RENEW OR SUBSCRIBE TO PPM
Subscription is FREE for qualified healthcare professionals in the US.
14 Articles in Volume 19, Issue #5
Agonism and Antagonism of the Muscles of the Shoulder Joint: An SEMG Approach
Analgesics of the Future: The Potential of IV Formulations for Post-Op Treatment of Pain
Blood Biomarkers Show Promise for Precision Pain Management
Can I Call Myself a “Pain Specialist?”
Cases in Urine Drug Monitoring Interpretation: How to Stay in Control (Part 2)
Fear-Avoidance and Chronic Pain: Helping Patients Stuck in the Mouse Trap
How to Avoid Patient Alienation When Discussing Stress
Managing Phantom Limb Pain with Medication
Nerve Blocks Lead to Improved Quality of Life
Sacroiliac Joint Dysfunction: New Methods in Evaluation and Management
SCS Therapy in a Patient with Advanced Bilateral Kienbocks
Thoracic Epidural Abscess with Cord Compression Following a High-Frequency SCS Trial
What is the evidence to support clonidine as an adjuvant analgesic?
What’s In A Name? In This Case, That Which We Call Addiction Is Not Dependence

Thoracic Epidural Abscess with Cord Compression Following a High-Frequency SCS Trial

After an unfortunate complication of spinal cord compression resulting from a brief stimulator trial, the authors share how they approached further care.
Pages 24-27

The current rise in opioid narcotic dependency and its correlation with patients living in chronic pain is well known. A study from the Institute of Medicine reported that more than 100 million Americans suffer from chronic pain, many of whom have spine-related pain complaints.1,2 Given the declared opioid crisis, it is pertinent for clinicians to consider non-opioid alternatives such as spinal cord stimulation (SCS) for the management of chronic spine-related pain. Recent evidence of SCS interventions have demonstrated an overall opioid-sparing effect,1,3 however increased utilization of these minimally invasive procedures may lead to an increased incidence of complications.4 Potential complications that may occur including spinal epidural abscess (SEA), which raises the question as to what guidelines need to be instituted for both SCS trials and permanent SCS implants.

In general, SCS is considered an effective, minimally invasive, and reversible intervention for patients with complex regional pain syndrome (CRPS), failed back surgery syndrome (FBSS), and post-laminectomy syndrome (PLS).5,6 Inhibition of pain transmission along the dorsal column via electrical stimulation has been documented as early as 50 years ago by Norman Shealy, MD [now an editorial advisory board member to this journal], when the first neuroaugmentive device was placed in 1967.5,7 Since that time, the utilization of SCS treatments for other pain syndromes have been well studied and found to not only provide pain relief for patients but to have an overall reduction in patient opioid requirements.3 While the risk for life-threatening complications related to SCS trials are low, complications have been reported given the increased use.1 More common complications include lead migration, surgical site infection, cerebral spinal fluid leakage, pain at surgical or implant site.1,8 Less common complications include epidural abscess and even more rare development of cord compression as a result of an abscess or hematoma.

High morbidity outcomes associated with SEA tend to result from nonspecific presentations, which may lead to a delay in diagnosis in up to 75% of cases.9 Although SEA is uncommon, studies have shown an incidence as high as two cases per 10,000 hospital admissions, with an expected further rise given the increased prevalence of patients with risk factors for spinal epidural abscess.9-11 Risk factors may include: diabetes mellitus, morbid obesity, ethanol and/or intravenous drug abuse, immunocompromised states, previous spinal surgeries, epidural SCS or catheters, as well as local or systemic infections.9-12 Methicillin-resistant Staphylococcus aureus (MRSA) accounts for the majority of SEA cases with MRSA incidence increasing.9-14

Back pain is the most common presenting symptom of SEA, as typically severe and localized with a duration of one day to two months prior to presentation.9,10,13 Fever is typically found in 50% of cases and point tenderness is even less reported.6,7,10 Of the reported cases, neurological symptoms have only been noted in half, with sudden paralysis and urinary retention rarely reported.9,10 Mortality has significantly decreased from 15% in the mid-1990s due to medical advances such as MRI, antibiotics, and advanced surgical technique.1,15 In SCS trials, the Standard of Operating Procedures (SOP) guidelines set by the Neurostimulation Appropriateness Consensus Committee (NACC) for implantation includes perioperative antibiotic, not post-operative antibiotic therapy.16 Utilization of post-operative antibiotics is often reserved for those patients with increased risk factors as stated above.16

Figures 1 and 2. MRIs of the thoracic and lumbar spine of a 47-year-old woman show bone destruction of T11 and T12, with paravertebral abscess and epidural abscess (Richman Photo, Shutterstock).

Below is a retrospective case report of a patient with PLS and radiculopathy who developed SEA within days of the trial insertion.

Case: Spinal Epidural Abscess after SCS Trial for Post-Laminectomy Syndrome with Radiculopathy

The patient was a 51-year-old male with chronic back pain secondary to PLS with radiculopathy. He had received thoracic and lumbar laminectomies and fusions three years prior. Conservative management included chronic oral narcotics, other adjuvant medications, physical therapy, psychiatric evaluation, and various minimally invasive interventional procedures. Pain was reported as thoracic and lumbar spinal distribution with radiation to bilateral lower extremities with associated numbness, tingling, and muscle weakness. After limited response to conservative therapy and evaluation with neurosurgery, the patient was recommended for an SCS trial.

Preoperatively, on the day of procedure, 1 g of IV vancomycin was administered. The skin was prepped with three series of betadine and a sterile drape was applied. Sterile drying towels were applied, and skin was prepped again with a 2% CHG / 70% isopropyl alcohol solution. Utilizing sterile technique with full gown, gloves, and drapes, fluoroscopic guidance was used to identify the epidural space.

The epidural space was accessed at levels T9 to T10. At that time, the device trial leads were soaked in antibiotic solution and advanced in the posterior epidural space under continued antero-posterior (AP) fluoroscopic guidance. The leads were advanced without eliciting paresthesia up to level of T7 with verification of the leads in AP and lateral fluoroscopic views. Impedance measurements of bilateral leads were within normal limits. The leads were protected with the antibiotic ointment and steri-strips, then secured with sterile tegaderm and adhesive tape. The patient was discharged home with no complaints or signs of complications.

On post-operative Day 1, the patient reported minimal improvement utilizing the SCS at 1000 Hz. He denied fever, chills, urinary retention/incontinence, or worsening sensation/motor deficits. Pain reported was similar to the patient’s presentation before the SCS trial. However, on a repeated X-ray, it appeared that the left epidural lead may have migrated cephalad from original placement. Patient presented to our office where the left lead was adjusted under sterile conditions with impedance monitoring. Days after readjustment, the patient continued to report minimal improvement and, thus, the stimulator was removed in the office under sterile conditions two days after placement. The lumbar insertion site was unremarkable at that time, without signs of infection.

Patient reported persistent pain after removal of the SCS trial leads and was instructed multiple times to present to our medical center emergency department or to the pain management office for examination and evaluation. Unfortunately, the patient declined medical advice until presenting to our facility 10 days after the SCS trial. On physical examination, the patient had worsened bilateral lower extremity weakness and gait imbalance, but no new sensory deficits. Patient was afebrile, normotensive, and all laboratory blood work was normal, including white blood cell (WBC) levels. During the ER course of admission, the patient developed urinary retention and complete loss of sensation from bilateral feet to the T10 distribution. On repeated physical examination, the patient showed reduced lower extremity motor capabilities, loss of bilateral Achilles, patellar, and cremaster reflexes, along with loss of rectal sphincter tone. MRI of the thoracic spine showed an abscess/phlegmonous change with regional osteomyelitis involving T7, T8, T9, T10 with moderate to severe central narrowing with thoracic cord compression.

Surgical decompression was performed on this patient without complication with frank purulent material expelled from the epidural space. An epidural drain was placed, and empiric broad-spectrum antibiotics were utilized for the postoperative period. During hospital course, the patient had improvement of motor and sensory deficits, and was ambulating with physical therapy. Surgical cultures yielded methicillin-sensitive Staphylococcus aureus (MSSA). Patient was discharged to inpatient rehabilitation. On post-operative Day 2, he reported a return of urinary function and also had significant improvement in both sensation and motor function of bilateral lower extremities.

Neuraxial implantation of any foreign body may serve as a nidus for infection and subsequent development of a spontaneous epidural abscess. (Source: 123RF)

Discussion 

Comparable Cases

Neuraxial implantation of any foreign body may serve as a nidus for infection and subsequent development of a spontaneous epidural abscess.17 However rare, infection rates may be as high as 2 to 5% for permanent SCS implantations, despite aseptic surgical technique, preoperative antibiotic use, and proper occlusive dressing application.5,17-19 This case presents a severe and emergent SEA with cord compression resulting from an SCS trial just 10 days after removal of the leads. In a literature search, there were very few cases of SEA reported to have occurred during an SCS trial compared to an SCS permanent insertion, let alone progression to cord compression greater than one week after removal of the implant.1,13,20 Large-scale studies have not determined into SCS trial infection rates as there are very few published cases.1,18 The first published case study of an epidural abscess in an SCS trial implantation was reported by Rauchwerger, et al, in 2008.17 In that trial, the patient demonstrated relief with implantation but subsequently developed fever and severe back pain, with appreciation of purulent drainage from implantation sites within 72 hours of trial.17

A more recent case reported SEA with an SCS trial where the patient presented with back pain, fever, and infection at the insertion sites 72 hours after implantation. The resulting SEA resolved with utilization of intravenous antibiotics.1 In comparison to other published reports, in this case presentation, the patient did not display symptoms of infection like fever, leukocytosis, or neurological symptoms prior to admission to the ER.

Return to the Case

Localized, severe back pain is the most common presenting symptom of SEA, occurring in 70% to 100% of patients.9,11-14 The pain may present anywhere from one day to two months after a spinal procedure.6,9-11,14 The classic textbook symptoms of SEA such as fever and leukocytosis only occur 17% of the time, and neurological deficits are typically reported in only half of those cases with septic presentations.9,10 This prevalence suggests that the typical triad of back pain, fever, and neurological deficits may occur in a minority of patients with SEA. 9,10

With back pain as the most common presenting symptom, early diagnosis is often delayed. It may be challenging to differentiate between pain due to post-procedural pain and pain due to a new entity such as an abscess, especially in the case presented where the patient had known post-laminectomy syndrome.9 Another unique aspect of this case study was the delay in onset of symptoms even after removal of the SCS device, leaving to question whether this particular patient had underlying osteomyelitis or infection prior to insertion (the MRI did show regional osteomyelitis). However, a thoracic spine MRI conducted in 2017 did not show osteomyelitis at that time. There are no current guidelines regarding full spinal MRI utilization for the assessment of SCS trial complications.21

Gaps in Standard of Care Guidelines

The standard of care for trialing SCS lead placement for infection prevention is not as well studied as those published for permanent implant placement.20,22 The NACC’s SOP guidelines include recommendations that, when properly followed, should improve patient safety and reduce risk of complication with implantable devices.16 Key features of preventive measures that clinicians may take include utilization of: aseptic surgical technique, preoperative antibiotic, and a sterile occlusive dressing application.15,19

The role of a prophylactic perioperative antibiotic for SCS trials has been well established, however, the use of post-operative antibiotic has yet to be studied on a larger scale.4,17-19,22 A recent large-scale multicenter retrospective study (n = 2737) SCS permanent implantations showed that utilization of post-operative antibiotics such as Keflex or Clindamycin for an average duration of 7.6 days, resulted in a significant decrease in infection rate.4 However, on literature review, no such studies have been conducted with SCS trials and correlation with post-operative antibiotic.4

Conclusion

The case presented demonstrated a severe complication of a high-frequency SCS trial implantation related to an unusual presentation of spinal epidural abscess, which led to cord compression necessitating urgent surgical intervention. Current guidelines for patient selection, aseptic technique, and periprocedural antibiotic may not be adequate to prevent complications, such as SEA.16 As SEA is reported as an extreme rarity in SCS trials, its incidence may be higher given the difficulty of diagnosis and lack of diagnostic imaging as a standard of care for pain reported post procedure. In addition, the adoption of high-frequency trials has resulted in an increased length of SCS trials, suggesting a need for post-insertion antibiotics.

With the growing US opioid crisis, SCS implantations may offer treatment options for the reduction of narcotic requirements for those patients with failed back surgery syndrome or post-laminectomy syndrome. However, current standards of care for post-operative management of SCS trial implantations need to be further developed. Large-scale studies on SCS trials are necessary given the already known significant reduction of infection rates with utilization of post-operative antibiotic therapy with permanent SCS implants. Furthermore, a new standard of care, including post-operative antibiotic therapy, may mitigate the risk of high-frequency SCS trial implantations. With a high degree of vigilance and strict standards to which the pain management community upholds, these potential additions to post-operative management of SCS trials may make significant impacts on the overall success of spinal cord stimulator implantations.

Last updated on: August 2, 2019
Continue Reading:
SCS Therapy in a Patient with Advanced Bilateral Kienbocks
close X
SHOW MAIN MENU
SHOW SUB MENU