Treatment Strategies for Generator Pocket Pain.

OBJECTIVE: Generator site pain is a relatively common phenomenon in patients undergoing spinal cord stimulation (SCS) that complicates management and effective pain relief. This pain may be managed conservatively, with repositioning of the battery and, in some cases, with explant. Here we explore our experience with management of generator site pain ("pocket pain") in a large single-center study. METHODS: All SCS permanent implants and implantable pulse generator (IPG) placements over 9 years were reviewed. Of 785 cases, we identified 43 patients with pocket pain (5.5%). Demographics and treatments of the pocket pain cohort were analyzed. RESULTS: The mean age (± SEM) of the pocket pain cohort was 46.86 ± 1.06, and there were 10/33 males/females. Females were overrepresented in pocket pain cohort (76.7%) when compared with the total SCS cohort (59.0%) (X2 = 5.93, P = 0.015). Diagnosis included failed back surgery syndrome (51.2%), complex regional pain syndrome (23.3%), and chronic neuropathic pain (25.5%). No patients improved with conservative therapy. All patients either went on to revision (n = 23) or explant (n = 20). Time from initial surgery to development of pocket pain was 7.5 months (range: 0.3-88) and from pocket pain to revision surgery was 4.5 months (range: 0.4-26). In addition, significantly more pocket pain patients (65.1%) had workers' compensation (WC) insurance compared with patients without pocket pain (24.9%) (X2 = 33.3, P < 0.001). CONCLUSION: In our institutional experience, pocket pain was inadequately managed with conservative treatments. Being female and having SCS filed under WC increased risk of pocket pain. Future work will explore the nuances in device placement based on body shape and manual activity responsibilities.

Correlations Between Family History of Psychiatric Illnesses and Outcomes of Spinal Cord Stimulation.

OBJECTIVES: Spinal cord stimulation (SCS) is a well-established procedure for chronic neuropathic pain. Research has established patients with personal psychiatric history do not fare as well as their correspondents following SCS surgery. We explored whether a documented psychiatric family history (PFH) correlated with worse outcomes following SCS surgery. MATERIALS AND METHODS: We retrospectively reviewed our single-center, prospectively collected database of patients who received permanent SCS implants over the past eight years. Subjects were separated into those with documented PFH and those without. Subjects completed validated scales at preoperative, 6 ± 2 postoperative, and 12 ± 3 months postoperative visits. The percent change in scores from preoperative to postoperative timepoints was compared between subjects with PFH vs. controls. RESULTS: SCS subjects reporting a PFH demonstrated significantly worse 6-month outcomes on Pain Catastrophizing Scale-rumination subscale (p = 0.02), numeric rating scale (NRS) scores on "pain at its least" (p = 0.04) and NRS "pain right now" (p = 0.02). This group also endorsed greater disability as measured by the Oswestry Disability Index (ODI) throughout the follow-up period (p = 0.04 at 6 ± 2 months, p = 0.001 at 12 ± 3 months). CONCLUSIONS: Subjects with PFH may experience less improvement in disability following SCS as compared to subjects without PFH. They may take longer to achieve the same outcomes, including pain relief and decrease in pain rumination. Our findings show that improvements in the PFH cohort are equivalent to that of the no PFH cohort on all measures except ODI at 12-month follow-up. Thus obtaining a detailed PFH prior to performing SCS is important in order to implement pre-operative coping training for PFH patients, rather than exclusion from SCS.