Experiences with Spinal Cord Stimulator in Patients with Chronic Neuropathic Back Pain

Neuropathic pain is a complex, chronic, and disabling condition that has physical, functional, and psychosocial repercussions. Although the estimated prevalence of neuropathic pain in the general population ranges from 1.5% to 8%, neuropathic pain is frequently underdiagnosed and undertreated. The aims of this study were to examine the experience of patients treated with spinal cord stimulation as a pain-relieving treatment and how this may influence the patient’s ability to participate in everyday life activities. A qualitative approach based on seven telephone interviews was performed. The participants were recruited from a university hospital in Norway, and all used spinal cord stimulation as a pain-relieving treatment. Qualitative content analysis was used. Two thematic findings emerged: (1) pain relief with spinal cord stimulation as a complex and individual experience and (2) challenges in adaptations in everyday life with spinal cord stimulation. Findings indicate that spinal cord stimulation can offer pain relief that can help patients achieve a meaningful life despite chronic pain. Spinal cord stimulation also may have disadvantages that should be considered before offering this treatment. It seems evident that extended information needs about working mechanism of SCS and precautions as well as follow-up are required to meet unexpected challenges in adaptation. Here the nurse has an important role when informing and following this patient group.     

Totally Implantable Spinal Cord Stimulation for Chronic Pain: Design and Efficacy

Neurostimulators used to treat chronic, intractable pain have evolved from technical developments in pacemaker technology. A totally implantable spinal cord stimulation (SCS) system was designed based on elements of a widely used cardiac pacemaker. This paper reports on the transformation of pacemaker technology for neurostimulation applications and presents results of using this system for the treatment of 90 patients with chronic, intractable pain of the low back and/or legs. Significant reduction in pain levels resulted from use of a totally implantable spinal cord stimulation system. Seventy percent of the patients experienced good or excellent pain relief at an average of 14.5 months after implant. Patients who used an automatic ON/OFF cycling mode of stimulation reported greater pain relief than patients who were stimulated continuously.     

Time Dependent Variations of Stimulus Requirements in Spinal Cord Stimulation for Angina Pectoris

The aim of the study was to observe changes over time of the stimulation requirements in spinal cord stimulation (SCS). Of 60 patients treated with SCS, 25 patients were selected because they had neurostimulators capable of measuring impedance noninvasively, and had not experienced electrode displacement. All 25 patients had Medtronic Pisces Quad 3487A (Medtronic, Inc.) neuroelectrodes with the tip positioned in the thoracic epidural space. The accuracy of the neurostimulators impedance measuring circuit was investigated in a test circuit. The error was < 11%. Stimulus requirements and impedance were recorded at the implantation and at follow-ups during a period of 24 months. During the first month after implantation, the stimulus requirements for satisfactory effect varied between +406% and -34%. After that period, only minor deviations were observed in most patients. To optimize the pain reducing effect of the spinal cord stimulation, frequent follow-ups are recommended during the first month; later on, the follow-up intervals can be extended. No tolerance development or pain resistance developed during SCS treatment     

Spinal Cord Stimulation (SCS) in Deafferentation Pain

Spinal cord stimulation is considered to be ineffective in relieving deafferentation pain. We have retrospectively analyzed the results obtained in a series of 41 patients. Sixteen suffered from pain associated with an incomplete traumatic spinaJ lesion, 15 from a posttherapeutic neuralgia, and 10 from pain due to root and/or nerve damage. At the end of the test period, 43.7% of the patients with paraplegic pain, (40% of those with peripheral deafferentation pain and 66.6% of the ones with postherapeutic neuralgia), reported satisfactory pain relief and were connected to a chronic stimulation system. At mean follow-up (15 months), only 20% of the patients of the first two groups reported sufficient pain relief In the postherapeutic group the figure of responders was unchanged. The mean analgesia achieved was 70%. From this analysis we conclude that the results achieved in the postherapeutic pain patients, although positive in only 66% of them, are remarkably stable with time. Therefore, we recommend a percutaneous test trial of SCS in every case of postherapeutic pain resistant to medical treatment.     

Spinal Cord Electrical Stimulation in Severe Angina Pectoris: Surgical Technique, Intraoperative Physiology, Complications, and Side Effects

Twenty patients with angina pectoris were treated with spinal cord stimulation (SCS) at the T₁, T₂ level of the spinal cord since June 1985. These patients were not candidates for angioplasty or coronary bypass or those procedures had failed. There were no injections. One lead broke and one lead migrated. Both were corrected migrally and regained some relief. The relief of pain with SCS may be an alternative treatment to coronary bypass or angioplasty in some patients.     

Modification of blood flow to the extremities by electrical stimulation of the nervous system.

Sixteen patients who had electrical stimulation applied to various portions of the nervous system were examined for increase in blood flow to the extremities. Clinical observations and a one-channel plethysmograph were used to measure arterial dilatation. Seven patients had transcutaneous stimulation applied over the cervical or thoracic spinal cord, peripheral nerves, or low lumbar region; eight had electrical stimulators implanted over the spinal cord in attempts to relieve intractable pain or some of the symptoms of multiple sclerosis; and one patient had electrical stimulators implanted over the C-6 dorsal roots for small artery disease of the upper extremities. Twelve of 13 patients who had electrical stimulation applied to the spinal cord or dorsal roots had significant arterial dilatation in one or more extremities. Electrical stimulation applied to the ulnar nerves did cause arterial dilatation. One patient did not show any change in the central arterial pressure curve during transcutaneous stimulation of the cervical spinal cord.     

Subcutaneous Target Stimulation–Peripheral Subcutaneous Field Stimulation in the Treatment of Refractory Angina: Preliminary Case Reports

Abstract: Spinal cord stimulation is now established as an effective treatment for refractory angina. We present the use of an alternative approach to neuromodulation of anginal pain using subcutaneous leads placed at the site of pain. In this case series, five patients with refractory angina received successful treatment with subcutaneous target stimulation–peripheral subcutaneous field stimulation. This technique was able to provide good analgesia in two patients that had had poor pain relief from existing spinal cord stimulators. All five patients achieved significant pain relief with a reduction in symptoms and a decrease in the use of pain medication.     

Electrical spinal cord stimulation in painful diabetic polyneuropathy, a systematic review on treatment efficacy and safety

Introduction: Painful diabetic polyneuropathy is a common complication of diabetes mellitus. Drug therapies are ineffective in many patients. Therefore other treatment modalities should be considered, including spinal cord stimulation. We performed a systematic review to evaluate treatment efficacy and safety of spinal cord stimulation in painful diabetic polyneuropathy. Search strategy and selection criteria: A systematic search with reference tracing was conducted in Pubmed and Embase from January 1980 to March 2010 to determine possible eligible articles. Reports were identified using the following keywords: (1) “diabetic neuropathies” AND “electric stimulation”; (2) “diabetic neuropathies” AND “spinal cord” and (3) “pain” AND “electric stimulation” AND “spinal cord”. Subsequently, data were recruited on the efficacy and safety of spinal cord stimulation in this disorder. Data collection and analysis: The search strategy was designed by one reviewer. Study selection and data extraction were performed by two reviewers. Data for individual studies was reported and pooled data analysis was performed if appropriate. Results: Three prospective case series and one retrospective cohort study were identified (including 25 patients). At 1 year spinal cord stimulation resulted in ≥50% pain relief in 63% of patients. After 1 year analgesics usage was reduced in most SCS‐treated patients with complete withdrawal in 60%. No major adverse events were reported. Conclusion: Available literature shows promising results for the pain‐relieving effect of spinal cord stimulation in painful diabetic polyneuropathy. The outcome of a randomized clinical trial is needed before spinal cord stimulation can be considered to be integrated in the standardized treatment algorithm.     

Naloxone does not affect pain relief induced by electrical stimulation in man

We wished to determine if pain relief that resulted from transcutaneous (TNS) or spinal cord electrical stimulation in patients with chronic pain was due to activation of an endogenous opiate-related pain control system. Naloxone (0.4–10 mg) or saline was injected in double-blind fashion intravenously into opiate-naive subjects with chronic pain who achieved 30% or greater pain relief with spinal cord stimulation (4 patients) or TNS (9 patients). Subjects rated their pain during stimulation and 2, 5, 10 and 15 min after the injection. Two days or more later the procedure was repeated using the alternate agent (naloxone or saline). Naloxone did not decrease the pain relief induced by stimulation, and therefore the effects of stimulation are probably not mediated by the endogenous opiates.     

Spinal cord stimulation in the treatment of failed back surgery syndrome

A significant number of patients undergoing lumbar spine surgery do not obtain pain relief. Such patients with chronic low back or lower extremity pain may be difficult to treat. A frequent component of therapy is the use of spinal cord stimulation to help control pain. With careful patient selection, many patients can achieve reasonable levels of pain relief. We review recent clinical reports, including prospective and randomized studies, that demonstrate up to three quarters of patients implanted with a spinal cord stimulator for the treatment of failed back surgery syndrome may benefit from its use. This technology must not be indiscriminately applied. Careful patient selection and a period of trial stimulation are vital to the successful use of spinal cord stimulation as treatment for chronic pain.     

Spinal Cord Stimulation as a Novel Approach to the Treatment of Refractory Neuropathic Mediastinal Pain

Spinal cord stimulation (SCS) offers new hope for patients with neuropathic pain. SCS "neuromodulates" the transmission and response to "painful" stimuli. The efficacy of SCS has been established in the treatment of a variety of neuropathic pain conditions and more recently in refractory angina pectoris, peripheral vascular disease, and failed back surgery syndrome. Recent publications suggest that visceral pain could be successfully treated with SCS. We report the first successful use of a spinal cord stimulator in the treatment of refractory neuropathic mediastinal, esophageal, and anterior neck pain following esophagogastrectomy.     

Compound action potentials recorded in the human spinal cord during neurostimulation for pain relief

Electrical stimulation of the spinal cord provides effective pain relief to hundreds of thousands of chronic neuropathic pain sufferers. The therapy involves implantation of an electrode array into the epidural space of the subject and then stimulation of the dorsal column with electrical pulses. The stimulation depolarises axons and generates propagating action potentials that interfere with the perception of pain. Despite the long-term clinical experience with spinal cord stimulation, the mechanism of action is not understood, and no direct evidence of the properties of neurons being stimulated has been presented. Here we report novel measurements of evoked compound action potentials from the spinal cords of patients undergoing stimulation for pain relief. The results reveal that Aβ sensory nerve fibres are recruited at therapeutic stimulation levels and the Aβ potential amplitude correlates with the degree of coverage of the painful area. Aβ-evoked responses are not measurable below a threshold stimulation level, and their amplitude increases with increasing stimulation current. At high currents, additional late responses are observed. Our results contribute towards efforts to define the mechanism of spinal cord stimulation. The minimally invasive recording technique we have developed provides data previously obtained only through microelectrode techniques in spinal cords of animals. Our observations also allow the development of systems that use neuronal recording in a feedback loop to control neurostimulation on a continuous basis and deliver more effective pain relief. This is one of numerous benefits that in vivo electrophysiological recording can bring to a broad range of neuromodulation therapies.     

Beneficial Effects of Cervical Spinal Cord Stimulation (cSCS) on Patients with Impaired Consciousness: A Preliminary Report

Electrical stimulation of the spinal cord can be used for treatment of intractabie pain and spasticity. Based on our experimental findings cervical spinal cord stimulation (cSCS) was performed on eight patients with severe brain dysfunction due to traffic accidents, pronounced vasospasm caused by subarachnoid hemorrhage or surgery of huge cerebral tumors (chordoma). After a 1 to 2 month period of stimulation, two patients became conscious and began to speak. It remains unclear whether cSCS induced the restoration of consciousness and improved neurological deficits. Although the successful results might be due to chance, cSCS might have stimulated brain function. This preliminary report shows such excellent results that further studies are warranted.     

Dorsal root ganglion stimulation for the treatment of joint pain with predominantly nociceptive characteristics: A case series

Introduction

Dorsal root ganglion stimulation (DRG-S) has recently emerged as a novel therapy in neuromodulation that demonstrated a higher rate of success than spinal cord stimulation (SCS) in a prospective, head-to-head randomized comparative trial to treat complex regional pain syndrome (CRPS) and causalgia. In contrast to SCS, DRG-S also shows promise in treating conditions that are not purely neuropathic such as axial low back pain, which has a prominent nociplastic pain component. It is not known to what extent the effectiveness of DRG-S for such indications is due to effective treatment of the neuropathic pain component versus the effects of DRG-S on mechanical pain. Although rarely studied, reporting outcomes of DRG-S to treat predominantly mechanical/nociceptive pain may help point toward expanding the utility of this therapy. Here, we present five cases of refractory mechanical pain treated with DRG-S.

Methods

A retrospective analysis of all patients who underwent a successful DRG-S trial and implant between September 2017 and September 2021 at our institute was performed. Patients who had intractable joint pain without strong evidence of neuropathic pain were included in this case series. The Budapest criteria for CRPS, the Douleur Neuropathique 4 Questions (DN4) survey, or a definable nerve injury were used to determine the presence of neuropathic pain. Baseline assessments for pain (Numeric Rating Scale [NRS]), function (Oswestry Disability Index [ODI]), quality of life (EuroQol-5 Dimension [EQ-5D]), and other applicable joint surveys were extracted from pre-trial baseline and follow-up appointments.

Results

Five patients were identified and included. Patient diagnoses consisted of refractory joint pain of the hip, knee, or ankle. Mean NRS pain scores improved by 74% from 9.2 at baseline to 2.4 at the last follow-up (mean = 28 months post-implant). From baseline to the last follow-up, mean ODI scores improved by 65% from 66 to 23 and EQ-5D scores more than doubled from an average of 0.371 to 0.797.

Conclusion

This clinical report illustrates the potential utility DRG-S has in treating pain that clinically presents as predominantly refractory mechanical joint pain without a significant neuropathic component. The physiological reasons for our observations may be that DRG-S is able to directly influence the conduction of nociceptive signaling at the DRG and within the spinal cord. Further investigations are warranted to determine if DRG-S is a potential treatment option for chronic mechanical pain.     

Electroencephalographic evoked pain response is suppressed by spinal cord stimulation in complex regional pain syndrome: a case report

Pain is a subjective response that limits assessment. The purpose of this case report was to explore how the objectivity of the electroencephalographic response to thermal stimuli would be affected by concurrent spinal cord stimulation. A patient had been implanted with a spinal cord stimulator for the management of complex regional pain syndrome of both hands for 8 years. Following ethical approval and written informed consent we induced thermal stimuli using the Medoc PATHWAY Pain & Sensory Evaluation System on the right hand of the patient with the spinal cord stimulator switched off and with the spinal cord stimulator switched on. The patient reported a clinically significant reduction in thermal induced pain using the numerical rating scale (71.4 % reduction) with spinal cord stimulator switched on. Analysis of electroencephalogram recordings indicated the occurrence of contact heat evoked potentials (N2–P2) with spinal cord stimulator off, but not with spinal cord stimulator on. This case report suggests that thermal pain can be reduced in complex regional pain syndrome patients with the use of spinal cord stimulation and offers objective validation of the reported outcomes with this treatment.     

The role of N‐methyl‐d‐aspartate receptor subunit NR2B in spinal cord in cancer pain

Cancer pain is one kind of the most common and severe kinds of chronic pain. No breakthrough regarding the mechanisms and therapeutics of cancer pains has yet been achieved. Based on the well established involvement of the NMDA (N‐methyl‐d ‐aspartate) receptor containing NR2B in inflammatory pain and neuropathic pain and the effective pain relief obtained with ketamine in cancer patients with intractable pain, we supposed that NR2B in the spinal cord was an important factor for cancer pain. In this study, we investigated the possible role of NR2B in the spinal cord using a murine model of bone cancer pain. C3H/HeJ mice were inoculated into the intramedullary space of the right femur with Osteosarcoma NCTC 2472 cells to induce ongoing bone cancer‐related pain behaviors. At day 14 after operation, the expression of NR2B mRNA and NR2B protein in the spinal cord were higher in tumor‐bearing mice compared to the sham mice. Intrathecal administration of 5 and 10 μg of NR2B subunit‐specific NMDA receptor antagonist ifenprodil attenuated cancer‐evoked spontaneous pain, thermal hyperalgesia and mechanical allodynia. These results suggest that NR2B in the spinal cord may participate in bone cancer pain in mice, and ifenprodil may be a useful alternative or adjunct therapy for bone cancer pain. The findings may lead to novel strategies for the treatment of bone cancer pain.     

Neurotoxins in the Neurobiology of Pain

Migraine is a common, chronic, incapacitating, neurovascular disorder that affects an estimated 12% of the population. Understanding the basic mechanisms of pain is important when treating patients with chronic pain disorders.
Pain, an unpleasant sensory and emotional experience, is usually triggered by stimulation of peripheral nerves and often associated with actual or potential tissue damage. Peripheral nerve fibers transmit pain signals from the periphery toward the spinal cord or brain stem. The different diameter pain fibers (A and C) vary in the speed of conduction and the type of pain transmitted (eg, sharp versus dull). When stimulated, peripheral pain fibers carrying sensory input from the body enter at different layers of the dorsal horn, which is then propagated toward the thalamus via the spinothalamic tract within the spinal cord. Conversely, sensory input from the face does not enter the spinal cord but enters the brain stem via the trigeminal nerve.
This review describes in detail the neurobiological mechanisms and pathways for pain sensation, with a focus on migraine pain.     

Failed Back Surgery Syndrome and intrathecal drugs infusion

Even if there is no study evaluating how often Failed Back Surgery Syndrome is the cause of pain in patients who need spinal drugs infusion to control their symptoms, it seems that in most centres, Failed Back Surgery Syndrome was the most frequent indication for spinal cord stimulation and for intrathecal analgesic delivery pumps implantation. In our experience of spinal drug delivery for pain, about one third of the patients (35.7%) had undergone one or more spinal surgeries.A literature search was performed looking for intrathecal drugs infusion and Failed Back Surgery Syndrome or chronic back and leg pain without specification of previous surgery. The data in which we were interested were trialling methods, drugs used, outcomes and side effects. A comparison was made with the 14 years experience in intrathecal drugs infusion in our centre.We evaluated the side effects reported with chronic spinal drugs infusion even if not specific for patients with Failed Back Surgery Syndrome.     

Spinal cord stimulation relieves chemotherapy-induced pain: a clinical case report

We present two patients with chemotherapy-induced painful neuropathy that had been poorly controlled with medications but successfully treated with spinal cord stimulation (SCS). A trial period of SCS provided effective pain relief in both patients who subsequently underwent permanent stimulator implantation. Psychophysical tests were performed before and after the implantation of trial and permanent stimulators. SCS improved pain scores and facilitated a reduction of medications. Both patients reported improved gait and one of them also reported an increase in leg flexibility. Psychophysical tests demonstrated an improvement in touch and sharpness detection thresholds. In summary, SCS offers a therapeutic option for patients with chemotherapy-induced peripheral neuropathy who have poor pain relief with standard medical treatment.