Management of chronic severe pain: spinal neuromodulatory and neuroablative approaches

The use of spinal cord stimulation in pain management

SUMMARY Pain is a complex behavior process, the anatomy and physiology of which is not completely understood, and is subject to continuous exploration and research. Following on the heels of Melzack and Wall's gate control theory of pain (1965), Shealey et al., in 1967, were the first to implant stimulation electrodes over the dorsal columns in an attempt to provide relief for patients with chronic, intractable pain. Since then, significant strides in both the technological and therapeutic sides have facilitated the evolution of spinal cord stimulation (SCS) in the management of a variety of pain pathologies. High-quality evidence attests to the efficacy and cost-effectiveness of this modality. In contrast to conventional medical management, SCS offers long-lasting symptom relief, improved quality of life and functional capability, often achieving these goals at a reduced cost. This article illustrates the present status, challenges and future of SCS.

Dorsal column stimulator applications

Background:

Spinal cord stimulation (SCS) has been used to treat neuropathic pain since 1967. Following that, technological progress, among other advances, helped SCS become an effective tool to reduce pain.

Methods:

This article is a non-systematic review of the mechanism of action, indications, results, programming parameters, complications, and cost-effectiveness of SCS.

Results:

In spite of the existence of several studies that try to prove the mechanism of action of SCS, it still remains unknown. The mechanism of action of SCS would be based on the antidromic activation of the dorsal column fibers, which activate the inhibitory interneurons within the dorsal horn. At present, the indications of SCS are being revised constantly, while new applications are being proposed and researched worldwide. Failed back surgery syndrome (FBSS) is the most common indication for SCS, whereas, the complex regional pain syndrome (CRPS) is the second one. Also, this technique is useful in patients with refractory angina and critical limb ischemia, in whom surgical or endovascular treatment cannot be performed. Further indications may be phantom limb pain, chronic intractable pain located in the head, face, neck, or upper extremities, spinal lumbar stenosis in patients who are not surgical candidates, and others.

Conclusion:

Spinal cord stimulation is a useful tool for neuromodulation, if an accurate patient selection is carried out prior, which should include a trial period. Undoubtedly, this proper selection and a better knowledge of its underlying mechanisms of action, will allow this cutting edge technique to be more acceptable among pain physicians.

Spinal cord stimulation: therapeutic benefits and movement generation after spinal cord injury

Spinal cord injury (SCI) is a devastating neurological condition that leads to loss of motor and sensory function. It commonly causes impairments in limb movements, respiration, bowel and bladder function, as well as secondary complications including pain, spasticity, and pressure ulcers. Numerous interventions such as neuroprotection, regeneration, pharmacology, rehabilitation training, and functional electrical stimulation are under investigation for improving function after SCI. This chapter discusses the use of spinal cord stimulation (epidural and intraspinal electrical stimulation) for alleviating pain and spasticity, and restoring standing and walking. Epidural stimulation is effective in reducing the intensity of intractable pain, but its effectiveness in the treatment of spasticity remains unclear. It can induce rhythmic, locomotor-like movements in the legs, presumably due to the activation of afferent pathways. Intraspinal microstimulation is a new electrical stimulation approach that activates locomotor-related networks within the ventral regions of the lumbosacral spinal cord. In animals, this approach is capable of producing prolonged, fatigue-resistant standing and stepping of the hindlegs. While the results in animals have been very encouraging, technical advancements are necessary prior to its implementation in humans with SCI. Taken collectively, spinal cord stimulation holds substantial promise in restoring function after neural injury or disease.

[Selected interventional methods for the treatment of chronic pain : part 2: regional anesthetic techniques close to the spinal cord and neuromodulative methods]

Approximately 5-8 million people in Germany suffer from chronic pain and some patients can profit from specific interventional techniques. In detail these are regional anesthetic techniques close to the spinal cord, neuromodulation, blocks of the sympathetic chain and peripheral nerve blocks. Part 2 of the article presents regional anesthetic techniques close to the spinal cord and neuromodulative methods. Regional anesthetic techniques close to the spinal cord are of high importance for the treatment of chronic low back pain although the efficiency is highly disputed due to the lack of evidence. Neuromodulation includes amongst others intrathecal pharmacotherapy and spinal cord stimulation, which are used for highly selected patients and can lead to very good results for these patients.

Neurosurgical advances in cancer pain management

Neurosurgical procedures to treat pain are mainly destructive and involve the spinal cord and occasionally the brain. Targets include the spinothalamic tract, the trigeminal tract nucleus, the midline ascending visceral pain pathway, the brainstem spinal lemniscus, the thalamus, and the cingulate gyrus. Since the introduction of intrathecal opioids, the need for neurosurgical destructive procedures has been in decline. In recent years, cordotomy, trigeminal tractotomy, and dorsal root entry zone (DREZ) operations are the neurosurgical procedures most often utilized to treat cancer pain. The addition of CT guidance to spinal cord pain pathway ablation was a major addition and refinement to the procedure. Here the authors review the latest techniques and recently published results for CT-guided cordotomy, CT-guided trigeminal tractotomy, and DREZ operations utilized to treat cancer pain.