Progress in neurological surgery
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Cluster headache is well known as one of the most painful primary neurovascular headache. Since 1% of chronic cluster headache patients become refractory to all existing pharmacological treatments, various invasive and sometimes mutilating procedures have been tempted in the last decades. Recently, neurostimulation methods have raised new hope for drug-resistant chronic cluster headache patients. ⋯ Other peripheral nerve stimulation approaches used for this indication are also reviewed in detail. Although available studies are limited to a relatively small number of patients and placebo-controlled trials are lacking, existent clinical data suggest that occipital nerve stimulation should nonetheless be recommended for intractable chronic cluster headache patients before more invasive deep brain stimulation surgery. More studies are needed to evaluate the usefulness of supraorbital nerve stimulation and of vagus nerve stimulation in management of cluster headaches.
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Neuromodulation practitioners increasingly recognize the potential for peripheral nerve field stimulation (PNfS) to treat pain originating from the trunk. Conditions resulting in truncal pain that may respond to PNfS include cervical and lumbar postlaminectomy syndrome, inguinal neurapraxia, post-herpetic neuralgia, and post-thoracotomy pain. The focus of this chapter is to review the mechanism of action in PNfS, patient selection factors, programming strategies, and technical considerations.
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Recently, there has been a tremendous evolution in the field of neurostimulation, both from the technological point of view and from development of the new and different indications. In some areas, such as peripheral nerve stimulation, there has been a boom in recent years due to the variations in the surgical technique and the improved results documented by in multiple published papers. ⋯ The confusion arises when attempting to describe peripheral nerve stimulation and subcutaneous stimulation. Peripheral nerve stimulation, in its pure definition, involves implanting a lead on a nerve, with the aim to produce paresthesia along the entire trajectory of the stimulated nerve.
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Since its inception in the 1970s, peripheral neuromodulation has become an increasingly common procedure to treat chronic neuropathic disorders. Historically, peripheral nerve stimulation (PNS) originated with the placement of large surface cuff electrodes, which was refined by the introduction of functional nerve mapping with circumferential electrical stimulation. This substantially improved the targeting of sensory fascicles. ⋯ To further refine functional mapping for the placement of these percutaneous electrodes, radiofrequency needle probes have more recently been employed to elicit paresthesias in awake patients to map the pain generators and guide treatment. In this chapter, we provide a description of the development and basic mechanisms of peripheral nerve stimulation, as well as a more detailed description of the two most commonly employed forms of peripheral nerve stimulation: occipital nerve stimulation for occipital neuralgia, and subcutaneous peripheral nerve field stimulation to stimulate free nerve endings within the subcutaneous tissue when the pain is limited to a small, well-localized area. The closely related ideas of internal and external targeted subcutaneous stimulation are also discussed.
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Although commonly used in clinical practice, peripheral nerve stimulation (PNS) for treatment of chronic pain is performed mainly with devices developed and marketed for spinal cord stimulation applications. This may be one of the reasons why PNS approach is marked by a very high complication rate, as the anatomy of peripheral nerves and the surrounding soft tissues is quite different from epidural spinal space for which the current devices are designed. ⋯ Based on the literature data and the analysis of the author's experience with PNS procedures it appears that although the rate of complications is relatively high, the morbidity associated with PNS approach is very minor and most problems may be resolved with simple re-operations, usually on outpatient basis. The reduction in complication rate is expected to occur when the hardware used in PNS procedures is appropriately adapted for PNS applications.