A retrospective study on patients with chronic knee pain treated with ultrasound-guided radiofrequency of the genicular nerves (RECORGEN trial).

INTRODUCTION: Radiofrequency (RF) treatment of the genicular nerves is a promising treatment for chronic osteoarthritic and persistent postsurgical knee pain (PPSP), refractory to conventional medical management. METHODS: The RECORGEN study is a retrospective single-center cohort study of patients treated with ultrasound-guided conventional RF of the genicular nerves for chronic knee pain in Hospital Oost-Limburg, Genk from September 2017 to June 2020. Subgroup analysis based on etiology of pain (PPSP and degenerative knee pain) was performed in addition to the total study population analysis. Outcome parameters were global perceived effect (GPE), Numeric Rating Scale for pain, consumption of strong opioids, and safety of the treatment at 6 weeks and cross-sectionally at a variable time point. Treatment success was defined as GPE≥50%. RESULTS: Sixty-eight cases were screened of which 59 (46 diagnosed with PPSP and 13 with degenerative knee pain) were included in the study. Treatment success at 6 weeks was achieved in 19 of 59 interventions (32.2%) and was similar in both groups. Seventeen responders were evaluated at follow-up. 45.1% (8/17) continued to have a positive effect at the second time point. The mean duration of effect of the RF treatment was 8.3 months. Safety analysis at 6 weeks and at the second time point showed a good safety profile of the treatment. CONCLUSION: Conventional RF of the genicular nerves was clinically successful in more than 30% of the study population refractory to conventional medical management. Overall, the treatment was well tolerated. The mean duration of effect was 8.3 months.

Does the presence of cranial contrast spread during a sacroiliac joint injection predict short-term outcome?

BACKGROUND: The innervation of the sacroiliac joint (SIJ) is complex, with a dual innervation originating from the lumbosacral plexus anteriorly as well as the sacral lateral branches posteriorly. Nociceptors are found in intra-articular structures as well as periarticular structures. In patients with SIJ pain, a fluoroscopy-guided SIJ injection is usually performed posteriorly into the bottom one-third of the joint with local anesthetic and corticosteroids, but this does not always reach all intra-articular structures. The correlation between a cranial contrast spread and clinical success is undetermined in patients with SIJ pain. METHODS: In a tertiary referral pain center, electronic medical records of patients who underwent an SIJ injection were retrospectively analyzed. Only patients with at least three positive provocation maneuvers for SIJ pain were selected. Contrast images of the SIJ were classified as with or without cranial spread on fluoroscopy as a marker of intra-articular injection. Clinical success was defined as ≥50% improvement in the patient's global perceived effect after 3-4 weeks. The primary outcome was defined as the correlation between cranial contrast spread and clinical success after an SIJ injection. RESULTS: 128 patients in total were included. In 68 patients (53.1%) fluoroscopy showed cranial contrast spread. Clinical success was higher in patients with cranial spread of contrast (55 of 68, 81%) versus those without (35 of 60, 58%) (p=0.0067). In a multivariable analysis with age, gender, presence of rheumatoid arthritis, side, and number of positive provocation maneuvers, the cranial spread of contrast remained the only independent factor of clinical success (p=0.006; OR 3.2, 95% CI 1.4 to 7.7). CONCLUSION: In patients with SIJ pain, identified by positive pain provocation maneuvers, cranial contrast spread as a marker of intra-articular injection, with subsequent injection of 3 mL of local anesthetic and methylprednisolone 40 mg, was significantly correlated with clinical success up to 4 weeks. Therefore, attempts should be made to reach this final needle position before injecting local anesthetic and corticosteroids. This result needs to be confirmed in a high-quality prospective trial.

Does the Use of Epiduroscopic Lysis of Adhesions Reduce the Need for Spinal Cord Stimulation in Failed Back Surgery Syndrome? A Short-Term Pilot Study.

BACKGROUND AND AIMS: Persistent low back pain after initially successful surgery that is not attributed to structural deficits is called failed back surgery syndrome (FBSS). When conservative and minimal invasive therapy fail, the recommended treatment is spinal cord stimulation (SCS). Because epidural fibrosis can be a contributing factor in the majority of FBSS patients, lumbosacral epiduroscopic lysis of adhesions may be considered as a less invasive alternative treatment option. We hypothesized that the use of epiduroscopic lysis of adhesions could reduce the need for SCS. METHODS: A pilot study was performed in 35 consecutive patients with FBSS who underwent epiduroscopic lysis of adhesions. SCS was considered if epiduroscopic lysis of adhesions gave less than 50% global perceived effect (GPE) improvement after 15 months of follow-up. The GPE was measured 1 week and 6 months after the procedure. RESULTS: Over a period of 69 months, 35 patients were included. After 15 months of follow-up, 43% of patients required SCS. Eight of the 15 patients who reported no short-term improvement needed SCS; those patients had severe epidural fibrosis. One week after epiduroscopic lysis of adhesions, 34%, 23%, and 43% of patients reported GPE improvement of > 50%, 20% to 50%, and < 20%, respectively. After 6 months, 5 patients were lost to follow-up, and 30%, 17%, and 16% of patients reported improvement of > 50%, 20% to 50%, and < 20%, respectively. CONCLUSIONS: In this pilot study we observed a reduced need for SCS when lumbosacral epiduroscopic lysis of adhesions was used for patients with FBSS and magnetic resonance imaging-proven adhesions. These observations justify the evaluation of both treatment options in a prospective observational trial.

Effect of minocycline on lumbar radicular neuropathic pain: a randomized, placebo-controlled, double-blind clinical trial with amitriptyline as a comparator.

BACKGROUND: Less than 50% of patients experience sufficient pain relief with current drug therapy for neuropathic pain. Minocycline shows promising results in rodent models of neuropathic pain but was not studied in humans with regard to the treatment of neuropathic pain. METHODS: In this randomized, double-blind, placebo-controlled clinical trial, patients with subacute lumbar radicular pain received placebo, amitriptyline 25 mg, or minocycline 100 mg once a day (n = 20 per group) for 14 days. Primary outcome measure was the pain intensity in the leg as measured by a numeric rating scale ranging from 0 to 10 on days 7 and 14. Secondary outcome measures were the reduction of neuropathic pain symptoms in the leg as determined with a neuropathic pain questionnaire, consumption of rescue medication, and adverse events on days 7 and 14. RESULTS: Sixty patients were randomized and included in an intention-to-treat analysis. After 14 days, patients in the minocycline and amitriptyline groups reported a reduction of 1.47 (95% confidence interval, 0.16-2.83; P = 0.035) and 1.41 (95% confidence interval, 0.05-2.78; P = 0.043), respectively, in the numeric rating scale compared to the placebo group. No differences were seen in the neuropathic pain questionnaire values at any time point during treatment between the three groups. The rate of adverse events in the amitriptyline group was 10% versus none in the minocycline and placebo groups. No differences were noted in the consumption of rescue medication. CONCLUSIONS: Although both groups differed from placebo, their effect size was small and therefore not likely to be clinically meaningful.

Establishing the diagnosis of low back pain: patient selection for interventional pain medicine.

SUMMARY Low back pain is one of the most prominent healthcare problems but there is no gold standard for its diagnosis. Aspecific low back pain can be subdivided into radicular and mechanical pain. The diagnosis mainly relies on a combination of elements, such as medical history, physical examination, medical imaging and other possible additional tests. Once a working diagnosis has been established, confirmation of the causative structure and level is sought by means of diagnostic blocks. The use of the different diagnostic tests and blocks should be guided by the balance between the potential benefit (mainly in terms of improved treatment outcome, the possible burden for the patient and the chances of withholding potential effective treatment to patients) with false-negative test results.