Leanne Hall

Altered trunk muscle coordination during rapid trunk flexion in people in remission of recurrent low back pain

People with a history of low back pain (LBP) are at high risk to encounter additional LBP episodes. During LBP remission, altered trunk muscle control has been suggested to negatively impact spinal health. As sudden LBP onset is commonly reported during trunk flexion, the aim of the current study is to investigate whether dynamic trunk muscle recruitment is altered in LBP remission. Eleven people in remission of recurrent LBP and 14 pain free controls performed cued trunk flexion during a loaded and unloaded condition. Electromyographic activity was recorded from paraspinal (lumbar and thoracic erector spinae, latissimus dorsi, deep and superficial multifidus) and abdominal muscles (obliquus internus, externus and rectus abdominis) with surface and fine-wire electrodes. LBP participants exhibited higher levels of co-contraction of flexor/extensor muscles, lower agonistic abdominal and higher antagonistic paraspinal muscle activity than controls, both when data were analyzed in grouped and individual muscle behavior. A sub-analysis in people with unilateral LBP (n = 6) pointed to opposing changes in deep and superficial multifidus in relation to the pain side. These results suggest that dynamic trunk muscle control is modified during LBP remission, and might possibly increase spinal load and result in earlier muscle fatigue due to intensified muscle usage. These negative consequences for spinal health could possibly contribute to recurrence of LBP.

Adaptive Changes in Anticipatory Postural Adjustments With Novel and Familiar Postural Supports

Anticipatory postural adjustments (APAs) serve to stabilize posture prior to initiation of voluntary movement. This study examined the effects of changes in postural support on APAs using novel and familiar support paradigms. We also investigated whether postural strategies were refined with practice and how the CNS responded when multiple supports were available. Twelve healthy subjects stood on dual force platforms and performed 20 randomized left and right rapid leg-lift tasks in response to a visual cue under four conditions: unsupported, bilateral handgrip, bite plate, and a combined handgrip and bite plate condition. Vertical ground reaction forces, electromyography of limb, trunk and jaw muscles, and forces exerted on the support apparatus were recorded. Shift in center-of-pressure amplitude and duration were reduced with increased support. Muscles were recruited in advance of the focal movement when able to contribute to stability, and activity was modulated based on the amount of support available. The CNS adapted anticipatory postural strategies immediately with changes in condition regardless of familiarity with the support; however, adaptation was only complete at the first repetition in conditions that involved familiar support strategies. Tasks that involved a novel bite strategy continued to adapt with practice. In the multiple support condition, both hand and bite strategies were immediately incorporated; however, the contribution of each was not identical to conditions where supports were provided individually. This study emphasizes the flexibility of the CNS to organize postural strategies to meet the demands of postural stability in both familiar and novel situations.

Measuring the Lifespace of People With Parkinson’s Disease Using Smartphones: Proof of Principle

Background Lifespace is a multidimensional construct that describes the geographic area in which a person lives and conducts their activities, and reflects mobility, health, and well-being. Traditionally, it has been measured by asking older people to self-report the length and frequency of trips taken and assistance required. Global Positioning System (GPS) sensors on smartphones have been used to measure Lifespace of older people, but not with people with Parkinson’s disease (PD). Objective The objective of this study was to investigate whether GPS data collected via smartphones could be used to indicate the Lifespace of people with PD. Methods The dataset was supplied via the Michael J Fox Foundation Data Challenge and included 9 people with PD and 7 approximately matched controls. Participants carried smartphones with GPS sensors over two months. Data analysis compared the PD group and the control group. The impact of symptom severity on Lifespace was also investigated. Results Visualization methods for comparing Lifespace were developed including scatterplots and heatmaps. Lifespace metrics for comparison included average daily distance, percentage of time spent at home, and number of trips into the community. There were no significant differences between the PD and the control groups on Lifespace metrics. Visual representations of Lifespace were organized based on the self-reported severity of symptoms, suggesting a trend of decreasing Lifespace with increasing PD symptoms. Conclusions Lifespace measured by GPS-enabled smartphones may be a useful concept to measure the progression of PD and the impact of various therapies and rehabilitation programs. Directions for future use of GPS-based Lifespace are provided.

Multifidus Muscle Changes After Back Injury Are Characterized by Structural Remodeling of Muscle, Adipose and Connective Tissue, but Not Muscle Atrophy: Molecular and Morphological Evidence.

Study Design. Longitudinal case-controlled animal study. Objective. To investigate putative cellular mechanisms to explain structural changes in muscle and adipose and connective tissues of the back muscles after intervertebral disc (IVD) injury. Summary of Background Data. Structural back muscle changes are ubiquitous with back pain/injury and considered relevant for outcome, but their exact nature, time course, and cellular mechanisms remain elusive. We used an animal model that produces phenotypic back muscle changes after IVD injury to study these issues at the cellular/molecular level. Methods. Multifidus muscle was harvested from both sides of the spine at L1–L2 and L3–L4 IVDs in 27 castrated male sheep at 3 (n = 10) or 6 (n = 17) months after a surgical anterolateral IVD injury at both levels. Ten control sheep underwent no surgery (3 mo, n = 4; 6 mo, n = 6). Tissue was harvested at L4 for histological analysis of cross-sectional area of muscle and adipose and connective tissue (whole muscle), plus immunohistochemistry to identify proportion and cross-sectional area of individual muscle fiber types in the deepest fascicle. Quantitative polymerase chain reaction measured gene expression of typical cytokines/signaling molecules at L2. Results. Contrary to predictions, there was no multifidus muscle atrophy (whole muscle or individual fiber). There was increased adipose and connective tissue (fibrotic proliferation) cross-sectional area and slow-to-fast muscle fiber transition at 6 but not 3 months. Within the multifidus muscle, increases in the expression of several cytokines (tumor necrosis factor &agr; and interleukin-1&bgr;) and molecules that signal trophic/atrophic processes for the 3 tissue types (e.g., growth factor pathway [IGF-1, PI3k, Akt1, mTOR], potent tissue modifiers [calcineurin, PCG-1&agr;, and myostatin]) were present. Conclusion. This study provides cellular evidence that refutes the presence of multifidus muscle atrophy accompanying IVD degeneration at this intermediate time point. Instead, adipose/connective tissue increased in parallel with the expression of the genes that provide putative mechanisms for multifidus structural remodeling. This provides novel targets for pharmacological and physical interventions. Level of Evidence: N/A

Can proinflammatory cytokine gene expression explain multifidus muscle fiber changes after an intervertebral disc lesion

Study Design. Longitudinal case-controlled animal study. Objective. To investigate the effect of an intervertebral disc (IVD) lesion on the proportion of slow, fast, and intermediate muscle fiber types in the multifidus muscle in sheep, and whether muscle fiber changes were paralleled by local gene expression of the proinflammatory cytokines tumor necrosis factor &agr; (TNF-&agr;) and interleukin 1-&bgr;. Summary of Background Data. Structure and behavior of the multifidus muscle change in acute and chronic back pain, but the mechanisms are surprisingly poorly understood and the link between structure and behavior is tenuous. Although changes in muscle fiber types have the potential to unify the observations, the effect of injury on muscle fiber distribution has not been adequately tested, and understanding of possible mechanisms is limited. Methods. The L1–L2, L3–L4, and L5–L6 IVDs of 11 castrated male sheep received anterolateral lesions. Six control sheep underwent no surgical procedures. Multifidus muscle tissue was harvested at L4 for muscle fiber analysis using immunohistochemistry and L2 for cytokine analysis with polymerase chain reaction for local gene expression of TNF-&agr; and interleukin-1&bgr;. Results. The proportion of slow muscle fibers in multifidus was significantly less in the lesioned animals both ipsilateral and contralateral to the IVD lesion. The greatest reduction in slow fibers was in the deep medial muscle region. A greater prevalence of intermediate fibers on the uninjured side implies a delayed fiber-type transformation on that side. TNF-&agr; gene expression in multifidus was greater on both sides in the lesion animals than in the muscle of control animals. Interleukin-1&bgr; was increased only on the injured side. Conclusion. These data provide evidence of muscle fiber changes after induction of an IVD lesion and a parallel increase in TNF-&agr; expression. Proinflammatory cytokine changes provide a novel mechanism to explain behavioral and structural changes in multifidus. Level of Evidence: N/A

The effect of Parkinson's disease and levodopa on adaptation of anticipatory postural adjustments.

Postural support alters anticipatory postural adjustments (APAs). Efficient adaptation to changes in postural support in reactive and centrally initiated postural synergies is impaired in Parkinsons disease (PD). This study examined whether APAs are affected differently by familiar and novel supports in people with PD, ON and OFF levodopa. The effect of PD and levodopa on the ability to immediately adapt APAs to changes in support and refine with practice was also investigated. Fourteen people with PD and 14 healthy control participants performed 20 single rapid leg lift tasks in four support conditions: unsupported, bilateral handgrip (familiar), bite plate (novel) and a combined handgrip+bite plate condition. APAs, identified from force plate data, were characterized by an increase in the vertical ground reaction force under the lifted leg as a result of a shift of weight toward the stance limb. Results showed the ability to incorporate familiar and novel external supports into the postural strategy was preserved in PD. Controls and PD patients in the OFF state further refined the postural strategy with practice as evidenced by changes in amplitude of vertical ground reaction forces and forces applied to support apparatus within conditions between the initial and final trials. In the ON state, people with PD failed to refine the use of postural supports in any condition. The results suggest that immediate postural adaptation is intact in people with PD and unaffected by levodopa administration but the ability to refine postural adaptations with task experience is compromised by dopamine therapy.

Mesenchymal Stem Cell Treatment of Intervertebral Disc Lesion Prevents Fatty Infiltration and Fibrosis of the Multifidus Muscle, but not Cytokine and Muscle Fiber Changes.

Study Design. Longitudinal case-control animal model. Objective. To investigate effects of mesenchymal stem cell (MSC) treatment on multifidus muscle remodeling after intervertebral disc (IVD) lesion. Summary of Background Data. Lesion and degeneration of IVDs cause structural remodeling of the multifidus muscle. Proinflammatory cytokines are thought to contribute. MSC treatment restores IVD health after lesion but its effects on surrounding tissues remains unknown. Using an animal model of IVD degeneration, we assessed the effects of MSC treatment of IVDs on the structural remodeling and cytokine expression within the multifidus muscle. Methods. An anterolateral lesion was performed on the L1–2, L3–4, and L5–6 IVDs in sheep. At either 4 (early treatment) or 12 (late treatment) weeks after IVD lesion, MSCs were injected into the lesioned IVD. Multifidus muscle was harvested from L2 (gene expression analysis) and L4 (histological analysis) at 3 or 6 months after IVD lesion and naïve controls for histological analysis of muscle, adipose, and connective tissue cross-sectional areas, and immunohistochemistry to study muscle fiber types. Real-time polymerase chain reactions quantified expression of tumor necrosis factor, interleukin-1&bgr;, and transforming growth factor-&bgr;1. Results. MSC treatment of IVD lesion prevented the increased adipose and connective tissue cross-sectional area expected after IVD lesion. MSC treatment did not prevent slow-to-fast muscle fiber type transformation. Gene expression of proinflammatory cytokines within the muscle was altered by the MSC treatment of IVD. Increased interleukin-1&bgr; expression was prevented in the early treatment group and tumor necrosis factor and transforming growth factor-&bgr;1 expression was upregulated at 6 months. Conclusion. Results show that although MSC treatment prevents fatty infiltration and fibrosis of the multifidus muscle after IVD lesion, it cannot prevent a muscle inflammatory response and muscle fiber transformation. These findings highlight the potential role of MSC therapy after IVD injury, but reveals that other interventions may also be necessary to optimize recovery of muscle. Level of Evidence: 4

Location-specific responses to nociceptive input support the purposeful nature of motor adaptation to pain

Abstract Movement is changed in pain, but the mechanisms remain unclear. Key questions are unresolved such as whether activation can be inhomogeneously distributed within a muscle in a manner that is specific to the location of noxious input. This study addressed this question using high-density electromyography (EMG) to study regional redistribution of muscle activation within the vasti muscles and changes in knee extension force direction in response to noxious stimulation applied to muscular and nonmuscular tissues around the knee. Fourteen participants performed a low-force knee extension contraction at baseline, during, and after pain induced in 4 locations (infrapatellar fat pad, vastus lateralis, distal vastus medialis, or proximal vastus medialis). The knee extension force direction was estimated from a 3-dimensional load cell positioned just above the ankle. Regional muscle activation was estimated from amplitude of high-density surface EMG signals from vastus medialis and lateralis. Pain-induced spatial variations of activation were identified as the position of the 5 channels that showed the largest decrease (or smallest increase) in amplitude from baseline to pain or after pain. Knee extension force was produced more medially during pain after infrapatellar pad injection only (P = 0.01). Preferential reduction of activation of the distal region of vastus medialis was observed when distal vastus medialis (P < 0.001) or vastus lateralis (P < 0.05) was injected. Both adaptations persisted after pain resolution. These results support the hypothesis that specific adaptation depends on the location of a noxious stimulus and imply that recovery of pain is not necessarily concomitant with return of the EMG to prepain patterns.

Design of programs to train pelvic floor muscles in men with urinary dysfunction: Systematic review

Pelvic floor muscle training (PFMT) is a first line conservative treatment for men with urinary dysfunction, but reports of its efficacy are variable. This study aimed to systematically review the content of PFMT programs used for urinary dysfunction in men.

Mesenchymal Stem Cell Treatment of Disc Lesion Prevents Fatty Infiltration and Fibrosis, but not Muscle Fibre Transformation of the Multifidus Muscle

Introduction The multifidus muscle undergoes structural and behavioral changes with back pain and injury. After intervertebral disc (IVD) lesion in animals the multifidus muscle undergoes a transformation of muscle fiber types from slow-to-fast, and extensive structural remodelling with increased adipose and connective tissue. Increased expression of pro-inflammatory cytokines (tumor necrosis factor (TNF) and interleukin 1β (ΙΛ−1β)) parallel these changes and may be responsible. Treatment of IVD lesions with mesenchymal stem cells (MSC) prevents or restores loss of IVD height and proteoglycans in the nucleus pulposus, depending on the timing of application. Whether the resolution of IVD changes by MCS treatment prevents or restores changes in the multifidus muscle structure and muscle fiber composition is unknown. This study aimed to investigate whether muscle changes are prevented or restored by early or late MSC treatment of the IVD lesion, respectively, and whether this is related to modification of inflammatory cytokine expression. Material and Methods The L1–2 and L3–4 IVDs of 18 sheep received left anterolateral partial thickness annular lesions. Six control sheep underwent no surgery. At four (3-month (n = 6) and 6-month acute (n = 6) treatment groups) or twelve (established (n = 6) treatment group) weeks after initial surgery, animals received MSC injections (0.2ml) to the operated IVD. Three (3-month acute treatment group) and six (6-month acute and established treatment groups) months after initial surgery the L4 multifidus muscle was harvested for muscle fiber type analysis using immunohistochemistry and evaluation of cross sectional area (CSA) of muscle, adipose and connective tissue using standard histology. L2 muscle was harvested for quantitative PCR measures of pro-inflammatory cytokine gene expression (TNF, ΙΛ−1β). Results Unlike the response to IVD lesion without MSC treatment (increased connective tissue and adipose CSA), acute MSC treatment prevented increase in adipose (acute treatment=control at 3- and 6-months; p = 0.28 and p = 0.07) and connective tissue CSA (acute treatment < control at 3-months; p < 0.001, acute=control at 6-months; p = 0.39). This paralleled reduced expression of IL-1β at 3-months (acute treatment versus control; p < 0.001). MCS treatment of established treatment animals restored adipose and connective tissue CSA (established treatment=control at 6 months; P > 0.60). The effect of MSC on muscle CSA depended on the treatment timing. At 6 months, acute treatment animals had larger whole muscle CSA than controls (p = 0.002). Control and established treatment animals did not differ (p = 0.73). Despite optimistic data for tissue CSA, muscle harvested at 6 months showed reduced proportion of slow muscle fibers and increased intermediate fibers throughout the multifidus muscle (acute and established treatment group versus control; p < 0.05). TNF expression was greater at 6 months in acute and established treatment groups than control (p < 0.001). Conclusion These results indicate that MSC treatment of the IVD lesion prevents and restores muscle structural changes, but is unable to prevent changes to multifidus muscle fiber type. This is likely to have functional relevance for neuromuscular control of the healed IVD. MSC appear to have and anti-inflammatory effect on muscle in the early phase when IVD is healing, but cannot influence the later elevation of TNF, which appears destructive for muscle fibers.