The Prevalence of Elevated Impedances and Magnetic Resonance Imaging Ineligibility Following Implantation of 10 kHz Spinal Cord Stimulation Devices: A Retrospective Review.

OBJECTIVES: Spinal cord stimulation (SCS) is increasingly utilized in the treatment of multiple chronic pain conditions. However, patients will continue to experience other medical issues and the potential for future magnetic resonance imaging (MRI) needs must not be overlooked. SCS devices have device-specific MRI conditional labeling and if impedances are elevated the patient may not be able to obtain an MRI. With 10 kHz SCS devices specifically, an impedance value above 10,000 ohms (Ω) is MRI ineligible. The primary objective of this article was to report the incidence of elevated impedances with a multilumen lead design per electrode, per lead, and to describe the total number of MRI ineligible patients due to elevated impedances using 10 kHz SCS cutoff values. The secondary objective was to determine whether certain patient demographics or surgery characteristics put patients at increased risk of elevated impedances. MATERIALS AND METHODS: We performed a retrospective review of 327 patients who were implanted with a 10 kHz SCS device between January 2015 and November 2020. Regression models were fitted to determine associations between MRI ineligibility status with clinical characteristics including age, sex, BMI, lead location, implantable pulse generator (IPG) location, and time since implant. RESULTS: We found elevated impedances with subsequent MRI ineligibility in 13 patients (4.0%). Regression analysis did not identify any associations with MRI ineligibility and patient risk factors including age, sex, body mass index, lead location, IPG location, and follow-up time since implant. CONCLUSION: We found the prevalence of elevated impedances above 10,000 Ω to be 4% of implanted patients. This information is important for patients and physicians alike and should be considered when device selection is occurring in the pre-operative visits.

The incidence of lumbar spine surgery following Minimally Invasive Lumbar Decompression and Superion Indirect Decompression System for treatment of lumbar spinal stenosis: a retrospective review.

INTRODUCTION: Lumbar spinal stenosis affects more than 200,000 adults in the United States, resulting in approximately 38,000 operations among the Medicare population and greater than $1.5 billion in hospital bills alone. Fortunately, Minimally Invasive Lumbar Decompression (MILD) and the Superion Indirect Decompression System have shown lasting benefit and cost savings compared to more aggressive surgical options. OBJECTIVE: Our primary objective was to retrospectively determine the rate of lumbar decompression surgery following the MILD and Superion procedures. MATERIALS AND METHODS: This was a pooled retrospective review of LSS patients who received MILD and/or Superion procedures between January 2011 and July 2019. Adult patients with CPT codes for MILD and Superion procedures were identified. Patients were included if they had a follow-up visit at least 2 years from the procedure date, preprocedural MRI results, and surgical notes. RESULTS: A total of 199 patients were included in the final analysis, of which 57 patients (28.6%) underwent MILD procedure only, 124 patients (62.3%) underwent Superion only, and 18 patients (9.0%) underwent an MILD procedure initially followed by a Superion procedure. Two patients had an MILD procedure performed twice at the same level at separate encounters. A total of four patients in the entire cohort (2.0%; MILD 5.3%, Superion 0.8%) underwent subsequent lumbar spine surgery when followed for at least 2 years. It is notable that some of these patients may not have been surgical candidates and this may have skewed the results. CONCLUSIONS: Patients undergoing minimally invasive decompression treatment of lumbar spinal stenosis have low rates of subsequent open surgery which potentially results in cost savings and a reduction in severe adverse events. The reason for low surgical rate may reflect improvement in their symptoms, a preference to avoid surgery, or being deemed not a surgical candidate.