Spinal cord stimulation in severe cases of complex regional pain syndrome: A retrospective cohort study with long-term follow-up

Socioeconomic Determinants of Initiating Neuromodulation for Chronic Pain: A Systematic Review

OBJECTIVES

Neuromodulation is an effective treatment for chronic pain; however, socioeconomic differences may influence decision-making to initiate this therapy. This review investigated potential differences in accessibility of neuromodulation for patients with chronic pain due to socioeconomic determinants.

MATERIALS AND METHODS

Four electronic databases were used for this systematic review: MEDLINE, Embase, Scopus, and Web of Science. Risk of bias was assessed using the modified version of the Downs and Black checklist. The study protocol was prospectively registered on PROSPERO (CRD42023426035).

RESULTS

The initial database search identified a total of 1118 unique studies, of which 36 were eventually included in the systematic review. Of the 36 included studies, six studies reported on education, 24 on employment status, ten on insurance, five on household income, and three on miscellaneous topics. Neuromodulation seems accessible for patients with different education levels and different types of insurance. Additionally, it is not restricted to patients who are (un)employed. When comparing patients who initiated neuromodulation with those who did not, a significantly higher number of patients in the top quartile for education were found in the group without neuromodulation. Regarding insurance, inconclusive evidence was found.

CONCLUSIONS

Although neuromodulation was accessible for patients with varying levels of socioeconomic determinants, disparities were noted. When comparing the socioeconomic profiles of patients who receive neuromodulation and those who do not, education levels differ. Health-related inequality should be carefully monitored in chronic pain management with neuromodulation to ensure that potential disparities do not increase.

Does Spinal Cord Stimulation Improve Sleep Disturbances Independently of Pain Relief in Patients With Chronic Pain? An Explorative, Observational Study

OBJECTIVES

Chronic pain poses a significant health challenge worldwide and is associated with both disability and reduced quality of life. Sleep disturbances are reported in 67% to 88% of patients with chronic pain. Pain and sleep affect each other reciprocally; we aimed to study this bidirectional relationship in patients treated with spinal cord stimulation (SCS) for chronic pain. Specifically, we investigated whether sleep improves after treatment with SCS and whether this improvement may be mediated by pain reduction.

MATERIALS AND METHODS

An observational cohort study was conducted in patients with chronic neuropathic pain treated with SCS at a single neurosurgical department in Denmark. Outcomes were assessed preoperatively and at three, six, and 12 months postoperatively, and thereafter annually. Primary outcomes were pain intensity (numeric rating scale) and insomnia at first follow-up (Insomnia Severity Index). The association between sleep and pain was investigated using linear regression and mediation analysis.

RESULTS

Forty-three patients were included in the study. The mean insomnia score was reduced by 25% from 18.1 (SD 6.0) to 13.5 (SD 6.6) (p = 0.0001). Pain intensity was reduced 38% from 7.4 (SD 1.6) to 4.6 (SD 2.1) at the first follow-up (p ≤ 0.0001). Changes in pain and changes in insomnia scores were significantly but weakly associated (regression coefficient = 1.3, 95% CI [0.3; 2.2], p = 0.008, r2 = 15.7%); and changes in pain score were not found to mediate changes in sleep score (β = -0.02, 95% CI [-0.15; 0.11], p = 0.76).

CONCLUSIONS

We found that patients treated with SCS showed significant improvements in both insomnia and pain intensity at first follow-up. Improvements in insomnia and pain intensity were significantly but weakly associated, and improvements in pain intensity score did not mediate improvements in insomnia score. Thus, improvements in self-reported insomnia in patients treated with SCS for chronic pain may predominantly be caused by other factors than reduced pain intensity.

Emotional and psychosocial function after dorsal column spinal cord stimulator implantation: a systematic review and meta-analysis

BACKGROUND

The efficacy of spinal cord stimulation (SCS) in chronic pain studies is traditionally assessed by pain scores, which do not reflect the multidimensional nature of pain perception. Despite the evidence of SCS's influence on emotional functioning comprehensive assessments of its effect remain lacking.

OBJECTIVE

To assess changes in emotional and psychosocial functioning in patients who underwent SCS implantation for chronic pain.

EVIDENCE REVIEW

Ovid MEDLINE, EMBASE, PsychINFO, Cochrane CENTRAL and Scopus databases were searched for original peer-reviewed publications reporting emotional functioning after SCS. The primary outcomes were a pooled mean difference (MD) in anxiety, depression, global functioning, mental well-being and pain catastrophizing at 12 months. The Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) was used to determine the quality of evidence.

FINDINGS

Thirty-two studies were included in the primary analysis. Statistically significant improvements were observed in anxiety (MD -2.16; 95% CI -2.84 to -1.49; p<0.001), depression (MD -4.66; 95% CI -6.26 to -3.06; p<0.001), global functioning (MD 20.30; 95% CI 14.69 to 25.90; p<0.001), mental well-being (MD 4.95; 95% CI 3.60 to 6.31; p<0.001), and pain catastrophizing (MD -12.09; 95% CI -14.94 to -9.23; p<0.001). Subgroup analyses revealed differences in Global Assessment of Functioning and mental well-being based on study design and in depression based on waveform paradigm.

CONCLUSION

The results highlight the statistically and clinically significant improvements in emotional and psychosocial outcomes in patients with chronic pain undergoing SCS therapy. However, these results need to be interpreted with caution due to the very low certainty of evidence per the GRADE criteria.

PROSPERO REGISTRATION

CRD42023446326.

Exploring Patient Satisfaction and Other Outcome Measures With Pain Relief in Spinal Cord Stimulation: A Single-Site, Cohort Audit

Context Spinal cord stimulation (SCS) is an approved treatment for chronic pain of neuropathic origin. Initial research suggests a close relationship between pain relief and patient satisfaction with SCS. Objectives To see whether similar patterns were observed in our center and to identify areas of improvement, this single-site, cohort audit explored the association between pain relief and satisfaction as well as specific factors that influence satisfaction at follow-up in patients with fully implanted SCS. Methods Age, gender, pain condition, SCS system, average pain (numerical rating scale, NRS), and worst pain (NRS) scores at baseline and the most recent follow-up visit were collected. Percentage change in average pain was calculated, and the patients were allocated to one of three pain improvement groups: <30%, 30%-50%, or >50%. A telephone survey explored patient outcomes including patient satisfaction, sleep, fatigue, quality of life (QoL), walking ability, and medication use. Chi-square tests of independence were performed. Results The final sample comprised 87 patients (<30%: n = 26; 30%-50%: n = 29; >50%: n = 32). The pain improvement group was significantly associated with satisfaction (p = 0.010): all patients in the >50% improvement group reported being either very satisfied or somewhat satisfied with SCS. The pain improvement group was also significantly associated with change in sleep (p < 0.001), fatigue (p = 0.001), QoL (p = 0.003), and opioid consumption (p = 0.010). Improvements were most frequently reported in the >50% improvement group. Conclusion Findings point to an association between pain relief and patient satisfaction with SCS. Other factors, including sleep, fatigue, QoL, and opioid consumption, may influence this association and deserve further exploration.

Latent infection after spinal cord stimulation device implantation for complex regional pain syndrome: A case report

RATIONALE

Spinal cord stimulation (SCS) is one of the invasive treatments of complex regional pain syndrome (CRPS). The positive effect has been observed for several years after implantation. However, infection is a common cause of SCS failure and device removal.

PATIENT CONCERNS

Here we describe a case of latent infection at the implantable generator pocket site 9 years after SCS implantation in a patient with CRPS.

DIAGNOSES

A 52-year-old patient was diagnosed with type 1 CRPS. The right foot pain was intractable with standard treatments. SCS implantation was performed and SCS worked well without complication. Nine years later, the patient revisited due to pain, tenderness, and redness at the abdominal wall for 2 weeks. The right foot pain was maintained with NRS 4 for 8 years, and the stimulation stopped 1 year back. SCS infection was diagnosed.

INTERVENTIONS

The patient underwent SCS removal surgery.

OUTCOMES

All SCS devices were removed successfully. The patient was discharged without any complications.

CONCLUSIONS

While uncommon, infection after SCS implantation can occur even 9 years later. Immediate diagnosis, proper antibiotics, and surgical removal could be needed to prevent further spread of infection and better prognosis.

Spinal cord stimulation as a treatment option for complex regional pain syndrome: a narrative review

Objectives: This review aims to analyze the last years' experience of applying spinal cord stimulation (SCS) in complex regional pain syndrome (CRPS) patients with persistent or refractory chronic pain. Methods: This is a narrative review which was executed based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and was carried out through the following databases: PUBMED and Cochrane Library. Also, a search for trials in the metaRegister of controlled trials (www.clinicaltrials.gov) was performed. Results: SCS provides pain reduction and improves sensory, vasomotor and sudomotor symptoms. It can reduce opioid using, offering better life quality for the patients. Conclusions: SCS found to be an excellent therapeutic alternative for patients with CRPS. It offers immediate pain relief and allows patients to regain functionality and have a better quality of life.

Short- and long-term effects of conventional spinal cord stimulation on chronic pain and health perceptions: A longitudinal controlled trial

BACKGROUND

The effectiveness and long-term outcomes of spinal cord stimulation (SCS) are not fully established, especially considering that data from patients who withdrew from the trial are rarely analysed, which may lead to overestimation of SCS efficacy. We evaluated short- and long-term effects of SCS on chronic pain and perceived health, beyond natural variability in these outcomes.

METHODS

In a prospective design, 176 chronic pain patients referred to SCS were evaluated five times (baseline; retest ~6 weeks later; post-SCS trial; 8 and 28 weeks post-permanent implantation). Patients whose SCS trial failed (Temp group) were followed up and compared to those who underwent permanent SCS (Perm group).

RESULTS

Analyses revealed a non-linear (U-shaped) trend significantly different between the two groups. In the Perm group, a significant improvement occurred post-SCS implantation in pain severity, pain interference, health-related quality of life and self-rated health, which was followed by gradual worsening and return to baseline values at end of follow-up. In the Temp group, only minor changes occurred in these outcomes over time. On average, baseline and end of follow-up values in the Perm and Temp groups were similar: ~40% in each group exhibited an increase in pain severity over time and 38% and 33%, respectively, exhibited reductions in pain severity over time.

CONCLUSIONS

Since the greatest improvement in the outcome measures occurred from baseline to post-SCS trial (T1-T3) followed by a gradual decline in the effect, it appears that SCS may not be effective for the majority of chronic pain patients.

SIGNIFICANCE

This longitudinal study evaluated short and long term effects of spinal cord stimulation (SCS) on chronic pain outcome measures, beyond their natural variation in time. Despite significant short term improvements, by the end of the seven months' follow-up, the outcomes in the treatment group (people who received the permanent implantation) were similar to those of the control group (people whose SCS trial failed and did not continue to permanent implantation) suggesting SCS may not be cost-effective for chronic pain patients.