Hypoalgesia post-manipulative therapy: a review of a potential neurophysiological mechanism

Changes in pain sensitivity following spinal manipulation: a systematic review and meta-analysis

Spinal manipulation (SMT) is commonly used for treating individuals experiencing musculoskeletal pain. The mechanisms of SMT remain unclear; however, pain sensitivity testing may provide insight into these mechanisms. The purpose of this systematic review is to examine the literature on the hypoalgesic effects of SMT on pain sensitivity measures and to quantify these effects using meta-analysis. We performed a systematic search of articles using CINAHL, MEDLINE, PsycINFO, and SPORTDiscus from each databases' inception until May 2011. We examined methodological quality of each study and generated pooled effect size estimates using meta-analysis software. Of 997 articles identified, 20 met inclusion criteria for this review. Pain sensitivity testing used in these studies included chemical, electrical, mechanical, and thermal stimuli applied to various anatomical locations. Meta-analysis was appropriate for studies examining the immediate effect of SMT on mechanical pressure pain threshold (PPT). SMT demonstrated a favorable effect over other interventions on increasing PPT. Subgroup analysis showed a significant effect of SMT on increasing PPT at the remote sites of stimulus application supporting a potential central nervous system mechanism. Future studies of SMT related hypoalgesia should include multiple experimental stimuli and test at multiple anatomical sites.

Bilateral leg symptoms--the T10 syndrome?

Prior studies have investigated the role of the sympathetic nervous system and the thoracic spine related to the upper extremities (known as the T4 syndrome). However, there is only little known about the role of the thoracic spine related to the lower extremities. In this case report, a patient with a heavy, tired feeling in both legs and hypomobile thoracic segments was treated with passive mobilisations of the thoracic spine.

Applying Joint Mobilization at Different Cervical Vertebral Levels does not Influence Immediate Pain Reduction in Patients with Chronic Neck Pain: A Randomized Clinical Trial

The aim of the present study was to compare the effects of applying joint mobilization at symptomatic and asymptomatic cervical levels in patients with chronic nonspecific neck pain. Forty-eight patients aged between 18 and 65 years and presenting nonspecific neck pain with a minimum duration of 3 months were recruited for the study. Included patients were randomized to one of two treatment groups: (i) control group: the most symptomatic vertebral level was mobilized; (ii) experimental group: a randomly selected vertebral level was chosen and mobilized. All patients received one treatment session. Pain intensity in resting position during the most painful active cervical movement as well as during vertebral palpation was quantified using an 11-point pain scale. Follow-up measures were taken immediately after intervention by a blinded assessor. The results showed no significant difference in pain intensity immediately after treatment between groups (symptomatic level treated vs. randomly chosen cervical vertebral level treated) during resting position, painful active movement, or vertebral palpation. Within-group comparisons showed significant pain relief after treatment during the most painful active movement as well as during vertebral palpation for both groups, but not during resting position. Significant change in immediate pain intensity during painful active movement and vertebral palpation was achieved after vertebral mobilization. however, both groups presented similar pain reductions suggesting that pain reduction due to joint mobilization is not specific to the vertebral level being mobilized.

Dynamic mobilisation exercises increase cross sectional area of musculus multifidus

REASON FOR PERFORMING STUDY

In human subjects with back pain, the deep spinal stabiliser m. multifidus is inhibited ipsilaterally leading to atrophy, asymmetry and intervertebral instability. Specific physiotherapeutic exercises are required to reactivate m. multifidus. This study assesses the effect of dynamic mobilisation exercises on size and symmetry of m. multifidus in the equine caudal thoracic and lumbar spine.

HYPOTHESES

Regular performance of dynamic mobilisation exercises over a period of 3 months increases cross sectional area (CSA) and left-right symmetry of m. multifidus muscles in the caudal thoracic and lumbar spine.

METHODS

Eight horses performed dynamic mobilisation exercises (3 cervical flexions, one cervical extension and 3 lateral bending exercises to the left and right sides) with 5 repetitions/exercise/day on 5 days/week for 3 months during which time they were not ridden. Left and right m. multifidus CSA was measured ultrasonographically at 6 levels from T10 to L5 at the start (initial evaluation) and end (final evaluation) of the 3 month study. Changes in CSA of the right and left m. multifidus muscles and symmetry of m. multifidus CSA on the right and left sides between the 2 evaluations were sought using analysis of variance (P<0.05).

RESULTS

Between the initial evaluation and final evaluation m. multifidus CSA increased significantly at all 6 spinal levels on both right and left sides. Asymmetries in m. multifidus CSA between the right and left sides decreased between the initial and final evaluations.

CONCLUSIONS

Hypertrophy of multifidus occurred over a 3 month period during which dynamic mobilisation exercises were the only exercise performed.

POTENTIAL RELEVANCE

Dynamic mobilisation exercises maybe a useful rehabilitative technique for horses in which m. multifidus has atrophied in response to back pain.

The role of manual therapies in equine pain management

Manual therapy includes a diverse array of techniques, such as touch therapies, massage, physical therapy, osteopathy, and chiropractic, that were originally developed for use in humans and have been gradually applied to horses. All forms of manual therapy have variable reported levels of effectiveness for treating musculoskeletal issues in humans, but mostly only anecdotal evidence exists in horses. This article explores the scientific literature for evidence of efficacy, safety, and common mechanisms of action of the different forms of manual therapies for potential use in managing acute or chronic pain syndromes in horses. Currently, there is limited evidence supporting the effectiveness of spinal mobilization and manipulation in reducing pain and muscle hypertonicity. Further research is needed to assess the efficacy of specific manual therapy techniques and their contribution to multimodal protocols for managing specific somatic pain conditions in horses.

A preliminary investigation into the magnitude of effect of lumbar extension exercises and a segmental rotatory manipulation on sympathetic nervous system activity

Two commonly utilised manual therapy techniques; McKenzie's lumbar extension exercises (EE); and segmental rotational grade V manipulation were investigated to determine their magnitude of neurophysiological effect. Proxy measures of sympathetic nervous system (SNS) activity (skin conductance) were utilised to ascertaining neurophysiological response. This study determined the neurological effects of these two treatment techniques in addition to establishing the Biopac System as a reliable measure of neurophysiological changes. A quasi-experimental, independent group's design was utilised, with random allocation of 50 normal, healthy participants into a manipulation or an EE group. Neurophysiological measurements of skin conductance were taken in the lower limbs before, during and after the administration of the techniques. Results were converted into percentage change calculations for the intervention and the post-intervention periods. Both treatments increased SNS activity during the intervention period, 63% for the manipulation group (p = 0.0005) and 42% for EE group (p = 0.0005) with the manipulative technique having significantly greater effect (p = 0.012). Further analysis of the manipulation group found no difference between the 'opening' and the 'closing' side of the technique (p = 0.76). Biopac System is a reliable method for measuring SNS activity with minimum measurement variability. Preliminary evidence now exists supporting the neurophysiological effects of two lumbar techniques.

The relationship of the audible pop to hypoalgesia associated with high-velocity, low-amplitude thrust manipulation: a secondary analysis of an experimental study in pain-free participants

OBJECTIVE

High-velocity, low-amplitude (HVLA) manipulation is an effective treatment of low back pain (LBP); however, the corresponding mechanisms are undetermined. Hypoalgesia is associated with HVLA manipulation and suggests specific mechanisms of action. An audible pop (AP) is also associated with HVLA manipulation; however, the influence of the AP on the hypoalgesia associated with HVLA manipulation is not established. The purpose of the current study was to observe the influence of the AP on hypoalgesia associated with HVLA manipulation.

METHODS

The current study represents a secondary analysis of 40 participants. All participants underwent thermal pain sensitivity testing to their leg and low back using protocols specific to A delta fiber-mediated pain and temporal summation. Next, participants received HVLA manipulation to their low back, and the examiner recorded whether an AP was perceived. Finally, participants underwent immediate follow-up thermal pain sensitivity testing using the same protocols. Separate repeated-measure analyses of variance (ANOVAs) were used to observe changes in pain sensitivity before and immediately after HVLA manipulation.

RESULTS

Hypoalgesia of A delta fiber-mediated pain was observed in the low back after HVLA (P < .05), and this was independent of whether an AP was perceived (P > .05). Hypoalgesia of temporal summation was observed in the lower extremity after HVLA (P < .05), and this was independent of whether an AP was perceived (P = .08). However, a moderate effect size for temporal summation was observed favoring participants in whom an AP was perceived.

CONCLUSION

The current study suggests hypoalgesia is associated with HVLA manipulation and occurs independently of a perceived AP. Inhibition of lower extremity temporal summation may be larger in individuals in whom an AP is perceived, but further study is necessary to confirm this finding.

Some factors predict successful short-term outcomes in individuals with shoulder pain receiving cervicothoracic manipulation: a single-arm trial

BACKGROUND

It has been reported that manipulative therapy directed at the cervical and thoracic spine may improve outcomes in patients with shoulder pain. To date, limited data are available to help physical therapists determine which patients with shoulder pain may experience changes in pain and disability following the application of these interventions.

OBJECTIVE

The purpose of this study was to identify prognostic factors from the history and physical examination in individuals with shoulder pain who are likely to experience rapid improvement in pain and disability following cervical and thoracic spine manipulation.

DESIGN

This was a prospective single-arm trial.

SETTING

This study was conducted in outpatient physical therapy clinics.

PARTICIPANTS

The participants were individuals who were seen by physical therapists for a primary complaint of shoulder pain.

INTERVENTION AND MEASUREMENTS

Participants underwent a standardized examination and then a series of thrust and nonthrust manipulations directed toward the cervicothoracic spine. Individuals were classified as having achieved a successful outcome at the second and third sessions based on their perceived recovery. Potential prognostic variables were entered into a stepwise logistic regression model to determine the most accurate set of variables for prediction of treatment success.

RESULTS

Data for 80 individuals were included in the data analysis, of which 49 had a successful outcome. Five prognostic variables were retained in the final regression model. If 3 of the 5 variables were present, the chance of achieving a successful outcome improved from 61% to 89% (positive likelihood ratio=5.3).

LIMITATIONS

A prospective single-arm trial lacking a control group does not allow for inferences to be made regarding cause and effect. The statistical procedures used may result in "overfitting" of the model, which can result in low precision of the prediction accuracy, and the bivariate analysis may have resulted in the rejection of some important variables.

CONCLUSIONS

The identified prognostic variables will allow clinicians to make an a priori identification of individuals with shoulder pain who are likely to experience short-term improvement with cervical and thoracic spine manipulation. Future studies are necessary to validate these findings.

Spinal manipulative therapy has an immediate effect on thermal pain sensitivity in people with low back pain: a randomized controlled trial

BACKGROUND

Current evidence suggests that spinal manipulative therapy (SMT) is effective in the treatment of people with low back pain (LBP); however, the corresponding mechanisms are unknown. Hypoalgesia is associated with SMT and is suggestive of specific mechanisms.

OBJECTIVE

The primary purpose of this study was to assess the immediate effects of SMT on thermal pain perception in people with LBP. A secondary purpose was to determine whether the resulting hypoalgesia was a local effect and whether psychological influences were associated with changes in pain perception.

DESIGN

This study was a randomized controlled trial.

SETTING

A sample of convenience was recruited from community and outpatient clinics.

PARTICIPANTS

Thirty-six people (10 men, 26 women) currently experiencing LBP participated in the study. The average age of the participants was 32.39 (SD=12.63) years, and the average duration of LBP was 221.79 (SD=365.37) weeks.

INTERVENTION AND MEASUREMENTS

Baseline demographic and psychological measurements were obtained, followed by quantitative sensory testing to assess temporal summation and Adelta fiber-mediated pain perception. Next, participants were randomly assigned to ride a stationary bicycle, perform low back extension exercises, or receive SMT. Finally, the same quantitative sensory testing protocol was reassessed to determine the immediate effects of each intervention on thermal pain sensitivity.

RESULTS

Hypoalgesia to Adelta fiber-mediated pain perception was not observed. Group-dependent hypoalgesia of temporal summation specific to the lumbar innervated region was observed. Pair-wise comparisons indicated significant hypoalgesia in participants who received SMT, but not in those who rode a stationary bicycle or performed low back extension exercises. Psychological factors did not significantly correlate with changes in temporal summation in participants who received SMT.

LIMITATIONS

Only immediate effects of SMT were measured, so the authors are unable to comment on whether the inhibition of temporal summation is a lasting effect. Furthermore, the authors are unable to comment on the relationship between their findings and changes in clinical pain.

CONCLUSIONS

Inhibition of Adelta fiber-mediated pain perception was similar for all groups. However, inhibition of temporal summation was observed only in participants receiving SMT, suggesting a modulation of dorsal horn excitability that was observed primarily in the lumbar innervated area.

Cervical lateral glide increases nociceptive flexion reflex threshold but not pressure or thermal pain thresholds in chronic whiplash associated disorders: A pilot randomised controlled trial

Sensory hypersensitivity indicative of augmented central pain processing is a feature of chronic whiplash associated disorders (WAD). This study investigated the immediate effects of a cervical spine manual therapy (SMT) technique on measures of central hyperexcitability. In a randomised, single blind, clinical trial, 39 participants with chronic WAD were randomly assigned to a cervical SMT (lateral glide) or manual contact intervention. The Neck Disability Index (NDI) and GHQ-28 were administered at baseline. Pressure pain thresholds (PPTs), thermal pain thresholds (TPTs) and Nociceptive Flexion Reflex (NFR) responses (threshold and VAS of pain) were measured pre and post intervention. There was a significantly greater increase in NFR threshold following SMT compared to the manual contact intervention (p = 0.04). PPTs at the cervical spine increased following both SMT (mean +/- SE: 24.1 +/- 7.3%) and manual contact (21 +/- 8.4%) with no difference between interventions. There was no difference between interventions for pain ratings with the NFR test, PPTs at the Median Nerve or Tibialis Anterior, heat or cold TPT. SMT may be effective in reducing spinal hyperexcitability in chronic WAD.

The mechanisms of manual therapy in the treatment of musculoskeletal pain: a comprehensive model

Prior studies suggest manual therapy (MT) as effective in the treatment of musculoskeletal pain; however, the mechanisms through which MT exerts its effects are not established. In this paper we present a comprehensive model to direct future studies in MT. This model provides visualization of potential individual mechanisms of MT that the current literature suggests as pertinent and provides a framework for the consideration of the potential interaction between these individual mechanisms. Specifically, this model suggests that a mechanical force from MT initiates a cascade of neurophysiological responses from the peripheral and central nervous system which are then responsible for the clinical outcomes. This model provides clear direction so that future studies may provide appropriate methodology to account for multiple potential pertinent mechanisms.

Effects of spinal manipulation on trunk proprioception in subjects with chronic low back pain during symptom remission

OBJECTIVE

The purpose of this study was to examine the immediate effects of spinal manipulative therapy (SMT) on trunk proprioception in subjects with asymptomatic chronic low back pain (CLBP) and determine if those effects lasted 1 week.

METHODS

This unbalanced randomized controlled crossover design examined 33 subjects with CLBP. Proprioception was tested via joint position sense, threshold to detect passive motion (TTDPM), direction of motion (DM), and force reproduction. Each subject received lumbar manipulation or a sham procedure followed by proprioception retest. This procedure was repeated 1 week later using the opposing treatment. Subjects receiving SMT in the second session returned a third time receiving the sham procedure again.

RESULTS

Spinal manipulative therapy produced an effect for TTDPM in the manipulation first group (P = .008), the sham procedure produced an effect for joint position sense in the sham first group (P = .005). Spinal manipulative therapy had a 1-week effect for the manipulation first group (P = .006). No effect was noted for either DM or force reproduction.

CONCLUSIONS

Results suggest SMT had minimal immediate effect on trunk proprioception. The effects noted occurred in session 1, implicating learning as a potential source. Learning, from repetitive proprioception training, may enhance neuromuscular control in subjects with CLBP before the use of therapeutic exercise. Subjects showed smaller deficits than previously reported for TTDPM or DM, suggesting proprioception deficits may correlate with pain level.

Predicting short-term response to thrust and nonthrust manipulation and exercise in patients post inversion ankle sprain

STUDY DESIGN

Prospective-cohort/predictive-validity study.

OBJECTIVES

To develop a clinical prediction rule (CPR) to identify patients who had sustained an inversion ankle sprain who would likely benefit from manual therapy and exercise.

BACKGROUND

No studies have investigated the predictive value of items from the clinical examination to identify patients with ankle sprains likely to benefit from manual therapy and general mobility exercises.

METHODS AND MEASURES

Consecutive patients with a status of post inversion ankle sprain underwent a standardized examination followed by manual therapy (both thrust and nonthrust manipulation) and general mobility exercises. Patients were classified as having experienced a successful outcome at the second and third sessions based on their perceived recovery. Potential predictor variables were entered into a stepwise logistic regression model to determine the most accurate set of variables for prediction of treatment success.

RESULTS

Eighty-five patients were included in the data analysis, of which 64 had a successful outcome (75%). A CPR with 4 variables was identified. If 3 of the 4 variables were present the accuracy of the rule was maximized (positive likelihood ratio, 5.9; 95% CI: 1.1, 41.6) and the posttest probability of success increased to 95%.

CONCLUSIONS

The CPR provides the ability to a priori identify patients with an inversion ankle sprain who are likely to exhibit rapid and dramatic short-term success with a treatment approach, including manual therapy and general mobility exercises.

LEVEL OF EVIDENCE

Prognosis, level 2b.

An investigation into the effects of a unilaterally applied lumbar mobilisation technique on peripheral sympathetic nervous system activity in the lower limbs

Physiotherapeutic management of lumbar disorders often utilises specific segmental joint mobilisation techniques; however, there is only limited evidence of any neurophysiological effects and much of this has focused on the cervical spine and upper limbs. This study aims to extend the knowledge base underpinning the use of a unilaterally applied lumbar spinal mobilisation technique by exploring its effects on the peripheral sympathetic nervous system (SNS) of the lower limbs. Using a double blind, placebo controlled, independent groups study design and based upon power calculations, 45 normal naïve healthy males were randomly assigned to one of three experimental groups (control, placebo or treatment; a unilaterally applied postero-anterior mobilisation to the left L4/5 zygopophyseal joint). SNS activity was determined by recording skin conductance (SC) obtained from lower limb electrodes connected to a BioPac unit. Validation of the placebo technique was performed by post-intervention questionnaire. Results indicated that there was a significant change in SC from baseline levels (13.5%) that was specific to the side treated for the treatment group during the intervention period (compared to placebo and control conditions). This study provides preliminary evidence that a unilaterally applied postero-anterior mobilisation technique performed, at a rate of 2 Hz, to the left L4/5 lumbar zygopophyseal joint results in side-specific peripheral SNS changes in the lower limbs.

The effects of the Mulligan Sustained Natural Apophyseal Glide (SNAG) mobilisation in the lumbar flexion range of asymptomatic subjects as measured by the Zebris CMS20 3-D motion analysis system

Background

Mulligan's mobilisation techniques are thought to increase the range of movement (ROM) in patients with low back pain. The primary aim of this study was to investigate the application of the Mulligan's Sustained Natural Apophyseal Glide (SNAG) technique on lumbar flexion ROM. The secondary aim was to measure the intra- and inter-day reliability of lumbar ROM employing the same procedure.

Methods

49 asymptomatic volunteers participated in this double-blinded study. Subjects were randomly assigned to receive either SNAG mobilisation (n = 25), or a sham mobilisation (n = 24). The SNAG technique was applied at the L₃and L₄ spinal levels with active flexion in sitting by an experienced manual therapist. Three sets of 10 repetitions at each of the two spinal levels were performed. The sham mobilisation was similar to the SNAG but did not apply the appropriate direction or force. Lumbar ROM was measured by a three dimensional electronic goniometer (Zebris CMS20), before and after each technique. For the reliability, five measurements in two different days (one week apart) were performed in 20 healthy subjects.

Results

When both interventions were compared, independent t tests yielded no statistically significant results in ROM between groups (p = 0.673). Furthermore no significant within group differences were observed: SNAG (p = 0.842), sham (p = 0.169). Intra- and inter-day reliability of flexion measurements was high (ICC_1,1 > 0.82, SEM < 4.0°, SDD<16.3%) indicating acceptable clinical applicability.

Conclusion

While the Zebris proved to be a reliable device for measuring lumbar flexion ROM, SNAG mobilisation did not demonstrate significant differences in flexion ROM when compared to sham mobilisation.

Trial registration

Current Controlled Trials NCT00678093.

Paradigm shift in manual therapy? Evidence for a central nervous system component in the response to passive cervical joint mobilisation

Segmental neurological modulation, neural hysteresis and biomechanical effects have been proposed as mechanisms underpinning the effects of manual therapy. An increasing number of studies hypothesise activation of the central nervous system resulting in a non-segmental hypoalgesic effect with concurrent activation of other neural pathways as a potential mechanism of action. Whether this model is consistent with the current literature is unknown. This systematic review aims to assess the consistency of evidence supporting an involvement of supraspinal systems in mediating the effects of passive cervical joint mobilisation. We searched randomised trials in three electronic databases from inception to November 2007, without language restriction, and checked reference lists of included studies. We assessed study validity and extracted salient features in duplicate. Fifteen studies met our inclusion criteria. The overall quality was high. We found consistency for concurrent hypoalgesia, sympathetic nervous system excitation and changes in motor function. Pooling of data suggested that joint mobilisation improved outcomes by approximately 20% relative to controls. This specific pattern suggests that descending pathways might play a key role in manual therapy induced hypoalgesia. Our review supports the existence of an alternative neurophysiological model, in which passive joint mobilisation stimulates areas within the central nervous system.

AAOMPT clinical guidelines: A model for standardizing manipulation terminology in physical therapy practice

We propose describing a manipulative technique using 6 characteristics: Rate of force application: Describe the rate at which the force was applied. Location in range of available movement: Describe whether motion was intended to occur only at the beginning of the available range of movement, towards the middle of the available range of movement, or at the end point of the available range of movement. Direction of force: Describe the direction in which the therapist imparts the force. Target of force: Describe the location to which the therapist intended to apply the force. Relative structural movement: Describe which structure or region was intended to remain stable and which structure or region was intended to move, with the moving structure or region being named first and the stable segment named second, separated by the word "on." Patient position: Describe the position of the patient, for example, supine, prone, recumbent. This would include any premanipulative positioning of a region of the body, such as being positioned in rotation or side bending.

Diagnosis and classification of pelvic girdle pain disorders--Part 1: a mechanism based approach within a biopsychosocial framework

The diagnosis and classification of pelvic girdle pain (PGP) disorders remains controversial despite a proliferation of research into this field. The majority of PGP disorders have no identified pathoanatomical basis leaving a management vacuum. Diagnostic and treatment paradigms for PGP disorders exist although many of these approaches have limited validity and are uni-dimensional (i.e. biomechanical) in nature. Furthermore single approaches for the management of PGP fail to benefit all. This highlights the possibility that 'non-specific' PGP disorders are represented by a number of sub-groups with different underlying pain mechanisms rather than a single entity. This paper examines the current knowledge and challenges some of the common beliefs regarding the sacroiliac joints and pelvic function. A hypothetical 'mechanism based' classification system for PGP, based within a biopsychosocial framework is proposed. This has developed from a synthesis of the current evidence combined with the clinical observations of the authors. It recognises the presence of both specific and non-specific musculoskeletal PGP disorders. It acknowledges the complex and multifactorial nature of chronic PGP disorders and the potential of both the peripheral and central nervous system to promote and modulate pain. It is proposed that there is a large group of predominantly peripherally mediated PGP disorders which are associated with either 'reduced' or 'excessive' force closure of the pelvis, resulting in abnormal stresses on pain sensitive pelvic structures. It acknowledges that the interaction of psychosocial factors (such as passive coping strategies, faulty beliefs, anxiety and depression) in these pain disorders has the potential to promote pain and disability. It also acknowledges the complex interaction that hormonal factors may play in these pain disorders. This classification model is flexible and helps guide appropriate management of these disorders within a biopsychosocial framework. While the validity of this approach is emerging, further research is required.

The initial effects of knee joint mobilization on osteoarthritic hyperalgesia

Physiotherapists often employ lower limb joint mobilization to reduce pain and increase function. However, there is little experimental data confirming its efficacy. The purpose of this study was to investigate the initial effects of accessory knee joint mobilization on measures of pain and function in individuals with knee osteoarthritis. The study employed a double-blind, controlled, within-subjects repeated-measures design. Thirty-eight subjects with mild to moderate knee pain participated. The effects of a 9-min, non-noxious, AP mobilization of the tibio-femoral joint were compared with manual contact and no-contact interventions. Pressure pain threshold (PPT) and 3-m 'up and go' time were measured immediately before and after each intervention. Results demonstrated a significantly greater mean (95% CI) percentage increase in PPT following knee joint mobilization (27.3% (20.9-33.7)) than after manual contact (6.4% (0.4-12.4)) or no-contact (-9.6% (-20.7 to 1.6)) interventions. Knee joint mobilization also increased PPT at a distal, non-painful site and reduced 'up and go' time significantly more (-5% (-9.3 to 0.8)) than manual contact (-0.4% (-4.2 to 3.5)) or no-contact control (+7.9% (2.6-13.2)) interventions. This study therefore provides new experimental evidence that accessory mobilization of an osteoarthritic knee joint immediately produces both local and widespread hypoalgesic effects. It may therefore be an effective means of reducing pain in this population.

Mulligan's mobilization-with-movement, positional faults and pain relief: Current concepts from a critical review of literature

There are an increasing number of reports espousing the clinically beneficial effects of Mulligan's mobilization-with-movement (MWM) treatment techniques. The most frequent reported effect is that of an immediate and substantial pain reduction accompanied by improved function. Prompted by these dramatic effects are questions regarding the mechanism(s) of action that underpins MWM. It appears timely that a review of the current literature is performed to synthesize and evaluate claims of the effectiveness of MWM and speculation about the proposed mechanisms of action. This article provides an overview of the literature concerning the clinical efficacy, effects and putative mechanisms of action of the MWM approach in the treatment of musculoskeletal conditions. The literature regarding the mechanisms of action in both the biomechanical and pain science paradigms is covered herein by reviewing all available scientific evidence from laboratory-based studies. Limitations of reported studies and directions for further research are also considered.

Efficacy of a C1-C2 self-sustained natural apophyseal glide (SNAG) in the management of cervicogenic headache

STUDY DESIGN

Randomized, double-blind, placebo controlled trial.

OBJECTIVES

To determine the effect of a C1-C2 self-sustained natural apophyseal glide (SNAG) on cervicogenic headache.

BACKGROUND

Cervicogenic headache is a common condition causing significant disability. Recent studies have shown a high incidence of C1-C2 dysfunction, evaluated by the flexion-rotation test (FRT), in subjects with cervicogenic headache. To manage this dysfunction, Mulligan has described a C1-C2 self-SNAG, though no studies have investigated the efficacy of this intervention approach.

METHODS

A sample of 32 subjects (mean _ SD age, 36 +/- 3 years) with cervicogenic headache and FRT limitation were randomized into a C1-C2 self-SNAG or placebo group. After an initial instruction and practice visit in the clinic, interventions consisted of exercises applied independently by the subject twice daily at home on a continual basis. FRT range was measured twice, before and immediately after the instruction and practice visit. Headache symptoms were determined by a headache index over time, assessed by questionnaire preintervention, at 4 weeks postintervention, and at 12 months postintervention.

RESULTS

No differences were found in baseline measures between groups. Immediately after the initial instruction and practice visit performed with the supervision of the therapist, FRT range increased by 15 degrees (SD, 9) for the C1-C2 self-SNAG group (P < .001), which was significantly more than 5 degrees (SD, 5) for the placebo intervention (P < .001). There was also a significant interaction for the variable headache index between group and time (P < .001), indicating that group difference was dependent on time. There was no difference in headache index scores at baseline between groups. Headache index scores were substantially less in the C1-C2 self-SNAG group (mean +/- SD points at 4 weeks, 31 +/- 9; mean +/- SD points at 12 months, 24 +/- 9) compared to the placebo group (mean +/- SD points at 4 weeks, 51 +/- 15; mean +/- SD points at 12 months, 44 +/- 13) at 4 weeks (P < .001) and 12 months (P < .001), with an overall (+/-SD) reduction of 54% (+/-17%) for the individuals in the C1-C2 self-SNAG group.

CONCLUSIONS

These results provide evidence for the efficacy of the C1-C2 self-SNAG technique in the management of individuals with cervicogenic headache.

The initial effects of a Mulligan's mobilization with movement technique on range of movement and pressure pain threshold in pain-limited shoulders

There is little known about the specific manual therapy techniques used to treat painfully limited shoulders and their effects on range of movement (ROM) and pressure pain threshold (PPT). The objective of this study was to investigate the initial effects of a Mulligan's mobilization with movement (MWM) technique on shoulder ROM in the plane of the scapula and PPT in participants with anterior shoulder pain. A repeated measures, double-blind randomized-controlled trial with a crossover design was conducted with 24 subjects (11 males and 13 females). ROM and PPT were measured before and after the application of MWM, sham and control conditions. Significant and clinically meaningful improvements in both ROM (15.3%, F (2,46)=16.31 P=0.00) and PPT (20.2%, F(2,46)=3.44, P=0.04) occurred immediately after post treatment. The results indicate that this specific manual therapy treatment has an immediate positive effect on both ROM and pain in subjects with painful limitation of shoulder movement. Further study is needed to evaluate the duration of such effects and the mechanism by which this occurs.

Effects of a manual therapy technique in experimental lateral epicondylalgia

In patients with lateral epicondylalgia, mobilization-with-movement (MWM) is used as an intervention aimed at achieving analgesia and enhancing grip force, although the mechanisms underlying these effects are unclear. The present study investigated the acute sensory and motor effects of an MWM intervention in healthy controls with experimentally induced lateral epicondylalgia. Twenty-four subjects were randomly allocated to either a MWM or a placebo group (n=12). In both groups, to generate the model of lateral epicondylalgia, delayed onset muscle soreness (DOMS) was provoked in one arm 24h prior (Day 0) to hypertonic saline-induced pain in the extensor carpi radialis brevis muscle (Day 1). Either a MWM or placebo intervention was applied during the saline-induced pain period. Saline-induced pain intensity (visual analogue scale: VAS), pain distribution and pain quality were assessed quantitatively. Pressure pain thresholds (PPTs) were recorded at the common extensor origin and the extensor carpi radialis brevis muscle. Maximal measures of grip and wrist extension force were recorded. In both groups (pooled data), DOMS was efficiently induced as demonstrated by a significant decrease in pre-exercise to pre-injection PPT at the common extensor origin (-45+/-19%) and at the extensor carpi radialis brevis (-61+/-23%; P<0.05), and a significant decrease in maximal grip force (-25+/-6%) and maximal wrist extension force (-40+/-12%; P<0.001). Moreover, both groups experienced a significant increase in muscle soreness (3.9+/-0.2; P<0.0001) at Day 1 compared to pre-exercise. During saline-induced pain and in response to intervention, there were no significant between-group differences in VAS profiles, pain distributions, induced deep tissue hyperalgesia or force attenuation. These data suggest that the lateral glide-MWM does not activate mechanisms associated with analgesia or force augmentation in subjects with experimentally induced features simulating lateral epicondylalgia.

A preliminary investigation into the relationship between cervical snags and sympathetic nervous system activity in the upper limbs of an asymptomatic population

Spinal manipulative therapy techniques are commonly employed by physiotherapists in the clinical setting for the management of neuromusculoskeletal pain and dysfunction, although their underlying mechanism is not fully understood. Mulligan's sustained natural apophyseal glides (SNAGs) constitute one of these techniques. This preliminary investigation was undertaken to investigate the relationship between the application of cervical SNAGs to the C5/6 intervertebral joint (with cervical right rotation) and indirect measures of sympathetic nervous system (SNS) activity. Previous investigations have suggested that cervical manipulative therapy techniques, separate to cervical SNAGs, result in a sympatheoexcitatory effect and that this may be instrumental in producing an analgesic response. Sixteen asymptomatic subjects participated in a laboratory-based experiment. A single blind, randomized, within subject, repeated measures study design which included control, placebo and treatment comparisons was used. Measures of skin conductance (SC) and skin temperature (ST) in the right and left upper limbs were used as indicators of SNS activity. The cervical SNAG technique produced a sympathoexcitatory response demonstrated by a significant increase in SC during application of the treatment intervention (P<0.0005) and for a 2-min period after the intervention (P=0.001) compared with control. There was also a significant increase in SC for the placebo condition, both during intervention (P=0.015) and after intervention (P=0.011) compared with control. There was a statistically significant difference in SC between placebo and treatment conditions for the 2-min period after the intervention had been applied (P=0.01). A trend did emerge for ST change, illustrating a decrease in ST for the treatment and placebo conditions compared with control, however this did not reach statistically significant levels. There were no apparent left/right upper limb differences for SC and ST for each condition. The results of this study suggest that cervical SNAG techniques, performed on naïve asymptomatic subjects, have a sympathoexcitatory effect as measured by changes in SC and ST. The importance of this sympathoexcitatory effect in relation to potential mechanisms for manipulation induced analgesia are discussed, and further areas of research proposed.

Chiropractic Manipulation Affects the Difference Between Arterial Systolic Blood Pressures on the Left and Right in Normotensive Subjects

OBJECTIVE

The purpose of this study is to determine whether chiropractic manipulation is associated with any measurable changes in the difference between the arterial blood pressures on the left and right before and after treatment in normotensive subjects.

METHODS

A nonrandomized, matched pair, controlled clinical trial, with the treatment (manipulation) group and control (resting) group matched for age and sex, was performed in chiropractic student clinics in London, UK. The treatment group consisted of 35 new patients presenting to a single student chiropractor between the start of April 2003 and the end of August 2003. The control group consisted of 35 nonpatients matched for sex and age. The intervention was chiropractic manipulation. Preintervention and postintervention systolic and diastolic blood pressures were recorded in both arms through the use of a digital oscillometric sphygmomanometer.

RESULTS

A significant difference was found between the pre- and posttreatment blood pressure differences for systolic pressures (P = .01), but no significant difference was found in either set of control data or the treatment diastolic values. A significant difference was also found between the treatment and control group's preintervention systolic differences (P = .002), but not between the groups at any other time.

CONCLUSION

Chiropractic treatment appears to have an effect on the difference in systolic blood pressure between the arms, which is not shown in the control group or the diastolic treatment group values. This may be attributable to a difference between the 2 groups' preintervention systolic values; however, there was no significant difference between the 2 groups after intervention.

The impact of neurodynamic testing on the perception of experimentally induced muscle pain

Neurodynamic tests such as the straight leg raising (SLR) and slump test are frequently used for assessment of mechanosensitivity of neural tissues. However, there is ongoing debate in the literature regarding the contributions of neural and non-neural tissues to the elicited symptoms because many structures are affected by these tests. Sensitizing manoeuvres are limb or spinal movements added to neurodynamic tests, which aim to identify the origin of the symptoms by preferentially loading or unloading neural structures. A prerequisite for the use of sensitizing manoeuvres to identify neural involvement is that the addition of sensitizing manoeuvres has no impact on pain perception when the origin of the pain is non-neural. In this study, experimental muscle pain was induced by injection of hypertonic saline in tibialis anterior or soleus in 25 asymptomatic, naive volunteers. A first experiment investigated the impact of hip adduction, abduction, medial and lateral rotation in the SLR position. In a second experiment, the different stages of the slump test were examined. The intensity and area of experimentally induced muscle pain did not increase when sensitizing manoeuvres were added to the SLR or throughout the successive stages of the slump test. The findings of this study lend support to the validity of the use of sensitizing manoeuvres during neurodynamic testing.

A randomized clinical trial comparing two physiotherapy interventions for chronic low back pain

STUDY DESIGN

A randomized clinical trial with blinded assessment.

OBJECTIVES

To investigate the clinical efficacy of 2 active interventions for patients with chronic low back pain.

SUMMARY OF BACKGROUND DATA

Manual therapy and exercise prescription are treatments frequently prescribed for patients with chronic low back pain. The evidence for the relative benefit of these treatments is limited, and questions concerning the most appropriate type of intervention remain unanswered.

METHODS

Eighty patients with chronic low back pain (>3 months) were randomized to one of the following treatments, involving 8 treatments over 8 weeks; 1) one-to-one treatment involving 30 minutes of manual therapy (mobilizations to the spine) and spinal stabilization exercises, and 2) a 10 station exercise class involving aerobic exercises, spinal stabilization exercises, and manual therapy. Three physiotherapists led the hour long group with a maximum of 10 patients. Questionnaires were completed, and physical measurements were taken by a blinded observer before randomization, at the completion of treatment, and at 6 months and 12 months after the completion of treatment. The intention-to-treat principle was used in data analysis.

RESULTS

Eleven patients dropped out of the individual treatment sessions and 7 dropped out of the exercise group. There was a significant reduction (reduced disability) in the questionnaire score in both groups, and there were significant increases in range for all the physical movements tested in both groups. The exercise group was 40% more cost effective than the individual treatments.

CONCLUSION

Both forms of intervention were associated with significant improvement. On-going clinical research is necessary to provide guidance as to the clinical efficacy of various forms of intervention.

The sensory and sympathetic nerve supply within the cervical spine: review of recent observations

The purpose of this review is to identify recently observed features of the sympathetic and sensory systems and their pathways which characterize cervical spine innervation and their potential relevance to the clinical pain syndromes. The results of studies examining the innervation patterns of the zygoapophysial joints serve to demonstrate that structures in the cervical spine, as in other spinal regions, are partly innervated by sensory nerves traveling along sympathetic pathways. These studies also demonstrate that the neuropeptide levels in the cell bodies located within the dorsal root ganglion of these sensory nerves fluctuate according to the physiological state of the zygoapophysial joint. Additional to the sympathetic nerves accompanying the vertebral artery, the innervation patterns of dura and posterior longitudinal ligament in the upper cervical spine are distinctive features of cervical spine innervation. The possible clinical implications of cervical innervation patterns are considered with reference to referred pain, the pain patterns associated with a dissecting vertebral artery and cervicogenic headaches.

Naloxone Fails to Antagonize Initial Hypoalgesic Effect of a Manual Therapy Treatment for Lateral Epicondylalgia

BACKGROUND

Recent research has shown that Mulligan's Mobilization With Movement treatment technique for the elbow (MWM), a peripheral joint mobilization technique, produces a substantial and immediate pain relief in chronic lateral epicondylalgia (48% increase in pain-free grip strength).([1]) This hypoalgesic effect is far greater than that previously reported with spinal manual therapy treatments, prompting speculation that peripheral manual therapy treatments may differ in mechanism of action to spinal manual therapy techniques. Naloxone antagonism and tolerance studies, which employ widely accepted tests for the identification of endogenous opioid-mediated pain control mechanisms, have shown that spinal manual therapy-induced hypoalgesia does not involve an opioid mechanism.

OBJECTIVE

The aim of this study was to evaluate the effect of naloxone administration on the hypoalgesic effect of MWM.

METHODS

A randomized, controlled trial evaluated the effect of administering naloxone, saline, or no-substance control injection on the MWM-induced hypoalgesia in 18 participants with lateral epicondylalgia. Pain-free grip strength, pressure pain threshold, thermal pain threshold, and upper limb neural tissue provocation test 2b were the outcome measures.

RESULTS

The results demonstrated that the initial hypoalgesic effect of the MWM was not antagonized by naloxone, suggesting a nonopioid mechanism of action.

CONCLUSIONS

The studied peripheral mobilization treatment technique appears to have a similar effect profile to previously studied spinal manual therapy techniques, suggesting a nonopioid-mediated hypoalgesia following manual therapy.