Innervation of the sacroiliac joint in rats by calcitonin gene-related peptide-immunoreactive nerve fibers and dorsal root ganglion neurons

Understanding and managing pelvic girdle pain from a person-centred biopsychosocial perspective

INTRODUCTION

Clinicians need support to effectively implement a biopsychosocial approach to people with pelvic girdle pain disorders.

PURPOSE

A practical clinical framework aligned with a contemporary biopsychosocial approach is provided to help guide clinician's management of pelvic girdle pain. This approach is consistent with current pain science which helps to explain potential mechanistic links with co/multi-morbid conditions related to pelvic girdle pain. Further, this approach also aligns with the Common-Sense Model of Illness and provides insight into how an individual's illness perceptions can influence their emotional and behavioural response to their pain disorder. Communication is critical to supporting recovery and facilitating behaviour change within the biopsychosocial context and in this context, the patient interview is central to exploring the multidimensional nature of a persons' presentation. Focusing the biopsychosocial framework on targeted cognitive-functional therapy as a key component of care can help an individual with pelvic girdle pain make sense of their pain, build confidence and self-efficacy and facilitate positive behaviour and lifestyle change. There is growing evidence of the efficacy for this broader integrative approach, although large scale effectiveness trials are still needed. An in-depth case study provides guidance for clinicians, showing 'how to' implement these concepts into their own practice within a coherent practical framework.

IMPLICATIONS

This framework can give clinicians more confidence in understanding and managing pelvic girdle pain. The framework provides practical strategies to assist clinicians with implementation; assisting the transition from knowing to doing in an evidence-informed manner that resonates with real world practice.

Histology, vascularity and innervation of the glenoid labrum

BACKGROUND

Although the glenoid labrum has an important role in shoulder stability, little is known about its composition, vascularity and innervation. The aims of this study were therefore to evaluate the histology, vascularity and innervation of the glenoid labrum.

MATERIALS AND METHODS

Ten glenoid labrum specimens (three male, two female: mean age 81.2 years, range 76-90 years) were detached at the glenoid neck. Following decalcification, sections were cut through the whole thickness of each specimen perpendicular to the glenoid labrum at 12 radii corresponding to a clock face superimposed on the glenoid fossa. Then they were stained using haematoxylin and eosin, a silver nitrate protocol or subjected to immunohistochemistry using anti-protein gene protein 9.5 to demonstrate neuronal processes.

RESULTS

The labrum was fibrocartilaginous, being more fibrous in its free margin. There was a variable distribution of blood vessels, being more vascular in its periphery, with many originating from the fibrous capsule and piercing the glenoid labrum. Immunohistochemistry revealed positive staining of nerve fibres within the glenoid labrum.

CONCLUSION

The glenoid labrum is fibrocartilaginous, being more fibrous in its periphery, and is vascularized, with the anterosuperior aspect having a rich blood supply. Free sensory nerve fibres were also present; no encapsulated mechanoreceptors were observed. The presence of sensory nerve fibres in the glenoid labrum could explain why tears induce pain. It is postulated that these sensory fibres could play a role in glenohumeral joint proprioception.

The Prevalence of Facet Tropism and Its Correlation with Low Back Pain in Selected Community-Based Populations

Background

The incidence of facet tropism (FT) and its correlation with low back pain (LBP) have, to our knowledge, not yet been investigated among selected community-based populations who visited departments unrelated to LBP with their chief complaints unrelated to LBP. In this study, we aimed to evaluate the prevalence of FT among selected patients in whom LBP was not the chief complaint and the correlation between FT and LBP among these patients.

Methods

Among patients who underwent computed tomography during 2014 for reasons unrelated to LBP, we enrolled 462 patients who satisfied the inclusion and exclusion criteria. The degree of tropism was defined as grade 0, 1, and 2 for FT, FT+, and FT++, respectively. LBP was evaluated using a modified version of the Nordic low back pain questionnaire. For additional evaluation of dynamic LBP, the question, "Did your pain go away when lying down still or standing up straight, and did it also intensify when you bend or stretch your back?," was included in the questionnaire.

Results

The L4-5 intervertebral area was most frequently and severely affected by FT with an incidence rate of 46.3%, and severe FT was observed in 24.7% of the patients. FT increased with age at L2-3 and L5-S1 levels. FT at L2-3 level was correlated with LBP (p = 0.035) and dynamic LBP (p = 0.033). The FT grade at L2-3 level was correlated with dynamic LBP (p = 0.022) but not with LBP (p = 0.077). The relative risk of FT at L2-3 level was 1.614 for LBP and 1.724 for dynamic LBP.

Conclusions

The prevalence of FT among community-based populations was 46.3% and its severe form was more frequently observed at L4-5 level (24.7%). LBP was correlated with FT at L2-3 level. The relative FT-associated risk of LBP was 1.6 at L2-3 level, and the relative L2-3 FT-associated risk of dynamic LBP was 1.724.

CGRP and Painful Pathologies Other than Headache

CGRP has long been suspected as a mediator of arthritis pain, although evidence that CGRP directly mediates human musculoskeletal pain remains circumstantial. This chapter describes in depth the evidence surrounding CGRP's association with pain in musculoskeletal disorders and also summarises evidence for CGRP being a direct cause of pain in other conditions. CGRP-immunoreactive nerves are present in musculoskeletal tissues, and CGRP expression is altered in musculoskeletal pain. CGRP modulates musculoskeletal pain through actions both in the periphery and central nervous system. Human observational studies, research on animal arthritis models and the few reported randomised controlled trials in humans of treatments that target CGRP provide the context of CGRP as a possible pain biomarker or mediator in conditions other than migraine.

[Diagnostic test scale SI5: Assessment of sacroiliac joint dysfunction]

OBJECTIVE

Sacroiliac joint dysfunction is a known cause of low back pain. We think that a diagnostic score scale (SI5) may be performed to assess diagnostic utility of clinical signs of sacroiliac joint dysfunction. The primary aim of the present study was to conduct the pilot study of our new diagnostic score scale, the SI5, for sacroiliac joint syndrome.

MATERIAL AND METHODS

We reviewed the literature on clinical characteristics, diagnostic tests and imaging most commonly used in diagnosing sacroiliac joint dysfunction. Our group evaluated the diagnostic utility of these aspects and we used those considered most representative to develop the SI5 diagnostic scale. The SI5 scale was applied to 22 patients with low back pain; afterwards, the standard test for diagnosing this pathology (selective blockage of the SI joint) was also performed on these patients. The sensitivity and specificity for each sign were also assessed and the diagnostic scale called SI5 was then proposed, based on these data.

RESULTS

The most sensitive clinical tests for diagnosing SI joint dysfunction were 2 patient-reported clinical characteristics, the Laguerre Test, sacroiliac rocking test and Yeomans test (greater than 80% sensitivity). The tests with greatest diagnostic specificity (>80%) were the Lewitt test, Piedallu test and Gillet test. The proposed SI5 test score scale showed sensitivity of 73% and specificity of 71%.

CONCLUSIONS

Sacroiliac joint syndrome has been shown to produce low back pain frequently; however, the diagnostic value of examination tests for sacroiliac joint pain has been questioned by other authors. The pilot study on the SI5 diagnostic score scale showed good sensitivity and specificity. However, the process of statistical validation of the SI5 needs to be continued.

Experimental pelvic pain facilitates pain provocation tests and causes regional hyperalgesia

The extra-articular sacroiliac joint (SIJ) structure is a potential source for low back and pelvic pain. This study hypothesised that experimental pain induced in a superficial pelvic ligament causes (1) hyperalgesia to pressure, (2) distinct pain referral, and (3) an increased frequency of positive pain provocation tests of the SIJ complex. Thirty healthy subjects (15 females) participated in this study designed as a randomised crossover trial. Pain was induced in the long posterior sacroiliac ligament by injection of hypertonic saline, with the contralateral ligament injected with isotonic saline as control. Pain intensity was assessed on an electronic visual analogue scale (VAS). Pressure pain thresholds (PPTs) and pain provocation tests were assessed on 3 occasions: at baseline, after injection, and when pain had subsided. PPT sites were located bilaterally at the injection site, lateral to spinous processes of S2 and L5, and at the gluteus medius and gastrocnemius muscles. Hypertonic saline caused significantly higher VAS scores and more extended pain referral than isotonic saline (P<0.001). PPTs at the injection site and lateral to S2 were significantly reduced after hypertonic saline compared with baseline and isotonic saline (P<0.002). Significantly more subjects had positive pain provocation tests after hypertonic (67% of subjects) compared with isotonic saline (20%; P<0.001). These data demonstrate that the extra-articular SIJ structure accommodates nociceptors that are capable of inducing pain referral and regional hyperalgesia sensitive to manual pain provocation tests similar to what previously have been found in pelvic girdle pain patients.

Assessment of gait in a rat model of myofascial inflammation using the CatWalk system

STUDY DESIGN

Gait analysis and immunohistological analysis in a rat model of myofascial inflammation in low back.

OBJECTIVE

To investigate gait in a rat model of myofascial inflammation using the CatWalk gait analysis system.

SUMMARY OF BACKGROUND DATA

There are few reports examining low back pain behavior in animal models. The CatWalk is a computer-assisted gait analysis system that provides an automated way to assess gait function and this behavior during pain.

METHODS

In a myofascial inflammation group, 0.5 mL of 4% paraformaldehyde buffer and 0.5 mL of 5% Fluoro-Gold (FG) buffer were injected into bilateral multifidus muscles of rats. In a control group, FG buffer alone was injected. Five days after surgery, the gait of rats in both groups was investigated using the CatWalk system. In the present study a total of 36 gait parameters were quantified and used to judge pain-related behavior. Bilateral dorsal root ganglia (DRGs) from L1 to L6 levels were resected, and immunostained for calcitonin gene-related peptide (CGRP).

RESULTS

In the myofascial inflammation group, the mean duty cycle (duration of paw contact divided by time between consecutive paw contacts) of each paws (front and hind) were significantly higher and mean stride length (the distance between successive placements of the same paw) of each paws were significantly shorter compared with the control group. Furthermore, mean minimum contact intensity of the complete paw and mean contact intensity of each paws in the myofascial inflammation group were significantly higher compared with the control group. The proportion of CGRP-immunoreactive FG-labeled neurons among all FG-labeled DRG neurons in the myofascial inflammation group was significantly higher than the proportion in the control group.

CONCLUSION

These results suggest that myofascial inflammation in low back caused the changes to the rat's gait, including long stands, short stride, and strong paw contact.

Possible nociceptive structures in the sacroiliac joint cartilage: An immunohistochemical study

The sacroiliac joint (SI joint) is a known source of low back pain. In the absence of validated physical signs and imaging studies, the diagnosis of SI joint pain can be secured by positive response to SI joint intra-articular infiltration with local anesthetics. The current anatomical and histological knowledge concerning intra-articular structures of the sacroiliac joint is insufficient to explain the efficacy of this infiltration. Consequently, this study was undertaken to detect the intra-articular presence of substance P and calcitonin gene-related peptide (CGRP) positive nerve fibers, providing indirect evidence of nociceptive innervation of the SI joint. Free-floating sections, obtained from iliac and sacral cartilage and subchondral bone of the SI joint and adjacent ligamentous tissue, of 10 human cadavers were studied immunohistochemically. Tissue of nine human cadavers showed the presence of substance P and CGRP immunoreactivity in the superficial layer of sacral and iliac cartilage, and the surrounding ligamentous structures. Subchondral bone reacted weakly to the antisera used. These findings support the view that the SI joint may be capable of intra-articular nociception and may explain the positive response to the intra-articular deposition of local anesthetic.

Clinical study of low back pain and radicular pain pathways by using l2 spinal nerve root infiltration: a randomized, controlled, clinical trial

STUDY DESIGN

Randomized control trial (RCT) for L2 spinal nerve infiltration (L2 block) in clinical cases.

OBJECTIVES

To confirm or refute the effect of L2 block using RCT, and to study the pathway of low back pain (LBP) and radicular pain in clinical cases.

SUMMARY OF BACKGROUND DATA

It has been reported in animal experiments that one of the main pathways of pain originating from the lumbar spine is the sympathetic trunk through the L2 spinal nerve rootvia sympathetic afferents.

METHODS

To evaluate the effectiveness of L2 block, patients who had LBP and were treated with nonsteroidal anti-inflammatory drugs for at least 2 weeks were then randomized to the L2 block or control block groups. The intensities of LBP and radicular pain were measured using visual analog scale and face scale before and at 5 minutes and 7 days after the injection. These values were compared, and the effects of the injections on the pain pathway were studied.

RESULTS

The average visual analog scale scores for LBP before and at 5 minutes and 7 days after the injection were 69, 14, and 44 mm in the L2 block group and 68, 62, and 59 mm in the control block group, respectively. After L2 block, 28 patients reported adequate therapeutic effect at 10 weeks, and the effect lasted for more than 24 weeks in 10 of these patients. After control block, 9 patients reported adequate therapeutic effect at 10 and 24 weeks.

CONCLUSION

The LBP and radicular pain pathways were likely interrupted by L2 block. An L2 block is useful in reducing LBP due to the disorders of L2 spinal nerve-innervated structures, such as the disc, facet joint, and sacroiliac joint. However, the therapeutic value of an L2 block may be occasionally insufficient to alleviate pain completely because of the short duration of its' effect.