Neuromodulation in the Treatment of Postoperative Epidural Fibrosis: Comparison of the Extent of Epidural Fibrosis and the Effect of Stimulation

The goal was to prove that when a cohort of patients is chosen precisely, dorsal column stimulation provides significant improvement to quality of life. We studied a cohort of 50 patients with the history of failed back surgery syndrome coupled with epidural fibrosis (EF). A percutaneous implantation technique was used in each of the 50 patients. The study group was composed of 20 women and 28 men aged 26-67 years (mean age 49). A prospective observational questionnaire-based study was used. According to the methods, Ross's classification was adjusted to four degrees of scar size for our study objective. Despite this adjustment, it was not possible to statistically evaluate our research, due to very similar results in Groups I, III and IV. Patients without epidural fibrosis were assigned to Group 0, and patients with EF of different ranges were assigned to Group 1. The mean change in visual analogue scale ΔVAS after our division into Group 0 was 4.82; for Group 1 it was 6.13. Evaluation of EF and ΔVAS correlation by paired t-test shows a statistically higher effect of spinal cord stimulation (SCS) in the epidural fibrosis group, compared to group 0 without postope-rative epidural fibrosis (p=0.008). The extent of epidural fibrosis is an important factor for Failed back surgery syndrome (FBSS). FBSS is the basis for the existence of neuropathic pain after lumbar spinal surgery. There is clear evidence of a correlation between patients with epidural scar formation on MR scan and the effect of dorsal column stimulation.

A Brain to Spine Interface for Transferring Artificial Sensory Information

Lack of sensory feedback is a major obstacle in the rapid absorption of prosthetic devices by the brain. While electrical stimulation of cortical and subcortical structures provides unique means to deliver sensory information to higher brain structures, these approaches require highly invasive surgery and are dependent on accurate targeting of brain structures. Here, we propose a semi-invasive method, Dorsal Column Stimulation (DCS) as a tool for transferring sensory information to the brain. Using this new approach, we show that rats can learn to discriminate artificial sensations generated by DCS and that DCS-induced learning results in corticostriatal plasticity. We also demonstrate a proof of concept brain-to-spine interface (BTSI), whereby tactile and artificial sensory information are decoded from the brain of an “encoder” rat, transformed into DCS pulses, and delivered to the spinal cord of a second “decoder” rat while the latter performs an analog-to-digital conversion during a tactile discrimination task. These results suggest that DCS can be used as an effective sensory channel to transmit prosthetic information to the brain or between brains, and could be developed as a novel platform for delivering tactile and proprioceptive feedback in clinical applications of brain-machine interfaces.

The use of high-dose cervical spinal cord stimulation in the treatment of chronic upper extremity and neck pain

Background: Dorsal column spinal cord stimulation is used for the treatment of chronic neuropathic pain of the axial spine and extremities. Recently, high-dose (HD) thoracic dorsal column stimulation for paresthesias has been successful. This study evaluates the utility of HD stimulation in the cervical spine for managing upper neck and upper extremity pain and paresthesias. Methods: Three patients suffering from cervical and upper extremity chronic pain were assessed. Each underwent a two-stage process that included a trial period, followed by permanent stimulator implantation. Therapy included the latest HD stimulation settings including a pulse width of 90 μs, a frequency setting of 1000 Hz, and an amplitude range of 1.5 amps–2.0 amps. Pain relief was measured utilizing relative percent pain improvement as self-reported by each patient before and after surgery. Results: After permanent implantation, (range 15–21 months), all three patients continued to experience persistent pain and paresthesia relief (70%–90%). Conclusions: In three patients, HD cervical spinal cord stimulation successfully controlled upper extremity chronic pain/paresthesias.

Preoperative Surveillance Thoracic MRI for Thoracic Dorsal Column Stimulation: Case Series

Background: To date, there have been no guidelines, studies, or consensus statements regarding the use of advanced imaging studies as a preoperative screening tool prior to patients undergoing spinal cord stimulation (SCS). Objectives: The purpose of this case series is to highlight the importance of obtaining thoracic imaging studies as part of a thorough initial clinical assessment prior to percutaneously or surgically placing an SCS electrode. Methods: We undertook a 3-year retrospective review of patients undergoing evaluation for SCS therapy in an academic interventional pain management and neurosurgery practice. Patients with chronic neuropathic pain underwent a trial with percutaneous dorsal column stimulation, and if response to the trial was > 50% reduction in pain and improvement in function, the patient was implanted using either a percutaneous approach or placement of a paddle electrode with an internal pulse generator (IPG). All patients had advanced thoracic imaging performed (magnetic resonance imaging [MRI] if possible, or computed tomography [CT] if contraindicated) prior to percutaneous trial or paddle electrode implantation. Results: In 3 years, 88 patients underwent a trial of SCS, of which 75 patients (85%) were referred for implantation of a permanent percutaneous or paddle stimulator with IPG. Two patients (1.2%) treated by trial and implant were found to have a thoracic lesion on surveillance imaging, which contraindicated SCS implantation. One patient had thoracic imaging prior to undergoing the trial and one patient had thoracic surveillance imaging after the trial, but before surgical paddle placement. Limitations: The retrospective nature and lack of a control group in this case series are limitations of this study. Conclusion: This case series outlines the importance of considering advanced thoracic imaging studies for screening/surveillance purposes prior to SCS therapy. Placement of SCS electrodes in the thoracic epidural space without prior understanding of spinal anatomy potentially puts patients at unnecessary risk. In the cases presented, had patients undergone SCS trial and subsequent implant without screening imaging, thoracic lesions would have been missed, increasing the likelihood of diagnostic and therapeutic complications. Our incidental findings of lesions on MRI prior to SCS trial or implant support the use of a screening protocol for other centers providing thoracic SCS therapies. Key words: Thoracic, dorsal column stimulation, chronic pain, surveillance MRI, patient selection

Advances in Dorsal Column Stimulation

Spinal cord stimulation (SCS) has been a long established therapy for various pain conditions including low back pain, failed back surgery syndrome, complex regional pain syndrome, and other neuropathic and nociceptive pain states. Since the first report of SCS in 1967 by Shealy, advances have occurred in the technology used to achieve clinical analgesia. Developments in both the hardware and software involved have led to significant improvements in functional specificity, as seen in dorsal root ganglion stimulation, along with increasing breadth and depth of the field of neuromodulation. The patient experience during the implantation of the systems, as well as post-procedurally has been enhanced with improvements in programming. These technological improvements have been validated in quality evidenced-based medicine: what was a static area now is a dynamic field, with neuromodulation poised to allow physicians and patients more viable options for better pain control for chronic painful conditions.

Considerations for the Use of Dorsal Column Stimulation for Lumbosacral Radiation Neuritis of the Nerve Root in the Spine Tumor Patient (A Case Series)

Background: Radiation therapy (RT) has become a mainstay in the treatment of various malignancies. Unfortunately, a potential side effect of this modality is radiation-induced neuritis. The time-course is varied and the emergence of pain syndromes can be delayed by several years after the completion of treatment. Risk factors include the total radiation dose, fractionation schedule, and radiation field size. Spinal cord stimulation (SCS) may have an important role in attenuating the symptoms of radiation-induced neuritis. Objectives: We aim to characterize a case series of oncologic patients who underwent SCS to treat iatrogenic radiation neuritis of the lumbosacral nerve roots. Study Design: This is a retrospective review of 4 cases of patients who were eligible for either intrathecal drug delivery or SCS (magnetic resonance imaging [MRI] conditional devices for spine surveillance), of which each patient elected to have a SCS trial and possible permanent implantation. Setting: The data were collected at a major cancer center in the US. Methods: In this case series, we present 4 patients with radiation-induced neuropathy. For each patient, we describe the use of SCS, which uses electric impulse generation, in an effort to treat the patient’s symptoms. To assess for efficacy, we compare pre- and post-procedure numerical rating scale (NRS) pain scores and post-procedure pain medication requirements. Results: Each patient had marked improvement in their pain (> 50%) during the trial lead placement and proceeded to the permanent implant. In subsequent months and years, the patients decreased their opioid utilization and reported an improvement in their overall pain. Limitations: This case series is a small sample size of heterogeneous malignancies with radiation treatment to the spine. Conclusions: Radiation-induced neuritis remains a severe and limiting outcome that some patients must live with after RT. Survivors of malignancy have often found this pathology to severely impact their quality of life, and it is difficult to treat. We have described the utilization of spinal cord neuromodulation as an effective treatment modality in the spine tumor patient population. Further research is needed to maximize the benefit and ensure appropriate case selection in the future. Key words: Radiation neuritis, radiation neuropathy, oncologic lumbar radiculopathy, spinal cord stimulation, neuromodulation, dorsal column stimulation, spinal tumor pain, MRI conditional spinal cord stimulation

Dorsal Column Stimulation Treats Pain from Chemotherapy-induced, Small Fiber Neuropathy

Small fiber neuropathy (SFN) is a disorder of small afferent nerve fibers that can result in debilitating pain and functional limitations. There are many etiologies including, but not limited to, diabetes, vitamin deficiencies, infections, and exposure to neurotoxic drugs such as chemotherapeutics. The constellation of signs and symptoms overlap with other disease states leading to potential misdiagnosis. New tests including histologic studies of skin biopsies and autonomic nerve tests have emerged in the last 20 years improving differentiation between these disease processes and SFN. Multiple chemotherapeutic medications have been implicated in causing SFN, including vincristine which was the causative agent in this case report. The exact incidence of chemotherapy-induced peripheral neurotoxicity (CIPN) is currently unknown, but according to some publications it has been reported to be as high as 40% in patients that have been treated with chemotherapy. As the number of cancer survivors continues to grow, the number of patients with painful SFN will potentially increase. Devising an effective analgesic regimen for patients with painful SFN can be difficult, and often requires the pain physician to employ multiple pharmacologic and non-pharmacologic therapies. Treatments include analgesics from several drug classes: antidepressants, opioids, and anticonvulsants. Often times however, more advanced interventional techniques must be employed as effective pain control may be limited by medication side effects or inadequate return of function. While dorsal column stimulation was approved for a limited number of applications, a number of new applications are reported in the literature. In this paper, we present a case of vincristineinduced SFN successfully treated with neuromodulation via spinal cord stimulator. Key words: Vincristine, vinblastine, chemotherapy- induced neuropathy, chronic pain, spinal cord stimulation, dorsal column stimulation, neuromodulation, small fiber neuropathy, neuropathic pain