Spinal cord injury is not a feature of chronic whiplash-associated disorder: a magnetic resonance spectroscopy study.

PURPOSE: Injury to the cervical spinal cord has been suggested as a mechanism that may underpin chronic whiplash-associated disorder (WAD). This study aimed to assess metabolite concentrations indicative of neuronal injury or pathology in the cervical cord in people with chronic WAD. METHODS: Forty-one people with chronic WAD (mean [SD] age 39.6 [11.0] years, 25 females) and 14 healthy controls (39.2 [12.6] years, 9 females) underwent cervical spinal cord magnetic resonance spectroscopy to measure the metabolites N-acetylaspartate (NAA), creatine (Cr) and choline (Cho). Participants with WAD completed clinical questionnaires on pain intensity (Visual Analogue Scale), disability (Neck Disability Index) and psychological factors (Pain Catastrophising Scale, Post-traumatic Diagnostic Scale), and underwent cervical range of motion assessment and pain threshold testing to cold and pressure stimuli. Data were analysed using hypothesis testing and Spearman correlations (p < 0.05). RESULTS: There were no differences between the WAD and control groups for NAA/Cr (median [IQR] WAD 1.73 [1.38, 1.97], controls 2.09 [1.28, 2.89], p = 0.37), NAA/Cho (WAD 1.50 [1.18, 2.01], controls 1.57 [1.26, 1.93], p = 0.91) or Cr/Cho (WAD 0.84 [0.64, 1.17], controls 0.76 [0.60, 0.91], p = 0.33). There were no significant correlations between NAA/Cr, NAA/Cho or Cr/Cho and any clinical variable (p ≥ 0.06). CONCLUSIONS: Findings are consistent with major metabolic changes not being present in chronic WAD.

Comparative Strength and Endurance Parameters of the Craniocervical and Cervicothoracic Extensors and Flexors in Females With and Without Idiopathic Neck Pain.

Isometric strength and endurance performance of cervical flexor and extensor muscles were compared in women with (n = 30) and without (n = 30) idiopathic neck pain at the craniocervical and cervicothoracic axes. Strength and endurance time (time to task failure in seconds) at 50% maximal voluntary contraction were recorded in 4 directions (craniocervical flexion/extension and cervicothoracic flexion/extension) and 6 strength and endurance ratios were calculated. Participants in both groups were matched for body mass index. The idiopathic neck pain group demonstrated significantly less strength for the cervicothoracic flexors and extensors (1.58-4.7 N·m [12.4%-17.9%] less, P < .04) and significantly less endurance time for the cervicothoracic and craniocervical flexors (10.77-10.9 s [23.3%-27.5%] less, P < .03). The cervicothoracic extension to craniocervical flexion strength ratio was also lower in the idiopathic neck pain group (P = .01); however, no other strength or endurance ratio was significantly different between groups. This exploratory study suggests assessing specific performance parameters accounting for regional muscular differences in the upper and lower neck is potentially informative to understanding impairments in neck pain conditions, particularly as impairments may not be uniform across muscle groups.

Morphological changes in the cervical muscles of women with chronic whiplash can be modified with exercise-A pilot study.

INTRODUCTION: In this preliminary study we determined whether MRI markers of cervical muscle degeneration [elevated muscle fatty infiltration (MFI), cross-sectional area (CSA), and reduced relative muscle CSA (rmCSA)] could be modified with exercise in patients with chronic whiplash. METHODS: Five women with chronic whiplash undertook 10 weeks of neck exercise. MRI measures of the cervical multifidus (posterior) and longus capitus/colli (anterior) muscles, neck muscle strength, and self-reported neck disability were recorded at baseline and at completion of the exercise program. RESULTS: Overall significant increases in CSA and rmCSA were observed for both muscles, but significant reductions in MFI were only evident in the cervical multifidus muscle. These changes coincided with increased muscle strength and reduced neck disability. CONCLUSIONS: MRI markers of muscle morphology in individuals with chronic whiplash appear to be modifiable with exercise.

Further exploring the relationship between pressure pain thresholds and function in knee osteoarthritis.

BACKGROUND: Studies in Knee Osteoarthritis (KOA) have shown lowered Pressure Pain Threshold (PPT) values compared to healthy controls potentially signifying mechanical hypersensitivity, although the relevance of these findings to knee function remains unclear. OBJECTIVE: This study further explores the relationship between PPT measures and knee function (self-reported, physical) in individuals undergoing total knee arthroplasty for advanced KOA. DESIGN: Cross-sectional observational study. METHODS: PPT's were recorded both local to the affected knee and at a remote site (deltoid) in 79 individuals with advanced KOA. Participants also completed self-report (Knee Society Score - functional sub-score) and physical (6-min walk test distance)) measures of knee function, as well as measures of pain-related psychological distress. Hierarchical linear regression models evaluated the relationship between the measures of function (self-report and physical measures modelled separately), PPT measures (local and remote), while accounting for demographic and psychological distress measures. RESULTS: Higher knee PPT scores were independently associated with higher self-reported knee function (ß 0.33, p < 0.02) and higher 6-min walk test distance (ß 0.41, p < 0.01), although pain self-efficacy (ß 0.33, p < 0.01) was also a significant variable in both models. Nearly identical findings were evident for PPT's measured at the deltoid. Overall PPT's could only explain a modest portion of variance (adjusted R2 = 0.15 to 0.17) in the functional measures. CONCLUSIONS: PPT measures may be limited in their capacity to distinguish the impact of peripheral and central pain mechanisms on knee function in individuals undergoing total knee arthroplasty for advanced KOA.

Magnetic Resonance Spectroscopy Assessment of Brain Metabolite Concentrations in Individuals With Chronic Whiplash-associated Disorder: A Cross-sectional Study.

OBJECTIVES: Pathophysiologic mechanisms underpinning ongoing pain in whiplash-associated disorder (WAD) are not well understood, however, alterations in brain morphology and function have been observed in this population and in other chronic pain conditions. This study investigated metabolite profiles of brain regions in people with chronic WAD compared with controls. MATERIALS AND METHODS: Thirty-eight individuals with chronic WAD (mean [SD] age, 39.5 [11.3] years, 23 female individuals) and 16 pain-free controls (38.9 [12.7] years, 11 female individuals) underwent multivoxel brain magnetic resonance spectroscopy. At the anterior cingulate cortex (ACC), primary motor cortex (1MC), and somatosensory cortex (SSC), ratios of metabolite concentrations were calculated for N-acetylaspartate (NAA), creatine (Cr), choline (Cho), myo-inositol (Ins), and glutamate/glutamine (Glx). Chronic WAD group participants completed clinical questionnaires and cold and pressure pain threshold assessment. Data were analyzed with hypothesis testing and Spearman correlations (P≥0.05), with Benjamini-Hochberg corrections (5% false discovery rate). RESULTS: No group differences were observed for NAA:Cr, NAA:Cho, Cr:Cho, Glx:NAA, Glx:Cr, Glx:Cho, Ins:NAA, Ins:Cr, Ins:Cho or Ins:Glx for left or right ACC, 1MC, or SSC following correction for multiple comparisons. No significant correlations were observed between metabolite ratios and any clinical variable. DISCUSSION: These results suggest that ongoing pain and disability in this population may not be underpinned by metabolite aberrations in the brain regions examined. Further research is required to progress our understanding of cortical contributions to neurophysiologic mechanisms in chronic WAD.

Diffusion-weighted magnetic resonance imaging for the healthy cervical multifidus: a potential method for studying neck muscle physiology following spinal trauma.

STUDY DESIGN: Cross-sectional. OBJECTIVE: To develop a new magnetic resonance imaging (MRI) measure for the diffusive properties of the healthy cervical multifidus and to determine the interrater and intrarater reliability of the measurement. BACKGROUND: Diffusion-weighted MRI, via calculation of the apparent diffusion coefficient (ADC), provides a representation of microscopic movements of water molecules in human tissues and may be useful to assess structural changes in neck muscle, as has been observed following whiplash. The optimal imaging parameters, however, have not been established. METHODS: A diffusion-weighted MRI measure was developed, and, for the basic examination, the right cervical multifidus muscle at the C5 level was studied. A total of 6 asymptomatic volunteer individuals (3 females and 3 males) underwent a single diffusion-weighted MRI scan. Interrater and intrarater agreement was evaluated using Bland-Altman plots and intraclass correlation coefficients. RESULTS: Mean ADCb0-b50 and ADCb50-250 were significantly different from one another (P=.03). The plots confirmed the agreement of raters for ADC of the right cervical multifidus at C5. CONCLUSIONS: A quantitative and reliable diffusion-weighted MRI measure of cervical multifidus ADC has been described. There appears to be a fast and slow component ADC for the healthy multifidus, suggesting changes in extracellular and intracellular volume. Further comparative study is needed to quantify ADCs in the neck muscles in patients with traumatic whiplash.

Investigating the Fear Avoidance Model in People With Whiplash: The Association Between Fear of Movement and In Vivo Activity.

OBJECTIVES: The aims of this study were to examine the relationship between fear of movement and activity levels in people with whiplash-associated disorders (WAD) over the first 3 months postinjury, to determine the mediating effect of: fear of movement on the relationship between catastrophizing and activity levels, and activity levels on the relationship between fear of movement and disability in patients with WAD. MATERIALS AND METHODS: Ambulatory monitoring of physical activity was conducted for a minimum of 8 waking hours on 2 consecutive days within 4 weeks postinjury and at 12 weeks postinjury for 103 (74 female) people with WAD. Time spent in upright postures (uptime) and time in motion (TIM) were collected along with measures of pain, disability, pain catastrophizing, and fear of movement. The association of self-report outcome measures with uptime and TIM were examined. Mediation analyses were performed to determine the mediating effect of: fear of movement on the relationship between catastrophizing and activity, and activity levels on the relationship between fear of movement and disability. RESULTS: Fear of movement was significantly related to uptime but not TIM. Mediation analyses showed that the relationship between fear of movement and disability was not mediated by activity levels, and that the relationship between catastrophizing and activity levels was not mediated by fear of movement. DISCUSSION: Our data suggests measures of Fear Avoidance Model are not related to general physical activity in people with WAD. Investigation of movements specific to the cervical spine and alternative explanatory models may be required.

The influence of isometric exercise on endogenous pain modulation: comparing exercise-induced hypoalgesia and offset analgesia in young, active adults.

Background and aims Impairment of endogenous analgesia has been associated with the development, maintenance and persistence of pain. Endogenous analgesia can be evaluated using exercise-induced hypoalgesia (EIH) and offset analgesia (OffA) paradigms, which measure temporal filtering of sensory information. It is not clear if these paradigms are underpinned by common mechanisms, as EIH and OffA have not previously been directly compared. A further understanding of the processes responsible for these clinically relevant phenomena may have future diagnostic and therapeutic utility in management of individuals with persistent pain conditions. The primary aim of this study was to investigate if there is a correlation between the magnitudes of EIH and OffA. The secondary aim of the study was to examine whether exercise influences OffA. Methods Thirty-six healthy, pain-free participants were recruited. EIH was evaluated using pressure pain thresholds (PPT) and pain ratings to suprathreshold pressure stimuli over tibialis anterior and the cervical spine. OffA evaluation utilised a three-step protocol, whereby individualised heat pain thermal stimuli [Numerical Rating Scale (NRS)=50/100] were applied (T1), before increasing 1 °C (T2), followed by 1 °C reduction (T3). The magnitude of OffA was calculated as the percentage reduction in the NRS from T2 to T3. PPT/suprathreshold pain ratings and OffA measures were recorded, before and after 5 min of isometric quadriceps exercise performed at 20-25% maximum voluntary contraction (MVC); and following a 15 min rest period. Data were analysed using repeated measures (RM) ANCOVA and correlational analyses. Results There was no correlation between EIH measures (PPTs or pain ratings to suprathreshold pressure stimuli over tibialis anterior or the cervical spine) and OffA (p>0.11 for all). OffA was induced and not modulated by exercise (p=0.28). Conclusions Five minutes of 20-25% MVC lower limb isometric exercise provided non-pharmacological pain modulation in young, active adults. Magnitude of EIH was not correlated with that of OffA, and exercise did not influence magnitude of OffA. Implications These results suggest that in young, pain-free individuals, separate testing of these two paradigms is required to comprehensively evaluate efficacy of endogenous analgesia. If these results are replicated in patient populations, alternative or complementary methods to exercise interventions may be required to modulate impaired OffA.

Evidence of generalised mechanical hyperalgesia in patients with advanced knee osteoarthritis undergoing total knee arthroplasty.

BACKGROUND AND OBJECTIVE: Persistent pain is reported in up to 34% of patients following total knee arthroplasty (TKA) for management of knee osteoarthritis (KOA). Persistent pain in this group is thought to be at least partly reflective of pain sensory hypersensitivity. The objective of this study was to evaluate sensory hypersensitivity, using mechanical and thermal quantitative sensory testing, in patients about to undergo TKA. DESIGN AND METHODS: Pressure pain thresholds (PPT) and cold pain thresholds (CPT) were recorded from 30 participants prior to their TKA, and compared with recordings taken from 30 healthy control participants of similar age and gender. Thresholds were recorded locally and remotely (other knee, deltoid) to the operative knee. Group comparisons (KOA, control, groups) were made using a general linear mixed models approach with age, gender, and body mass index (BMI) included as covariates. Pairwise comparisons were conducted with Bonferonni correction for multiple comparisons. RESULTS: Significantly lower PPTs were at all measured sites in the KOA group compared to the control group (P<0.001 at all sites, except the deltoid P=0.004). Males demonstrated higher pain threshold compared to females, averaged over all sites, P=0.02. There were no observed between-group differences in CPT (P=0.122). CONCLUSIONS: This study suggested that some individuals about to undergo TKA for their advanced KOA demonstrated widespread mechanical sensory hypersensitivity. These findings have potentially important clinical implications regarding perioperative and longer-term pain management in these patients.

Intramuscular fat is present in cervical multifidus but not soleus in patients with chronic whiplash associated disorders.

The presence of intramuscular fat (IMF) in the cervical spine muscles of patients with whiplash associated disorders (WAD) has been consistently found. The mechanisms underlying IMF are not clear but preliminary evidence implicates a relationship with stress system responses. We hypothesised that if systemic stress system responses do play a role then IMF would be present in muscles remote to the cervical spine. We aimed to investigate if IMF are present in muscle tissue remote (soleus) to the cervical spine in people with chronic WAD. A secondary aim was to investigate associations between IMF and posttraumatic stress symptom levels. Forty-three people with chronic WAD (25 female) and 16 asymptomatic control participants (11 female) participated. Measures of pain, disability and posttraumatic stress symptoms were collected from the WAD participants. Both groups underwent MRI measures of IMF in cervical multifidus and the right soleus muscle. There was significantly greater IMF in cervical multifidus in patients with WAD and moderate/severe disability compared to controls (p = 0.009). There was no difference in multifidus IMF between the mild and moderate/severe disability WAD groups (p = 0.64), or the control and mild WAD groups (p = 0.21). IMF in the right soleus was not different between the groups (p = 0.47). In the WAD group, we found no correlation between PDS symptoms and cervical multifidus IMF or between PDS symptoms and soleus IMF. Global differences in IMF are not a feature of chronic WAD, with differences in IMF limited to the cervical spine musculature. While the mechanisms for the development of IMF in the cervical spine following whiplash injury remain unclear, our data indicate that local factors more likely contribute to these differences.

Exercise induced hypoalgesia is elicited by isometric, but not aerobic exercise in individuals with chronic whiplash associated disorders.

BACKGROUND AND AIMS: Reduced pain sensitivity following exercise is termed exercise induced hypoalgesia (EIH). Preliminary evidence suggests that impairment of EIH is evident in individuals with whiplash associated disorders (WAD) following submaximal aerobic exercise. This study aimed to compare EIH responses to isometric and aerobic exercise in patients with chronic WAD and healthy controls and investigate relationships between EIH, conditioned pain modulation (CPM) and psychological factors in patients with chronic WAD. METHODS: A cross sectional pre-post study investigated the effect of a single session of submaximal aerobic cycling exercise and a single session of isometric timed wall squat exercise on EIH in a group of participants with chronic WAD (n=21) and a group of asymptomatic control participants (n=19). Bivariate analyses between EIH and baseline measures of CPM and psychological features (fear of movement, pain catastrophization and posttraumatic stress symptoms) were also investigated. RESULTS: The isometric wall squat exercise but not the aerobic cycling exercise resulted in EIH in both groups (P<.023) with no between-group differences (P>.55) demonstrated for either exercise. There were no significant associations measured between EIH (for either exercise performed), and CPM, or any of the psychological variables. CONCLUSIONS: This study showed that individuals with chronic WAD and mild to moderate pain and disability, and no evidence of dysfunctional CPM, demonstrated reduced pain sensitivity, both in the cervical spine and over the tibialis anterior following an isometric, timed wall squat exercise. Cycling exercise did not increase pain sensitivity. IMPLICATIONS: Individuals with chronic WAD and mild to moderate levels of neck pain and disability may experience less pain sensitivity both locally and remotely following an exercise program directed at non-painful muscles performing isometric exercises. Individuals cycling for 30min at 75% of age-predicted heart rate maximum do not experience increased pain sensitivity.

Comparison of spatial summation properties at different body sites.

BACKGROUND AND AIMS: The nociceptive system appears to have evolved a range of protective characteristics that are of great interest in understanding both acute and chronic pain. Spatial summation is one important characteristic, whereby increasing area of a stimulus, or distance between multiple stimuli, results in more intense pain-not only greater area of pain. One of the mysteries of chronic pain is why spinal pain is so prevalent relative to pain at other sites. Since pathological tissue models have failed to fully explain spinal pain, we theorized that body region specific differences in sensory processing-such as a greater propensity for spatial summation-may help to explain its vulnerability. We aimed to examine this by comparing the properties of summation at different body parts: the dorsal forearm, neck, and back. METHODS: Spatial summation of pain was investigated using noxious intra-dermal electrical stimuli in healthy pain-free adults (14 males, 6 females), and the perceived pain intensity was rated on a 0-100 pain scale. Area-based stimulation was investigated by doubling the stimulation area with the addition of a second electrode placed adjacent to the first. Distance-based summation was investigated by randomly varying the separation distance between paired noxious electrical stimuli at separations of 0, 10, 15, and 20cm. RESULTS: This study demonstrated that the properties of area- and distance-based summation are uniform across the neck, back, and forearm in healthy adults. Spatial summation of pain was also found to be greatest at 15- and 20-cm paired separations for all body regions tested, confirming that noxious information can be integrated over an extensive anatomical area. CONCLUSION: Data from this investigation refutes the thesis that spatial summation of pain may be a contributing factor for the reported difference in chronicity rates between spinal and peripheral sites. It remains, however, a potentially important mechanism by which noxious inputs from multi-level pathology might integrate and contribute to pain. IMPLICATIONS: While data from this project suggest that there are no regional differences in the properties of spatial summation of noxious stimuli, regional differences in other characteristics of the nociceptive system may yet provide insight into why some spinal pain is so highly prevalent; nociceptive distance-based summation may be highly relevant where two or more conditions co-exist in close proximity.

Multivariate pattern analysis utilizing structural or functional MRI-In individuals with musculoskeletal pain and healthy controls: A systematic review.

OBJECTIVE: The purpose of this systematic review is to systematically review the evidence relating to findings generated by multivariate pattern analysis (MVPA) following structural or functional magnetic resonance imaging (fMRI) to determine if this analysis is able to: a) Discriminate between individuals with musculoskeletal pain and healthy controls, b) Predict pain perception in healthy individuals stimulated with a noxious stimulus compared to those stimulated with a non-noxious stimulus. METHODS: MEDLINE, CINAHL, Embase, PEDro, Google Scholar, Cochrane library and Web of Science were systematically screened for relevant literature using different combinations of keywords regarding structural and functional MRI analysed with MVPA, both in individuals with musculoskeletal pain and healthy controls. Reference lists of included articles were hand-searched for additional literature. Eligible articles were assessed on risk of bias and reviewed by two independent researchers. RESULTS: The search query returned 18 articles meeting the inclusion criteria. Methodological quality varied from poor to good. Seven studies investigated the ability of machine-learning algorithms to differentiate patient groups from healthy control participants. Overall, the review demonstrated that MVPA can discriminate between individuals with MSK pain and healthy controls with an overall accuracy ranging from 53% to 94%. Twelve studies utilized healthy control participants (using them as their own controls), during experimental pain paradigms aimed to investigate the ability of machine-learning to differentiate individuals stimulated with noxious stimuli from those stimulated with non-noxious stimuli, with 'pain' detection rates ranging from 60% to 94%. However, significant heterogeneity in patient conditions, study methodology and brain imaging techniques resulted in various findings that make study comparisons and formal conclusions challenging. CONCLUSION: There is preliminary and emerging evidence that MVPA analyses of structural or functional MRI are able to discriminate between patients and healthy controls, and also discriminate between noxious and non-noxious stimulation. No prospective studies were found in this review to allow determination of the prognostic or diagnostic capabilities or treatment responsiveness of these analyses. Future studies would also benefit from combining various behavioural, genotype and phenotype data into analyses to assist with development of sensitive and specific signatures that could guide future individualized patient treatment options and evaluate how treatments exert their effects.

Evaluating the neck joint position sense error with a standard computer and a webcam.

Joint Position Sense Error (JPSE) is a measure of cervical spine proprioception, and a simple method for measuring the JPSE could help in monitoring and evaluating the outcomes of rehabilitation of people with neck pain. In this study we demonstrate preliminary results of a method for measuring JPSE that does not require the participant to wear any equipment. Based on free publicly available head tracking software, compatible with any webcam, we developed a webpage which instructs the participant in performing a self-administered version of the test. The aim of this proof-of-concept study was to demonstrate the viability of this system. We compared our absolute error values (3.68 ± 1.2° after extension, 3.46 ± 1.66° after flexion, 3.89 ± 2.34° after rotation to the left and 4.02 ± 1.82°after rotation to the right) to values from literature, finding that our results do not differ from those of 6 out of 11 studies (which used more complex and expensive setups). The results indicate that our system allows assessment of the JPSE with a standard computer. Being based on a website, the system has potential for telemedicine use. Further research is required to validate the system before it can be recommended for use in clinical practice.

Addition of posttraumatic stress and sensory hypersensitivity more accurately estimates disability and pain than fear avoidance measures alone after whiplash injury.

The fear avoidance model (FAM) has been proposed to explain the development of chronic disability in a variety of conditions including whiplash-associated disorders (WADs). The FAM does not account for symptoms of posttraumatic stress and sensory hypersensitivity, which are associated with poor recovery from whiplash injury. The aim of this study was to explore a model for the maintenance of pain and related disability in people with WAD including symptoms of PTSD, sensory hypersensitivity, and FAM components. The relationship between individual components in the model and disability and how these relationships changed over the first 12 weeks after injury were investigated. We performed a longitudinal study of 103 (74 female) patients with WAD. Measures of pain intensity, cold and mechanical pain thresholds, symptoms of posttraumatic stress, pain catastrophising, kinesiophobia, and fear of cervical spine movement were collected within 6 weeks of injury and at 12 weeks after injury. Mixed-model analysis using Neck Disability Index (NDI) scores and average 24-hour pain intensity as the dependent variables revealed that overall model fit was greatest when measures of fear of movement, posttraumatic stress, and sensory hypersensitivity were included. The interactive effects of time with catastrophising and time with fear of activity of the cervical spine were also included in the best model for disability. These results provide preliminary support for the addition of neurobiological and stress system components to the FAM to explain poor outcome in patients with WAD.

Physiotherapists' Beliefs About Whiplash-associated Disorder: A Comparison Between Singapore and Queensland, Australia.

BACKGROUND AND PURPOSE: Healthcare providers' beliefs may play a role in the outcome of whiplash-associated disorders (WAD), a condition which is proposed to be culturally dependent. Clinical practice guidelines recommend an active approach for the management of WAD, which is often delivered by physiotherapists. However, there is no data on physiotherapists' whiplash beliefs. Our primary objective was to determine physiotherapists' beliefs from Queensland (Australia) and Singapore, two cultures with differing prevalence of chronic musculoskeletal pain and chronic WAD. METHODS: A pen and paper survey of musculoskeletal physiotherapists practicing in Queensland and Singapore was conducted. Participants completed questionnaires consisting of patient vignettes and statements inquiring knowledge and attitudes towards WAD. Chi-square tests of significance were used to compare the responses of physiotherapists from both samples. RESULTS: Ninety-one (response rate 45%) Queensland-based and 94 (response rate 98%) Singapore-based physiotherapists participated in the study. The beliefs in the management strategies for the patient vignettes were generally consistent with practice guidelines. A higher proportion of Queensland-based physiotherapists expected permanent disabilities for the patient vignette depicting chronic WAD (Queensland: 55% Singapore: 28% Pearson chi-sq 18.76, p < 0.005).Up to 99% of the physiotherapists from both samples believed in encouragement of physical activity, the effectiveness of exercise and multimodal physiotherapy for WAD. Significantly higher proportions of Singapore-based physiotherapists believed in ordering radiographs for acute WAD (Pearson chi-sq 41.98, p < 0.001) and also believed in a psychogenic origin of chronic WAD (Pearson chi-sq 22.57, p 0.001). CONCLUSION: The majority of beliefs between physiotherapists in Queensland and Singapore were similar but there were specific differences. Physiotherapists' whiplash beliefs in Queensland and Singapore did not clearly reflect the difference in prevalence of chronic musculoskeletal pain or chronic WAD in Queensland and Singapore.

The geography of fatty infiltrates within the cervical multifidus and semispinalis cervicis in individuals with chronic whiplash-associated disorders.

STUDY DESIGN: Cross-sectional. OBJECTIVES: To quantify the magnitude and distribution of muscle fat infiltration (MFI) within the cervical multifidus and semispinalis cervicis muscles in participants with chronic whiplash-associated disorders (WADs) compared to those who have fully recovered from a whiplash injury and healthy controls. BACKGROUND: Previous research has established the presence of increased MFI throughout the cervical extensor muscles of individuals with WAD when compared to healthy controls. These changes appear to be greater in the deepest muscles (eg, multifidus and semispinalis cervicis) than in the more superficial muscles. A detailed analysis of the distribution of MFI within these deep extensor muscles in chronic WAD, recovered, and control groups would provide a foundation for further investigation of specific mechanisms, etiologies, and targets for treatments. METHODS: Fifteen participants (WAD, n = 5; recovered, n = 5; and control, n = 5) were studied using a 3-D fat-water separation magnetic resonance imaging sequence. Bilateral measures of cervical multifidus and semispinalis cervicis MFI in 4 quartiles (1 [medial] to 4 [lateral]) at cervical levels C3 through C7 were included in the analysis. Intrarater and interrater reliability were established. A mixed-model analysis was performed to control for covariates, identify interaction effects, and compare MFI distribution between groups. RESULTS: The limits of agreement confirmed strong intrarater and interrater agreement at all levels (C3-C7). Sex, age, and body mass index were identified as significant covariates for MFI. Significant interactions were found between group and muscle quartile (P<.001) and between muscle quartile and cervical level (P<.001). Pairwise comparisons for intraquartile MFI between groups revealed significantly greater MFI in the WAD group when compared to the recovered group in the first quartile (P<.001), second quartile (P<.001), and third quartile (P = .03). When compared to the control group, the WAD group had significantly greater MFI in the first quartile (P = .002) and the second quartile (P = .045). The control group had significantly higher MFI in comparison to the recovered group in the first quartile (P = .048). CONCLUSION: This study provides preliminary data mapping the spatial distribution of MFI in the cervical multifidus and semispinalis cervicis muscles in individuals with chronic WAD, those who have recovered from a whiplash injury, and healthy controls. Muscle fat infiltration is more concentrated in the medial portion of the muscles in all participants. However, the magnitude of MFI in the medial quartiles (1 and 2) is greatest in the chronic WAD group.

Less efficacious conditioned pain modulation and sensory hypersensitivity in chronic whiplash-associated disorders in Singapore.

OBJECTIVES: Cultural differences in pain perception exist. Although chronic whiplash-associated disorder (WAD) is well investigated in western countries, little is known about its presentation in Singapore. We studied the neck motion and pain sensitivity in people with chronic WAD in Singapore. MATERIALS AND METHODS: Thirty chronic WAD participants (>3 mo, Neck Disability Index: 40% [SD 17%]) were age, sex, and ethnicity matched with 30 pain-free controls. All 60 participants underwent the following tests: active neck motion, pain thresholds (pressure, brachial plexus provocation test [BPPT], cold), cold pain tolerance, and conditioned pain modulation (CPM). The test stimulus of contact heat and conditioning stimulus of cold water immersion was used to assess CPM. Data were evaluated to determine differences between WAD and control groups. RESULTS: Active neck motion (F1,29=80.02), pain thresholds of blunt pressure (F1,29=20.84), BPPT (F1,29=54.56), and cold (Z=-4.31) were significantly lower in participants with WAD (P<0.0001). Cold pressor pain tolerance was significantly lower in participants with WAD (Z=-2.89, P=0.02). A less efficacious CPM was also demonstrated in participants with WAD (F1,29=9.20, P=0.03). A combination of BPPT and cold hyperalgesia best predicted the WAD group (sensitivity=96.7%, specificity=96.7%). DISCUSSION: These findings of sensory hypersensitivity and decreased neck motion in Singaporeans with chronic WAD are consistent with physical impairments reported in western populations.

Differential changes in muscle composition exist in traumatic and nontraumatic neck pain.

STUDY DESIGN: A population based cross-sectional study. OBJECTIVE: To clarify relative constituents of viable muscle in 2-dimensional cross-sectional area (CSA) measures of ventral and dorsal cervical muscles in patients with chronic whiplash-associated disorders (WAD), idiopathic neck pain, and healthy controls. SUMMARY OF BACKGROUND DATA: Previous data using T1-weighted magnetic resonance image demonstrated large amounts of neck muscle fat infiltration and increased neck muscle CSA in patients with chronic WAD but not in idiopathic neck pain or healthy controls. METHODS: Magnetic resonance images were obtained for 14 cervical muscle regions in 136 females, including 79 with chronic whiplash, 23 with chronic idiopathic neck pain, and 34 healthy controls. RESULTS: Without fat removed, relative CSA of 7 of 14 muscle regions in the participants with chronic WAD was larger, 3 of 14 smaller and 4 of 14 similar to healthy individuals. When T1-weighted signal representing the lipid content of these muscles was removed, 8 of 14 relative muscle CSA in patients with whiplash were similar, 5 of 14 were smaller and only 1 of 14 was larger than those observed in healthy controls. Removal of fat from the relative CSA measurement did not alter findings between participants with idiopathic neck pain and healthy controls. CONCLUSION: These findings clarify that previous reports of increased relative CSA in patients with chronic whiplash represent cervical muscle pseudohypertrophy. Relative muscle CSA measures reveal atrophy in several muscles in both patients with WAD and idiopathic neck pain, which supports inclusion of muscle conditioning in the total management of these patients. LEVEL OF EVIDENCE: 3.

Patients with chronic whiplash can be subgrouped on the basis of symptoms of sensory hypersensitivity and posttraumatic stress.

The lack of efficacy of rehabilitative approaches to the management of chronic whiplash-associated disorders (WAD) may be in part due to heterogeneity of the clinical presentation of this patient population. The aim of this study was to identify homogeneous subgroups of patients with chronic WAD on the basis of symptoms of PTSD and sensory hypersensitivity and to compare the clinical presentation of these subgroups. Successive k-means cluster analyses using 2, 3 and 4 cluster solutions were performed by using data for 331 (221 female) patients with chronic (>3 months) WAD. The 4 cluster solution was identified as the most clinically relevant, yielding 4 distinct clusters: no to mild posttraumatic stress symptoms and no sensory hypersensitivity (nPnH), no to mild posttraumatic stress symptoms and sensory hypersensitivity (nPH), moderate to severe posttraumatic stress and no sensory hypersensitivity (PnH) and moderate to severe posttraumatic stress and sensory hypersensitivity (PH). The nPnH cluster was the largest cluster, comprising 43.5% of the sample. The PH cluster had significantly worse disability, pain intensity, self-reported mental health status and cervical range of motion in comparison to the nPnH and nPH clusters. These data provide further evidence of the heterogeneity of the chronic WAD population and the association of a more complex clinical presentation with higher disability and pain in this patient group.