Spinal Cord Stimulation in Pregnancy: A Literature Review

Objective: Currently, the use of spinal cord stimulation (SCS) therapy is not recommended in pregnancy because the effects of SCS on the pregnancy and developing fetus are unknown. However, many SCS recipients are women of childbearing age who may later become pregnant. The purpose of the present report is to review and summarize the existing literature on the use of SCS therapy during the prenatal period. Methods: We first present the case of a 38‐year‐old woman from our center who became pregnant after receiving an SCS implantation. We then provide a synopsis of previous reports that were identified in a literature search. We highlight the key findings from these cases as they relate to the course of pregnancy, fetal development, labor and delivery management, fertility, and technical complications. Results: In our literature review, we identified 12 cases of pregnancy in 8 women. To these we add the present case. Conclusions: Women of childbearing age who are candidates for SCS implantation should be tested for pregnancy prior to implantation surgery. They also should be informed about the limited state of our scientific knowledge regarding the impact of this technology on reproductive health. For patients already implanted with SCS, decisions about ongoing use in the event of pregnancy should be made on an individual basis after a careful consideration of potential risks and benefits.     

Spinal Cord Stimulation in the First Two Trimesters of Pregnancy: Case Report and Review of the Literature

Introduction. Spinal cord stimulation (SCS) is an accepted cost‐effective therapy for many chronic pain syndromes. Its effects on pregnancy have not been studied because of stringent regulation and manufacturers' recommendations. However, childbearing women who had SCS become or choose to become pregnant despite these policies. It is paramount to monitor, document, and report these effects of SCS during pregnancy to build clinical experience and guide recommendations and management. Methods. We reviewed the literature for SCS in pregnancy and added new case report of a young woman who had SCS implanted for chronic pain, became pregnant and at the end of the second trimester the lead extender had to be divided to relief pain at the lead site. Results. We found only one previous case report in this field and we add another case. Discussion. Our case is different from the previously reported case in that the implantable pulse generator (IPG) of our case was implanted in the anterior abdominal wall, while the previously reported case was implanted in the subclavicular fossa. Therefore our case highlights the need to implant the IPG in a way that avoids stretching the lead extender by the expanding abdomen. Conclusion. SCS seems to be safe in the first two trimesters of pregnancy based on these two case reports and the abdominal wall should be avoided as a site for IPG implantation in these patients. However, more cases are required to establish the safety of SCS in pregnancy.     

Ultra-Low Energy Cycled Burst Spinal Cord Stimulation Yields Robust Outcomes in Pain,Function, and Affective Domains: A Subanalysis From Two Prospective,Multicenter, International Clinical Trials

IntroductionDeRidder's burst stimulation design has become a key spinal cord stimulation (SCS) waveform because it reduces the intensity of pain as well as its associated emotional distress. The brain pathways underlying these outcomes may also allow for the effects of stimulation to carry over after stimulation is turned off, making it amenable to intermittent application. Here, the utility of intermittently cycled burst was evaluated using data from two large real-world prospective studies (TRIUMPH, REALITY).Materials and MethodsSubjects used intermittent dosing in a 1:3 ratio (30 sec on, 90 sec off; N = 100) in TRIUMPH and 1:12 ratio in REALITY (30-sec on, 360-sec off; N = 95) for six months. Pain intensity (0–10 numeric rating scale), pain-related emotions on the pain catastrophizing scale (PCS), and physical function on PROMIS questionnaires were compared with preimplant baseline ratings and by group.ResultsIn both groups, mean pain intensity decreased by nearly 50% relative to baseline, PCS scores significantly decreased, and physical function improved. Importantly, no differences between the 1:3 and 1:12 groups were identified. A high proportion, 80% and 77% of the 1:3 and 1:12 groups, respectively, were considered responders on a multiple measures. No adverse events were associated with intermittent stimulation.DiscussionIntermittent cycling of burst SCS lowers the overall electric charge delivered to the spinal cord and preserves battery consumption, without compromising pain relief and associated symptoms.     

A Prospective,Randomized Single-Blind Crossover Study Comparing High-Frequency 10,000 Hz and Burst Spinal Cord Stimulation

ObjectivesAlthough both high-frequency and burst spinal cord stimulation (SCS) have shown improved efficacy and patient satisfaction compared with conventional tonic stimulation, there are limited data directly comparing the two. This study aimed to compare both high-frequency 10,000 Hz and burst SCS in the same patients in terms of pain relief and satisfaction in those with axial back pain with or without leg pain.Materials and MethodsThis prospective, single-blind, randomized controlled trial was conducted at an outpatient pain clinic within an academic medical center. Participants were randomly allocated to one of two groups in which they trialed either burst or high-frequency 10,000 Hz SCS over five days, followed by a 24- to 48-hour washout period with no stimulation, and the alternative therapy over the remaining four days. Visual analog scale (VAS) scores were collected immediately before and after both therapy trials. Secondary end points included percentage change in VAS score and patient preference.ResultsOf 25 participants, those receiving burst followed by high-frequency SCS (n = 11) had a mean VAS difference of 4.73 after the first trial period and 2.86 after the second. Of those receiving high-frequency followed by burst SCS (n = 14), mean VAS difference after the first trial period was 4.00 and 1.93 after the second trial period. Four participants were withdrawn owing to lead migration. Both therapies showed statistically significant differences in pre- minus post-VAS scores and percent relief. There were no significant differences in carryover or treatment effects between the two groups. There was a statistically significant association between trial sequence and stimulator type implanted because the first stimulator trialed was more likely to be chosen.ConclusionsThere were no observed differences in VAS pain score decrease when comparing burst and high-frequency 10,000 Hz SCS programming therapies. Patient preference followed an order effect, favoring the first programming therapy in the trial sequence.     

A Socioeconomic Survey of Spinal Cord Stimulation (SCS) Surgery

Objective: We evaluated trends in inpatient spinal cord stimulation (SCS) for the 14‐year period from 1993 to 2006. Materials and Methods: We utilized the Nationwide Inpatient Sample data base from the Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality. Results: A total of 57,486 patients underwent inpatient placement of SCS systems from 1993 to 2006. Length of stay steadily decreased from 4.0 days in 1993 to 2.1 days in 2006. Average cost increased from $15,342 in 1993 to nearly $58,088 in 2006. The National Bill for SCS surgery in 2006 alone totaled nearly $215MM. Medicare accounted for 35% of payers, while private insurance accounted for 41% of claims. Conclusions: Given the expense of these systems, it is important to assess not only the efficacy of novel neuromodulatory interventions, but also their cost. Future studies should be designed with these important outcome measures in mind.     

Psychological Variables Associated With Outcome of Spinal Cord Stimulation Trials

Study Design. This is a prospective study designed to identify psychological factors associated with response to spinal cord stimulation (SCS) trial. Summary of Background Data. In most centers, implantation of a permanent SCS system is preceded by a trial of a temporary stimulating electrode. Yet, even among those who report greater than 50% pain reduction during trial, a significant number of these patients fail to receive long-term pain relief from the permanent system. Because mood disorders can alter pain report, we hypothesized that refined definition of the psychological factors associated with SCS success could result in improved selection of candidates for SCS trial. Methods. The study sample consisted of 43 chronic pain patients (72% failed back surgery syndrome, 77% with radiating low back pain) who were referred for implantable pain management. Following psychological evaluation, patients were admitted for a three-day inpatient trial of SCS. Report of at least 50% pain relief during trial was considered a success and resulted in implantation of the permanent stimulator. Patients were retrospectively divided into two groups: those whose pretrial pain was relieved by at least 50% (“success”) and those whose pain was relieved by less than 50% (“failure”). Results. Univariate t-test or chi-square analyzes of group means of an extensive psychological battery followed by a global, stepwise logistic regression model of trial outcome was used to analyze between group results of a psychological test battery. MMPI depression and mania subscores were found to be significantly elevated among the two outcome groups (p = 0.007 and 0.025, respectively). Conclusions. Patient mood state is an important predictor of trial outcome. Specific indicators of SCS trial outcome are the MMPI depression and mania subscale scores with successful trials being associated with individuals who are less depressed and have higher energy levels.