Biomedical subjects

Mats Djupsjöbacka

Publications and source records attributed to Mats Djupsjöbacka.

12 recordsLinked to original sources

PubMed2007

Sensorimotor disturbances in chronic neck pain--range of motion, peak velocity, smoothness of movement, and repositioning acuity.

The purpose of this pilot study was to evaluate sensorimotor functions in patients with chronic neck pain with objective and quantitative methods. A group of 16 patients with chronic idiopathic neck pain of insidious onset or whiplash associated disorders (WAD) was compared to an equally sized group of healthy subjects. Kinematics were investigated during voluntary head rotations by measuring range of motion, variability of range of motion (ROM-Variability), peak velocity, and smoothness of movement (jerk index). Repositioning acuity after cervical rotations was evaluated by analysing constant and variable error (VE). In comparison to the healthy subjects, the patients showed significantly larger jerk index, ROM-Variability and VE. No statistically significant differences were found between insidious neck pain and WAD. It is concluded that jerky and irregular cervical movements and poor position sense acuity are characteristic sensorimotor symptoms in chronic neck pain. The observed individuality in sensorimotor disturbances emphasizes the importance of developing specific rehabilitation programs for specific dysfunctions, and of using objective and quantitative methods for evaluation of rehabilitation.

Adult↗

PubMed2006

Are lumbar repositioning errors larger among patients with chronic low back pain compared with asymptomatic subjects?

OBJECTIVE: To resolve the debate over whether lumbar repositioning acuity is reduced in patients with chronic low back pain (CLBP) by using a study design and methodology to minimize the effects of potential confounders. DESIGN: A single-blinded, controlled, multigroup comparative study. SETTING: Vocational rehabilitation center. PARTICIPANTS: Ninety-two patients with CLBP, divided into subgroups based on severity of symptoms and diagnostic characteristics. An age- and sex-matched group (n=31) of healthy subjects were the control. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We measured repositioning errors (variable, constant) at 3 positions of the lumbar spine. Subjects were guided to a sitting target posture and asked to perform lumbar flexion before reproducing the target posture. Self-assessed pain, self-efficacy, and functional ability were addressed through questionnaires. RESULTS: There were no differences in repositioning errors between the patients with CLBP or the subgroups of patients and the control group. We found only weak correlations between the repositioning errors and the self-reported data on functional disability, self-efficacy, and pain. CONCLUSIONS: We suggest that sensorimotor dysfunctions in CLBP should be evaluated with methods other than repositioning tests in order to generate data relevant to the development of rational diagnostic methods and rehabilitation programs.

Adult↗

PubMed2006

Predictive and discriminative value of shoulder proprioception tests for patients with whiplash-associated disorders.

OBJECTIVE: To evaluate whether patients suffering from whiplash-associated disorders have impaired shoulder proprioception and whether the acuity of shoulder proprioception is reflected in the patients' symptoms and self-rated function. DESIGN: A comparative group design, including a correlation design for the patient group. SUBJECTS: Patients with chronic whiplash-associated disorders (n=37) and healthy subjects (n=41). The groups were matched for age and gender. METHODS: All subjects underwent a shoulder proprioception test involving active ipsilateral arm position-matching. Group difference was evaluated by multiple analysis of variance and analysis of variance. The patient group completed questionnaires addressing functioning and health and performed pain ratings. Associations between proprioceptive acuity and self-rated functioning and symptoms were studied by correlation and regression analyses. RESULTS: The patient group showed significantly lower acuity of shoulder proprioception. Moderate correlations were found between proprioceptive acuity and questionnaire scores representing physical functioning, so that low proprioceptive acuity was associated with low self-rated physical functioning. Scores representing pain-intensity did not correlate with proprioceptive acuity. CONCLUSION: The results show that, at the group level, patients with whiplash-associated disorders have impaired shoulder proprioception. The clinical relevance of this finding is strongly supported by the association between shoulder proprioceptive acuity and self-rated functioning in the patient group.

Adult↗

PubMed2005

Effects in feline gastrocnemius-soleus motoneurones induced by muscle fatigue.

Responses of gastrocnemius-soleus (G-S) motoneurones to stretches of the homonymous muscles were recorded intracellularly in decerebrate cats before, during and after fatiguing stimulation (FST) of G-S muscles. Ventral roots (VR) L7 and S1 were cut, and FST was applied to VR S1, a single FST session including 4 to 5 repetitions of 12-s periods of regular 40 s(-1) stimulation. Muscle stretches consisted of several phases of slow sinusoidal shortening-lengthening cycles and intermediate constant lengths. The maximal stretch of the muscles was 8.8 mm above the rest length. Effects of FST on excitatory postsynaptic potentials (EPSPs) and spikes evoked by the muscle stretches were studied in 12 motoneurones from ten experiments. Stretch-evoked EPSPs and firing were predominantly suppressed after FST, with the exception of a post-contraction increase of the first EPSP after FST, which was most likely due to after-effects in the activity of muscle spindle afferents. The post-fatigue suppression of EPSPs and spike activity was followed by restoration within 60-100 s. Additional bouts of FST augmented the intensity of post-fatigue suppression of EPSPs, with the spike activity sometimes disappearing completely. FST itself elicited EPSPs at latencies suggesting activation of muscle spindle group Ia afferents via stimulation of beta-fibres. The suppression of the stretch-evoked responses most likely resulted from fatigue-evoked activity of group III and IV muscle afferents. Presynaptic inhibition could be one of the mechanisms involved, but homosynaptic depression in the FST-activated group Ia afferents may also have contributed.

Animals↗

PubMed2005

Joint angle variability in 3D bimanual pointing: uncontrolled manifold analysis.

The structure of joint angle variability and its changes with practice were investigated using the uncontrolled manifold (UCM) computational approach. Subjects performed fast and accurate bimanual pointing movements in 3D space, trying to match the tip of a pointer, held in the right hand, with the tip of one of three different targets, held in the left hand during a pre-test, several practice sessions and a post-test. The prediction of the UCM approach about the structuring of joint angle variance for selective stabilization of important task variables was tested with respect to selective stabilization of time series of the vectorial distance between the pointer and aimed target tips (bimanual control hypothesis) and with respect to selective stabilization of the endpoint trajectory of each arm (unimanual control hypothesis). The components of the total joint angle variance not affecting (V(COMP)) and affecting (V(UN)) the value of a selected task variable were computed for each 10% of the normalized movement time. The ratio of these two components R(V)=V(COMP)/V(UN) served as a quantitative index of selective stabilization. Both the bimanual and unimanual control hypotheses were supported, however the R(V) values for the bimanual hypothesis were significantly higher than those for the unimanual hypothesis applied to the left and right arm both prior to and after practice. This suggests that the CNS stabilizes the relative trajectory of one endpoint with respect to the other more than it stabilizes the trajectories of each of the endpoints in the external space. Practice-associated improvement in both movement speed and accuracy was accompanied by counter-intuitive lack of changes in R(V). Both V(COMP) and V(UN) variance components decreased such that their ratio remained constant prior to and after practice. We conclude that the UCM approach offers a unique and under-explored opportunity to track changes in the organization of multi-effector systems with practice and allows quantitative assessment of the degree of stabilization of selected performance variables.

Adult↗

PubMed2005

Handgrip maximum force and the visual horizontal-vertical illusion.

The visual horizontal-vertical illusion (HVI) refers to the tendency to overestimate vertical distances relative to horizontals in both 2-D and 3-D presentations. Although the HVI is evident across a wide range of different stimuli, no general theoretical account fully explains the illusion. Some recent authors have proposed the 'effort' account of HVI, contending that vertical overestimation is mediated by effort assessment of gravitational challenges offered by the stimulus. The theory has been supported by a set of studies showing that the height overestimation of large-scale 3-D objects is inversely related to perceivers' fitness and strength. We explored if the large-scale HVI/strength dependence extends to the evaluation of small-scale 2-D line stimuli, traditionally used in HVI studies. We measured the maximum handgrip strength, and assessed the HVI with a computerised line-adjustment task in thirty-two individuals. Compatible with earlier findings in the context of large-scale 3-D stimuli, a significant negative correlation was found between the strength of the dominant hand and amount of HVI. In addition, the variability of HVI was negatively correlated with maximum grip strength of both hands. The results are discussed with reference to the 'effort' account of HVI.

Female↗

PubMed2004

Glutamate and prostaglandin E2 in the trapezius muscle of female subjects with chronic muscle pain and controls determined by microdialysis.

Much is still unknown concerning the mechanisms underlying the development of chronic muscle pain. The presence and magnitude of inflammatory substances and neurotransmitters in chronic painful conditions is not clear. The aims of the present study were to determine, with the use of microdialysis, the interstitial concentrations and the equilibration times for PGE2 and glutamate in the trapezius muscles of nine female subjects with chronic muscle pain, and nine pain-free age-matched controls. A microdialysis probe was implanted in the upper part of the trapezius muscle and perfused with Ringer-acetate solution at a flow rate of 0.3 microL/min. Samples were obtained every 30 min, during a 4-h rest period. At equilibration, the mean concentrations (+/-SE) of PGE2 were 0.71 (+/-0.11) ng/mL for the pain-group and 0.97 (+/-0.35) ng/mL for the controls. For glutamate the mean concentrations for the pain-group were 66.3 (+/-13.3) micromol/L and 60.6 (+/-22.9) micromol/L for the controls. For the pain group and the control group, respectively, equilibration for PGE2 was reached at 180 and 150 min, and for glutamate at 150 and 120 min. The present study showed no differences between groups in the concentrations of PGE2 and glutamate in the trapezius muscle. Further, it revealed that when using the slow-flow method, a period of at least 2.0-2.5 h is needed, after probe insertion, to reach steady state for glutamate and PGE2.

Adult↗

PubMed2002

Increased intra-articular concentration of bradykinin in the temporomandibular joint changes the sensitivity of muscle spindles in dorsal neck muscles in the cat.

The aim of the present study was to investigate to what extent activation of bradykinin-sensitive nerve endings of the temporomandibular joint (TMJ) might induce changes in the muscle spindles output from neck muscles through reflex effects on cervical fusimotor neurones. To this end, 26 muscle spindle afferents (MSAs) emanating from the trapezius and splenius muscles of the anaesthetised cat (alpha-chloralose, initial dosage 60 mg/kg) were recorded during injection of Bradykinin (BK) (12.5-50 microg/ml) in the ipsilateral TMJ. Fifteen (58%) MSAs exhibited statistically significant fusimotor effects to injection of BK into the TMJ. Of the 15, ten MSAs showed a response related to activation of static fusimotor neurones, three MSAs showed a response related to an activation of both static and dynamic fusimotor neurones and two MSAs showed a inhibition of both static and dynamic fusimotor neurones. The control experiments suggests that the effects observed were due to activation of BK sensitive nerve endings in the TMJ. It seems possible that the reflex connections between TMJ nociceptors and the fusimotor-muscle spindle system of dorsal neck muscles might be involved in the pathophysiological mechanisms responsible for the sensory-motor disturbances in the neck region often found on patients with temporomandibular disorders.

Animals↗

PubMed2002

Spinal and supraspinal effects of activity in ligament afferents.

In this paper available knowledge on effects from joint and ligament afferents on spinal neurones and pathways are briefly reviewed, and possible functional implications discussed. Ligament afferents may contribute to joint stability, muscle coordination and proprioception through direct polysynaptic reflex effects onto ascending pathways and skeletomotoneurones, and/or indirectly via reflex actions on the gamma-muscle spindle system. Theoretical and experimental evidence indicate that ligament afferents, together with afferents from other joint structures, muscles and the skin, provide the CNS with information on movements and posture through ensemble coding mechanisms, rather than via modality specific private pathways. The existence and functional relevance of ligamentomuscular protective reflexes, that are triggered when the ligament is threatened by potentially harmful loads, has been seriously questioned. It seems more likely that peripheral sensory inputs from ligament afferents participate in a continuous control of the muscle activity through feedforward, or preprogramming, mechanisms. In line with these ideas it has been suggested that ligament mechanoreceptors have an important role in muscle coordination and in the reflex regulation of the functional joint stability, by contributing to the preprogramming of the muscle stiffness through reflex modulation of the gamma-muscle spindle system.

Afferent Pathways↗

PubMed2001

Effects on the fusimotor-muscle spindle system induced by intramuscular injections of hypertonic saline.

Intramuscular injection of hypertonic saline (HS) is a procedure widely adopted to experimentally induce deep muscle pain in humans. This study was undertaken to test whether intramuscular injections of HS (5%) influence the activity of primary and secondary muscle spindle afferents (MSAs) from homonymous as well as heteronymous muscles. The experiments were performed on six cats anaesthetised with alpha-chloralose. Usually responses of two to nine MSAs from gastrocnemius medialis (GM) and/or gastrocnemius lateralis (GL) muscles were recorded simultaneously, while HS was injected either into the receptor-bearing muscle (homonymous responses) or into a close (GM/GL) or remote synergistic muscle (posterior biceps, PB, heteronymous responses). The mean rate of discharge and the depth of modulation of the MSA responses to sinusoidal stretching of the receptor-bearing muscle were calculated. Out of the 42 afferents tested (7 from GM and 35 from GL), 38 (90%) exhibited statistically significant responses to injections of HS into homonymous and/or heteronymous muscles. With injections into the homonymous muscle, the average maximal increase in mean rate of discharge was 74% and the average decrease in depth of modulation was --18%. The mean duration of the effects was 2.1 min. The corresponding values for heteronymous injections into a close synergist were 87%, -17% and 2.1 min (GM or GL), and for injections into PB 52%, -11%, and 1.8 min. The majority of the responses (72%) were compatible with reflex action on static fusimotor neurones, whereas 20% of the responses could be attributed to mixed static and dynamic fusimotor action. The remaining 8% of the responses were attributed to inhibition of fusimotor activity. There were no statistically significant differences between the responses following injections into homonymous or heteronymous muscles. Injections of Tyrode's solution did not induce any significant alterations in MSA responses, implying that they were not induced by direct and/or injury effects of the injections. HS-related changes in MSA activity were completely abolished after the nerves to corresponding muscles were cut, confirming the reflex nature of the effects. Thus, intramuscular injections of HS induce reflex changes in MSA activity from both homonymous and heteronymous muscles, most likely via fusimotor reflexes. Predominantly static fusimotor neurones were activated. The possible role of the fusimotor-muscle spindle system in altered motor control during experimentally induced muscle pain is discussed.

Action Potentials↗

PubMedDate not supplied

Correlation analysis of proprioceptive acuity in ipsilateral position-matching and velocity-discrimination.

In order to plan and control movements the central nervous system (CNS) needs to continuously keep track of the state of the musculoskeletal system. Therefore the CNS constantly uses sensory input from mechanoreceptors in muscles, joints and skin to update information about body configuration on different levels of the CNS. On the conscious level, such representations constitute proprioception. Different tests for assessment of proprioceptive acuity have been described. However, it is unclear if the proprioceptive acuity measurements in these tests correlate within subjects. By using both uni- and multivariate analysis we compared proprioceptive acuity in different variants of ipsilateral active and passive limb position-matching and ipsilateral passive limb movement velocity-discrimination in a group of healthy subjects. The analysis of the position-matching data revealed a higher acuity of matching for active movements in comparison to passive ones. The acuity of matching was negatively correlated to movement extent. There was a lack of correlation between proprioceptive acuity measurements in position-matching and velocity-discrimination.

Adult↗

PubMedDate not supplied

Acute muscle stretching and shoulder position sense.

CONTEXT: Stretching is common among athletes as a potential method for injury prevention. Stretching-induced changes in the muscle spindle properties are a suggested mechanism, which may imply reduced proprioception after stretching; however, little is known of this association. OBJECTIVE: To evaluate whether acute stretching of the shoulder muscles affects position sense. DESIGN: A crossover design with subjects randomized to 3 groups. SETTING: A university human research laboratory. PATIENTS OR OTHER PARTICIPANTS: Nine male (age = 24 +/- 3 years) and 9 female (age = 21 +/- 2 years) healthy volunteers. INTERVENTION(S): Stretching of shoulder (1) agonists or (2) antagonists or (3) nonstretching control. MAIN OUTCOME MEASURE(S): We determined position sense acuity of the right shoulder before and after the interventions by having subjects attempt to reproduce arm positions of 15 degrees and 30 degrees (shoulder adduction) while starting at 45 degrees to the sagittal plane. The outcome variables were response variability (variable error) and overall accuracy (absolute error). RESULTS: The relative change in variable error (ie, variable error after/variable error before) was not significantly different between the interventions ( P = .38). Similarly, no change in absolute error was found ( P = .76). Furthermore, no differences were noted regarding test sequence or the interaction of intervention x sequence for either variable error ( P = .73 and .53, respectively) or absolute error ( P = .71 and .67, respectively). CONCLUSIONS: We found no effect on shoulder position sense after an acute bout of stretching of either agonist or antagonist shoulder muscles.

Journal Article↗