Epidural Abscess Due to Spinal Cord Stimulator Trial

Epidural spread of surgical site infection from spinal cord stimulation trial

We present a case of deep surgical site infection (SSI) at a spinal cord stimulator (SCS) trial implantation site, resulting from an allergic reaction to an unknown agent. A 38-year-old female with complex regional pain syndrome began an SCS trial, noting 100% pain relief for 5 days. Fluid drainage from the surgical site was reported on POD6 and trial leads were removed the following day. The patient was hospitalized with sepsis. Blood cultures revealed Staphylococcus aureus. MRIs showed skin breakdown and cellulitis of the paraspinal musculature extending into the epidural space. The patient was maintained with antibiotics and rigorous wound care for 9 days and the surgical site infection resolved. The patient proceeded to SCS implantation, and reported good pain relief with the implanted device.

Cervical spinal cord stimulator trial complicated by epidural abscess

Back ground

Spinal cord stimulation (SCS) is a growing interventional treatment modality in patients experiencing intractable pain refractory to conservative treatments. Many patients with chronic low back and leg pain that persists after surgery have found pain relief, and more evidence is suggesting that chronic upper limb and neck pain may respond just as well to this therapy. However, the placement of foreign body, for instance SCS leads, in the epidural space can become the source for deep intra-spinal infection.

Case report

We present a 49-year-old robust male who underwent a temporary cervical SCS trial and was diagnosed with epidural abscess on the day 9 when the leads were pulled. The trial phase was complicated by immediate and prolonged post procedure pain. The diagnosis of epidural abscess was made soon after clinical presentation with no neurological deficits or escalation in pain but new onset fever. He made a complete recovery after extensive laminectomy and antibiotic treatment.

Conclusion

The decision to extend the SCS trial length poses a question of risk versus benefit in regards to potential infectious complications versus pain relief. Continuing antibiotic therapy during a SCS trial phase is a possible strategy but of uncertain benefit.

Categories

Anesthesiology, Pain Management.

Factfinders for patient safety: Antibiotics for disc access and spinal cord stimulation trials

This series of FactFinders presents a brief summary of the evidence and outlines recommendations regarding the use of antibiotics for disc access and spinal cord stimulation trials. The evidence in support of the following facts is presented: (1) There is a low but nonzero risk of discitis due to percutaneous intervertebral disc access. Strategies to mitigate this risk include use of strict aseptic technique, use of a needle stylet, and prophylactic intravenous or intra-discal antibiotics. (2) In low-risk patients, it may not be necessary to continue antibiotics throughout the percutaneous or staged trial period; however, in high-risk patients, or in trials lasting more than five days, antibiotics should be considered on a case-by-case basis.

A Comprehensive Review of Spinal Cord Stimulator Infections

Spinal cord stimulator (SCS) is approved to treat various pain conditions and is commonly seen in the chronic pain patient population. Due to the nature of the device and its location, infections associated with SCS have a particularly high morbidity. According to post-market data and medical device reports, 87% of patients receiving SCS implants were given perioperative antibiotics as the implantable neurostimulator or receiver pocket serve as the most common sites of infection. The most common antibiotics for surgical prophylaxis given are first-generation cephalosporins (cefalexin, cefazolin) at the time of implantation. If deep infection is suspected, imaging in the form of CT scan should be obtained as physical exam is not always sufficient. For infections involving the epidural space, vertebra, or intervertebral discs, MRI is the preferred imaging modality. If meningitis is suspected, a lumbar puncture is recommended. Positive cultures can help guide antibiotic therapy.

A case series of new radicular pain following the insertion of spinal cord stimulator

Purpose

Although spinal cord stimulation (SCS) is a safe procedure, equipment-related, biological and neurological complications have been observed in previous research, particularly case reports. No reports of new neuropathic pain in the absence of neurological deficit or positive MRI findings have been described. We detail three cases of new-onset radicular pain in the L5/S1 dermatome following insertion of SCS.

Methods

This was a retrospective case series of three patients. Details of clinical background, indications for SCS and events occurring during insertion and further management were recorded.

Results

All three cases were technically difficult and required multiple epidural entry levels, with repeated passage of the electrode into and within the epidural space. All cases involved accessing epidural space T12/L1 and L1/L2. A possible explanation for the new-onset radicular pain could concern oedema to the conus medullaris, resulting from repeated passage of the electrode at the T12/L1 level. Alternative explanations could be direct trauma to transiting nerve roots, neuroplastic changes resulting in peripheral and central sensitisation and immune-mediated nerve injury.

Conclusion

MRI imaging should be analysed prior to the SCS procedure to identify the level of the conus medullaris, with the aim of avoiding repeated passage of electrodes at that level. Unintended neurological adverse events should be discussed with patients during the consent process. Careful patient selection and psychological screening may also help identify patients who may be unlikely to respond to SCS therapy. Further reporting of new radiculopathic pain following SCS insertion is required to strengthen understanding of its potential causes.

Cervical epidural abscess due to implantation of a spinal cord stimulation lead

Spinal cord stimulation (SCS) for intractable pain syndromes has become a pillar of modern pain management. Common complications include lead migration, implant infection, cerebral spinal fluid leak, and lead fracture. Spinal epidural abscess due to spinal cord stimulator implantation is a very rare occurrence with only two cases reported in the literature so far. We present an illustrative case and discuss the pathophysiology and best clinical management for this very rate entity.

Spinal Cord Stimulator Infection: Approach to Diagnosis, Management, and Prevention

Spinal cord stimulation (SCS) is the most utilized invasive electrical neuromodulation treatment for the management of refractory chronic pain syndromes. Infection is one of the most dreaded complications related to SCS implantation and may prevent patients from receiving adequate pain treatment, adding to the initial cost and disability. Most SCS infections present as generator pocket infection. However, delay in diagnosis may lead to complications such as meningitis, epidural abscess, and/or vertebral osteomyelitis. Early recognition of SCS-related infections and associated complications is based on clinical suspicion, laboratory testing, and appropriate diagnostic imaging. While superficial surgical site infection following SCS implant may be treated with antibiotic therapy alone, deep infection involving implant warrants device removal to achieve cure. Duration of antimicrobial therapy depends on severity of clinical presentation and presence or absence of associated complications. Several preventive strategies can be incorporated in surgical practice to reduce the risk of SCS infection.

Electrode movement prevention – an animal model

Electrode migration is the most common complication of spinal cord stimulation (SCS). The problem of longitudinal migration has already been solved, but lateral migration remains the most common current complication. The present article describes new electrodes fixation opportunities for the reduction of lateral migration in SCS. The pig was chosen as an animal model to illustrate a new protocol of electrode fixation for the control of lateral and longitudinal migration. The displacement of the electrode was measured using two different optical methods: the digital image stereo-correlation and the digital image processing methods. Fixation with two anchors has always considerably reduced electrode displacement and when fixation is done with two anchors and a loop then lateral migration is reduced by 62.5 % and longitudinal migration is reduced by 94.1 %. It was shown that the results are significantly different at the α=0.001 significance level. Based on a statistical evaluation it is possible to state that the differences between experimental results obtained for three different protocols of lead fixation are statistically significant and we can recommend the new fixation method for common practice.

Epidural Abscess During a Spinal Cord Stimulator Trial: A Case Report

BACKGROUND

Spinal cord stimulation (SCS) can be beneficial for low back and radicular pain. A short trial of SCS evaluates the potential effectiveness of this therapy for a specific patient, while also decreasing the likelihood of a failed permanent implant. While rare, an epidural abscess is difficult to diagnose based on its nonspecific and unreliable clinical presentation.

CASE

We present a case of an acute-onset methicillin-sensitive Staphylococcus aureus epidural abscess 72 to 96 hours into a trial of a percutaneous spinal cord stimulator. The patient had no prior medical history of an immunocompromised state or other significant risk factors.

DISCUSSION

An epidural abscess can rapidly arise from an SCS trial despite strict aseptic technique and prophylactic pre-procedural antibiotics. Spinal epidural abscesses are being detected earlier, and an increasing number of patients are being managed medically. However, it may be challenging to differentiate focal back pain from acute or chronic pain, expected post-procedural pain, and a new entity such as an abscess.

The Neurostimulation Appropriateness Consensus Committee (NACC) Recommendations for Infection Prevention and Management

INTRODUCTION

The use of neurostimulation for pain has been an established therapy for many decades and is a major tool in the arsenal to treat neuropathic pain syndromes. Level I evidence has recently been presented to substantiate the therapy, but this is balanced against the risk of complications of an interventional technique.

METHODS

The Neurostimulation Appropriateness Consensus Committee (NACC) of the International Neuromodulation Society convened an international panel of well published and diverse physicians to examine the best practices for infection mitigation and management in patients undergoing neurostimulation. The NACC recommendations are based on evidence scoring and peer-reviewed literature. Where evidence is lacking the panel added expert opinion to establish recommendations.

RESULTS

The NACC has made recommendations to improve care by reducing infection and managing this complication when it occurs. These evidence-based recommendations should be considered best practices in the clinical implantation of neurostimulation devices.

CONCLUSION

Adhering to established standards can improve patient care and reduce the morbidity and mortality of infectious complications in patients receiving neurostimulation.

The Neurostimulation Appropriateness Consensus Committee (NACC) Safety Guidelines for the Reduction of Severe Neurological Injury

INTRODUCTION

Neurostimulation involves the implantation of devices to stimulate the brain, spinal cord, or peripheral or cranial nerves for the purpose of modulating the neural activity of the targeted structures to achieve specific therapeutic effects. Surgical placement of neurostimulation devices is associated with risks of neurologic injury, as well as possible sequelae from the local or systemic effects of the intervention. The goal of the Neurostimulation Appropriateness Consensus Committee (NACC) is to improve the safety of neurostimulation.

METHODS

The International Neuromodulation Society (INS) is dedicated to improving neurostimulation efficacy and patient safety. Over the past two decades the INS has established a process to use best evidence to improve care. This article updates work published by the NACC in 2014. NACC authors were chosen based on nomination to the INS executive board and were selected based on publications, academic acumen, international impact, and diversity. In areas in which evidence was lacking, the NACC used expert opinion to reach consensus.

RESULTS

The INS has developed recommendations that when properly utilized should improve patient safety and reduce the risk of injury and associated complications with implantable devices.

CONCLUSIONS

On behalf of INS, the NACC has published recommendations intended to reduce the risk of neurological injuries and complications while implanting stimulators.

The Incidence of Spinal Cord Injury in Implantation of Percutaneous and Paddle Electrodes for Spinal Cord Stimulation

OBJECTIVE

Spinal cord stimulation (SCS) has been proven effective for multiple chronic pain syndromes. Over the past 40 years of use, the complication rates of SCS have been well defined in the literature; however, the incidence of one of the most devastating complications, spinal cord injury (SCI), remains largely unknown. The goal of the study was to quantify the incidence of SCI in both percutaneous and paddle electrode implantation.

METHODS

We conducted a retrospective review of the Thomson Reuter's MarketScan database of all patients that underwent percutaneous or paddle SCS implantation from 2000 to 2009. The main outcome measures of the study were the incidence of SCI and spinal hematoma within 30 days following operation.

RESULTS

Overall 8326 patients met inclusion criteria for the study (percutaneous: 5458 vs. paddle: 2868). The overall incidence of SCI was 177 (2.13%) (percutaneous: 128 (2.35%) vs. paddle: 49 (1.71%), p = 0.0556). The overall incidence of spinal hematoma was 59 (0.71%) (percutaneous: 41 (0.75%) vs. paddle: 18 (0.63%), p = 0.5230).

CONCLUSION

Our study shows that the overall incidence of SCI in SCS is low (2.13%), supporting that SCS is a safe procedure. No significant difference was found in the rates of SCI or spinal hematoma between the percutaneous and paddle groups. Further studies are needed to characterize the mechanisms of SCI in SCS and long-term outcomes in these patients.

Spinal stimulator peri-electrode masses: case report

The authors describe a case of delayed spastic quadriparesis caused by a peri-electrode mass following the implantation of a minimally invasive percutaneous spinal cord stimulator (SCS). Prior reports with paddle-type electrodes are reviewed, and a detailed histological and pathophysiological comparison with the present case is made. The patient developed tolerance to a cervical percutaneous SCS 4 months after implantation, followed by the onset of spastic quadriparesis 9 months after implantation. The stimulator was removed, and contrast-enhanced MRI revealed an enhancing epidural mass where the system had been placed, with severe spinal cord compression. Decompression was carried out, and the patient experienced neurological improvement. Pathological examination revealed fibrotic tissue with granulomatous and multinucleated giant cell reactions. No evidence of infection or hemorrhage was found. Professionals treating patients with SCSs or contemplating their insertion should be aware of this delayed complication and associated risk factors.

Novel use of noninvasive high-intensity focused ultrasonography for intercostal nerve neurolysis in a swine model

BACKGROUND

High-intensity focused ultrasound (HIFU) is a noninvasive thermal ablation technique. High-intensity focused ultrasound has been used in small-animal models to lesion neural tissue selectively. This study aimed to evaluate the efficacy of HIFU in a large-animal model for ablation of nerves similar in size to human nerves.

METHODS

Twelve acute magnetic resonance-guided HIFU ablation lesions were created in intercostal nerves in a swine model. In a second pig, as a control, 4 radiofrequency ablation and 4 alcohol lesions were performed on intercostal nerves under ultrasound guidance. Preprocedural and postprocedural magnetic resonance imaging was then performed to evaluate radiologically the lesion size created by HIFU. Animals were euthanized 1 hour postprocedure, and necropsy was performed to collect tissue samples for histopathologic analysis.

RESULTS

On gross and histological examination of the intercostal nerve, acute HIFU nerve lesions showed evidence of well-demarcated, acute, focally extensive thermal necrosis. Four intercostal nerves ablated with HIFU were sent for histopathologic analysis, with 2 of 4 lesions showing pathologic damage to the intercostal nerve. Similar results were shown with radiofrequency ablation technique, whereas the intercostal nerves appeared histologically intact with alcohol ablation.

CONCLUSIONS

High-intensity focused ultrasound may be used as a noninvasive neurolytic technique in swine. High-intensity focused ultrasound may have potential as a neuroablation technique for patients with chronic and cancer pain.

Prospective clinical study of a new implantable peripheral nerve stimulation device to treat chronic pain

OBJECTIVES

To evaluate clinical use of the StimRouter, an investigational implanted peripheral nerve stimulator for treating chronic neuropathic pain, using the median nerve as a model for that general application.

METHODS

Eight patients with carpal tunnel syndrome and chronic pain despite both carpal tunnel release and treatment with oral pain medications were enrolled in a single-center, open-label trial after institutional review board approval. Primary endpoints were successful implantation near the target peripheral nerve and safety. All 8 patients were implanted temporarily at the median nerve in at least one arm and 2 patients were implanted bilaterally, with 10 implants total. Each implant was considered a separate "patient." For 5 days, all patients received 6 hours of daily transdermal electrical stimulation targeting the median nerve. Pain was measured at baseline, during implant, and after explant.

RESULTS

Two patients experienced clinically meaningful (>or=30%) pain reduction throughout the entire 5-day treatment period. Apparent carryover effect in pain reduction also was observed after daily stimulation. After explant, pain returned to baseline, increasing 36.8% to 45.6% relative to average reduced pain with daily stimulation. No significant or unexpected adverse events occurred. Mean patient study satisfaction was 96%, and 100% of patients indicated a preference for permanent implant.

DISCUSSION

Temporary implant of the StimRouter device resulted in both pain reduction and reduced use of oral opioid pain medication during the 5-day stimulation period. The results suggest that permanent implant of the StimRouter System may be safe and effective for treating chronic peripheral neuropathic pain.