Trigeminal and occipital peripheral nerve stimulation for craniofacial pain: a single-institution experience and review of the literature

Peripheral neuromodulation for the treatment of refractory trigeminal neuralgia

Trigeminal neuralgia is an extremely painful condition. Treatment options for trigeminal neuralgia include anticonvulsants, opioids and surgical methods; however, some cases may be refractory to these therapies. In this article, the authors report a case involving a patient for whom conventional treatments failed; she underwent a successful trial of peripheral nerve stimulation and subsequently opted for a permanent implantation of an internal pulse generator, leading to long-term relief of her pain.

Trigeminal neuralgia is a type of orofacial pain that is diagnosed in 150,000 individuals each year, with an incidence of 12.6 per 100,000 person-years and a prevalence of 155 cases per 1,000,000 in the United States. Trigeminal neuralgia pain is characterized by sudden, severe, brief, stabbing or lancinating, recurrent episodes of pain in the distribution of one or more branches of the trigeminal nerve, which can cause significant suffering for the affected patient population.

In many patients, a combination of medication and interventional treatments can be therapeutic, but is not always successful. Peripheral nerve stimulation has gained popularity as a simple and effective neuromodulation technique for the treatment of many pain conditions, including chronic headache disorders. Specifically in trigeminal neuralgia, neurostimulation of the supraorbital and infraorbital nerves may serve to provide relief of neuropathic pain by targeting the distal nerves that supply sensation to the areas of the face where the pain attacks occur, producing a field of paresthesia within the peripheral distribution of pain through the creation of an electric field in the vicinity of the leads.

The purpose of the present case report is to introduce a new, less-invasive interventional technique, and to describe the authors’ first experience with supraorbital and infraorbital neurostimulation therapy for the treatment of trigeminal neuralgia in a patient who had failed previous conservative management.

Use of botulinum toxin injections to treat peripheral stimulator induced facial muscle twitching: a case report

Background

Facial pain can be a management challenge. Peripheral nerve/field stimulation may be an effective option for refractory cases, but direct muscle stimulation with facial twitching may result. Botulinum toxin injections have been used for blepharospasm and may be effective when facial stimulation results in unacceptable facial muscle twitching due to peripheral stimulation.

Case presentation

A 53-year old female suffered with chronic, refractory facial pain and migraines. Her facial pain began after a root canal of a left upper molar. She was trialed and then permanently implanted with a 1 × 8 sub-compact percutaneous stimulator lead, resulting in improved pain control and reduced medication use. However, she experienced blepharospasm whenever the amplitude was above 2.75 A. Therefore, she was treated with botulinum toxin injections into her bilateral cheek, face, temple and occiput. This treatment provided excellent relief of the facial spasms, allowing her to use her stimulator at high amplitudes, and thereby maximizing her pain relief. She received two subsequent treatments of botulinum toxin injections at 5-month intervals with similar results.

Conclusion

Peripheral nerve/field stimulation is being used for headaches and facial pain. An undesirable side effect of this emerging therapy is direct muscle stimulation. Botulinum toxin injections may be an effective treatment modality when stimulation techniques provide pain relief but also causes muscle twitching.

The Impact of Peripheral Nerve Stimulation on Disability and Depression

BACKGROUND

Peripheral nerve stimulation (PNS) of the named nerves of the head has been shown to be effective in reducing pain levels in patients with chronic pain refractory to other treatments. However, the impact of cranial PNS on depression and disability has not been well documented.

OBJECTIVES

We prospectively examine the impact of PNS on quality of life via validated survey scores which assess symptoms of depression and daily functional capacities within patients.

METHODS

Patients who underwent permanent PNS implantation completed five validated questionnaires: Oswestry Disability Index (ODI), the Beck's Depression Inventory (BDI), the Pain Catastrophizing Scale (PCS), McGill Pain Questionnaire (MPQ), and the visual analog scale (VAS) score. These were completed at baseline, six months, and one year to assess changes in functioning levels. Results were analyzed via repeated measures ANOVA and bivariate analysis.

RESULTS

Compared with baseline, at six months patients showed significantly less depression on BDI (F = 7.9, p = 0.021), and at one year, a significant decrease in disability was observed on the ODI (F = 6.1, p = 0.036). At both six months and one year, patients showed a significant decrease in pain on VAS (F = 16.5, p = 0.012). We noted a trend for ODI to correlate with BDI at six months (R = 0.616, p = 0.077).

DISCUSSION

Our prospective data show PNS to be an effective modality in improving overall life quality by limiting depression and disability as well as pain.

Peripheral nerve field stimulation for trigeminal neuralgia, trigeminal neuropathic pain, and persistent idiopathic facial pain

Objective

Peripheral nerve field stimulation (PNFS) is a promising modality for treatment of intractable facial pain. However, evidence is sparse. We are therefore presenting our experience with this technique in a small patient cohort.

Methods

Records of 10 patients (five men, five women) with intractable facial pain who underwent implantation of one or several subcutaneous electrodes for trigeminal nerve field stimulation were retrospectively analyzed. Patients’ data, including pain location, etiology, duration, previous treatments, long-term effects and complications, were evaluated.

Results

Four patients suffered from recurrent classical trigeminal neuralgia, one had classical trigeminal neuralgia and was medically unfit for microvascular decompression. Two patients suffered from trigeminal neuropathy attributed to multiple sclerosis, one from post-herpetic neuropathy, one from trigeminal neuropathy following radiation therapy and one from persistent idiopathic facial pain. Average patient age was 74.2 years (range 57–87), and average symptom duration was 10.6 years (range 2–17). Eight patients proceeded to implantation after successful trial. Average follow-up after implantation was 11.3 months (range 5–28). Using the visual analog scale, average pain intensity was 9.3 (range 7–10) preoperatively and 0.75 (range 0–3) postoperatively. Six patients reported absence of pain with stimulation; two had only slight constant pain without attacks.

Conclusion

PNFS may be an effective treatment for refractory facial pain and yields high patient satisfaction.

Trigeminal branch stimulation for the treatment of intractable craniofacial pain

OBJECT

Trigeminal branch stimulation has been used in the treatment of craniofacial pain syndromes. The risks and benefits of such an approach have not been clearly delineated in large studies, however. The authors report their experience in treating craniofacial pain with trigeminal branch stimulation and share the lessons they have learned after 93 consecutive electrode placements.

METHODS

A retrospective review of all patients who underwent trigeminal branch electrode placement by the senior author (C.J.W.) for the treatment of craniofacial pain was performed.

RESULTS

Thirty-five patients underwent implantation of a total of 93 trial and permanent electrodes between 2006 and 2013. Fifteen patients who experienced improved pain control after trial stimulation underwent implantation of permanent stimulators and were followed for an average of 15 months. At last follow-up 73% of patients had improvement in pain control, whereas only 27% of patients had no pain improvement. No serious complications were seen during the course of this study.

CONCLUSIONS

Trigeminal branch stimulation is a safe and effective treatment for a subset of patients with intractable craniofacial pain.

Concordant occipital and supraorbital neurostimulation therapy for hemiplegic migraine; initial experience; a case series

INTRODUCTION

Hemiplegic migraine is a particularly severe form of the disease that often evolves to a debilitating chronic illness that is resistant to commonly available therapies. Peripheral neurostimulation has been found to be a beneficial therapy for some patients among several diagnostic classes of migraine, but its potential has not been specifically evaluated for hemiplegic migraine.

MATERIALS AND METHODS

Four patients with hemiplegic migraine were treated with concordant, combined occipital and supraorbital neurostimulation over periods ranging 6-92 months. The clinical indicators followed included assessments of headache frequency and severity, frequency of hemiplegic episodes, functional impairment, medication usage, and patient satisfaction.

RESULTS

All reported a positive therapeutic response, as their average headache frequency decreased by 92% (30 to 2.5 headache days/month); Visual Analog Score by 44% (9.5 to 5.3); frequency of hemiplegic episodes by 96% (7.5 to 0.25 hemiplegic episodes/month); headache medication usage by 96% (6 to 0.25 daily medications); and Migraine Disability Assessment score by 98% (249 to 6). All were satisfied and would recommend the therapy, and all preferred combined occipital-supraorbital neurostimulation to occipital neurostimulation alone.

CONCLUSIONS

Concordant combined occipital and supraorbital neurostimulation may provide effective therapy for both the pain and motor aura in some patients with hemiplegic migraine.

Novel High-Frequency Peripheral Nerve Stimulator Treatment of Refractory Postherpetic Neuralgia: A Brief Technical Note

OBJECTIVES

The study aims to describe an ultrasound (US)-guided peripheral nerve stimulation implant technique and describe the effect of high-frequency peripheral nerve stimulation on refractory postherpetic neuralgia.

MATERIALS AND METHODS

Following a cadaver pilot trial using US and confirmatory fluoroscopic guidance, a 52-year-old man with refractory left supraorbital neuralgia underwent combined US and fluoroscopic-guided supraorbital peripheral nerve stimulator trial. The patient was subsequently implanted with a percutaneous lead over the left supraorbital and supratrochlear nerve utilizing a high-frequency stimulation paradigm.

RESULTS

At 9 months follow-up, the pain intensity had declined from a weekly average of 8/10 to 1/10 on the pain visual analog scale (VAS). After implant, both nerve conduction and blink reflex studies were performed, which demonstrated herpetic nerve damage and frequency-specific peripheral nerve stimulation effects. The patient preferred analgesia in the supraorbital nerve distribution accomplished with high-frequency paresthesia-free stimulation (HFS) at an amplitude of 6.2 mA, a frequency of 100-1200 Hz, and a pulse width of 130 μsec, to paresthesia-mediated pain relief associated with low-frequency stimulation.

CONCLUSION

We report the implant of a supraorbital peripheral nerve stimulating electrode that utilizes a high-frequency program resulting in sustained suppression of intractable postherpetic neuralgia.

Neuromodulation as a last resort option in the treatment of chronic daily headaches in patients with idiopathic intracranial hypertension

OBJECTIVE

To determine the feasibility and efficacy of occipital nerve stimulation (ONS) in patients with refractory headaches secondary to idiopathic intracranial hypertension (IIH).

BACKGROUND

IIH is a syndrome characterized by elevated intracranial pressures in the absence of a mass lesion. These patients typically present with chronic and intractable headaches. Cerebrospinal fluid (CSF) diversion fails in relieving the headache in a significant proportion of this population. ONS has been shown to be effective in medically refractory headaches and to our knowledge, has not been attempted as a therapeutic modality in this population.

METHODS

Four patients with occipital predominant chronic daily headaches and IIH who failed medical management underwent bilateral ONSs. Octopolar percutaneous electrodes were implanted in the defined area of pain. Visual Analog Scale (VAS) was used as an outcome measure. Patient demographics and surgical complications were also reviewed in this retrospective study. Following the trial period, all patients had >50% pain reduction resulting in permanent implantation.

RESULTS

All 4 patients had an average improvement of their VAS scores by 75%, with 85% spatial coverage and the remainder of the uncovered region being frontal. Sustained benefits were seen up to 3 years of follow-up. One patient had a lead erosion requiring removal followed by delayed re-implantation and another lost treatment efficacy at 2 years resulting in explantation. One patient required CSF diversion due to visual threat during the follow-up period but maintained sustained benefit from her ONS.

CONCLUSIONS

Bilateral ONS may be a useful treatment option in the management of selected patients with IIH, after standard surgical interventions have been attempted. Bilateral ONS may provide therapeutic option for management of residual headaches in these complicated patients.

A systematic review of peripheral nerve interventional treatments for chronic headaches

OBJECTIVE

This study aimed to systematically compare the outcomes of different types of interventional procedures offered for the treatment of headaches and targeted toward peripheral nerves based on available published literature.

BACKGROUND

Multiple procedural modalities targeted at peripheral nerves are being offered to patients for the treatment of chronic headaches. However, few resources exist to compare the effectiveness of these modalities. The objective of this study was to systematically review the literature to compare the published outcomes and effectiveness of peripheral nerve surgery, radiofrequency (RF) therapy, and peripheral nerve stimulators for chronic headaches, migraines, and occipital neuralgia.

METHODS

A broad literature search of the MEDLINE and CENTRAL (Cochrane) databases was undertaken. Relevant studies were selected by 2 independent reviewers and these results were narrowed further by the application of predetermined inclusion and exclusion criteria. Studies were assessed for quality, and data were extracted regarding study characteristics (study type, level of evidence, type of intervention, and number of patients) and objective outcomes (success rate, length of follow-up, and complications). Pooled analysis was performed to compare success rates and complications between modality types.

RESULTS

Of an initial 250 search results, 26 studies met the inclusion criteria. Of these, 14 articles studied nerve decompression, 9 studied peripheral nerve stimulation, and 3 studied RF intervention. When study populations and results were pooled, a total of 1253 patients had undergone nerve decompression with an 86% success rate, 184 patients were treated by nerve stimulation with a 68% success rate, and 131 patients were treated by RF with a 55% success rate. When compared to one another, these success rates were all statistically significantly different. Neither nerve decompression nor RF reported complications requiring a return to the operating room, whereas implantable nerve stimulators had a 31.5% rate of such complications. Minor complication rates were similar among all 3 procedures.

CONCLUSIONS

Of the 3 most commonly encountered interventional procedures for chronic headaches, peripheral nerve surgery via decompression of involved peripheral nerves has been the best-studied modality in terms of total number of studies, level of evidence of published studies, and length of follow-up. Reported success rates for nerve decompression or excision tend to be higher than those for peripheral nerve stimulation or for RF, although poor study quantity and quality prohibit an accurate comparative analysis. Of the 3 procedures, peripheral nerve stimulator implantation was associated with the greatest number of complications. Although peripheral nerve surgery seems to be the interventional treatment modality that is currently best supported by the literature, better controlled and normalized high-quality studies will help to better define the specific roles for each type of intervention.

Peripheral neuromodulation: a review

Peripheral nerve stimulation (PNS) is likely the most diverse and rapidly expanding area of neuromodulation. Its expansion has become possible due to both technological and clinical advances in pain medicine. The first implantable systems were surgically placed. However, it is currently commonplace to use percutaneous leads, as this approach has become instrumental in its expansion. The first percutaneous peripheral nerve stimulators were reported in 1999. Cylindrical leads were implanted to stimulate the greater occipital nerve to manage intractable headache. It has been expanded into other individual nerves or nerve plexuses to treat neuropathic, visceral, cardiac, abdominal, low back and facial pain. The use of PNS in modulating organ function in treatment of syndromes such as epilepsy, incontinence and obesity with vagal, tibial and gastric stimulation is under extensive investigation. New technologies that allow easier and safer electrode placement are expected to further expand the uses of PNS. A noninvasive stimulation will open this treatment modality to more clinicians of varying backgrounds.

Technological innovations in implants used for pain therapies

The field of pain management has experienced tremendous growth in implantable therapies secondary to the innovations of bioengineers, implanters, and industry. Every aspect of neuromodulation is amenable to innovation from implanting devices to anchors, electrodes, programming, and even patient programmers. Patients with previously refractory neuropathic pain syndromes have new and effective pain management strategies that are a direct result of innovations in implantable devices.

Occipital neuralgia: anatomic considerations

Occipital neuralgia is a debilitating disorder first described in 1821 as recurrent headaches localized in the occipital region. Other symptoms that have been associated with this condition include paroxysmal burning and aching pain in the distribution of the greater, lesser, or third occipital nerves. Several etiologies have been identified in the cause of occipital neuralgia and include, but are not limited to, trauma, fibrositis, myositis, fracture of the atlas, and compression of the C-2 nerve root, C1-2 arthrosis syndrome, atlantoaxial lateral mass osteoarthritis, hypertrophic cervical pachymeningitis, cervical cord tumor, Chiari malformation, and neurosyphilis. The management of occipital neuralgia can include conservative approaches and/or surgical interventions. Occipital neuralgia is a multifactorial problem where multiple anatomic areas/structures may be involved with this pathology. A review of these etiologies may provide guidance in better understanding occipital neuralgia.

Peripheral nerve/field stimulation for chronic pain

Peripheral nerve stimulation and peripheral nerve field stimulation involve the delivery of electrical stimulation using implanted electrodes either over a target nerve or over the painful area with the goal of modulating neuropathic pain. The selection of appropriate candidates for this therapy hinges on skillful application of inclusion and exclusion criteria, psychological screening, and an invasive screening trial. Patients with significant improvement in pain severity and pain-related disability during the trial are considered candidates for implantation of a permanent system. As with other implanted devices for neuromodulation, risks of mechanical failures, infection, and neurologic complications exist.

Peripheral trigeminal nerve field stimulation: report of 6 cases

OBJECT

Peripheral nerve field stimulation has been successfully used for many neuropathic syndromes. However, it has been reported as a treatment for trigeminal neuropathic pain or persistent idiopathic facial pain only in the recent years.

METHODS

The authors present a review of the literature and their own series of 6 patients who were treated with peripheral nerve stimulation for facial neuropathic pain, reporting excellent pain relief and subsequent better social relations and quality of life.

RESULTS

On average, pain scores in these patients decreased from 10 to 2.7 on the visual analog scale during a 17-month follow-up (range 0-32 months). The authors also observed the ability to decrease trigeminal pain with occipital nerve stimulation, clinically confirming the previously reported existence of a close anatomical connection between the trigeminal and occipital nerves (trigeminocervical nucleus).

CONCLUSIONS

Peripheral nerve field stimulation of the trigeminal and occipital nerves is a safe and effective treatment for trigeminal neuropathic pain and persistent idiopathic facial pain, when patients are strictly selected and electrodes are correctly placed under the hyperalgesia strip at the periphery of the allodynia region.

Refractory headaches treated with bilateral occipital and temporal region stimulation

OBJECTIVES

To describe use of bilateral temporal and occipital stimulator leads for a refractory headache disorder.

MATERIALS AND METHODS

A 31-year-old female had a 10-year history of chronic, severe occipital and temporal region headaches. The patient underwent permanent implant of an occipital stimulator system that resulted in sustained, compete resolution of her occipital pain. However, she continued to suffer disabling (10/10) temporal region headaches and was bedbound most days of the week. Therefore, bilateral temporal stimulator leads were implanted and tunneled to her internal pulse generator.

RESULTS

At 12-month follow-up, the patient enjoyed sustained improvement in her pain scores (8/10) and marked increase in her level of functioning. Taking into account increased activity level, she rated her overall improvement at 50%. Unfortunately, infection and erosion of her right temporal lead necessitated temporal stimulator removal.

CONCLUSION

Headache disorders may require stimulation of all painful cephalic regions. However, our success in this case must be considered in light of the technical challenges and expense of placing stimulator leads subcutaneously around the head and neck, including the risk of infection, lead breakage, erosion, and migration.

Supraorbital and supratrochlear stimulation for trigeminal autonomic cephalalgias

Trigeminal autonomic cephalalgias (TAC) is a rare primary headache disorder with challenging and limited treatment options for those unfortunate patients with severe and refractory pain. This article will review the conventional pharmacologic treatments as well as the new neuromodulation techniques designed to offer alternative and less invasive treatments. These techniques have evolved from the treatment of migraine headache, a much more common headache syndrome, and expanded towards application in patients with TAC. Specifically, the article will discuss the targeting of the supratrochlear and supraorbital nerves, both terminal branches of the trigeminal nerve.

Supraorbital stimulation does not induce an antidepressant-like response in rats

BACKGROUND

Neuromodulation therapies are currently being investigated as potential treatments for depression. One of these treatments involves the stimulation of supraorbital branches of the trigeminal nerve.

OBJECTIVE

To show that supraorbital stimulation is effective in preclinical models.

METHODS

Rats were given supraorbital stimulation at different settings in the forced swim test (FST) and open field.

RESULTS

Supraorbital stimulation did not induce an antidepressant-like response in rats undergoing the FST. This is in contrast to other neuromodulation treatments, such as deep brain stimulation, vagus nerve stimulation and electroconvulsive therapy, which are all effective in this paradigm.

CONCLUSIONS

Supraorbital stimulation was ineffective in rats undergoing the FST. Such findings do not invalidate results of recent clinical trials.

Optical control of neuronal excitation and inhibition using a single opsin protein, ChR2

The effect of electrical stimulation on neuronal membrane potential is frequency dependent. Low frequency electrical stimulation can evoke action potentials, whereas high frequency stimulation can inhibit action potential transmission. Optical stimulation of channelrhodopsin-2 (ChR2) expressed in neuronal membranes can also excite action potentials. However, it is unknown whether optical stimulation of ChR2-expressing neurons produces a transition from excitation to inhibition with increasing light pulse frequencies. Here we report optical inhibition of motor neuron and muscle activity in vivo in the cooled sciatic nerves of Thy1-ChR2-EYFP mice. We also demonstrate all-optical single-wavelength control of neuronal excitation and inhibition without co-expression of inhibitory and excitatory opsins. This all-optical system is free from stimulation-induced electrical artifacts and thus provides a new approach to investigate mechanisms of high frequency inhibition in neuronal circuits in vivo and in vitro.

Salvage treatment of trigeminal neuralgia by occipital nerve stimulation

BACKGROUND

Although most patients suffering from trigeminal neuralgia (TN) respond to medical or surgical treatment, nonresponders remain in very severe painful condition.

CASE RESULT

We describe for the first time a case of severe refractory classical TN treated successfully (follow-up one year) by chronic bilateral occipital nerve stimulation (ONS), because other classic medical and surgical options failed or could not be performed.

CONCLUSIONS

This single case suggests that ONS might be offered to TN patients refractory both to standard drugs and interventions, with a favorable risk/benefit ratio, although its long-term efficacy remains unknown.

Peripheral neuromodulation and headaches: history, clinical approach, and considerations on underlying mechanisms

Implantable peripheral neurostimulation was introduced in 1969 as a potential treatment for certain neuropathic pain syndromes, primarily involving the limbs. While a few early studies included implants for occipital neuralgia, serious interest in its potential as a treatment for head pain came only after our 1999 report of positive findings in a series of patients with occipital neuralgia. Subsequent investigators confirmed these initial findings, and then extended the application to patients with various primary headache disorders, including migraine. While most found a therapeutic response, the degree of that response varied significantly, and analysis suggests that the issue of paresthesia concordancy may be central, both in explaining the data, as well as providing direction for future endeavors. Therefore, while at present peripheral neurostimulation is gaining increasing acceptance as a treatment for chronic headaches, the precise clinical indications and procedures, as well as the underlying neurophysiological mechanisms, are still being worked out.

Neuromodulation for cephalgias

Headaches (cephalgias) are a common reason for patients to seek medical care. There are groups of patients with recurrent headache and craniofacial pain presenting with malignant course of their disease that becomes refractory to pharmacotherapy and other medical management options. Neuromodulation can be a viable treatment modality for at least some of these patients. We review the available evidence related to the use of neuromodulation modalities for the treatment of medically refractory craniofacial pain of different nosology based on the International Classification of Headache Disorders, 2(nd) edition (ICHD-II) classification. This article also reviews the scientific rationale of neuromodulation application in management of cephalgias.

Updated perspectives on occipital nerve stimulator lead migration: case report and literature review

OBJECTIVES

Patients with occipital neuralgia are often refractory to or intolerant of standard pharmacological and interventional management strategies. Although occipital nerve stimulation (ONS) may provide a unique alternative for such cases, a steep technical learning curve still exists. Lead migration (LM) is among the most challenging issues facing implanters performing ONS implantation. We present an unusual case of LM after ONS implantation and discuss technical aspects for successful revision.

METHODS

A retrospective review of medical records and fluoroscopic images was conducted to provide a case report of ONS LM and revision. A PubMed online search for the keywords occipital, stimulation, migration, and revision was also performed for literature review.

CASE REPORT

A 35-year-old man with refractory occipital neuralgia had loss of greater occipital nerve paresthesia coverage and worsened occipital headaches 11 months after ONS implantation using a midline approach. Fluoroscopic imaging confirmed lateral LM. Although most LMs occur in the lateral-to-medial trajectory, this case was unique in that LM occurred from a medial-to-lateral trajectory despite using current standard safeguards.

DISCUSSION

In an era in which reducing health care expenditures is becoming increasingly important, current complication rates could curtail future acceptance and utilization of ONS. This fact and our case report underscore the importance of a continued drive toward technical advances and a reduction in complications associated with this important treatment modality. Further prospective investigation into the mechanism of action, mechanism of complications, optimization of surgical techniques, and long-term efficacy is warranted.

The treatment of chronic incisional pain and headache after retromastoid craniectomy

Background:

A seldom emphasized complication of retromastoid craniectomy is chronic postcraniectomy incisional pain or headache. Although hypotheses have been proposed to explain this problem, there have been few attempts to treat patients in a delayed fashion. The results of postoperative treatments for chronic postretromastoid craniectomy pain and their rationales are discussed in a preliminary number of patients.

Methods:

Eight patients with chronic postretromastoid craniectomy pain who did not have placement of a cranioplasty at their initial operation underwent placement of a methylmethacrylate cranioplasty as a separate procedure. Three additional patients who did have a cranioplasty, but who had chronic pain underwent selective blocking of the ipsilateral second cervical nerve. If blocks resulted in relief of pain they then underwent a dorsal rhizotomy or ganglionectomy.

Results:

Two of the eight patients undergoing a cranioplasty had excellent results and one partial improvement while five failed at last follow-up. The three patients with a cranioplasty representing four symptomatic sides underwent a dorsal rhizotomy or ganglionectomy after a positive selective cervical nerve blocking. All four operations resulted in excellent relief with one side failing 3 months postop after a motor vehicle accident.

Conclusion:

Chronic headache or incisional pain after retromastoid craniectomy remains a significant complication of the operation. The patients presented here support the contention that multiple etiologies may play a role. Pain caused by scalp to dura adhesions can be treated effectively with a simple cranioplasty while occipital nerve injury can be identified using selective second cervical nerve blocking, and long-term relief obtained with a dorsal rhizotomy or ganglionectomy.

Surgical treatment of primary headaches

Neuromodulation for the treatment of drug-refractory cranial neuralgias constitutes an exciting field of research for physicians; in the last decade, several methodologies have been described which could help many patients to exit such desperate conditions; although the exact mechanisms of action of these techniques are still matter of debate, several experimental and neuroradiological modalities can help us to get near the concept of understanding them. In this paper, the authors summarize the most recent surgical procedures used to treat severe and pharmaco-resistant cranial painful conditions, along with brief descriptions of the results obtained in the several published so far.

Clinical outcomes of pulsed radiofrequency neuromodulation for the treatment of occipital neuralgia

Objective

Occipital neuralgia is characterized by paroxysmal jabbing pain in the dermatomes of the greater or lesser occipital nerves caused by irritation of these nerves. Although several therapies have been reported, they have only temporary therapeutic effects. We report the results of pulsed radiofrequency treatment of the occipital nerve, which was used to treat occipital neuralgia.

Methods

Patients were diagnosed with occipital neuralgia according to the International Classification of Headache Disorders classification criteria. We performed pulsed radiofrequency neuromodulation when patients presented with clinical findings suggestive occipital neuralgia with positive diagnostic block of the occipital nerves with local anesthetics. Patients were analyzed according to age, duration of symptoms, surgical results, complications and recurrence. Pain was measured every month after the procedure using the visual analog and total pain indexes.

Results

From 2010, ten patients were included in the study. The mean age was 52 years (34-70 years). The mean follow-up period was 7.5 months (6-10 months). Mean Visual Analog Scale and mean total pain index scores declined by 6.1 units and 192.1 units, respectively, during the follow-up period. No complications were reported.

Conclusion

Pulsed radiofrequency neuromodulation of the occipital nerve is an effective treatment for occipital neuralgia. Further controlled prospective studies are necessary to evaluate the exact effects and long-term outcomes of this treatment method.

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.

Subcutaneous peripheral neurostimulation for the treatment of severe chronic poststernotomy neuralgia

OBJECTIVE

Poststernotomy pain frequently develops after sternotomy in thoracic and cardiovascular surgery, and may affect patients' quality of life. In some cases of severe poststernotomy neuralgia, pharmacologic therapy does not provide adequate relief.

CASE REPORT

We report on a 42- year-old woman who underwent sternotomy for aortic and mitral valve replacement. She developed severe chronic poststernotomy neuralgia that was refractory to medical treatment. After local anesthesia markedly but only transiently alleviated pain, we considered the option of subcutaneous peripheral neurostimulation (SPNS). Plate electrodes were implanted bilaterally in the parasternal region at the site of maximal pain. After a period of test stimulation, the electrodes were connected to a dual-channel implantable pulse generator. SPNS induced paresthesias in the painful area. Revision surgery was necessary twice because of electrode migration. Chronic SPNS markedly alleviated pain (visual-analog scale, VAS, 9/10 preoperatively, 2/10 postoperatively) and allodynia (VAS 9/10 preoperatively, 2/10 postoperatively) at the last available follow-up, 15 months postoperatively.

CONCLUSIONS

SPNS may be a viable treatment option in patients with severe chronic poststernotomy neuralgia.

Anatomical study of the third occipital nerve and its potential role in occipital headache/neck pain following midline dissections of the craniocervical junction

OBJECTIVE

Occipital neuralgia can be a debilitating disease and may occur following operative procedures near the occipital and nuchal regions. One nerve of this region, the third occipital nerve (TON), has received only scant attention, and its potential contribution to occipital neuralgia has not been appreciated. Therefore, in the present study the authors aimed to detail the anatomy of this nerve and its relationships to midline surgical approaches of the occiput and posterior neck.

METHODS

Fifteen adult cadavers (30 sides) underwent dissection of the upper cervical and occipital regions. Special attention was given to identifying the course of the TON and its relationship to the soft tissues and other nerves of this region. Once identified superficially, the TON was followed deeply through the nuchal musculature to its origin in the dorsal ramus of C-3. Measurements were made of the length and diameter of the TON. Additionally, the distance from the external occipital protuberance was measured in each specimen. Following dissection of the TON, self-retaining retractors were placed in the midline and opened in standard fashion while observing for excess tension on the TON.

RESULTS

Articular branches were noted arising from the deep surface of the nerve in 63.3% of sides. The authors found that the TON was, on average, 3 mm lateral to the external occipital protuberance, and small branches were found to cross the midline and communicate with the contralateral TON inferior to the external occipital protuberance in 66.7% of sides. The TON trunk became subcutaneous at a mean of 5 cm inferior to the external occipital protuberance. In all specimens, the cutaneous main trunk of the TON was intimately related to the nuchal ligament. Insertion of self-retaining retractors in the midline placed significant tension on the TON in all specimens, both superficially and more deeply at its adjacent facet joint.

CONCLUSIONS

Although damage to the TON may often be unavoidable in midline approaches to the craniocervical region, appreciation of its presence and knowledge of its position and relationships may be useful to the neurosurgeon who operates in this region and may assist in decreasing postoperative morbidity.

A technique of distal to proximal revision of peripheral neurostimulator leads: technical note

BACKGROUND

Peripheral nerve stimulation for chronic pain states is a safe and efficacious technique, being used with increasing frequency. The incidence of hardware-related complications requiring revision remains high.

OBJECTIVES

The authors describe a technique of distal to proximal neurostimulator lead revision, which does not require the changing of generators or extension leads, and thus presumably will minimize further device-related complications.

METHODS

The authors present a case series of 3 patients where the distal to proximal neurostimulator lead revision technique was utilized.

RESULTS

The technique was well tolerated in each instance and all patients reported >50% pain reduction at long-term follow-up.

CONCLUSIONS

The distal to proximal neurostimulator lead revision technique quickly and safely adjusts lead position, including both lead depth and lead tip location, without a need for replacement of components or revision of the entire system.

What's new in the diagnosis and treatment of peripheral nerve entrapment neuropathies

Entrapment neuropathies can be common conditions with the potential to cause significant disability. Correct diagnosis is essential for proper management. This article is a review of recent developments related to diagnosis and treatment of various common and uncommon nerve entrapment disorders. When combined with classical peripheral nerve examination techniques, innovations in imaging modalities have led to more reliable diagnoses. Moreover, innovations in conservative and surgical techniques have been controversial as to their effects on patient outcome, but randomized controlled trials have provided important information regarding common operative techniques. Treatment strategies for painful peripheral neuropathies are also reviewed.

Ultrasound-guided, percutaneous peripheral nerve stimulation: technical note

BACKGROUND

Peripheral nerve stimulation is a form of neuromodulation that applies electric current to peripheral nerves to induce stimulation paresthesias within the painful areas.

OBJECTIVE

To report a method of ultrasound-guided, percutaneous peripheral nerve stimulation. This technique utilizes real-time imaging to avoid injury to adjacent vascular structures during minimally invasive placement of peripheral nerve stimulator electrodes.

MATERIAL AND METHODS

We describe a patient that presented with chronic, bilateral foot pain following multiple foot surgeries, for whom a comprehensive, pain management treatment strategy had failed. We utilized ultrasound-guided, percutaneous tibial nerve stimulation at a thigh level to provide durable pain relief on the right side, and open peripheral nerve stimulation on the left.

RESULTS

The patient experienced appropriate stimulation paresthesias and excellent pain relief on the plantar aspect of the right foot with the percutaneous electrode. On the left side, we were unable to direct the stimulation paresthesias to the sole of the foot, despite multiple electrode repositionings. A subsequent, open placement of a left tibial nerve stimulator was performed. This revealed that the correct electrode position against the tibial nerve was immediately adjacent to the popliteal artery, and was thus not appropriate for percutaneous placement.

CONCLUSION

We describe a method of ultrasound-guided peripheral nerve stimulation that avoids the invasiveness of electrode placement via an open procedure while providing excellent pain relief. We further describe limitations of the percutaneous approach when navigating close to large blood vessels, a situation more appropriately managed with open peripheral nerve stimulator placement. Ultrasound-guided placement may be considered for patients receiving peripheral nerve stimulators placed within the deep tissues, and not easily placed in a blind fashion.

Case report: successful epiradicular peripheral nerve stimulation of the C2 dorsal root ganglion for postherpetic neuralgia

BACKGROUND

Postherpetic neuralgia (PHN) is the most common complication following an acute varicella zoster virus infection. PHN often results in a chronic severe pain condition refractory to conservative pain management treatments. Peripheral nerve stimulation over the affected spinal nerve root may be an effective treatment option for patients with intractable PHN.

OBJECTIVE

To describe a successful case of peripheral nerve stimulation of the second cervical dorsal root ganglion for the treatment of intractable PHN.

CASE REPORT

An 80-year-old man with a 15-month history of severe PHN was referred to our clinic for pain management. His pain was localized to the left side in the distribution of the C2 dermatome. The patient's pain was unresponsive to comprehensive conventional treatments for PHN including physical therapy, membrane stabilizing medications, opioids, anti-inflammatories, cervical epidural steroid injections, cervical facet joint injections, and dorsal root ganglion blockade with pulsed radiofrequency. After failing to respond to conservative and interventional therapies, a peripheral nerve stimulator trial was conducted for a period of seven days. The lead was placed within the epidural space over the atlanto-axial joint under fluoroscopy to stimulate the left C2 nerve root. This trial resulted in a significant decrease of the patient's pain, and discontinuation of all pain medications.

CONCLUSION

We describe a case of successful electrode placement at the C2 spinal level for the treatment of refractory PHN.

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.

Prospective clinical study of a new implantable peripheral nerve stimulation device to treat chronic pain

OBJECTIVES

To evaluate clinical use of the StimRouter, an investigational implanted peripheral nerve stimulator for treating chronic neuropathic pain, using the median nerve as a model for that general application.

METHODS

Eight patients with carpal tunnel syndrome and chronic pain despite both carpal tunnel release and treatment with oral pain medications were enrolled in a single-center, open-label trial after institutional review board approval. Primary endpoints were successful implantation near the target peripheral nerve and safety. All 8 patients were implanted temporarily at the median nerve in at least one arm and 2 patients were implanted bilaterally, with 10 implants total. Each implant was considered a separate "patient." For 5 days, all patients received 6 hours of daily transdermal electrical stimulation targeting the median nerve. Pain was measured at baseline, during implant, and after explant.

RESULTS

Two patients experienced clinically meaningful (>or=30%) pain reduction throughout the entire 5-day treatment period. Apparent carryover effect in pain reduction also was observed after daily stimulation. After explant, pain returned to baseline, increasing 36.8% to 45.6% relative to average reduced pain with daily stimulation. No significant or unexpected adverse events occurred. Mean patient study satisfaction was 96%, and 100% of patients indicated a preference for permanent implant.

DISCUSSION

Temporary implant of the StimRouter device resulted in both pain reduction and reduced use of oral opioid pain medication during the 5-day stimulation period. The results suggest that permanent implant of the StimRouter System may be safe and effective for treating chronic peripheral neuropathic pain.

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+).