Peripheral neurostimulation for control of intractable occipital neuralgia

Neuromodulatory approaches to the treatment of trigeminal autonomic cephalalgias

The trigeminal autonomic cephalalgias (TACs) are a group of primary headache syndromes characterised by intense pain and associated activation of cranial parasympathetic autonomic outflow pathways out of proportion to the pain. The TACs include cluster headache, paroxysmal hemicrania and SUNCT (short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing). The pathophysiology of these syndromes involves activation of the trigeminal-autonomic reflex, whose afferent limb projects into the trigeminocervical complex in the caudal brainstem and upper cervical spinal cord. Functional brain imaging has shown activations in the posterior hypothalamic grey matter in TACs. This paper reviews the anatomy and physiology of these conditions and the brain imaging findings. Current treatments are summarised and the role of neuromodulation procedures, such as occipital nerve stimulation and deep brain stimulation in the posterior hypothalamus are reviewed. Neuromodulatory procedures are a promising avenue for these highly disabled patients with treatment refractory TACs.

Spinal nerve root stimulation

Spinal nerve root stimulation is a recently developed form of neuromodulation used for the treatment of chronic pain conditions. Unlike spinal cord stimulation, in which electrical impulses are directed at the dorsal columns, spinal nerve root stimulation guides electrical current directly to one or more nerve roots. There are a variety of techniques by which this can be accomplished, yet no consistent terminology to describe these variations exists. In this review, the authors group the various techniques according to anatomical approach, define each category, describe and illustrate each of the techniques, review the available reports on their uses, and discuss the advantages and disadvantages of each one.

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

OBJECT

Treatment of chronic neuropathic pain in the region of the head and face presents a challenge for pain specialists; patients who do not respond to conventional treatment modalities usually continue to suffer from pain due to the lack of reliable medical and surgical approaches. Peripheral nerve stimulation (PNS) has been used to treat neuropathic pain for many decades, but only recently has it been applied systematically to the craniofacial region. To advance the study of this treatment option, the authors present their initial experience with this approach, summarize published data on the use of PNS in treatment of craniofacial pain, and discuss some technical details of the craniofacial PNS procedure.

METHODS

A review of prospectively collected data in 30 patients who underwent PNS surgery for craniofacial pain was performed. The pain location, duration, cause, and previous treatments were analyzed, along with the surgical details, initial and long-term results, complications, and repeated operations. Stimulated nerves in this group included supraorbital (seven patients), infraorbital (six), and occipital (21); in 19 patients more than one nerve was stimulated. Twenty-two patients proceeded with implantation of a permanent system after the trial. Of these, at the time of the latest evaluation (mean follow-up duration 35 months), in two patients the devices had been removed because of pain improvement over time, in three the devices were removed due to loss of effectiveness (two cases) or late infection (one), and the rest are enjoying either complete (15 patients) or partial (two patients) pain relief. Three patients underwent repeated operation due to lead erosion, infection, or migration.

CONCLUSIONS

Peripheral nerve stimulation appears to be a safe and effective approach in the treatment of craniofacial neuropathic pain. The growing body of literature supports a wider acceptance of this approach in the field of pain surgery.

Migraine: emerging treatment options for preventive and acute attack therapy

This review discusses emerging treatments of migraine in the context of what is now available. At present, patients are treated with a range of acute attack medicines or preventive treatments, with many having significant drawbacks. Important unmet needs are acute attack treatments that act by exclusively neural mechanisms with no vascular effects, and effective, well tolerated preventive medicines. Calcitonin gene-related peptide receptor antagonist, vanilloid receptor antagonists and nitric oxide synthase inhibitors are all in clinical trials for acute migraine. Tonaberset (a gap-junction blocker), an inducible nitric oxide synthase inhibitor and botulinum toxin A are in clinical trials for preventive therapy. Device-based approaches using neurostimulation of the occipital nerve are being studied, although the first study of patent foramen ovale closure for migraine prevention failed.

Neurostimulation for chronic noncancer pain: an evaluation of the clinical evidence and recommendations for future trial designs

Object

Neurostimulation to treat chronic pain includes approved and investigational therapies directed at the spinal cord, thalamus, periaqueductal or periventricular gray matter, motor cortex, and peripheral nerves. Persistent pain after surgery and work-related or neural injuries are common indications for such treatments. In light of the risks, efforts, costs, and expectations associated with neurostimulation therapies, a careful reexamination of the methods used to gather evidence for this treatment’s long-term efficacy is in order.

Methods

The authors combed English-language publications to determine the nature of the evidence supporting the efficacy of neurostimulation therapies for chronic noncancer pain. To formulate recommendations for the design of future studies, the results of their analysis were compared with established guidelines for the evaluation of medical evidence.

Evidence supporting the efficacy of neurostimulation has been collected predominantly from retrospective series or from prospective studies whose design or methods of analysis make them subject to limited interpretation. To date, there has been no successful clinical study focused on establishing the efficacy of neurostimulation for pain and incorporating sufficient numbers of participants, matched control groups, sham stimulation, randomization, prospectively defined end points, and methods for controlling experimental bias. Currently available data provide little support for the common practices of psychological or pharmacological screening or trial stimulation to predict and/or improve long-term results.

Conclusions

These findings do not diminish the value of previous investigations or positive patient experiences and do not mean that the treatments are ineffective; rather, they reveal that new data are required to answer the questions raised in and by previous study data. Future analyses of emerging neurostimulation modalities for pain should, whenever feasible, require unambiguous diagnoses as an entry criterion and should involve the use of randomization, parallel control groups that receive sham stimulation, and blinding of patients, investigators, and device programmers. Given the chronicity of patient symptoms and stimulation therapies, efficacy should be studied for 1 year or longer after device implantation. Meticulous study methods are especially important to evaluate new therapies like motor cortex and occipital nerve stimulation.

Occipital nerve electrical stimulation via the midline approach and subcutaneous surgical leads for treatment of severe occipital neuralgia: a pilot study

Persistent occipital neuralgia can produce severe headaches that may not be controllable by conservative or surgical approaches. We describe a case series of 6 patients who had chronic headaches over an average of 4.9 yr who underwent occipital nerve electrical stimulation lead implantation using a modified midline approach. The patients had received conservative and surgical therapies in the past including oral antidepressants, membrane stabilizers, opioids, occipital nerve blocks, and radiofrequency ablations. Significant decreases in pain visual analog scale (VAS) scores and drastic improvement in functional capacity were observed during the occipital stimulation trial and during the 3-mo follow-up after implantation. The mean VAS score changed from 8.66 +/- 1.0 to 2.5 +/- 1.3 whereas pain disability index improved from 49.8 +/- 15.9 to 14.0 +/- 7.4. Our midline approach has several advantages compared with the submastoid approach used elsewhere. There is only one small midline incision over the upper neck and the strain on the lead extension occurs only with flexion and is minimal with lateral flexion and rotation, which contributes to overall stability of this system.

Spinal cord stimulation: a seven-year audit

OBJECTIVE

To evaluate the outcome and complications of spinal cord stimulation (SCS) for chronic neuropathic pain in an Australian population.

MATERIALS AND METHODS

An independent researcher retrospectively examined the records of 138 patients trialing SCS between 1995 and 2002 at our institution. Information collected included pain relief, ability to perform activities of daily living (ADLs), return to work and reduction in opiate analgesia. Clinical, psychological, demographic and financial data were also collected.

RESULTS

Of 138 patients who trialed SCS, 103 (74.7%) achieved a greater than 50% reduction in their pain and proceeded to permanent implantation. At 1 year following permanent implantation, 84.4% of these still had a reduction in their pain by greater than 50%. The majority of patients, 59.1%, stated that their analgesia was good (50-74% pain reduction). All patients required opiate analgesics prior to SCS implantation, but this fell to 54.6% after SCS implantation. Additionally, 73.6% had a significant improvement in their ability to perform ADLs and 24% of patients were able to return to work.

CONCLUSION

SCS is an effective treatment in the control of chronic neuropathic pain, particularly in combination with comprehensive medical management within a multidisciplinary pain management centre.

Anchoring of Suboccipital Lead: Case Report and Technical Note

Suboccipital stimulation is a relatively new method of neuromodulation for treatment of intractable occipital headache and occipital neuralgia. The most common complication besides an infection is a lead displacement. Anchoring of a lead at the entry place partially solves the problem. Migration of electrode's tip is a major problem so far. A case report of electrode migration and a technique of retrograde lead insertion and subcutaneous anchoring of the tip by means of contralateral incision and suturing of lead is described.

Long-Term Peripheral Nerve Stimulation for Painful Nerve Injuries

BACKGROUND

Although peripheral nerve stimulation (PNS) has been used in the treatment of pain since 1965, only a few follow-up studies have been published. The aim of the present retrospective study was to carefully assess the long-term efficacy and safety of PNS in the treatment of painful nerve injuries.

METHODS

Patients suffering from intractable pain due to peripheral nerve injuries underwent PNS after careful selection. Long-term results were evaluated based upon patients' reports of pain intensity on a visual analog scale (VAS) and their consumption of analgesics. Two categories of results were chosen: good, referring to 50% or more relief of pain with abstinence from analgesic medications; and poor, with less than 50% improvement.

RESULTS

Of 154 referred patients, 46 (26 women and 20 men) were found suitable for PNS. Four etiologic factors were identified, the most common being nerve lesion following an operation in the region of the hip or knee. Other etiologies included entrapment neuropathy, pain following nerve graft, and painful neuropathy following a traumatic injection. The follow-up period was 3-16 years. Of the 46 patients who underwent surgery, the results were classified as good in 36 (78%) patients and as poor in 10 (22%) patients. Overall, pain intensity dropped from a VAS of 69 +/- 12 before surgery to 24 +/- 28 postoperatively (P < 0.001).

CONCLUSIONS

PNS can produce good pain relief in the majority of carefully selected patients suffering from isolated painful neuropathies.

Management of trigeminal autonomic cephalgias and hemicrania continua

The trigeminal autonomic cephalgias (TACs) are a group of primary headache disorders characterised by unilateral trigeminal distribution pain that occurs in association with ipsilateral cranial autonomic features. This group of headache disorders includes cluster headache, paroxysmal hemicrania and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT syndrome). Although hemicrania continua has previously been classified amongst the TACs, its nosological status remains unclear. Despite their similarities, these disorders differ in their clinical manifestations and response to therapy, thus underpinning the importance of recognising them. We have outlined the clinical manifestations, differential diagnoses, diagnostic workup and the treatment options for each of these syndromes.

Peripheral nerve neurostimulation

There is a renewed interest in the use of PNS for the control of intractable pain caused by peripheral mononeuropathies and sympathetically mediated chronic pain syndromes. Technical advances in neurostimulation hardware, specifically lead design and surgical advancements with percutaneous and subcutaneous techniques, fuel this interest in part. The use of multipolar electrode arrays placed percutaneously in the region of peripheral nerves or in their dermatomal distribution without the need for extensive surgical dissection should help to support the use of PNS as a reasonable alternative to potentially destructive surgical procedures for chronic pain control.

Spinal cord stimulation: patient selection, technique, and outcomes

Spinal cord stimulation, as with neuromodulation procedures in general, is a nondestructive, screenable, and reversible treatment option. Because there are no long-term side effects that have been reported; spinal cord stimulation is generally preferable as a first step when other less invasive treatments have failed to produce acceptable control of the pain.

Cervicogenic headache: interventional, anesthetic, and ablative treatment

Cervicogenic headache is becoming an accepted clinical syndrome in which headache pain is thought to originate from the cervical spine. Unfortunately, there are no diagnostic imaging techniques of the cervical spine and associated structures that can determine the exact source of pain. Therefore, diagnosis and treatment are based on the major accepted criteria of clinical presentation and the use of diagnostic nerve blocks to identify the source of the pain generator before considering further interventional or neuroablative treatment. This suggests that consistent reproducible anatomic and neurophysiologic pathways exist for the reproduction of typical clinical pain patterns and the ability of neuroblockade to consistently interrupt these pain pathways. This article describes the essential anatomy required to understand the use of diagnostic nerve blocks, and their predictive value in anticipating response to neuroablative and interventional therapy with a review of the major interventional, anesthetic, and ablative techniques for cervicogenic headache.

New trends in neuromodulation for the management of neuropathic pain

Since its first application in 1967, the methodology and technology of spinal cord stimulation for the management of chronic, intractable pain have evolved continuously. Despite these developments and improved knowledge of the effects of spinal anatomy and epidural contact configuration on paresthesia coverage, the clinical results of spinal cord stimulation-particularly the long-term effects-are still unsatisfactory in many patients. This dissatisfaction has come primarily from the failure of single-electrode configurations to provide consistent paresthesia coverage of the entire painful area. Therefore, new approaches were developed during the late 1990s that attempted to selectively cover one or more dermatomes with paresthesia as well as to provide sequential stimulation of different anatomic sites. These approaches have been applied both intraspinally and extraspinally by stimulating either the spinal nerves or the dorsal columns. To target parts of the latter, different methods have been developed and tested using either two-dimensional contact configurations or electronic field steering. These developments hold promise for improving long-term outcomes as well as increasing the number of pain conditions that can be treated with neuromodulation therapy. In this review, the history, theoretical basis, and evolution of these methodologies, as well as the ways in which they represent new trends in neuromodulation, are discussed.

Current and future trends in spinal cord stimulation for chronic pain

Spinal cord stimulation (SCS) is a reversible treatment for chronic pain that is gaining favor as a first-line therapy for many disease states. Because there are no addictive issues and no side effects systemically, the treatment is moving up the treatment continuum ladder. First used clinically in 1967, the procedure was used exclusively for failed back surgery syndrome. Over the past 30 years selection criteria, psychologic screening, and technology have improved. These advances have broadened the treatment options for many patients in pain. This review focuses on the selection, indications, techniques, new advances, complications, and outcomes involved with SCS. A review is provided for the treatment of radiculitis, failed back surgery syndrome, complex regional pain syndrome, peripheral neuropathies, pelvic pain, occipital neuralgia, angina, ischemic extremity pain, and spasticity. Technologic advances such as multi-lead and multi-electrode arrays are also discussed in regard to the impact these developments have on the clinical application of the therapy.

Stimulation methods for neuropathic pain control

Neurostimulation methods for control of chronic neuropathic pain have recently gained in popularity. The reasons for this are multifactorial. As opposed to nerve ablation, these methods are minimally invasive and reversible. The improvements in hardware design simplified implantation techniques and prolonged equipment longevity. Stimulation trials have become less invasive, allowing patients to test its effects before final implantation. Finally, the scientific evidence has shown good outcomes of neurostimulation methods for chronic neuropathic pain control. Recent research efforts have revealed new potential mechanisms of action of neurostimulation. Whereas its action was widely explained by gate control theory in the past, it seems that neuromodulation acts also by modulation of neurotransmitters in the central nervous system. Three neurostimulation methods are currently used in clinical practice: spinal cord stimulation (SCS), peripheral nerve stimulation (PNS), and deep brain stimulation (DBS). The SCS and PNS are excellent treatment choices for certain forms of neuropathic pain. The new indications for SCS are end-stage peripheral vascular disease and ischemic heart disease, whereas PNS is used for the treatment of occipital neuralgia and chronic pelvic pain. DBS is reserved for carefully selected patients in whom the other treatment modalities have failed. In a minority of patients the "tolerance" to neurostimulation develops after long-term use. Further research is needed to establish better outcome predictors to neurostimulation and possibly improve patient selection criteria.

Uncommon areas of electrical stimulation for pain relief

Uncommon stimulation refers to the use of peripheral nerve and spinal cord stimulation for nontraditional applications. There has been much interest recently with subcutaneous suboccipital stimulation for occipital neuralgia, sacral stimulation for pelvic pain, trigeminal stimulation for trigeminal neuralgia, and spinal cord stimulation for angina and peripheral ischemia. The indications and techniques used for accomplishing each method are discussed.