Gray Matter Morphology and Pain-related Disability in Young Adults with Low Back Pain

Structural neuroplasticity in the brain may contribute to the persistence of low back pain (LBP) symptoms and the disability associated with them. It is not known if structural adaptations are evident early in the lifespan in young adults with LBP. This study compared gray matter in cortical sensorimotor regions in young adults with and without persistent LBP and identified gray matter and clinical predictors of pain-related disability. Eighty-two individuals with and without a history of LBP participated. Peak and average gray matter density in cortical sensorimotor regions of interest was quantified using voxel-based morphometry. Pain-related disability, pain intensity, pain duration, and pain-related fear were also assessed. Multiple linear regression was used to determine independent predictors of pain-related disability. We document significantly greater peak gray matter density in individuals with LBP in the primary somatosensory cortex, angular gyrus, and the midcingulate cortex. Pain-related disability positively correlated with average gray matter density in the posterior cingulate cortex. The most robust predictors of disability were average gray matter in the posterior cingulate, pain intensity, and pain-related fear. We demonstrate that in young adults, persistent LBP, and pain-related disability, are linked with structural differences in regions forming part of the brain network termed the pain matrix. In contrast with studies of LBP in older adults, our findings of increased rather than decreased gray matter in young adults with LBP suggest that gray matter may increase initially in response to nociceptive pain

Structural Sensorimotor Adaptations in Young Adults with Low Back Pain

Chronic low back pain (CLBP) is the largest cause of disability worldwide. There is evidence for regional structural brain adaptation in CLBP. Most studies have investigated middle-aged adults and show decreased grey matter density in pain processing regions. It is not clear if these adaptations are evident early in the lifespan of individuals with CLBP. The purpose of the study was to compare sensorimotor gray matter density in young adults with a history of CLBP with back-healthy controls. 53 young adults with a greater than 1-year history of CLBP and 29 young adults with no history of LBP participated. Clinical characteristics of the LBP group were quantified with measures of pain duration and intensity as well as pain-related fear and disability. Gray matter density was quantified with voxel-based morphometry. Whole brain and sensorimotor region of interest (ROI) comparisons between groups were made after covarying for age, sex, and total intracranial volume. ROIs were determined a priori. Associations between clinical characteristics and average gray matter density in sensorimotor ROI comparisons were explored with Pearson\u27s correlation coefficients. Individuals with CLBP reported an average duration of pain of 4.9 (+/- 2.2 years) and average pain intensity of 5.0/10. The LBP group had greater gray matter in the right primary somatosensory cortex, right inferior parietal lobule, and right midcingulate cortex (all p \u3c 0.05 FWE corrected). There were significant positive associations between average gray matter and clinical characteristics in the anterior, mid, and posterior cingulate cortices, the supramarginal gyrus, superior parietal lobule and supplementary motor area (all p \u3c 0.05). We demonstrate that in young adults, CLBP is associated with structural neuroplasticity in regions involved in sensory processing, motor control, and the sensory and emotional aspects of pain experience. Increased grey matter density early in the lifespan of individuals with CLBP may reflect an adaptation to ongoing nociceptive input

Identifying the Neural Correlates of Anticipatory Postural Control: A Novel fMRI Paradigm

Altered postural control in the trunk/hip musculature is a characteristic of multiple neurological and musculoskeletal conditions. Previously it was not possible to determine if altered cortical and subcortical sensorimotor brain activation underlies impairments in postural control. This study used a novel fMRI-compatible paradigm to identify the brain activation associated with postural control in the trunk and hip musculature. BOLD fMRI imaging was conducted as participants performed two versions of a lower limb task involving lifting the left leg to touch the foot to a target. For the supported leg raise (SLR) the leg is raised from the knee while the thigh remains supported. For the unsupported leg raise (ULR) the leg is raised from the hip, requiring postural muscle activation in the abdominal/hip extensor musculature. Significant brain activation during the SLR task occurred predominantly in the right primary and secondary sensorimotor cortical regions. Brain activation during the ULR task occurred bilaterally in the primary and secondary sensorimotor cortical regions, as well as cerebellum and putamen. In comparison with the SLR, the ULR was associated with significantly greater activation in the right premotor/SMA, left primary motor and cingulate cortices, primary somatosensory cortex, supramarginal gyrus/parietal operculum, superior parietal lobule, cerebellar vermis, and cerebellar hemispheres. Cortical and subcortical regions activated during the ULR, but not during the SLR, were consistent with the planning, and execution of a task involving multisegmental, bilateral postural control. Future studies using this paradigm will determine mechanisms underlying impaired postural control in patients with neurological and musculoskeletal dysfunction

Effect of Overground Training Augmented by Mental Practice on Gait Velocity in Chronic, Incomplete Spinal Cord Injury

OBJECTIVE: To compare efficacy of a regimen combining mental practice (MP) with overground training with the efficacy of a regimen comprised of overground training only on gait velocity and lower extremity motor outcomes in individuals with chronic (> 12 months post injury), incomplete, spinal cord injury (SCI). DESIGN: Randomized controlled, single blinded, study SETTING: Outpatient rehabilitation laboratories located in the Midwestern and Western United States PARTICIPANTS: 18 subjects with chronic, incomplete SCI INTERVENTIONS: Subjects were randomly assigned to receive: (a) Overground Training only (OT), occurring 3 days/week for 8 weeks; or (b) OT augmented by MP (MP + OT), during which randomly assigned subjects listened to a mental practice audio recording directly following OT sessions. MAIN OUTCOME MEASURES: Subjects were administered a test of gait velocity as well as the Tinetti Performance Oriented Mobility Assessment (POMA), Spinal Cord Injury Independence Measure (SCIM), and Satisfaction with Life Scale (SWLS) on 2 occasions before intervention, 1 week after intervention, and 12 weeks after intervention. RESULTS: A significant increase in gait velocity was exhibited across subjects at both 1 week post-therapy (p=0.0046) and at 12 weeks post-therapy (p=0.0056). However, no differences were seen in intervention response at either 1 or 12 weeks post intervention among subjects in the MP + OT versus the OT groups. CONCLUSION: Overground training was associated with significant gains in gait velocity, and that these gains were not augmented by further addition of mental practice

Bilateral cervical contusion spinal cord injury in rats

There is increasing motivation to develop clinically relevant experimental models for cervical SCI in rodents and techniques to assess deficits in forelimb function. Here we describe a bilateral cervical contusion model in rats. Female Sprague-Dawley rats received mild or moderate cervical contusion injuries (using the Infinite Horizons device) at C5, C6, or C7/8. Forelimb motor function was assessed using a grip strength meter (GSM); sensory function was assessed by the von Frey hair test; the integrity of the corticospinal tract (CST) was assessed by biotinylated dextran amine (BDA) tract tracing. Mild contusions caused primarily dorsal column (DC) and gray matter (GM) damage while moderate contusions produced additional damage to lateral and ventral tissue. Forelimb and hindlimb function was severely impaired immediately post-injury, but all rats regained the ability to use their hindlimbs for locomotion. Gripping ability was abolished immediately after injury but recovered partially, depending upon the spinal level and severity of the injury. Rats exhibited a loss of sensation in both fore- and hindlimbs that partially recovered, and did not exhibit allodynia. Tract tracing revealed that the main contingent of CST axons in the DC was completely interrupted in all but one animal whereas the dorsolateral CST (dlCST) was partially spared, and dlCST axons gave rise to axons that arborized in the GM caudal to the injury. Our data demonstrate that rats can survive significant bilateral cervical contusion injuries at or below C5 and that forepaw gripping function recovers after mild injuries even when the main component of CST axons in the dorsal column is completely interrupted