Jonas Tesarz

Sensory innervation of the thoracolumbar fascia in rats and humans.

The available data on the innervation of the thoracolumbar fascia (TLF) are inconsistent and partly contradictory. Therefore, the role of the fascia as a potential source of pain in the low back is difficult to assess. In the present study, a quantitative evaluation of calcitonin gene-related peptide (CGRP) and substance P (SP)-containing free nerve endings was performed in the rat TLF. A preliminary non-quantitative evaluation was also performed in specimens of the human TLF. The data show that the TLF is a densely innervated tissue with marked differences in the distribution of the nerve endings over the fascial layers. In the rat, we distinguished three layers: (1) Outer layer (transversely oriented collagen fibers adjacent to the subcutaneous tissue), (2) middle layer (massive collagen fiber bundles oriented obliquely to the animals long axis), and (3) inner layer (loose connective tissue covering the paraspinal muscles). The subcutaneous tissue and the outer layer showed a particularly dense innervation with sensory fibers. SP-positive free nerve endings-which are assumed to be nociceptive-were exclusively found in these layers. Because of its dense sensory innervation, including presumably nociceptive fibers, the TLF may play an important role in low back pain.

Pain perception in athletes compared to normally active controls: a systematic review with meta-analysis.

Summary Differences in pain perception between athletes and nonathletes were meta‐analyzed. Available data suggest that regular physical activity is associated with specific alterations in pain perception. ABSTRACT This study systematically reviewed differences in pain perception between athletes and normally active controls. We screened MEDLINE, Sport‐Discus, EMBASE, Web of Science, PsycINFO, PSYNDEX, and the citations of original studies and systematic reviews. All studies on experimentally induced pain that compared pain perception between athletes and normally active controls were eligible. The main outcome measures were pain tolerance and pain threshold. Effects are described as standardized mean differences and were pooled using random‐effects models. Fifteen studies including 899 subjects met the inclusion criteria. Twelve of these studies assessed pain tolerance, and 9 studies examined pain threshold. A meta‐analysis of these studies revealed that athletes possessed higher pain tolerance compared to normally active controls (effect size calculated as Hedges’ g = 0.87, 95% confidence interval [CI95] 0.53–1.21; P < 0.00001), whereas available data on pain threshold were less uniform (Hedges’ g = 0.69, CI95 0.16–1.21; P = 0.01). After exclusion of studies with high risk of bias, differences between groups in pain threshold were not significant any longer. Our data suggest that regular physical activity is associated with specific alterations in pain perception. Psychological and biological factors that may be responsible for these alterations are discussed.

Quantitative sensory testing profiles in chronic back pain are distinct from those in fibromyalgia.

ObjectivesAlterations in the central nervous system leading to higher pain sensitivity have been shown in both chronic back pain (CBP) and fibromyalgia syndrome (FMS). The aim of this study was to disclose commonalities and differences in the pathophysiology of FMS and CBP. MethodsWe used the quantitative sensory testing protocol of the German Research Network on Neuropathic Pain to obtain comprehensive profiles of somatosensory functions. The protocol comprised thermal and mechanical detection and pain thresholds, vibration thresholds, and pain sensitivity to sharp and blunt mechanical stimuli. We studied 21 FMS patients (mean pain duration: 13.4 y), 23 CBP subjects (mean pain duration: 15.9 y), and 20 healthy controls (HCs). Each participant received the test battery on the back and on the dorsal hand (pain-free control site). ResultsOn the back, FMS patients showed increased thermal and mechanical pain sensitivity compared with HCs and CBP participants. On the hand dorsum, FMS patients showed higher mechanical pain sensitivity compared with CBP participants and HCs and higher cold pain sensitivity compared with HCs. CBP participants showed increased pressure pain sensitivity and lower vibration sensitivity on the back, but no significant differences on the hand dorsum compared with HCs. DiscussionFMS patients showed increased sensitivity for different pain modalities at all measured body areas, suggesting central disinhibition as a potential mechanism. CBP participants in contrast, showed localized alterations within the affected segment possibly due to peripheral sensitization.

Alterations in endogenous pain modulation in endurance athletes: an experimental study using quantitative sensory testing and the cold-pressor task.

&NA; Athletes were significantly less sensitive to mechanical pain but showed higher sensitivity to vibration compared with normally active controls. Assessment of conditioned pain modulation suggests that the endogenous pain‐inhibitory system is less responsive in athletes. &NA; There is evidence for long‐term alterations in pain tolerance among athletes compared with normally active controls. However, scientific data on pain thresholds in this population are inconsistent, and the underlying mechanisms for the differences remain unclear. Therefore, we assessed differences and similarities in pain perception and conditioned pain modulation (CPM) at rest in endurance athletes and normally active controls. The standardised quantitative sensory testing protocol (QST) of the ‘German‐Research‐Network‐on‐Neuropathic‐Pain’ was used to obtain comprehensive profiles on somatosensory functions. The protocol consisted of thermal and mechanical detection as well as pain thresholds, vibration thresholds, and pain sensitivity to sharp and blunt mechanical stimuli. CPM (the diffuse‐noxious‐inhibitory‐control‐like effect) was measured using 2 tonic heat pain test stimuli (at the temperature exceeding a subjective pain rating of 50/100) separated by a 2‐min cold‐pressor task (CPM‐TASK; conditioning stimulus). Pain ratings were measured with a numerical rating scale. Endurance capacity was validated by assessment of maximum oxygen uptake (VO2max). Participants included 25 pain‐free male endurance athletes (VO2max > 60 mL/min * kg) and 26 pain‐free normally active controls (VO2max < 45 mL/min * kg) matched based on age and body mass index. Athletes were significantly less sensitive to mechanical pain but showed higher sensitivity to vibration (P < 0.05). In athletes, CPM was significantly less activated by the conditioning stimuli (P < 0.05) when compared with normally active controls. Our data show that somatosensory processing in athletes differs in comparison with controls, and suggest that the endogenous pain inhibitory system may be less responsive. This finding may explain the paradoxical propensity of athletes to develop chronic widespread pain.

Altered pressure pain thresholds and increased wind-up in adult patients with chronic back pain with a history of childhood maltreatment: a quantitative sensory testing study.

Abstract Childhood maltreatment (CM) has been associated with an increased risk of nonspecific chronic low back pain (nsCLBP). However, the mechanisms underlying this association are unclear. Therefore, this study considered whether distinct types of CM are accompanied by specific alterations in somatosensory function. A total of 176 subjects with nsCLBP and 27 pain-free controls (PCs) were included. The Childhood Trauma Questionnaire (CTQ) was used to categorize patients into 2 groups (abused/neglected vs nonabused/nonneglected) for 5 types of CM (emotional abuse, physical abuse, sexual abuse, emotional neglect, and physical neglect). The standardized quantitative sensory testing protocol of the “German Research Network on Neuropathic Pain” was performed to obtain comprehensive profiles on somatosensory function, including detection and pain thresholds, pain sensitivity, and assessments of temporal summation (wind-up). Between 17.7% and 51.4% of subjects with nsCLBP reported CM, depending on the type of CM. Childhood Trauma Questionnaire subscores for emotional and sexual abuse were significantly higher in subjects with nsCLBP than in PCs. Compared with PCs, subjects with CM showed reduced pressure pain thresholds (PPTs), irrespective of the type of CM. Regarding distinct types of CM, subjects with nsCLBP with emotional abuse reported significantly higher wind-up than those without, and sexual abuse was accompanied by enhanced touch sensitivity. Our findings suggest that CM is nonspecifically associated with a decreased PPT in nsCLBP. Emotional abuse apparently leads to enhanced spinal pain summation, and sexual abuse leads to enhanced touch sensitivity. These results emphasize the importance of emotional abuse in nsCLBP and suggest that CM can induce long-term changes in adult somatosensory function.

Distinct quantitative sensory testing profiles in nonspecific chronic back pain subjects with and without psychological trauma.

Abstract Psychological trauma is associated with an increased risk for chronification of nonspecific chronic back pain (nsCLBP) independent of posttraumatic stress disorder (PTSD). However, the mechanisms underlying the role of psychological trauma in nsCLBP are less clear than in PTSD. Therefore, this study considered whether psychological trauma exposure (TE) is accompanied by specific alterations in pain perception. The study included 56 participants with nsCLBP and TE (nsCLBP-TE), 93 participants with nsCLBP without TE (nsCLBP-W-TE), and 31 pain-free controls. All participants underwent a thorough clinical evaluation. The standardized quantitative sensory testing protocol of the “German Research Network on Neuropathic Pain” was used to obtain comprehensive profiles on somatosensory functions in painful (back) and non-painful areas (hand). The protocol consisted of thermal and mechanical detection as well as pain thresholds, vibration thresholds, and pain sensitivity to sharp and blunt mechanical stimuli. Psychological trauma was validated by structured clinical interview. Trauma-associated symptom severity, anxiety, and depressive symptomatology were assessed by self-report questionnaires. Differences in somatosensory function were seen only for pressure pain thresholds. Compared with controls, nsCLBP-TE revealed hyperalgesia generalized in space with lower thresholds in painful and non-painful areas, whereas nsCLBP-W-TE demonstrated localized alterations with decreased thresholds only in the pain-affected area of the back (P ⩽ 0.006). Our findings suggest an augmented central pain processing in nsCLBP-TE (alterations in painful and non-painful areas), whereas nsCLBP-W-TE show only local changes (alterations only in the painful area) suggesting regional sensitization processes. This finding might explain why TE without PTSD is associated with an increased prevalence of chronic pain.

Ocular wavefront analysis of aspheric compared with spherical monofocal intraocular lenses in cataract surgery: Systematic review with metaanalysis.

This review was conducted to compare the physical effect of aspheric IOL implantation on wavefront properties with that of spherical IOL implantation. The peer-reviewed literature was systematically searched in Medline, Embase, Web of Science, Biosis, and the Cochrane Library according to the Cochrane Collaboration method. Inclusion criteria were randomized controlled trials comparing the use of aspheric versus spherical monofocal IOL implantation that assessed visual acuity, contrast sensitivity, or quality of vision. A secondary outcome was ocular wavefront analysis; spherical aberration, higher-order aberrations (HOAs), coma, and trefoil were evaluated. Effects were calculated as standardized mean differences (Hedges g) and were pooled using random-effect models. Thirty-four of 43 studies provided data for wavefront analysis. Aspheric monofocal IOL implantation resulted in less ocular spherical aberration and fewer ocular HOAs than spherical IOLs. This might explain the better contrast sensitivity in patients with aspheric IOLs.

Chronic Widespread Back Pain is Distinct From Chronic Local Back Pain: Evidence From Quantitative Sensory Testing, Pain Drawings, and Psychometrics.

Objectives:Whether chronic localized pain (CLP) and chronic widespread pain (CWP) have different mechanisms or to what extent they overlap in their pathophysiology is controversial. The study compared quantitative sensory testing profiles of nonspecific chronic back pain patients with CLP (n=48) and CWP (n=29) with and fibromyalgia syndrome (FMS) patients (n=90) and pain-free controls (n = 40). Materials and Methods:The quantitative sensory testing protocol of the “German-Research-Network-on-Neuropathic-Pain” was used to measure evoked pain on the painful area in the lower back and the pain-free hand (thermal and mechanical detection and pain thresholds, vibration threshold, pain sensitivity to sharp and blunt mechanical stimuli). Ongoing pain and psychometrics were captured with pain drawings and questionnaires. Results:CLP patients did not differ from pain-free controls, except for lower pressure pain threshold (PPT) on the back. CWP and FMS patients showed lower heat pain threshold and higher wind-up ratio on the back and lower heat pain threshold and cold pain threshold on the hand. FMS showed lower PPT on back and hand, and higher comorbidity of anxiety and depression and more functional impairment than all other groups. Discussion:Even after long duration CLP presents with a local hypersensitivity for PPT, suggesting a somatotopically specific sensitization of nociceptive processing. However, CWP patients show widespread ongoing pain and hyperalgesia for different stimuli that is generalized in space, suggesting the involvement of descending control systems, as also suggested for FMS patients. Because mechanisms in nonspecific chronic back pain with CLP and CWP differ, these patients should be distinguished in future research and allocated to different treatments.

Conditioned pain modulation in patients with nonspecific chronic back pain with chronic local pain, chronic widespread pain, and fibromyalgia

Abstract Findings considering conditioned pain modulation (CPM) in chronic back pain (CBP) are contradictory. This might be because many patients with CBP report pain in further areas of the body, and altered CPM might influence spatial extent of pain rather than CBP per se. Therefore, we compared CPM in patients with CBP with different pain extent. Patients with fibromyalgia syndrome (FMS), for whom CPM impairment is reported most consistently, were measured for comparison. Based on clinical evaluation and pain drawings, patients were categorized into chronic local back pain (CLP; n = 53), chronic widespread back pain (CWP; n = 32), and FMS (n = 92). Conditioned pain modulation was measured by the difference in pressure pain threshold (test stimuli) at the lower back before and after tonic heat pain (conditioning stimulus). We also measured psychosocial variables. Pressure pain threshold was significantly increased in CLP patients after tonic heat pain (P < 0.001) indicating induction of CPM. Conditioned pain modulation in CLP was significantly higher than that in CWP and FMS (P < 0.001), but CPM in CWP and FMS did not differ. Interestingly, a higher number of painful areas (0-10) were associated with lower CPM (r = 0.346, P = 0.001) in CBP but not in FMS (r = −0.013, P = 0.903). Anxiety and depression were more pronounced in FMS than in CLP or CWP (P values <0.01). Our findings suggest that CPM dysfunction is associated with CWP and not with FMS as suggested previously. FMS seems to differ from CWP without FMS by higher psychosocial burden. Moreover, patients with CBP should be stratified into CLP and CWP, and centrally acting treatments targeting endogenous pain inhibition seem to be more indicated the higher the pain extent.

The Course of the Spatial Extent of Pain in Nonspecific Chronic Back Pain: A Prospective Population-based Cohort Study With Clinical Evaluation.

Objectives:Longitudinal population-based studies on the natural course of nonspecific chronic back pain (nsCBP) concerning the spatial extent of pain are scarce. This study aims to assess the natural course of nsCBP patients concerning their spatial extent of pain and physical impairment over time. Methods:Analyses were based on a prospective, population-based survey with clinical evaluation. A representative population-based sample of 4000 German adults was sent a pain questionnaire. Patients mentioning nsCBP in the questionnaire were invited to a comprehensive clinical evaluation, including 1- and 2-year follow-ups. On the basis of pain drawings, the course of the spatial extent of pain over time was classified as “constant-local,” “constant-widespread,” “constant-amelioration,” “constant-spreading,” or “variable.” Physical impairment was assessed by the Back Performance Scale as an objective clinical assessment tool that measures self-reported activity limitation in daily functioning caused by nsCBP. Results:Pain drawings and physical assessment from 3 visits were available from 165 patients. The course of the spatial extent of pain was constant-local in 39.4% and constant-widespread in 18.2% of all patients, whereas 11.5% reported a variable course. Constant-amelioration was observed in 18.2% and constant-spreading was observed in 12.7%. Physical impairment remained unchanged over the time in all groups and was worst in the constant-widespread group. Discussion:Most nsCBP patients report a stable pain extent over the time of the study, whereas a constant spread of pain is observed only in a minority of nsCBP patients. These findings challenge the concept of a continuous transition from local to widespread pain.