Functional Connectivity Magnetic Resonance Imaging Sequences in Patients With Postsurgical Persistent Spinal Pain Syndrome Type 2 With Implanted Spinal Cord Stimulation Systems: A Safety, Feasibility, and Validity Study.

BACKGROUND: Chronic pain has been associated with alterations in brain connectivity, both within networks (regional) and between networks (cross-network connectivity). Functional connectivity (FC) data on chronic back pain are limited and based on heterogeneous pain populations. Patients with postsurgical persistent spinal pain syndrome (PSPS) type 2 are good candidates for spinal cord stimulation (SCS) therapy. We hypothesize that 1) FC magnetic resonance imaging (fcMRI) scans can be safely obtained in patients with PSPS type 2 with implanted therapeutic SCS devices and that 2) their cross-network connectivity patterns are altered and involve emotion and reward/aversion functions. MATERIALS AND METHODS: Resting-state (RS) fcMRI (rsfcMRI) scans were obtained from nine patients with PSPS type 2 implanted with therapeutic SCS systems and 13 age-matched controls. Seven RS networks were analyzed, including the striatum. RESULTS: Cross-network FC sequences were safely obtained on a 3T MRI scanner in all nine patients with PSPS type 2 with implanted SCS systems. FC patterns involving emotion/reward brain circuitry were altered as compared with controls. Patients with a history of constant neuropathic pain, experiencing longer therapeutic effects of SCS, had fewer alterations in their connectivity patterns. CONCLUSIONS: To our knowledge, this is the first report of altered cross-network FC involving emotion/reward brain circuitry in a homogeneous population of patients with chronic pain with fully implanted SCS systems, on a 3T MRI scanner. All rsfcMRI studies were safe and well tolerated by all nine patients, with no detectable effects on the implanted devices.

Preoperative Thoracic Spine Magnetic Resonance Imaging for Spinal Cord Stimulation: Should Such a Recommendation Be an Absolute Requirement?

OBJECTIVE: Current published guidelines recommend advanced imaging, specifically, thoracic magnetic resonance imaging (MRI), prior to implantation of epidural paddle spinal cord stimulator (SCS) leads. Preoperative imaging may affect surgical approach to minimize risk of complications. We aimed to assess the impact of preoperative thoracic MRI on surgical planning in a large series of surgical paddle SCS lead placements in a real-world setting. MATERIALS AND METHODS: This is a retrospective study of a prospectively maintained data base of 160 patients treated by SCS with awake thoracic surgical paddle lead placement in a single academic functional neurosurgery center from 2013 to 2021. All patients had a thoracic MRI prior to implantation. Abnormal MRI findings were reviewed to determine their potential impact on the safety of surgical paddle lead placement. A minor impact was defined as anatomical areas to avoid with paddle lead placement. Major impacts included significant deviations from standard approach to electrode placement. RESULTS: None of the 160 patients had signs or symptoms referable to thoracic spine pathology prior to lead implant. Sixty-seven had abnormal thoracic MRI findings, and 36 had abnormal MRI findings that impacted surgical planning. Thirty-one patients had MRI findings with minor impact. Five patients (more than 3%) had findings with major impact. CONCLUSIONS: This is the largest case series assessing the impact of preoperative thoracic MRI on surgical planning for patients undergoing paddle SCS placement. Twenty-two percent of patients had MRI findings that impacted surgical planning with 3% requiring additional surgical decompression for safe paddle lead placement. Without advanced imaging to inform surgical planning, unnecessary risk may have been placed on these patients. Although such imaging has been recommended by consensus committees in published guidelines, our study is the first to present a large institutional experience of real-world data that demonstrates its importance.

Spinal Cord Stimulation for Neurogenic Claudication Associated with Lumbar Spinal Stenosis.

BACKGROUND: There is a debate on the long-term outcomes of surgical decompression for lumbar spinal stenosis (LSS) as compared to conservative treatment, with even more limited outcomes in repeat surgeries. Hence, other less invasive treatment modalities, such as neuromodulation with a modern spinal cord stimulator (SCS), could be considered in the spectrum of management options for symptoms of neurogenic claudication (NC) related to LSS as an alternative to surgery. OBJECTIVE: Assessing the outcomes and efficacy of SCS in neurogenic claudication in patients with or without a prior lumbar surgery. STUDY DESIGN: This is a retrospective study of a prospectively collected database. SETTING: The research was conducted at the Medical College of Wisconsin (MCW), an academic medical center, in Milwaukee, Wisconsin. METHODS: This study reviewed all patients who had undergone SCS therapy for symptoms consistent with NC between 2013 through 2020. The data were collected from MCW. Only patients with at least one year of follow-up were included in outcome assessment. RESULTS: One hundred and eighteen patients with primary symptoms of NC underwent an SCS trial with an 86% pass-rate. A total of 69 of the 93 patients who underwent permanent SCS implantation had at least one year of follow-up. All patients reported initial improvement after permanent implantation. At one-year follow-up, 55 (80%) patients had sustained improvement of their pain levels and claudication symptoms, of whom 52 (75%) continued to experience benefit for an average of at least 27 months. For patients with no prior surgical decompression, 86% continued to experience sustained benefit at the latest follow-up. LIMITATIONS: This study has several limitations. It is of a retrospective nature that includes selection and recall biases. It is a single-center study that limits its generalizability. More limitations are discussed in the main article. CONCLUSIONS: With modern SCS techniques, the majority of patients can achieve sustained improvement of symptoms of NC of at least a 2-year duration regardless of previous history of lumbar decompressive surgery. SCS can be considered as part of the conservative treatment options before committing to surgical decompression.

Functional connectivity and structural analysis of trial spinal cord stimulation responders in failed back surgery syndrome.

BACKGROUND: Chronic pain has been associated with alterations in brain structure and function that appear dependent on pain phenotype. Functional connectivity (FC) data on chronic back pain (CBP) is limited and based on heterogeneous pain populations. We hypothesize that failed back surgery syndrome (FBSS) patients being considered for spinal cord stimulation (SCS) therapy have altered resting state (RS) FC cross-network patterns that 1) specifically involve emotion and reward/aversion functions and 2) are related to pain scores. METHODS: RS functional MRI (fMRI) scans were obtained for 10 FBSS patients who are being considered for but who have not yet undergone implantation of a permanent SCS device and 12 healthy age-matched controls. Seven RS networks were analyzed including the striatum (STM). The Wilcoxon signed-rank test evaluated differences in cross-network FC strength (FCS). Differences in periaqueductal grey (PAG) FC were assessed with seed-based analysis. RESULTS: Cross-network FCS was decreased (p<0.05) between the STM and all other networks in these FBSS patients. There was a negative linear relationship (R2 = 0.76, p<0.0022) between STMFCS index and pain scores. The PAG showed decreased FC with network elements and amygdala but increased FC with the sensorimotor cortex and cingulate gyrus. CONCLUSIONS: Decreased FC between STM and other RS networks in FBSS has not been previously reported. This STMFCS index may represent a more objective measure of chronic pain specific to FBSS which may help guide patient selection for SCS and subsequent management.

Non-Infectious Peri-Electrode Edema and Contrast Enhancement Following Deep Brain Stimulation Surgery.

BACKGROUND: Dramatic radiographic abnormalities seen after electrode placement (DRAAEP) in deep brain stimulation (DBS) surgery is rare and it has not been associated with infection or hemorrhage. It has consisted of peri-electrode low-attenuation signals on CT scans and extensive T2-hyperintense signals without associated contrast enhancement (CE) on MRI scans. OBJECTIVE: Report on the management of a patient with Parkinson's disease (PD) presenting with a seizure and findings of DRAAEP with positive CE 12 days after the placement of a subthalamic nucleus (STN) DBS electrode. METHODS: Head CT and contrasted brain MRI scans were completed on presentation. Standard laboratory work up was obtained to evaluate for infection. Operative exploration deep to the burr-hole site surrounding the electrode was performed and cultures were obtained. Serial contrasted MRI scans were completed to determine the abnormal signal duration. RESULTS: A MRI revealed extensive T2-hyperintensity and positive CE concentrated around the burr-hole site surrounding the electrode. Intraoperative exploration revealed no evidence of infection and electrode revision was avoided. There was near resolution of the abnormal T2 signal and CE at six weeks from detection. The patient remained without signs of intracranial infection and responded well to DBS. CONCLUSION: To our knowledge, this is the first reported case of DRAAEP with positive gadolinium enhancement. Despite the extensive contrast enhancement, these DRAAEP appear to remain benign transient events that, in the absence of clinical signs of infection or neurologic decline, may warrant no further aggressive intervention such as hardware removal.

A Novel Nonanchoring Technique for Implantation of Paddle Leads in the Cervical Spine Under Conscious Sedation.

OBJECTIVES: Spinal cord stimulation (SCS) revision surgery remains common, with a negative impact on cost-effectiveness and outcomes. The primary goal of this report was to retrospectively study the need for revision surgery in a cohort of complex regional pain syndrome type I (CRPS-1) patients with newly implanted cervical surgical paddle leads, focusing on a method of implantation to reduce the need for revision surgery. METHODS: Fifteen patients underwent implantation of paddle SCS leads in the cervical spine with cervical laminotomies under conscious sedation for CRPS-1 from 2008 to 2012. Electrodes were not anchored and 11 of the electrodes were three-column paddle leads. A disinterested third party performed initial chart reviews, supplemented by subsequent telephone interviews. The need for revision surgery was the endpoint. A single surgeon performed all implants with a consistent method. RESULTS: There were no paddle electrode lead revisions required for suboptimal lead placement, fracture, migration, or infection at a median follow-up period of 22 months. CONCLUSIONS: This study is the first to report on: 1) cervical electrode implantation with no anchoring; and 2) cervical paddle lead implantation (including three-column paddles) performed under conscious sedation. The specific method of nonanchoring of the paddle implants under conscious sedation may have contributed to low electrode lead revision rates.

Incidence of Revision Surgery in a Large Cohort of Patients With Thoracic Surgical Three-Column Paddle Leads: A Retrospective Case Review.

OBJECTIVES: Spinal cord stimulation (SCS) revision surgery remains common, with a negative impact on cost-effectiveness and outcomes. The primary goal in this report was to retrospectively study the need for revision surgery in a large cohort of patients with newly implanted thoracic surgical three-column paddle leads, focusing on a method of implantation to reduce the need for revision surgery. Clinical outcomes were also assessed. METHODS: The outcomes in 126 patients who received initial surgical paddle SCS implants for back and/or leg pain from 2008 to 2012 were retrospectively analyzed. A disinterested third party performed chart reviews and telephone interviews. A single surgeon with a consistent method performed all implants, with no lead anchoring. All three major commercial vendors were utilized. RESULTS: There were no paddle electrode lead revisions required for spontaneous fracture, migration, or infection at an average chart-review follow-up period of 20 months. With subsequent telephone interviews, a 65% clinical success rate was seen at 29 months. Significant suboptimal stimulation with body-position changes (SSBPC) was reported in less than 10% of patients. All results were vendor-independent. CONCLUSIONS: This report, the largest to date on patients with three-column paddle leads, shows low electrode revision rates with expected clinical success rates. Clinically relevant SSBPC was uncommon.