Intraoperative neurophysiological monitoring and spinal cord stimulator implantation.

INTRODUCTION: Spinal cord injury (SCI) is one of the most dreaded complications after spinal cord stimulation (SCS) implantation surgery. As a result, intraoperative neurophysiological monitoring (IONM) has been proposed to avoid accidental damage to nervous structures under anesthesia and confirm positioning for optimal stimulation. Our study uses a large administrative claims database to determine the 30-day risk of SCI after SCS implantation. METHODS: This retrospective cohort study used the IBM MarketScan Commercial and Medicare Supplemental Databases from 2016 to 2019. Adult patients undergoing SCS surgical procedures with at least 90 days of follow-up, IONM use, the type of sedation used during the procedure, and subsequent SCI were identified using administrative codes. In addition, logistic regression was used to examine the relationship between various risk factors and subsequent SCI. RESULTS: A total of 9676 patients underwent SCS surgery (64.7% percutaneous implants) during the study period. Nine hundred and forty-four (9.75%) patients underwent SCS implantation with IONM. Conscious sedation, Monitored Anesthesia Care anesthesia, and general anesthesia were used in patients with 0.9%, 60.2%, and 28.6%, respectively. Eighty-one (0.8%) patients developed SCI within 30 days after SCS implant surgery. The SCI rate was higher in the group that underwent IONM (2% vs 0.7%, p value <0.001) during the implantation procedure, reflecting the underlying risk. After adjustment for other factors, the OR of SCI is 2.39 (95% CI: 1.33 to 4.14, p value=0.002) times higher for those with IONM than those without IONM. CONCLUSIONS: Increased SCI risk among patients with IONM likely reflects higher baseline risk, and further research is needed for risk mitigation.

Neck Pain Secondary to Post Radiation Fibrosis Managed With Ultrasound-Guided Adhesiolysis.

BACKGROUND: Radiation therapy may result in complications, including fibrosis, which can result in pain and difficulty with movement - especially in the neck. CASE PRESENTATION: A 52-year-old man with right-sided vague neck pain unresponsive to conservative management had a computed tomography scan that showed a vagal paraganglioma in the carotid sheath surrounding the right carotid arteries and internal jugular vein. Following radiation therapy, he noticed a new pain in his right jaw and neck worse with certain movements of the neck. Nonsurgical conservative measures including physical therapy and pharmacological management were unsuccessful. An ultrasound evaluation demonstrated fibrosis beneath the sternocleidomastoid muscle and in proximity to the carotid sheath. After careful trajectory planning using ultrasound imaging, a 25 G needle was introduced real time in proximity to the fibrosis. Using a dexamethasone/saline mixture under real-time ultrasound guidance, adhesions were released. After 3 injections, the patient reported greater than 90% pain relief, which lasted 4 months. Subsequently, he required similar injections approximately every 3 months to achieve greater than 75% pain relief. CONCLUSIONS: This is a successful demonstration of the utility of ultrasound evaluation and guidance for adhesiolysis following radiation therapy.

Lead and Pulse Generator Migration After Spinal Cord Stimulation Implantation: Insights From an Analysis of 7322 Patients.

OBJECTIVES: Lead migration (LM) after spinal cord stimulation (SCS) implantation surgery is the most common device-related complication. Our study of lead and implantable pulse generator (IPG) migration using a large administrative claims data base aims to understand rates, risk factors, and outcomes after SCS implantation. MATERIALS AND METHODS: This retrospective cohort study used the IBM® MarketScan® (Armonk, NY) Commercial and Medicare Supplemental Databases from 2016 to 2018. Adult patients who underwent SCS surgical procedures with at least 90 days of follow-up were identified using Current Procedural Terminology (CPT®) codes. Patients with LM and IPG migration after SCS surgery were identified using the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10 CM) codes. Patients who underwent revision surgery after SCS implantation were identified using the CPT codes and ICD-10 CM codes. In addition, patient characteristics associated with LM or IPG migration, the temporal relationship of migration diagnosis, and revision surgery were evaluated in the cohort. Continuous outcomes were compared between groups using the two-sample Student t-test. The Fisher exact test was used to compare categorical outcomes between groups. RESULTS: A total of 7322 patients (64.4% percutaneous SCS) underwent SCS surgery during the study period. A total of 141 patients (1.9%) had LM or IPG migration. Of those, 116 patients (1.6%) had LM only; 18 patients (0.2%) had IPG migration; and seven patients (0.1%) had LM and IPG migration. The mean duration for migration diagnosis after initial SCS implantation was 168 (±163.1) days. The mean duration to revision surgery after the migration diagnosis was 12.3 (±35.2) days only. Most patients with migration (105, 74.5%) underwent revision surgery. Only younger age (p = 0.02) was associated with migration in this study. CONCLUSIONS: LM and pulse generator migration that required revision surgery occurred in a small proportion of patients who underwent SCS surgical procedures.

Postoperative Oral Antibiotic Use and Infection-Related Complications After Spinal Cord Stimulator Surgery.

OBJECTIVES: Spinal cord stimulation (SCS) is considered a minimally invasive and reversible neuromodulation therapy for various chronic pain disorders. The rates of infection following SCS surgery reported in the literature range from 2.8% to 10%. Several studies indicated no potential benefit of postoperative antibiotics (beyond 24 hours) on subsequent device infection. This study aimed to understand the characteristics of postoperative antibiotic prescriptions and subsequent infections following SCS surgery. MATERIALS AND METHODS: The study was a retrospective cohort using the IBM® MarketScan® Commercial and Medicare Supplemental Databases from 2013 to 2018. Adult patients undergoing SCS surgical procedures with at least 90 days of follow-up were identified using Current Procedural Terminology (CPT®) codes. Postprocedural oral antibiotics within 14 days and preprocedural corticosteroid use within seven days were identified using National Drug Codes (NDC). Administrative claims were analyzed to understand the characteristics of prescribed postoperative antibiotics. Infection-related complications within 90 days were identified using administrative codes. RESULTS: A total of 18,105 patients (age 55.5 ± 13.1 years, 40.2% male) underwent SCS surgery during the study period. Postprocedural oral antibiotics and preprocedural steroids were prescribed for 35.3% and 2.6%, respectively, for SCS surgery patients. The most commonly used postprocedural antibiotics were cephalexin (55.4%) and sulfamethoxazole-trimethoprim (10.6%). The most common duration of antibiotic prescriptions was seven, ten, and five days in our study, from most to least common duration. Superficial surgical site infection (SSI), deep SSI, device infection, or any infection within 90 days occurred in 2.9%, 1.0%, 1.8%, and 4%, respectively, of the patients undergoing SCS surgery. CONCLUSIONS: Prospective studies are needed to understand the reasons for noncompliance with expert consensus recommendations on postoperative antibiotic use beyond 24 hours of SCS surgery. Neuromodulation team members should play an important role in antibiotic stewardship.

Adverse Events and Complications Associated With Intrathecal Drug Delivery Systems: Insights From the Manufacturer and User Facility Device Experience (MAUDE) Database.

BACKGROUND: Modern intrathecal drug delivery systems (IDDS) are technologically advanced to deliver medication through various automated and patient-controlled programs. They also are associated with unique complications ranging from post-operative complications, medication-related adverse events (AE), device malfunction, to refill associated AE. OBJECTIVES: To systematically analyze real-world complications and AE reported on the Food and Drug Administration's Manufacturer and User Facility Device Experience database (MAUDE) associated with IDDS among patients predominantly with chronic pain disorders. MATERIALS AND METHODS: MAUDE database was sampled for a month four times a year during the study period, February 2018 to February 2019. The database was resampled every six months till August 2020 to evaluate for any additional reported cases during the index months. The two FDA approved IDDS, were included. AE were broadly classified into causes related to catheter malfunction, pump malfunction, biologic, and medication-related AE. RESULTS: A total of 1001 reports were included in the final analysis. The top three reasons for adverse report are infection/erosion (15.7%, n = 157), motor stall (12.4%, n = 125) and adverse medication reactions (11.8%, n = 119), respectively. There were five deaths among patients with IDDS. Epidural hematoma (n = 3) after IDDS surgery resulted in a death and residual neurological deficits after surgical evacuation. Programming errors, medication concentration discrepancy, and failure to turn on the pump after reprogramming are various preventable causes of medication-related IDDS AEs. CONCLUSIONS: Analysis of AE associated with IDDS from the MAUDE database provided a real-world perspective different from reported registry complications. Awareness and vigilance of preventable IDDS-related complications is the first step toward mitigating risks to provide safe and effective intrathecal drug delivery for chronic pain management.

Inappropriate Defibrillator Shocks During Cervical Medial Branch Radiofrequency Ablation: A Case Report.

A 52-year-old woman with a history of cervical spondylosis, nonischemic dilated cardiomyopathy, and complete heart block with implantation of a cardiac resynchronization therapy defibrillator (Inogen XR, Boston Scientific, Natick, MA) underwent bilateral fluoroscopy-guided radiofrequency ablation of the medial branch nerves at C4, C5, and C6 levels at an ambulatory surgery center. After completion of the seemingly routine procedure, several alerts, including 1 inappropriate shock, were received via Boston Scientific's remote monitoring system. Tracings also showed that pacing inhibition occurred. When performing radiofrequency ablation in patients with a cardiac implantable electronic device, it is imperative to follow published best practice recommendations to minimize the risk of adverse events.

Indented intrathecal drug delivery system with loss of reservoir volume.

OBJECTIVES: We report two patients who underwent elective revision surgery were found to have reduced reservoir volumes and indented bottom shield of intrathecal drug delivery system (IDDS). CASE REPORTS: Case #1: A 59-year-old man stable on IDDS medications for chronic neck and upper back pain was found to have an irreversible reduction in reservoir volume from 40 to 28 cc on routine refill appointment. Despite having stable pain control, the reservoir volume decreased from 40 to 22 cc and subsequently to 17 cc when the patient had inadequate pain control. During replacement surgery, the posterior shield of the IDDS was found to be collapsed. The patient had exposure to hyperbaric oxygen treatments for chronic non-healing wounds of the lower extremities. Case #2: A 68-year-old woman had an IDDS implanted for chronic low back pain secondary to failed back surgery syndrome. The reservoir volume was found to be reduced to 15 cc of medication from 20 cc during the seventh year of therapy. There was a report of a fall. Routine reservoir exchange at the end of battery life revealed that the bottom shield of the reservoir was indented. CONCLUSIONS: Inability to refill the medication to full capacity should be an indication to investigate device deformation. Information about exposure to hyperbaric therapy or local trauma should be obtained.

Painful neuromas.

OBJECTIVES: To perform a topical review of the published literature on painful neuromas. METHODS: A MEDLINE search was performed using the MESH terms "neuroma", "pain", "diagnosis", and "treatment" for all dates. RESULTS: Acoustic neuromas and intraabdominal neuromas were excluded from a total of 7616 articles. The reference lists from these articles were further reviewed to obtain other relevant articles. DISCUSSION: Neuromas develop as part of a normal reparative process following peripheral nerve injury. Painful neuromas can induce intense pain resulting in immense suffering and disability. MRI aids the diagnosis, but, ultrasound imaging allows cost effective accurate diagnosis and localization of neuromas by demonstrating their direct contiguity with the nerve of origin. Management options for painful neuromas include pharmacotherapy, prosthetic adjustments, steroid injection, chemical neurolysis, cryoablation, and radiofrequency ablation. Ultrasound imaging guidance has improved the success in localizing and targeting the neuromas. This review discusses the patho-physiology and accumulated evidence for various therapies and the current percutaneous interventional management options for painful neuromas.

Ultrasound demonstration of vascularity changes with changes in pain perception in a stump neuroma.

BACKGROUND: Pain in the residual limb after an amputation has posed many challenges in treatment. Ultrasound (US) imaging has helped in the visualization of neuroma and its selective targeting for interventions. OBJECTIVE: A 58-year-old man presented to the pain clinic with chronic stump pain after a below knee amputation during the Vietnam war. After multiple similar steroid injections around the area of pain in the following months, we decided to use the US to better target the stump neuroma. Color flow Doppler showed extensive vascularity around the posterior aspect of the neuroma where there was scar tissue. During a follow-up visit for intra-articular steroid injection to the L5-S1 left lumbar facet for coincidental lumbar facet arthropathy, an US scan of the stump neuroma with color flow Doppler was performed out of curiosity. Multiple US views of the neuroma with color flow Doppler was performed and all showed a significant decrease in vascularity. Similar absence of vascularity was noted after a spinal cord stimulator placement. CONCLUSION: This is a case report of US demonstration of increased vascularity in a stump neuroma coinciding with the patient's pain. This serendipitous demonstration makes the need for US visualization useful in the evaluation of neuroma. It is also useful to use US guidance to avoid the vascular structures when testing the beneficial response to various medications. Larger randomized controlled studies are needed to further correlate the US demonstration of vascularity and neuroma pain.

Ultrasound-Guided Localization of Difficult-to-Access Refill Port of the Intrathecal Pump Reservoir.

Introduction. Ultrasound guidance is being increasingly utilized in many chronic pain interventions. This is a report of the use of ultrasound imaging for accessing an intrathecal pump. Case Report. A 56-year-old patient with a programmable implanted intrathecal drug delivery system for chronic non-malignant pain needed a pump refill of sufentanil. Attempts to access the refill port using the manufacturer supplied template were difficult because of the presence of a seroma. Using ultrasound guidance, the seroma, reservoir, and the refill port were visualized and the pump was successfully accessed. This imaging-guided refill technique is fully described in this article. As the patient continued to have a collection of fluid during his following visit, the collection was aspirated under ultrasound guidance. The specimen revealed a proteinaceous collection with minimal quantities of sufentanil. Conclusion. This is a successful demonstration of ultrasound guidance to facilitate access to a difficult-to-access refill port of a pump reservoir secondary to the formation of a seroma.

Ultrasound-guided steroid injection for obturator neuralgia.

Obturator neuralgia (ON) presents with pain in the groin, medial thigh, and sometimes the medial aspect of the knee. The causes include trauma, obturator hernia, pelvic cancer, pelvic surgery, hip surgery, following pelvic fractures, endometriosis, retroperitoneal hematoma, pregnancy, and delivery. Ultrasound (US) guidance facilitates real-time imaging, identification of vascular structures, and improves patient comfort in situations where nerve stimulation can be unpleasant. This is a case report of ON successfully treated with US-guided steroid injection. A 55-year-old man was referred to the pain clinic with groin pain and allodynia in the medial thigh and knee following a fall. He had tried multiple other therapies and none of them provided significant relief. Using a 10-5-MHz multi-frequency, 38-mm linear array transducer, the obturator nerve was scanned in both longitudinal and transverse directions. Under real-time imaging 10 mg of medroxy-progesterone in a volume of 1 mL was injected. Following the injection, a small area of the medial side of knee was still tender to light touch. A second injection was placed inferiorly and provided pain relief for more than 5 months. This successful demonstration of US guidance in ON may further encourage US guidance in pain clinic interventions.

Choice of volatile anesthetic for the morbidly obese patient: sevoflurane or desflurane.

STUDY OBJECTIVE: Morbid obesity is associated with significant comorbidities. Desflurane has a low fat-blood solubility coefficient and may be better suited in this population to achieve a rapid emergence; however, sevoflurane has favorable cardiorespiratory properties that might also prove advantageous in the morbidly obese (MO) patient. This study used careful drug titration to determine if emergence differences between sevoflurane and desflurane could be minimized in MO patients. DESIGN: A randomized, prospective blinded study to determine the emergence profiles of desflurane and sevoflurane in MO patients when anesthetic drug titration is used. SETTING: Operating room of the VA Medical Center, Milwaukee, Wis. PATIENTS: Forty American Society of Anesthesiologists II and III, MO patients (body mass index > or = 35 kg/m2), who were scheduled for elective surgery predicted to last for more than 2 hours, were studied. INTERVENTIONS: Patients were induced with fentanyl, midazolam, and propofol and maintained with desflurane or sevoflurane, mixed in air and oxygen. Intraoperative bispectral index (BIS) was targeted to 45 to 50 and to 60 in the last 15 minutes of surgery. MEASUREMENTS: Intraoperative anesthetic concentration, BIS, and hemodynamics were recorded. During emergence, time to follow command and extubation were noted, with assessments of cognitive function via the Mini-Mental Status Test and psychomotor performance via the Digit Symbol Substitution Test. A blinded observer recorded key recovery events. MAIN RESULTS: Demographic data (age, 61 [36-83] years; body mass index, 38 [35-47] kg/m2), surgical procedures, length of anesthesia (approximately 3.5 hours), adjuvant drugs, and intraoperative BIS, heart rate, and mean arterial pressure were not significantly different. Hemodynamics, time to follow commands and to extubation, and results of Digit Symbol Substitution Test and Mini-Mental Status Test did not differ between anesthetic groups during recovery. CONCLUSIONS: There were no differences in emergence and recovery profiles in MO patients receiving desflurane or sevoflurane when anesthetic concentration was carefully titrated.