Spinal Cord Stimulation for Intractable Visceral Pain due to Chronic Pancreatitis

Pain caused by chronic pancreatitis is medically intractable and resistant to conventional interventional or surgical treatment. We report a case of spinal cord stimulation (SCS) for intractable pain due to chronic pancreatitis. The patient had a history of nonalcoholic chronic pancreatitis and multiple emergency room visits as well as repeated hospitalization including multiple nerve block and morphine injection for 3 years. We implanted surgical lead at T6-8 level on this patient after successful trial of percutaneous electrode. The patient experienced a decreased visual analog scale (VAS) scores for pain intensity and amount of opioid intake. The patient was followed for more than 14 months with good outcome and no further hospitalization. From our clinical case, spinal cord stimulation on intractable pain due to chronic pancreatitis revealed moderate pain control outcome. We suggest that SCS is an effective, noninvasive treatment option for abdominal visceral pain. Further studies and long term follow-up are needed to fully understand the effect of SCS on abdominal visceral pain.     

Phrenic Nerve Stimulation for Diaphragm Pacing in a Quadriplegic Patient

Chronic hypoventilation due to injury to the brain stem respiratory center or high cervical cord (above the C3 level) can result in dependence to prolonged mechanical ventilation with tracheostomy, frequent nosocomial pneumonia, and prolonged hospitalization. Diaphragm pacing through electrical stimulation of the phrenic nerve is an established treatment for central hypoventilation syndrome. We performed chronic phrenic nerve stimulation for diaphragm pacing with the spinal cord stimulator for pain control in a quadriplegic patient with central apnea due to complete spinal cord injury at the level of C2 from cervical epidural hematoma. After diaphragmatic pacing, the patient who was completely dependent on the mechanical ventilator could ambulate up to three hours every day without aid of mechanical ventilation during the 12 months of follow-up. Diaphragm pacing through unilateral phrenic nerve stimulation with spinal cord stimulator was feasible in an apneic patient with complete quadriplegia who was completely dependent on mechanical ventilation. Diaphragm pacing with the spinal cord stimulator is feasible and effective for the treatment of the central hypoventilation syndrome.     

Spinal Cord Stimulation Attenuates Below‐Level Mechanical Hypersensitivity in Rats After Thoracic Spinal Cord Injury

ObjectivesThe burden of pain after spinal cord injury (SCI), which may occur above, at, or below injury level, is high worldwide. Spinal cord stimulation (SCS) is an important neuromodulation pain therapy, but its efficacy in SCI pain remains unclear. In SCI rats, we tested whether conventional SCS (50 Hz, 80% motor threshold [MoT]) and 1200 Hz, low-intensity SCS (40% MoT) inhibit hind paw mechanical hypersensitivity, and whether conventional SCS attenuates evoked responses of wide-dynamic range (WDR) neurons in lumbar spinal cord.Materials and MethodsMale rats underwent a moderate contusive injury at the T9 vertebral level. Six to eight weeks later, SCS or sham stimulation (120 min, n = 10) was delivered through epidural miniature electrodes placed at upper-lumbar spinal cord, with using a crossover design. Mechanical hypersensitivity was examined in awake rats by measuring paw withdrawal threshold (PWT) to stimulation with von Frey filaments. WDR neurons were recorded with in vivo electrophysiologic methods in a separate study of anesthetized rats.ResultsBoth conventional SCS and 1200 Hz SCS increased PWTs from prestimulation level in SCI rats, but the effects were modest and short-lived. Sham SCS was not effective. Conventional SCS (10 min) at an intensity that evokes the peak Aα/β waveform of sciatic compound action potential did not inhibit WDR neuronal responses (n = 19) to graded or repeated electrical stimulation that induces windup.ConclusionsConventional SCS and 1200 Hz, low-intensity SCS modestly attenuated below-level mechanical hypersensitivity after SCI. Inhibition of WDR neurons was not associated with pain inhibition from conventional SCS.     

Treatment of Multifocal Pain with Spinal Cord Stimulation

Introduction: We report a retrospective case study of combined treatment of cancer‐related pain and chronic low back and lower extremity pain related to postlaminectomy syndrome (PLS) with one spinal cord stimulation (SCS) system. Methods: The patient underwent an uneventful SCS trial with percutaneous placement of two temporary eight‐electrode leads (Medtronic Inc., Minneapolis, MN) placed at the level of T8‐T9‐T10 and T5‐T6‐T7. Results: After successful trial, he was implanted with permanent leads and generator, reporting sustained pain relief at 12‐month follow‐up visit. Discussion: SCS is a trialable, reversible, and interactive therapy permitting patients to control the level of stimulation they feel based on their degree of pain. Conclusion: SCS provides an effective, alternative treatment for select patients with cancer‐related chest wall pain and pain related to PLS who have failed conservative treatment.     

Anterograde Revision of Cervical Spinal Cord Stimulator Paddle Electrode: A Case Report

Objectives: To illustrate a new surgical revision strategy for malfunctioning spinal cord stimulation (SCS) paddle electrodes. Background: SCS is a treatment for chronic neuropathic pain that delivers therapeutic doses of electric current to the dorsal columns resulting in dermatomal paresthesia and pain reduction. Reasons for SCS failure include hardware malfunction or breakage and medical complications. Case Report: A 34‐year‐old woman presented with a two‐year history of intractable pain in the left upper extremity and thoracic region which was previously controlled by SCS. Imaging demonstrated breakage of the cervical electrode wire that had been advanced in the caudal direction from the C1 spinal level. Revision of the broken electrode was performed by hemilaminectomy of C3‐C4 and the replacement electrode was advanced in the cephalad direction. Results: Ideal and exact paresthesia pattern was confirmed intraoperatively and the patient maintained successful pain reduction at five‐year follow‐up. Conclusion: Advancing SCS electrodes into the upper cervical spine in the cephalad direction, using the previously formed scar capsule, offers an alternate strategy for revision of malfunctioning SCS paddle electrodes.     

Spinal Cord Stimulation Enhances Microglial Activation in the Spinal Cord of Nerve-Injured Rats

Microglia can modulate spinal nociceptive transmission. Yet, their role in spinal cord stimulation (SCS)-induced pain inhibition is unclear. Here, we examined how SCS affects microglial activation in the lumbar cord of rats with chronic constriction injury (CCI) of the sciatic nerve. Male rats received conventional SCS (50 Hz, 80% motor threshold, 180 min, 2 sessions/day) or sham stimulation on days 18–20 post-CCI. SCS transiently attenuated the mechanical hypersensitivity in the ipsilateral hind paw and increased OX-42 immunoreactivity in the bilateral dorsal horns. SCS also upregulated the mRNAs of M1-like markers, but not M2-like markers. Inducible NOS protein expression was increased, but brain-derived neurotrophic factor was decreased after SCS. Intrathecal minocycline (1 μg–100 μg), which inhibits microglial activation, dose-dependently attenuated the mechanical hypersensitivity. Pretreatment with low-dose minocycline (1 μg, 30 min) prolonged the SCS-induced pain inhibition. These findings suggest that conventional SCS may paradoxically increase spinal M1-like microglial activity and thereby compromise its own ability to inhibit pain.     

脊髓和马尾神经损伤后慢性神经源性疼痛外科治疗策略

目的 探讨脊髓和马尾神经损伤后慢性神经源性疼痛的神经外科治疗策略.方法 脊髓和马尾神经损伤后慢性神经源性疼痛20例,年龄28～81岁,病程8个月～50年.共行镇痛手术23次,其中,脊髓背根入髓区显微外科切开术19次,脊髓电刺激术3次,鞘内靶控输注系统植入术1次.采用视觉模拟评分（VAS）来评估手术疗效,以术后疼痛缓解大于75%为疗效优秀,疼痛缓解50%～75%为良好,疼痛缓解小于50%为差.结果 随访6个月～4年,10例疼痛消失,停用镇痛剂,生活质量改善;7例疼痛明显减轻,VAS 2～4分,其中,5例停用镇痛剂,2例镇痛剂使用量明显下降,生活质量改善;3例疼痛无明显改善.结论 脊髓背根入髓区显微外科切开术和脊髓电刺激术对脊髓和马尾神经损伤后慢性神经源性疼痛患者疗效满意,但其适应证有差别,应根据患者的损伤节段、损伤程度和疼痛部位等具体情况选择手术方式.     

Putative mechanisms behind effects of spinal cord stimulation on vascular diseases: a review of experimental studies

Spinal cord stimulation (SCS) is a widely used clinical technique to treat ischemic pain in peripheral, cardiac and cerebral vascular diseases. The use of this treatment advanced rapidly during the late 80's and 90's, particularly in Europe. Although the clinical benefits of SCS are clear and the success rate remains high, the mechanisms are not yet completely understood. SCS at lumbar spinal segments (L2-L3) produces vasodilation in the lower limbs and feet which is mediated by antidromic activation of sensory fibers and decreased sympathetic outflow. SCS at thoracic spinal segments (T1-T2) induces several benefits including pain relief, reduction in both frequency and severity of angina attacks, and reduced short-acting nitrate intake. The benefits to the heart are not likely due to an increase, or redistribution of local blood flow, rather, they are associated with SCS-induced myocardial protection and normalization of the intrinsic cardiac nervous system. At somewhat lower cervical levels (C3-C6), SCS induces increased blood flow in the upper extremities. SCS at the upper cervical spinal segments (C1-C2) increased cerebral blood flow, which is associated with a decrease in sympathetic activity, an increase in vasomotor center activity and a release of neurohumoral factors. This review will summarize the basic science studies that have contributed to our understanding about mechanisms through which SCS produces beneficial effects when used in the treatment of vascular diseases. Furthermore, this review will particularly focus on the antidromic mechanisms of SCS-induced vasodilation in the lower limbs and feet.     

Spinal Geometry and Paresthesia Coverage in Spinal Cord Stimulation

Objective . To test the following hypotheses, based on computer modeling studies of spinal cord stimulation, by the analysis of data from chronic pain patients: I. the probability-of-paresthesia in a dermatome is highest when the cathode is placed at the corresponding segmental level; II. variation of the rostrocaudal position of the cathode in the lower cervical/high thoracic region results in less variation of the probability-of-paresthesia in a dermatome than stimulation in more caudal regions; III. when stimulating in the midthoracic region, the probability-of-paresthesia in a dermatome is low in comparison to other regions when the cathode is not at the corresponding segmental level. Method . The probability-of-paresthesia in 16 body segments as a function of the rostrocaudal position of the cathode was analyzed from the paresthesia coverage with 3,897 bipolar and unipolar combinations from 106 chronic pain patients. Results . The distributions of the probability-of-paresthesia in the upper and lower limb are in accordance with the hypotheses, but different distributions were found in all trunk areas. Conclusion . The success to be expected from spinal cord stimulation in chronic pain management is inversely related to the thickness of the dorsal cerebrospinal fluid layer at the cathode level. Therefore, preoperative measurement from transverse images can be helpful as a predictor for success.     

Anterior spinal artery syndrome of the cervical hemicord

Summary Three patients developed signs of a unilateral cervical cord lesion 6 to 36 h after the acute onset of severe cervico-brachial pain. The neurological deficit progressed over 6 to 18h. On the painful side a central Horner's syndrome, a hemiparesis with plegia of the hand, and a slight pallhypaesthesia were found. On the opposite side thermhypaesthesia and hypalgesia were noted with a level at the dermatome C5 or C6. T2-weighted MR images revealed in one patient a small area of increased signal intensity restricted to one half of the cervical cord, and electromyography in another patient showed after 6 months evidence of segmental chronic denervation. Both abnormalities were found at the clinically expected level. The findings are consistent with a small infarction of the cervical cord in the perfusion territory of a central (sulco-commissural) artery, a duplicated anterior spinal artery or an anterior spinal branch of the vertebral artery.     

Cheiromegaly and podomegaly associated with primary progressive multiple sclerosis: a case report]

Cheiromegaly is an extremely rare syndrome characterized by unilateral hand hypertrophy with hyperhydrosis. Unilateral foot hypertrophy has been described as podomegaly. Cheiromegaly/podomegaly is usually seen in patients with syringomyelia. Although the underlying pathophysiology remains unknown, it is speculated that chronic cervical cord injury including central descending sympathetic tract is essential for development of this syndrome. We report a cheiromegaly/podomegaly in a case with primary progressive multiple sclerosis. This 29-year-old woman developed cheiromegaly and podomegaly in her right hand and foot associated with chronic progressive cervical myelopathy. At age two, she developed transient paraparesis with full recovery, suggesting her symptomatic onset of her longstanding illness. At age 10, she had left leg weakness, and gradually worsened. On admission at age 29, she had muscular weakness in her left upper and both lower extremities. Sensory impairment was seen below her 5th cervical and 6th thoracic dermatome level. Her deep tendon reflexes were exaggerated in all extremities with bilateral Babinski's signs. MR imaging showed multiple plaques in the white matter of the brain associated with cervical spinal cord lesions. Taken together with the presence of oligoclonal band IgG in the cerebrospinal fluid, this patient met the criteria of multiple sclerosis. This is the first report presenting cheiromegaly/podomegaly not associated with syringomyelia, but with multiple sclerosis. It is suggested that cheiromegaly/podomegaly in present case may be caused by chronic cervical cord injury affecting descending central sympathetic tract associated with primary progressive multiple sclerosis.     

Intramedullary Sarcoidosis Presenting with Delayed Spinal Cord Swelling after Cervical Laminoplasty for Compressive Cervical Myelopathy

Sarcoidosis is a systemic disease of unknown etiology that may affect any organ in the body. The nervous system is involved in 5-16% of cases of sarcoidosis. Here, we report a case of intramedullary sarcoidosis presenting with delayed spinal cord swelling after laminoplasty for the treatment of compressive cervical myelopathy. A 56-year-old woman was admitted to our hospital complaining of upper extremity pain and gait disturbance. The patient had undergone laminoplasty for compressive cervical myelopathy 3 months previously. Follow-up magnetic resonance imaging revealed a large solitary intramedullary lesion with associated extensive cord swelling, signal changes, and heterogeneous enhancement of spinal cord from C2 to C7. Spinal cord biopsy revealed non-necrotizing granulomas with signs of chronic inflammation. The final diagnosis of sarcoidosis was based upon laboratory data, imaging findings, histological findings, and the exclusion of other diagnoses. Awareness of such presentations and a high degree of suspicion of sarcoidosis may help arrive at the correct diagnosis.     

Spatiotemporal Distribution of Electrically Evoked Spinal Compound Action Potentials During Spinal Cord Stimulation

ObjectivesRecent studies using epidural spinal cord stimulation (SCS) have demonstrated restoration of motor function in individuals previously diagnosed with chronic spinal cord injury (SCI). In parallel, the spinal evoked compound action potentials (ECAPs) induced by SCS have been used to gain insight into the mechanisms of SCS-based chronic pain therapy and to titrate closed-loop delivery of stimulation. However, the previous characterization of ECAPs recorded during SCS was performed with one-dimensional, cylindrical electrode leads. Herein, we describe the unique spatiotemporal distribution of ECAPs induced by SCS across the medial-lateral and rostral-caudal axes of the spinal cord, and their relationship to polysynaptic lower-extremity motor activation.Materials and MethodsIn each of four sheep, two 24-contact epidural SCS arrays were placed on the lumbosacral spinal cord, spanning the L3 to L6 vertebrae. Spinal ECAPs were recorded during SCS from nonstimulating contacts of the epidural arrays, which were synchronized to bilateral electromyography (EMG) recordings from six back and lower-extremity muscles.ResultsWe observed a triphasic P1, N1, P2 peak morphology and propagation in the ECAPs during midline and lateral stimulation. Distinct regions of lateral stimulation resulted in simultaneously increased ECAP and EMG responses compared with stimulation at adjacent lateral contacts. Although EMG responses decreased during repetitive stimulation bursts, spinal ECAP amplitude did not significantly change. Both spinal ECAP responses and EMG responses demonstrated preferential ipsilateral recruitment during lateral stimulation compared with midline stimulation. Furthermore, EMG responses were correlated with stimulation that resulted in increased ECAP amplitude on the ipsilateral side of the electrode array.ConclusionsThese results suggest that ECAPs can be used to investigate the effects of SCS on spinal sensorimotor networks and to inform stimulation strategies that optimize the clinical benefit of SCS in the context of managing chronic pain and the restoration of sensorimotor function after SCI.     

Estimulación de la médula espinal: más allá del manejo del dolor

IntroductionThe gate control theory of pain was the starting point of the development of spinal cord stimulation (SCS). We describe the indications for the treatment in pain management and other uses not related to pain.DevelopmentThere are currently several paradigms for SCS: tonic, burst, and high frequency. The main difference lies in the presence of paraesthesias. SCS is most beneficial for treating neuropathic pain. Patients with failed back surgery syndrome show the best response rates, although a considerable reduction in pain is also observed in patients with complex regional pain syndrome, diabetic neuropathy, radiculopathy, and low back pain without previous surgery. Phantom pain or pain related to cardiovascular or peripheral vascular disease may improve, although there is a lack of robust evidence supporting generalisation of its use. SCS also improves cancer-related pain, although research on this issue is scarce. Non-pain-related indications for SCS are movement disorders, spasticity, and sequelae of spinal cord injury. The main limiting factors for the use of SCS are mechanical complications and the cost of the treatment.ConclusionIn its 50-year history, SCS has progressed enormously. The perfection of hardware and software may improve its effectiveness and reduce the rate of complications. Indications for SCS could include other diseases, and its use could be expanded, if the costs of the technology are reduced.     

Attenuation by spinal cord stimulation of a nociceptive reflex generated by colorectal distention in a rat model

The mechanisms underlying the cause and treatment of visceral pain of gastrointestinal origin are poorly understood. Previous clinical studies have shown that spinal cord stimulation (SCS) attenuates neuropathic and ischemic pain, and animal experiments have provided knowledge about probable physiological mechanisms. The goal of the present study was to investigate whether SCS influences colonic sensitivity in a conscious rat. A visceromotor behavioral response (VMR), induced by colorectal distention, was used to quantify the level of colonic sensitivity. Under anesthesia, an electrode (cathode) was placed on the dorsal surface of the spinal cord at L1. One week after implantation of the SCS electrode, the effects of stimulation delivered with different intensities (50 Hz, 0.2 ms for 30 min) on colonic sensitivity were determined. Nociceptive levels of colorectal distention (60 mm Hg for 10 min) induced an enhanced VMR quantified as an increased number of abdominal muscle contractions compared to controls in which the balloon catheter was inserted into the colorectal region but not distended. Colonic sensitization with acetic acid increased the VMR to innocuous levels of colorectal distention (30 mm Hg for 10 min). We found that SCS induced a significant depression of the VMR produced by colorectal distention in both normal rats and those with sensitized colons. The suppressive effect of SCS on colonic sensitivity suggests that SCS may have therapeutic potential for the treatment of visceral pain of gastrointestinal origin associated with abdominal cramping and painful abdominal spasms.     

Neuromodulation of lower limb motor control in restorative neurology

One consequence of central nervous system injury or disease is the impairment of neural control of movement, resulting in spasticity and paralysis. To enhance recovery, restorative neurology procedures modify altered, yet preserved nervous system function. This review focuses on functional electrical stimulation (FES) and spinal cord stimulation (SCS) that utilize remaining capabilities of the distal apparatus of spinal cord, peripheral nerves and muscles in upper motor neuron dysfunctions. FES for the immediate generation of lower limb movement along with current rehabilitative techniques is reviewed. The potential of SCS for controlling spinal spasticity and enhancing lower limb function in multiple sclerosis and spinal cord injury is discussed. The necessity for precise electrode placement and appropriate stimulation parameter settings to achieve therapeutic specificity is elaborated. This will lead to our human work of epidural and transcutaneous stimulation targeting the lumbar spinal cord for enhancing motor functions in spinal cord injured people, supplemented by pertinent human research of other investigators. We conclude that the concept of restorative neurology recently received new appreciation by accumulated evidence for locomotor circuits residing in the human spinal cord. Technological and clinical advancements need to follow for a major impact on the functional recovery in individuals with severe damage to their motor system.     

Peripheral nerve grafts after cervical spinal cord injury in adult cats

Peripheral nerve grafts (PNG) into the rat spinal cord support axon regeneration after acute or chronic injury, with synaptic reconnection across the lesion site and some level of behavioral recovery. Here, we grafted a peripheral nerve into the injured spinal cord of cats as a preclinical treatment approach to promote regeneration for eventual translational use. Adult female cats received a partial hemisection lesion at the cervical level (C7) and immediate apposition of an autologous tibial nerve segment to the lesion site. Five weeks later, a dorsal quadrant lesion was performed caudally (T1), the lesion site treated with chondroitinase ABC 2 days later to digest growth inhibiting extracellular matrix molecules, and the distal end of the PNG apposed to the injury site. After 4-20 weeks, the grafts survived in 10/12 animals with several thousand myelinated axons present in each graft. The distal end of 9/10 grafts was well apposed to the spinal cord and numerous axons extended beyond the lesion site. Intraspinal stimulation evoked compound action potentials in the graft with an appropriate latency illustrating normal axonal conduction of the regenerated axons. Although stimulation of the PNG failed to elicit responses in the spinal cord distal to the lesion site, the presence of c-Fos immunoreactive neurons close to the distal apposition site indicates that regenerated axons formed functional synapses with host neurons. This study demonstrates the successful application of a nerve grafting approach to promote regeneration after spinal cord injury in a non-rodent, large animal model.     

Spinal Cord Injury Induced by a Cervical Spinal Cord Stimulator

Objective: The use of cervical spinal cord stimulators for the treatment of refractory neck and upper extremity pain is widely accepted and growing in use as a treatment modality. This case highlights a previously unreported potential complication of spinal cord stimulators. Methods: Analysis of a patient with a cervical spinal cord stimulator presenting with a spinal cord injury. Patient was followed from presentation in the emergency room until 1‐year follow‐up in the office. Results: The patient in this case presented after a fall and sustained a cervical spinal cord injury induced by the electrodes of her spinal cord stimulator working as a space occupying mass. Conclusion: As more patients are undergoing implantation of spinal cord stimulators we must be aware of the long‐term risks that can be encountered.     

Treatment of Chronic Chest Wall Pain in a Patient With Loeys-Dietz Syndrome Using Spinal Cord Stimulation

Objective: Spinal cord stimulation (SCS) has been used with increased frequency for the treatment of intractable pain including chronic chest pain. Methods: The patient with a history of Loeys‐Dietz syndrome who underwent repair of pectus excavatum with subsequent chronic chest wall pain underwent an uneventful SCS trial with percutaneous epidural placement of two temporary eight‐electrode leads placed at the level of T3‐T4‐T5. Results: After experiencing excellent pain relief over the next two days, the patient was implanted with permanent leads and rechargeable generator four weeks later and reported sustained pain relief at 12‐month follow‐up visit. Conclusion: SCS provides an effective, alternative treatment option for select patients with Loeys‐Dietz syndrome who underwent repair of pectus excavatum with subsequent chronic chest wall pain who have failed conservative treatment. SCS may provide pain relief with advantages over conservative treatments and more invasive techniques.     

Recommendations for patient selection in spinal cord stimulation

Studies have shown that spinal cord stimulation (SCS) can reduce chronic pain by at least 50% over prolonged periods, improve function and quality-of-life, reduce requirements for healthcare resources and enable return to work in appropriately selected patients. However, SCS does not provide pain relief in all patients and is an expensive, labor intensive and invasive procedure with complications and ongoing management that requires specialists with specific skills and judgment. Multidisciplinary selection of appropriate patients for SCS is essential to achieve maximal benefit from the procedure. The aim of the article is to provide a clinical practice guide to the likely effectiveness of SCS in treating various types of chronic pain, as supported by the literature. The article will summarize indications and contraindications for SCS, provide guidance on the selection and timing for referral, and highlight the benefits and complications associated with the procedure.