Allodynia, Hyperalgesia, (Quantitative) Sensory Testing and Conditioned Pain Modulation in Patients With Complex Regional Pain Syndrome Before and After Spinal Cord Stimulation Therapy.

OBJECTIVES: Complex regional pain syndrome (CRPS) is a chronic debilitating disease characterized by sensory abnormalities. Spinal cord stimulation (SCS) is an effective therapy for CRPS, but few studies have investigated the effects of SCS therapy on sensory characteristics. Therefore, this study investigated the effect of SCS on allodynia, hyperalgesia, electrical quantitative sensory testing (QST) parameters, and conditioned pain modulation (CPM) effect. MATERIALS AND METHODS: This study is part of a multicenter randomized controlled trial (ISRCTN 36655259). Patients with CRPS in one extremity and eligible for SCS were included. The outcome parameters allodynia (symptom and sign), hyperalgesia (symptom), sensory thresholds with QST, CPM effect, and pain scores were tested before and after three months of SCS (40-Hz tonic SCS). Both the CRPS-affected extremity and the contralateral, clinically unaffected extremity were used to test three sensory thresholds with electrical QST: current perception threshold (CPT), pain perception threshold (PPT), and pain tolerance threshold (PTT). The PTT also was used as a test stimulus for the CPM paradigm both before and after the conditioning ice-water test. Nonparametric testing was used for all statistical analyses. RESULTS: In total, 31 patients were included for analysis. Pain, allodynia (sign and symptom), and hyperalgesia (symptom) were all significantly reduced after SCS therapy. On the unaffected side, none of the QST thresholds (CPT, PPT, and PTT) was significantly altered after SCS therapy. However, the CPT on the CRPS-affected side was significantly increased after SCS therapy. A CPM effect was present both before and after SCS. CONCLUSIONS: Standard 40-Hz tonic SCS significantly reduces pain, hyperalgesia, and allodynia in patients with CRPS. These findings suggest that SCS therapy should not be withheld from patients who suffer from allodynia and hyperalgesia, which contradicts previous findings derived from retrospective analysis and animal research. ISRCTN Registry: The ISRCTN registration number for the study is ISRCTN 36655259.

Inter-rater reliability of diagnostic criteria for sacroiliac joint-, disc- and facet joint pain.

BACKGROUND/OBJECTIVE: Several diagnostic criteria sets are described in the literature to identify low back pain subtypes, but very little is known about the inter-rater reliability of these criteria. We conducted a study to determine the reliability of diagnostic tests that point towards SI joint-, disc- or facet joint pain. METHODS: Inter-rater reliability study alongside three randomized clinical trials. Multidisciplinary pain center of general hospital. Patients aged 18 or more with medical history and physical examination suggestive of sacroiliac joint-, disc- and facet joint pain on lumbar level. Making use of nowadays most common used diagnostic criteria, a physical examination is taken independently by three physicians (two pain physicians and one orthopedic surgeon). Inter-rater reliability (Kappa (κ) measure of agreement) and significance (p) between raters are presented. Strengths of agreement, indicated with κ values above 0,20, are presented in order of agreement. RESULTS: One hundred patients were included. None of the parameters from the physical investigation had κ values of more than 0.21 (fair) in all pairs of raters. Between two raters (C and D), there was an almost perfect agreement on three parameters, more specifically ``Abnormal sensory and motor examination, hyperactive or diminished reflexes'', ``Sitting exam shows no reflex, motor or sensory signs in the legs'' and ``Straight leg raising (Laségue) negative between 30 and 70 degrees of flexion''. The ``Drop test positive'' parameters had moderate strength of agreement between raters A and D and fair strength between raters A and B. The ``Digital interspinous pressure test positive'' had moderate strength of agreement between raters C and D and fair strength of agreement between raters A and B as well as raters B and C. Three other parameters had a fair strength of agreement between two raters, all other parameters had a slight or poor strength of agreement. Inter-rater reliability, confidence intervals and significance of pooled items for SI joint-, disc- and facet joint pain are represented; κ values for the pooled parameters of the physical examination suggestive of SI joint pain stayed below 0.20 between all raters. The same applies for the pooled parameters of the physical examination suggestive of facet joint or disc pain. CONCLUSIONS: The poor reliability of the diagnostic parameters seriously limits their predictive validity, and as such their use in patients with low back pain for more than 3 months.

Randomized Sham-controlled Double-Blind Multicenter Clinical Trial to Ascertain the Effect of Percutaneous Radiofrequency Treatment for Sacroiliac Joint Pain: Three-month Results.

OBJECTIVES: To investigate the effect of a percutaneous radiofrequency (RF) heat lesion compared with a sham procedure, applied to the lateral branches of L5, S1, S2, S3, and S4 nerve roots. MATERIALS AND METHODS: Sixty patients aged 18 years and above with a medical history and physical examination suggestive for sacroiliac joint pain and a reduction of 2 or more on a numerical rating scale (NRS, 0 to 10) after a sacroiliac joint test block were included in this study. Treatment group: percutaneous RF heat lesion at the lateral branches of S1, S2, S3, and S4 nerve roots and the posterior ramus dorsalis of L5; sham group: same procedure as the treatment group except for the RF heat lesion. PRIMARY OUTCOME MEASURE: pain reduction (NRS). Secondary outcome measure: Global Perceived Effect. RESULTS: No statistically significant differences in pain level over time between the groups (Group×Period) (F1,58=0.353; P=0.56) nor within the treatment Group (F1,58=0.212; P=0.65) were found. The Period factor, however, yielded a significant difference (F1,58=61.67; P<0.001), that is, when pooled together the mean pain level of the patients was significantly reduced at T1 compared with T0. In the crossover group, 42.1% experienced a reduction in NRS of 2 or more at 1 month (P=0.65). No statistically significant difference in satisfaction over time between the groups was found (F1,50=2.1; P=0.15). The independent factors Group (F1,50=2.02; P=0.16) and Period (F1,50=0.95; P=0.33) also showed no statistically significant difference. The same applies to recovery: no statistically significant Group×Period effect (F1,51=0.09; P=0.77) was found, neither an effect of Group (F1,51=0.004; P=0.95) nor of Period (F1,51=0.27; P=0.60). DISCUSSION: The hypothesis of no difference in pain reduction or in Global Perceived Effect between the treatment and sham group cannot be rejected. LEVEL OF EVIDENCE: Level 1A.