relief as assessed with a standard Visual Analog Scale score. Patients with a successful trial underwent permanent placement approximately 1 to 2 weeks later. Patients were assessed postoperatively for pain relief via the Visual Analog Scale.

RESULTS:

Sixty-eight percent of patients (15 of 22) had a successful stimulator trial and proceeded to permanent implantation. Of those implanted, 87% (13 of 15) reported continued pain relief at a mean follow-up of 18.9 months (range, 6–51 months). Device-related complications requiring additional surgeries occurred in 40% of patients.

CONCLUSION:

Occipital stimulation may provide significant long-term pain relief in selected Chiari I malformation patients with persistent occipital pain. Larger and longer-term studies are needed to further define appropriate patient selection criteria and to refine the surgical technique to minimize device-related complications.

[Peripheral nerve stimulation in the treatment of various types of headache]

BACKGROUND AND OBJECTIVE

Headache has a great impact on patients' quality of life and in industrialized countries there is economic impact as well. One of the pathophysiologic theories to explain headache is activation of afferent C2-C3 nerve fibers. Afferent peripheral nerve stimulation by occipital nerve provocation at C2-C3 seems to alleviate headache by acting on the trigeminocervical complex, which would largely explain the effectiveness of this modality. The aim of this study was to describe peripheral nerve stimulation as an alternative therapy in patients who do not respond to other headache treatments.

MATERIAL AND METHODS

Multicenter retrospective study between April 2005 and May 2009, analyzing cases of patients treated with nerve stimulation for severe chronic headache. In all patients the medical history included type of headache, intensity of pain on a numerical scale, medical treatment used, and number of headache episodes. We recorded the percentage of patients with negative tests. Patients implanted with a generator assessed effectiveness on the numerical scale; we analyzed the percentage of perceived improvement at 1, 3, 6, and 12 months. We also analyzed the extent of coverage provided by the electrodes, patient satisfaction, reduction in the number of episodes and medication, and complications.

RESULTS

Of 31 patients, 87% had positive results, with a significant decrease in pain from baseline (P < .001); 85.2% reported sustained improvement of > 50%, and 96.3% reported a decrease of > 2 points on the pain scale. All patients expressed satisfaction during the period of follow-up. Fifty-six percent had no headaches after a year and 47% had stopped taking medication. The most frequent complication was electrode migration.

Occipital nerve stimulation for medically refractory hypnic headache

OBJECTIVE

Hypnic headache is a rare, primary headache disorder that exclusively occurs regularly during sleep. We present a case of hypnic headache successfully managed with occipital nerve stimulation.

MATERIALS AND METHODS

A 64-year-old female presented with a four-year history of a right occipital headache that regularly awakened her from sleep. The headache, which was dull and throbbing, would awaken her regularly at 4:00 am, five hours after bedtime at 11:00 pm. No photophobia, nausea or vomiting, lacrimation, or other autonomic symptoms were present. The headache was refractory to various medical treatments, including indomethacin, flunarizine, propranolol. She underwent a trial of occipital nerve stimulation with a lead electrode using a medial approach.

RESULTS

During the ten-day trial stimulation, she reported almost complete relief from hypnic headache. Chronic occipital nerve stimulation replicated the trial results. The attacks of hypnic headache recurred in one year with loss of stimulation-induced paresthesia; a subsequent x-ray showed electrode migration. After revision of the electrode to the original location, the effectiveness of the occipital nerve stimulation against hypnic headache was achieved again, and this effect has been consistent through 36 months of follow-up.

CONCLUSION

Occipital nerve stimulation was effective in a patient with chronic, refractory hypnic headache.

Results of neuromodulation for the management of chronic pain

Background and purpose : Neuromodulative treatment of chronic pain syndromes is a modern mode of treatment of neuropathic and ischaemic pain. Its effectiveness is well documented in the literature. The objective of this work is to present the results of treatment of chronic pain syndromes on the basis of eight-year experience in our department. Material and methods : Since 2002, we have conducted 9 operations of motor cortex stimulation (MCS), 2 of deep brain stimulation (DBS), 45 of spinal cord stimulation (SCS) and 5 of sacral root stimulation (SRS) in the treatment of chronic pain. Results : We obtained good long-term results of neuromodulation in the form of clinical improvement (> 50%) in 4 of 9 patients with MCS (44%), in 13 diagnosed with failed back surgery syndrome (FBSS), 8 with other neuropathic pain, and 11 with angina pectoris from a group of 45 treated with SCS. Sacral root stimulation has been successful in 3 of 5 patients with perianal pain. The best treatment results in SCS, although not statistically significant, were observed in patients treated due to FBSS (13 out of 15) and angina pectoris (11 out of 15) (p = 0.12). In patients with neuropathic pain, peripheral and central, improvement was obtained in 8 out of 15 patients. Conclusions : A good indication for spinal cord stimulation is FBSS and angina pectoris. Motor cortex stimulation is helpful in the treatment of chronic central neuropathic pain. Further observations and a larger group of patients are necessary for a reliable assessment of the effectiveness of neuromodulative treatment of chronic pain in our clinic.

A voltage-controlled capacitive discharge method for electrical activation of peripheral nerves

OBJECTIVES

A voltage-controlled capacitive discharge (VCCD) method was investigated as an alternative to rectangular stimulus pulses currently used in peripheral nerve stimulation therapies.

METHODS AND MATERIALS

 In two anesthetized Gottingen mini pigs, the threshold (total charge per phase) for evoking a compound nerve action potential (CNAP) was compared between constant current (CC) and VCCD methods. Electrical pulses were applied to the tibial and posterior cutaneous femoralis nerves using standard and modified versions of the Medtronic 3778 Octad.

RESULTS

 In contrast to CC stimulation, the combined application of VCCD pulses with a modified Octad resulted in a marked decrease (-73 ± 7.4%) in the stimulation threshold for evoking a CNAP. This was consistent for different myelinated fiber types and locations of stimulation.

CONCLUSIONS

 The VCCD method provides a highly charge-efficient means of activating myelinated fibers that could potentially be used within a wireless peripheral nerve stimulator system.

Treatment of refractory chronic cluster headache by chronic occipital nerve stimulation

Background: Greater occipital nerve stimulation (ONS) has been recently proposed to treat severe chronic cluster headache patients (CCH) refractory to medical treatment. We report the results of a French multidisciplinary cohort study.

Methods: Thirteen CCH patients were operated and data were collected prospectively. All of them suffered from CCH according to the International Headache Society classification, lasting for more than 2 years, refractory to pharmacological prophylactic treatment with adequate trials, with at least one daily attack. Chronic ONS was delivered through a subcutaneous occipital electrode connected to an implanted generator, in order to induce paraesthesias perceived locally in the lower occipital region.

Results: After surgery (mean follow-up 14,6 months), the mean attack frequency and intensity decreased by 68% and 49%, respectively. At last follow-up, 10/13 patients were considered as responders (improvement >50%). Prophylactic treatment could be stopped or reduced in 8/13 cases. Local infection occurred in one patient, leading to hardware removal.

Conclusions: Our data confirmed the results of the 36 similar cases reported in the literature, suggesting that ONS may act as a prophylactic treatment in chronic CH. Considering their respective risks, ONS should be proposed before deep brain stimulation in severe refractory CCH patients.

[Therapeutic neuromodulation in primary headaches]

Neuromodulatory techniques have developed rapidly in the therapeutic management of refractory headaches. Invasive procedures comprise peripheral nerve stimulation (particularly occipital nerve stimulation), vagus nerve stimulation, cervical spinal cord stimulation and hypothalamic deep brain stimulation. Transcutaneous electrical nerve stimulation, repetitive transcranial magnetic stimulation and transcranial direct current stimulation are noninvasive variants. Based on current neuroimaging, neurophysiological and clinical studies occipital nerve stimulation and hypothalamic deep brain stimulation are recommended for patients with chronic cluster headache. Less convincing evidence can be found for their use in other refractory headaches such as chronic migraine. No clear recommendation can be given for the other neuromodulatory techniques. The emerging concept of intermittent stimulation of the sphenopalatine ganglion is nonetheless promising. Robust randomized and sham-controlled multicenter studies are needed before these therapeutic approaches are widely implemented. Due to the experimental nature all patients should be treated in clinical studies. It is essential to confirm the correct headache diagnosis and the refractory nature before an invasive approach is considered. Patients should generally be referred to specialized interdisciplinary outpatient departments which closely collaborate with neurosurgeons who are experienced in the implantation of neuromodulatory devices. It is crucial to ensure a competent postoperative follow-up with optimization of stimulation parameters and adjustment of medication.

Occipital peripheral nerve stimulation in the management of chronic intractable occipital neuralgia in a patient with neurofibromatosis type 1: a case report

Introduction

Occipital peripheral nerve stimulation is an interventional pain management therapy that provides beneficial results in the treatment of refractory chronic occipital neuralgia. Herein we present a first-of-its-kind case study of a patient with neurofibromatosis type 1 and bilateral occipital neuralgia treated with occipital peripheral nerve stimulation.

Case presentation

A 42-year-old Caucasian woman presented with bilateral occipital neuralgia refractory to various conventional treatments, and she was referred for possible treatment with occipital peripheral nerve stimulation. She was found to be a suitable candidate for the procedure, and she underwent implantation of two octapolar stimulating leads and a rechargeable, programmable, implantable generator. The intensity, severity, and frequency of her symptoms resolved by more than 80%, but an infection developed at the implantation site two months after the procedure that required explantation and reimplantation of new stimulating leads three months later. To date she continues to experience symptom resolution of more than 60%.

Conclusion

These results demonstrate the significance of peripheral nerve stimulation in the management of refractory occipital neuralgias in patients with neurofibromatosis type 1 and the possible role of neurofibromata in the development of occipital neuralgia in these patients.

Occipital neuromodulation: ultrasound guidance for peripheral nerve stimulator implantation

We report a case of chronic left-sided occipital neuralgia in a 21-year old female patient. The patient in question suffered from chronic greater occipital neuralgia for a duration of many years, which had been refractory to other conservative medical management strategies. Blockade of the greater occipital nerve with local anesthetic was consistently useful in attenuating the patient's pain, though the effects were always short lived. Consequently, a successful trial of greater occipital nerve stimulation was undertaken. Compared with spinal cord stimulation, peripheral nerve stimulation devices are often more difficult to precisely place given limited ability to visualize soft tissues with traditional fluoroscopic guidance. Additionally, there are anatomic subtleties relevant to the greater occipital nerve that potentially complicate stimulator lead placement, both from the standpoint of optimal neuromodulation efficacy and maximum safety. Ultrasound technology is a maturing imaging modality that allows soft tissue visualization and is consequently useful in addressing each of these aforementioned concerns. The specific use of high-frequency ultrasound guidance for this procedure simplified the initial device placement and allowed proper visualization of soft tissue structures, which facilitates precise device deployment. Additionally, the ability to identify relevant vascular structures may further increase the safety of stimulator lead placement. The potential advantages of ultrasound-augmented procedural techniques, specifically as they pertain to occipital stimulator lead placement, are discussed with particular emphasis on potentially decreasing intraoperative and postoperative complications while optimizing stimulation efficacy.

Occipital nerve stimulation for the treatment of intractable chronic migraine headache: ONSTIM feasibility study

BACKGROUND

Medically intractable chronic migraine (CM) is a disabling illness characterized by headache ≥15 days per month.

METHODS

A multicenter, randomized, blinded, controlled feasibility study was conducted to obtain preliminary safety and efficacy data on occipital nerve stimulation (ONS) in CM. Eligible subjects received an occipital nerve block, and responders were randomized to adjustable stimulation (AS), preset stimulation (PS) or medical management (MM) groups.

RESULTS

Seventy-five of 110 subjects were assigned to a treatment group; complete diary data were available for 66. A responder was defined as a subject who achieved a 50% or greater reduction in number of headache days per month or a three-point or greater reduction in average overall pain intensity compared with baseline. Three-month responder rates were 39% for AS, 6% for PS and 0% for MM. No unanticipated adverse device events occurred. Lead migration occurred in 12 of 51 (24%) subjects.

CONCLUSION

The results of this feasibility study offer promise and should prompt further controlled studies of ONS in CM.

Repositioning of supraorbital nerve stimulation electrode using retrograde needle insertion: a technical note

INTRODUCTION

With growing interest and acceptance of peripheral nerve stimulation (PNS) approach, there is now an increasing need in developing clear procedural details to resolve frequent complications and minimize associated tissue injury. Migration and suboptimal positioning of PNS electrodes are one of the most commonly observed complications of PNS approach.

MATERIALS AND METHODS

We present a simple technique for repositioning a supraorbital electrode using retrograde insertion of introducer needle that allows one to place percutaneous (cylindrical) PNS electrode into appropriate anatomical location with minimal additional injury to surrounding tissues.

RESULTS

This approach has been successfully used in multiple cases. An illustrative case of electrode revision with proposed technique is described in detail.

CONCLUSION

This technically simple approach to repositioning of cylindrical supraorbital electrodes using retrograde needle insertion eliminates the need for a more elaborate and invasive procedure. The technique can be used for electrode repositioning in most PNS applications.

14th International Headache Congress: clinical highlights

The 14th International Headache Congress was held in Philadelphia in September 2009. During the Congress, many important basic, translational, and patient-oriented research studies were presented. In this and an accompanying manuscript, the work that has been deemed to be among the most innovative and significant is summarized. This manuscript discusses the best clinical research, while the accompanying manuscript summarizes the top basic science research. Here, we provide background and summarize Congress presentations on novel agents for migraine treatment, botulinum toxin therapy for chronic migraine, new methods for administration of headache medications, and nerve stimulation for the treatment of medically refractory headaches.

8. Occipital neuralgia

Occipital neuralgia is defined as a paroxysmal shooting or stabbing pain in the dermatomes of the nervus occipitalis major and/or nervus occipitalis minor. The pain originates in the suboccipital region and radiates over the vertex. A suggestive history and clinical examination with short-term pain relief after infiltration with local anesthetic confirm the diagnosis. No data are available about the prevalence or incidence of this condition. Most often, trauma or irritation of the nervi occipitales causes the neuralgia. Imaging studies are necessary to exclude underlying pathological conditions. Initial therapy consists of a single infiltration of the culprit nervi occipitales with local anesthetic and corticosteroids (2 C+). The reported effects of botulinum toxin A injections are contradictory (2 C+/-). Should injection of local anesthetic and corticosteroids fail to provide lasting relief, pulsed radio-frequency treatment of the nervi occipitales can be considered (2 C+). There is no evidence to support pulsed radio-frequency treatment of the ganglion spinale C2 (dorsal root ganglion). As such, this should only be done in a clinical trial setting. Subcutaneous occipital nerve stimulation can be considered if prior therapy with corticosteroid infiltration or pulsed radio-frequency treatment failed or provided only short-term relief (2 C+).

Occipital nerve stimulation for headache disorders

Occipital nerve stimulation (ONS) was originally described in the treatment of occipital neuralgia. However, the spectrum of possible indications has expanded in recent years to include primary headache disorders, such as migraine and cluster headaches. Retrospective and some prospective studies have yielded encouraging results, and evidence from controlled clinical trials is emerging, offering hope for refractory headache patients. In this article we discuss the scientific rationale to use ONS to treat headache disorders, with emphasis on the trigeminocervical complex. ONS is far from a standardized technique at the moment and the recent literature on the topic is reviewed, both with respect to the procedure and its possible complications. An important way to move forward in the scientific evaluation of ONS to treat refractory headache is the clinical phenotyping of patients to identify patients groups with the highest likelihood to respond to this modality of treatment. This requires multidisciplinary assessment of patients. The development of ONS as a new treatment for refractory headache offers an exciting prospect to treat our most disabled headache patients. Data from ongoing controlled trials will undoubtedly shed new light on some of the unresolved questions.

Atypical retroauricular pain: a case report

Retroauricular pain is rarely seen in clinical practice. We present a 29-year-old man who suffered from an intractable and atypical retroauricular pain. The pain was refractory to medications (anticonvulsant drugs, selective serotonin reuptake inhibitors, and amitriptyline). Therefore, a local anesthetic injection for nerve block was done, despite the fact that the causative nerve could not be identified. We believe that this case report is important as we could not find another patient reported in literature with regard to similar headache characteristics and treatment strategy.