Trunk neuromuscular responses to a single whole-body vibration session in patients with chronic low back pain: a cross-sectional study.

OBJECTIVE: Whole-body vibration (WBV) exercise is progressively adopted as an alternative therapeutic modality for enhancing muscle force and muscle activity via neurogenic potentiation. So far, possible changes in the recruitment patterns of the trunk musculature after WBV remain undetermined. The main objective of this study was to evaluate the short-term effects of a single WBV session on trunk neuromuscular responses in patients with chronic low back pain (cLBP) and healthy participants. METHODS: Twenty patients with cLBP and 21 healthy participants performed 10 trunk flexion-extensions before and after a single WBV session consisting of five 1-minute vibration sets. Surface electromyography (EMG) of erector spinae at L2-L3 and L4-L5 and lumbopelvic kinematic variables were collected during the trials. Data were analyzed using 2-way mixed analysis of variance models. RESULTS: The WBV session led to increased lumbar EMG activity during the flexion and extension phases but yielded no change in the quiet standing and fully flexed phases. Kinematic data showed a decreased contribution to the movement of the lumbar region in the second extension quartile. These effects were not different between patients with cLBP and healthy participants. CONCLUSIONS: Increased lumbar EMG activity after a single WBV session most probably results from potentiation effects of WBV on lumbar muscles reflex responses. Decreased EMG activity in full trunk flexion, usually observed in healthy individuals, was still present after WBV, suggesting that the ability of the spine stabilizing mechanisms to transfer the extension torque from muscles to passive structures was not affected.

Physical and psychosocial predictors of functional trunk capacity in older adults with and without low back pain.

OBJECTIVE: The purpose of this study was to determine the physical and psychosocial predictors of functional trunk capacity in a group of healthy elderly individuals and a group of elderly patients with chronic low back pain (LBP). METHODS: The study was done in Canada and included 61 community-dwelling elderly individuals (29 patients with nonspecific chronic LBP and 32 healthy participants) who performed maximal trunk endurance and force tasks. Participants completed various psychologic and functional questionnaires. Sequential linear regression analyses were performed with functional capacity results (endurance and force) as dependent variables and questionnaire scores as independent variables. RESULTS: Endurance time and peak force were significantly lower in patients compared with healthy elderly individuals (all P values < .001), whereas pain-related fear of movement, pain catastrophizing, and depression levels were higher in patients than their healthy counterpart (all P values < .001). After adjusting for physical activity and disability levels (R(2) = 33.7%-50.5% in patients; R(2) = 0.1%-5.7% in healthy individuals), none of the psychologic questionnaire could explain variations observed in functional capacity in patients (R(2) changes, 4.8%-6.7%) and in healthy participants (R(2) changes, 5.2%-10.6%). CONCLUSION: Patients showed diminished functional capacity compared with healthy participants. Moreover, physical activity levels represent the most important predictors of functional capacity in elderly patients with LBP.

Modulation of pain-induced neuromuscular trunk responses by pain expectations: a single group study.

PURPOSE: The purpose of this study was to investigate the alteration of pain-induced neuromuscular trunk responses by expectations in healthy volunteers. METHODS: Twenty-three asymptomatic participants performed series of flexion-extension movements in 3 different experimental conditions: innocuous heat stimulation (control) and noxious heat stimulation associated with expectations of low or high pain intensity. These stimuli were administered by a contact thermode placed over the lumbar region (L4 and L5) to assess the modulation of neuromuscular responses and kinematics during the flexion-extension task. Surface electromyography (EMG) of lumbar erector spinae at L2 and L3 and L4 and L5 as well as lumbopelvic kinematic variables were compared across conditions. RESULTS: Noxious stimulation significantly altered EMG responses but only in full trunk flexion. Interestingly, this alteration was significant only for muscles where noxious stimulation was applied (L4 and L5) and not for the other segment (L2 and L3). Conversely, expectations significantly altered EMG activity at L2 and L3 but not at the segment where noxious stimulation was applied. CONCLUSION: These results confirm previous findings and indicate that experimental pain can alter neuromuscular responses during a trunk flexion-extension task. Furthermore, this study suggests that expectations can alter some of these alterations. Future studies should determine whether neuromuscular changes induced by expectations may contribute to the transition from acute to chronic low-back pain.

A randomised controlled trial of preventive spinal manipulation with and without a home exercise program for patients with chronic neck pain.

BACKGROUND: Evidence indicates that supervised home exercises, combined or not with manual therapy, can be beneficial for patients with non-specific chronic neck pain (NCNP). The objective of the study is to investigate the efficacy of preventive spinal manipulative therapy (SMT) compared to a no treatment group in NCNP patients. Another objective is to assess the efficacy of SMT with and without a home exercise program. METHODS: Ninety-eight patients underwent a short symptomatic phase of treatment before being randomly allocated to either an attention-group (n = 29), a SMT group (n = 36) or a SMT + exercise group (n = 33). The preventive phase of treatment, which lasted for 10 months, consisted of meeting with a chiropractor every two months to evaluate and discuss symptoms (attention-control group), 1 monthly SMT session (SMT group) or 1 monthly SMT session combined with a home exercise program (SMT + exercise group). The primary and secondary outcome measures were represented by scores on a 10-cm visual analog scale (VAS), active cervical ranges of motion (cROM), the neck disability index (NDI) and the Bournemouth questionnaire (BQ). Exploratory outcome measures were scored on the Fear-avoidance Behaviour Questionnaire (FABQ) and the SF-12 Questionnaire. RESULTS: Our results show that, in the preventive phase of the trial, all 3 groups showed primary and secondary outcomes scores similar to those obtain following the non-randomised, symptomatic phase. No group difference was observed for the primary, secondary and exploratory variables. Significant improvements in FABQ scores were noted in all groups during the preventive phase of the trial. However, no significant change in health related quality of life (HRQL) was associated with the preventive phase. CONCLUSIONS: This study hypothesised that participants in the combined intervention group would have less pain and disability and better function than participants from the 2 other groups during the preventive phase of the trial. This hypothesis was not supported by the study results. Lack of a treatment specific effect is discussed in relation to the placebo and patient provider interactions in manual therapies. Further research is needed to delineate the specific and non-specific effects of treatment modalities to prevent unnecessary disability and to minimise morbidity related to NCNP. Additional investigation is also required to identify the best strategies for secondary and tertiary prevention of NCNP. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00566930.

A comparison of 2 assessment protocols to specifically target abdominal muscle endurance.

OBJECTIVE: The purpose of this study was to compare 2 variations of a test designed to evaluate abdominal muscle endurance. METHODS: This study included 21 healthy adults (10 men and 11 women) aged 23.2 ± 3.3 years. Participants recruited from a chiropractic institution performed 2 fatiguing protocols (with a lordotic posture or free of instructions), each immediately preceded and followed by a maximum voluntary contraction. Force data and surface electromyography of 6 muscles were recorded. The influence of posture on endurance time as well as the effect of posture on MedF/time slopes for each individual muscle throughout the first 4 30-seconds time segments was assessed. RESULTS: Mean time until exhaustion was 261.3 ± 149.8 seconds for the lordotic condition and 358.8 ± 206.4 seconds for the free condition. The lordotic condition induced significantly more fatigue than the free condition in 3 muscles during the first 30 seconds. However, both conditions induced similar levels of fatigue for the following 30 seconds. After the first 60 seconds, no significant differences in fatigability were noted between the 2 experimental conditions. CONCLUSION: For the subjects studied, lumbar lordosis had a significant influence on trunk muscle fatigue during abdominal muscle endurance assessment. Specifically targeting the abdominal muscles during an endurance task remains a challenge.

Effect of pain on deafferentation-induced modulation of somatosensory evoked potentials.

There is a large body of evidence showing substantial sensorimotor reorganizations after an amputation. These reorganizations are believed to contribute to the development of phantom limb pain, but alternatively, pain might influence the plasticity triggered by the deafferentation. The aim of this study was to test whether pain impacts on deafferentation-induced plasticity in the somatosensory pathways. Fifteen healthy subjects participated in 2 experimental sessions (Pain, No Pain) in which somatosensory evoked potentials (SSEPs) associated with electrical stimulation of the ulnar nerve were assessed before and after temporary ischemic deafferentation induced by inflation of a cuff around the wrist. In the Pain session capsaicin cream was applied on the dorsum of the hand 30 minutes prior to cuff inflation. Results show that pain decreased the amplitude of the N20 (main effect of condition, p = 0.033), with a similar trend for the P25. Temporary ischemic deafferentation had a significant effect on SSEPs (main effect of time), with an increase in the P25 (p = 0.013) and the P45 amplitude (p = 0.005), together with a reduction of the P90 amplitude (p = 0.002). Finally, a significant time x condition interaction, reflecting state-dependent plasticity, was found for the P90 only, the presence of pain decreasing the reduction of amplitude observed in response to deafferentation. In conclusion, these results show that nociceptive input can influence the plasticity induced by a deafferentation, which could be a contributing factor in the cortical somatosensory reorganization observed in chronic pain populations.

Predictors of disability and absenteeism in workers with non-specific low back pain: A longitudinal 15-month study.

OBJECTIVES: The objective of this study was to identify baseline predictors of disability and absenteeism in workers with a history of non-specific low back pain (LBP). METHODS: One hundred workers with a history of non-specific LBP participated in three evaluations (baseline, 7 and 15 months follow-up). Current and past history of LBP, clinical pain intensity, disability, absenteeism, fear-avoidance beliefs, pain catastrophizing, pain hypervigilance, work satisfaction and patient stratification based on "risk of poor clinical outcome assessment" (RPCO) were evaluated using questionnaires and interviews. In addition, cutaneous heat pain thresholds, cutaneous heat pain tolerance thresholds, conditioned pain modulation (CPM), trunk kinematics and muscle activity were measured during each evaluation. Logistic regression models were used to determine predictors of LBP disability and absenteeism at 15-months. RESULTS: Sixty-eight workers returned for the 15-month follow-up and among this sample, 49% reported disability and 16% reported absenteeism at follow-up. Baseline clinical pain intensity predicted disability (OR = 1.08, 95%CI: 1.03-1.13) at 15-month while work satisfaction (OR = 0.93, 95%CI: 0.87-0.99) and RPCO (OR = 1.51, 95%CI: 1.05-2.16) predicted absenteeism. These results remained significant after adjustments for age, gender as well as type of work and intervention. CONCLUSION: This study highlights the importance of clinical pain and psychological factors in the prediction and potentially the prevention of future disability. Screening tools assessing these risk factors can be useful to evaluate workers with past history of low back pain.

Inhibition of Pain and Pain-Related Brain Activity by Heterotopic Noxious Counter-Stimulation and Selective Attention in Chronic Non-Specific Low Back Pain.

The aim of the present study was to assess inhibition of pain and somatosensory-evoked potentials (SEPs) by heterotopic noxious counter-stimulation (HNCS) and by selective attention in patients with chronic non-specific LBP. Seventeen patients and age/sex-matched controls were recruited (10 men, 7 women; mean age ±â€¯SD: 43.3 ±â€¯10.4 and 42.7 ±â€¯11.1, respectively). On average, patients with LBP reported pain duration of 7.6 ±â€¯6.5 years, light to moderate disability (19.3 ±â€¯5.7/100) and low clinical pain intensity (21.8 ±â€¯1.5/100), while pain catastrophizing, state and trait anxiety and depressive symptoms were not significantly different between groups (all p's >0.05). HNCS and selective attention had differential inhibitory effects on pain and SEP, but no difference was observed between groups. Across both groups, HNCS decreased pain (p = 0.06) as well as the N100 and the N150 components of SEP (p's <0.001), while selective attention only decreased pain (p < 0.01) and the N100 (p<0.001). In contrast, the P260 was decreased by HNCS only when attention was directed toward the HNCS stimulus (p<0.01). This indicates that patients with the characteristics described above do not show altered pain inhibitory mechanisms involved in HNCS and selective attention. Importantly, this experiment was carefully designed to control for non-specific effects associated with the repetition of the test stimulus and the effect of an innocuous counter-stimulation. It remains to be determined if these results hold for patients with severe LBP and psychological symptoms or whether symptom severity may be associated with pain inhibition deficits.

Primary Intestinal-Type Adenocarcinoma of Tongue: A Case Report with Immunohistochemical and Molecular Profiles and Review of the Literature.

Primary lingual intestinal-type adenocarcinomas are extremely rare with only a few cases described. A case with immunohistochemical expression of Androgen Receptor (AR) which was treated solely by chemo-radiotherapy is reported herein. A 54-year-old male was referred with symptoms of fullness in his tongue. Clinical examination showed an asymmetry of the tongue with a hard mass palpable within the middle of the tongue. Biopsy showed intestinal-type adenocarcinoma. The tumour showed positive staining with cytokeratin 7, cytokeratin 20, CDX2, AR, ß-catenin and was mismatch repair proteins (MMR) proficient. The molecular analysis did not show mutations in the KRAS, NRAS, BRAF and PIK3CA genes. The patient was treated with radiochemotherapy and is in remission 3.5 years after the diagnosis. This is the first case of intestinal-type tongue adenocarcinoma which showed AR expression and was treated solely with radical chemoradiotherapy.

Physiological and Psychological Predictors of Short-Term Disability in Workers with a History of Low Back Pain: A Longitudinal Study.

Despite an elusive pathophysiology, common characteristics are often observed in individuals with chronic low back pain (LBP). These include psychological symptoms, altered pain perception, altered pain modulation and altered muscle activation. These factors have been explored as possible determinants of disability, either separately or in cross-sectional studies, but were never assessed in a single longitudinal study. Therefore, the objective was to determine the relative contribution of psychological and neurophysiological factors to future disability in individuals with past LBP. The study included two experimental sessions (baseline and six months later) to assess cutaneous heat pain and pain tolerance thresholds, pain inhibition, as well as trunk muscle activation. Both sessions included the completion of validated questionnaires to determine clinical pain, disability, pain catastrophizing, fear-avoidance beliefs and pain vigilance. One hundred workers with a history of LBP and 19 healthy individuals took part in the first experimental session. The second experimental session was exclusively conducted on workers with a history of LBP (77/100). Correlation analyses between initial measures and disability at six months were conducted, and measures significantly associated with disability were used in multiple regression analyses. A first regression analysis showed that psychological symptoms contributed unique variance to future disability (R2 = 0.093, p = .009). To control for the fluctuating nature of LBP, a hierarchical regression was conducted while controlling for clinical pain at six months (R2 = 0.213, p < .001) where pain inhibition contributed unique variance in the second step of the regression (R2 change = 0.094, p = .005). These results indicate that pain inhibition processes may constitute potential targets for treatment to alleviate future disability in individuals with past or present LBP. Then again, the link between psychological symptoms and pain inhibition needs to be clarified as both of these factors are linked together and influence disability in their own way.

Neuromuscular adaptations predict functional disability independently of clinical pain and psychological factors in patients with chronic non-specific low back pain.

Patients with chronic low back pain exhibit characteristics such as clinical pain, psychological symptoms and neuromuscular adaptations. The purpose of this study was to determine the independent contribution of clinical pain, psychological factors and neuromuscular adaptations to disability in patients with chronic low back pain. Clinical pain intensity, pain catastrophizing, fear-avoidance beliefs, anxiety, neuromuscular adaptations to chronic pain and neuromuscular responses to experimental pain were assessed in 52 patients with chronic low back pain. Lumbar muscle electromyographic activity was assessed during a flexion-extension task (flexion relaxation phenomenon) to assess both chronic neuromuscular adaptations and neuromuscular responses to experimental pain during the task. Multiple regressions showed that independent predictors of disability included neuromuscular adaptations to chronic pain (ß=0.25, p=0.006, sr(2)=0.06), neuromuscular responses to experimental pain (ß=-0.24, p=0.011, sr(2)=0.05), clinical pain intensity (ß=0.28, p=0.002, sr(2)=0.08) and psychological factors (ß=0.58, p<0.001, sr(2)=0.32). Together, these predictors accounted for 65% of variance in disability (R(2)=0.65 p<0.001). The current investigation revealed that neuromuscular adaptations are independent from clinical pain intensity and psychological factors, and contribute to inter-individual differences in patients' disability. This suggests that disability, in chronic low back pain patients, is determined by a combination of factors, including clinical pain, psychological factors and neuromuscular adaptations.

Effect of experimental low back pain on neuromuscular control of the trunk in healthy volunteers and patients with chronic low back pain.

Studies of electromyographic (EMG) activity and lumbopelvic rhythm have led to a better understanding of neuromuscular alterations in chronic low back pain (cLBP) patients. Whether these changes reflect adaptations to chronic pain or are induced by acute pain is still unclear. This work aimed to assess the effects of experimental LBP on lumbar erector spinae (LES) EMG activity and lumbopelvic kinematics during a trunk flexion-extension task in healthy volunteers and LBP patients. The contribution of disability to these effects was also examined. Twelve healthy participants and 14 cLBP patients performed flexion-extension tasks in three conditions; control, innocuous heat and noxious heat, applied on the skin over L5 or T7. The results indicated that noxious heat at L5 evoked specific increases in LES activity during static full trunk flexion and extension, irrespective of participants' group. Kinematic data suggested that LBP patients adopted a different movement strategy than controls when noxious heat was applied at the L5 level. Besides, high disability was associated with less kinematic changes when approaching and leaving full flexion. These results indicate that experimental pain can induce neuromechanical alterations in cLBP patients and healthy volunteers, and that higher disability in patients is associated with decreased movement pattern changes.

Postural control during prolonged standing in persons with chronic low back pain.

Prolonged standing has been associated with the onset of low back pain symptoms in working populations. So far, it is unknown how individuals with chronic low back pain (CLBP) behave during prolonged unconstrained standing (PS). The aim of the present study was to analyze the control of posture by subjects with CLBP during PS in comparison to matched healthy adults. The center of pressure (COP) position of 12 CLBP subjects and 12 matched healthy controls was recorded in prolonged standing (30min) and quiet stance tasks (60s) on a force plate. The number and amplitude of COP patterns, the root mean square (RMS), speed, and frequency of COP sway were analyzed. Statistical analyses showed that CLBP subjects produced less postural changes in the antero-posterior direction with decreased postural sway during the prolonged standing task in comparison to the healthy group. Only CLBP subjects were influenced by the prolonged standing task, as demonstrated by their increased COP RMS, COP speed and COP frequency in the quiet standing trial after the prolonged standing task in comparison to the pre-PS trial. The present study provides additional evidence that individuals with CLBP might have altered sensory-motor function. Their inability to generate responses similar to those of healthy subjects during prolonged standing may contribute to CLBP persistence or an increase risk of recurrent back pain episodes. Moreover, quantification of postural changes during prolonged standing could be useful to identify CLBP subjects prone to postural control deficits.