Efficacy of Mobilization With Movement on Conditioned Pain Modulation in Chronic Low Back Pain Patients

Efficacy of Mobilization With Movement on Conditioned Pain Modulation in Chronic Low Back Pain Patients

Efficacy of Mobilization With Movement on Conditioned Pain Modulation in Chronic Low Back Pain Patients: A Randomized Controlled Trial

Patients with chronic low back pain may have altered endogenous mechanisms, which can be evaluated with conditioned modulation paradigms. Mobilization with movement has demonstrated improvements in endogenous analgesic mechanisms in conditions such as knee osteoarthritis or lateral epicondylalgia. However, its effects have not yet been studied in patients with chronic low back pain. The objective of this randomized clinical trial is to evaluate the efficacy of mobilization with movement compared to placebo on endogenous mechanisms in patients with chronic low back pain.

Low back pain is the leading cause of disability worldwide, and chronic low back pain (CLBP) has a prevalence of 2-25%, 80% of which are classified as non-specific low back pain because the causal factors have not yet been determined. Although different mechanisms can be attributed to the chronification of pain, a frequent denominator is the amplification of nociceptive transmission or decreased inhibition of nociceptive stimuli in the peripheral and/or central nervous system. To assess inhibitory pathways, conditioned pain modulation (CPM) paradigms are commonly used in humans. They are based on the idea that a noxious stimulus applied to one part of the body can inhibit pain elsewhere by activating the descending inhibitory system. When CPM is evaluated in patients with chronic low back pain, contradictory results are found, with studies reporting an alteration of pain modulation mechanisms and others not. Different studies found that manual therapy can improve CPM compared to sham in patients with chronic musculoskeletal pain, such as lateral epicondylalgia or knee osteoarthritis. However, its effects in patients with chronic low back pain have not yet been studied. Therefore, the aim of this study was to investigate the effect of mobilization with motion on CPM in patients with chronic musculoskeletal pain.

Randomization was conducted by single randomization. Allocation of the selected patients to different groups (A, intervention; B, placebo) was implemented by opaque envelopes. The randomization was performed by personnel not involved in the trial, such as clinics receptionist. The personnel placed the random characters into sealed opaque envelopes and provided the group allocation to patients. The envelopes were opened only by the manual therapist, without letting the patient know to which group they were assigned to. Additionally, outcomes assessor was blinded to which group patients were assigned to.

The MWM technique was performed by asking patients to perform their painful movement (flexion, extension…). If pain was not reproduced, a combination of movements (flexion + rotation…) was performed. The most painful vertebral level was also evaluated with passive accessory vertebral movements. Then, with the patient in a seated position on a stretcher with the feet supported and a belt around the waist, the therapist performed a sustained glide over the targeted vertebra (spinous process) with the force and direction that relieved pain to the lowest level and asked the patient to perform his previous painful movement, as described by Mulligan. Three sets of 10 repetitions were performed, with 1-2 minutes rest between sets.

Patients allocated to sham group received same evaluation and treatment process. However, only manual contact was performed over the spinous process of the targeted vertebra, without the sustained glide and without applying any force. Three sets of 10 repetitions were performed, with 1-2 minutes rest between sets.

Sustained neutral apophyseal glide (SNAG) mobilization with movement applied to targeted vertebra while patients performed their painful movement.

Manual contact (without any pressure) applied to targeted vertebra while patients performed their painful movement.

Conditioned pain modulation of low back, measured on interspace between L5 and S1. Pressure pain threshold (PPT) was used as test stimulus while ischemic pain (using cuff) was used as conditioning stimulus. CPM effect were calculated as the differences between the PPT values with and without the conditioning stimulus.

Pressure pain thresholds (PPT), measured on interspace between L5 and S1. PPT were measured with an algometer placed and applied perpendicular to the skin. Pressure was gradually increased at a rate of 1kg/sec over the targeted location until patient indicated verbally that the sensation became painful. Measurements were taken two times at the location with 30 seconds rest interval between each measurement. The mean of the two measurements for targeted location was calculated for statistical analysis.

Kinesiophobia was measured with Spanish version of Tampa Scale of Kinesiophobia. Higher scores denotes greater fear of experiencing pain while moving.

Depressive symptoms were measured with Spanish version of Beck Inventory II. 0-13 normal scores; 14-19 mild; 20-28 moderate; 29-63 severe depression.

Anxiety was measured with Spanish version of State-trait Anxiety Inventory (STAI). Scores of 20-37 indicate no or low anxiety; 38-44 moderate anxiety; 45-80 high anxiety.

Low back pain associated disability was measured with Spanish version of Roland-Morris Disability Questionnaire. Higher scores denotes greater pain-associated disability.

QoL was measured with Spanish version of EuroQol 5-Dimensions. Quality of life visual analogue scale consist of a scale from 0 (worse quality of life) to 100 (best quality of life). Additionally, quality of life index may be summarised by a series of five sentences, one for each dimension and stating the level within that dimension; or a label consisting of five ordinal numbers, one for each dimension (by convention, in the order these appear in the questionnaire), defining the severity level, where 1 means no problems.

Inclusion Criteria: Adults with chronic low back pain (>3 months of pain duration) 2 or more on a scale of 0 to 10. Exclusion Criteria: Radiculopathy Neurological signs, symptoms, or deficit Rheumatic or autoimmune disease Cutaneous disease History of fracture or spinal surgery Pregnancy Neuropathic pain Active cancer Spondylolysis/Spondylolisthesis Mild/Severe cognitive impairment which interferes with outcomes measurement

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