The Predicted Outcome of Spinal Cord Stimulation in Patients With a Psychopathological Disorder and Persistent Spinal Pain Syndrome Type 2: A Systematic Review From 2009 to 2021

OBJECTIVES

Psychologic screening is often included as a mandatory component of evaluation of the impact of psychopathology disorders on the predicted outcome of spinal cord stimulation (SCS) for patients with chronic pain due to persistent spinal pain syndrome type 2 (PSPS type 2). The conclusion of such screenings can influence the decision to offer SCS therapy to a patient. However, evidence on the impact of psychopathology on SCS outcomes is still scarce.

MATERIALS AND METHODS

To address this knowledge gap, we systematically reviewed the literature from 2009 to 2021 to explore the correlation between the presence of a psychopathological disorder and the predicted outcome of SCS in patients with PSPS type 2. The literature search was conducted using various online data bases with "failed back surgery syndrome," "psychopathology," and "spinal cord stimulation" used as essential keywords. The identified studies were organized in a Rayyan AI data base, and the quality was analyzed with the Critical Appraisal Skills Program tool.

RESULTS

Our search generated the identification of 468 original articles, of which two prospective and four retrospective studies met our inclusion criteria. These studies reported pain relief, a reduction of symptoms of anxiety and depression, and an improvement in rumination on the Pain Catastrophizing Scale in patients with PSPS type 2 after SCS therapy. The studies also found contradictory outcomes measured using the Oswestry Disability Index, and in terms of the impact of psychopathological disorder on the clinical outcome and revision rate of the SCS system.

CONCLUSION

In this systematic review, we found no convincing evidence that the presence of a psychopathological disorder affects the predicted outcome of SCS therapy in patients with PSPS type 2.

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.

Psychosocial characteristics of candidates for implantable pain devices: validation of an assessment model

Aim: To provide a detailed profile of Veteran and community patients with chronic pain who completed preprocedural psychological evaluations for implantable pain devices. Patients & methods: A total of 157 candidates completed a preimplantable pain device evaluation between June 2018 and October 2019 with a pain psychologist that included a structured interview, elicitation of patient-centered goals for the implantable device, and psychometric testing. Results: Candidates demonstrated moderate to high rates of sleep impairment (73%), depressive symptoms (62%), anxiety symptoms (61%), pain catastrophizing (37%), cognitive impairment screen (30%) and somatic symptoms (24%). Conclusion: Candidates for implantable pain devices report high rates of mood, sleep and cognitive impairment, reinforcing the value of preprocedural psychological evaluations.

Getting "Unstuck": A Multi-Site Evaluation of the Efficacy of an Interdisciplinary Pain Intervention Program for Chronic Low Back Pain

Chronic low back pain is one of the major health problems in the U.S., resulting in a large number of years of disability. To address the biopsychosocial nature of pain, interdisciplinary pain programs provide integrated interventions by an interdisciplinary team in a unified setting with unified goals. This study examined outcomes of an interdisciplinary program located at two sites with different staff, yet with a unified model of treatment and documentation. Efficacy at the combined sites was examined by comparing standard measures obtained upon admission to the program with measures at completion of a 3-4 week long program for 393 patients with chronic low back pain (CLBP). Repeated measures included pain severity, pain interference, efficacy of self-management strategies, hours of activity, depression, ability to do ADLs, and physical endurance. All repeated measures differed at the p < 0.001 level, with large effect sizes (0.66-0.85). Eighty-two percent of graduates reported being "very much improved" or "much improved". A second analyses provided evidence that treatment effects were robust across sites with no differences (<0.001) found on five of seven selected outcome measures. A third analysis found that number of days of treatment was correlated on three of seven measures at the <0.01 level. However, the amount of variance explained by days of treatment was under 5% on even the most highly correlated measure. These finding are consistent with previous research and explore short-term effectiveness of treatment across treatment sites and with variable duration of treatment.

Increased pain catastrophizing associated with lower pain relief during spinal cord stimulation: results from a large post-market study

BACKGROUND

Pain catastrophizing is a negative cognitive distortion to actual or anticipated pain. Our aim was to determine if greater catastrophizing has a deleterious relationship with pain intensity and efficacy outcomes in patients receiving SCS.

METHODS

As part of an ongoing Institutional Review Board-approved, multi-site, single arm post-market study, 386 patients were implanted with an Eon Mini™ SCS system and had follow-up visits at 3, 6, and 12 months post-implant. Outcomes collected during the study included, but were not limited to pain intensity using the numeric rating scale (NRS), patient reported pain relief (PRP), satisfaction with their SCS system, quality of life (QOL), pain catastrophizing scale (PCS) and state-trait anxiety index (STAI).

RESULTS

NRS scores were associated with higher PCS scores at six months (r = 0.50, p < 0.001). The PCS was a strong predictor of the NRS when controlled for known confounders. Patients with PCS ≥30 at 6-months post-implant had a lower six-month PRP (p < 0.001) and were five times more likely to report dissatisfaction with their SCS device (p < 0.001, OR = 5.46, 95% CI: 2.51-6.35). Additionally, at six months, those who were clinically catastrophizing were three times more likely to report deterioration in QOL (p < 0.002, OR = 3.12, 95% CI: 1.62-5.51). These findings were similar at the 12 months follow visit.

CONCLUSIONS

Our results indicate that patients with greater catastrophizing, post-implant, were more likely to report higher pain intensity and lower pain relief, quality of life and satisfaction with SCS. These results indicate that associations between pain intensity and pain-related mental health may contribute to influence the overall efficacy of SCS.