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- Sandlund, Jonas
(author)
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Position-matching and goal-directed reaching acuity of the upper limb in chronic neck pain : associations to self-rated characteristics
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Neck-shoulder pain is common in the general population and causes individual suffering as well as large costs for the society. Despite substantial efforts, there is still a shortage of methods for objective diagnosis and effective rehabilitation of such disorders. Thus, there is a great need to develop and evaluate new methods for these purposes. From clinical observations and recent research it has become evident that sensorimotor control can be impaired in people with neck-shoulder pain and may play a role in the pathogenesis of these disorders. In this thesis, precision of goal-directed arm movements, a previously unstudied class of movements in neck-shoulder pain, was studied. The main aim of the thesis was to investigate if people with chronic neck-shoulder pain have a reduced acuity of goal-directed movements of the upper extremity. A second aim was to study associations between reduced movement acuity and symptoms and self-rated characteristics. Upper limb repositioning acuity was assessed in blindfolded subjects performing tests of active, ipsilateral position-matching of two target positions (long and short) in movements constrained to horizontal-adduction of the shoulder. Reduced repositioning acuity, suggesting impaired shoulder proprioception, was found for both subjects with whiplash associated disorders (WAD) and non-specific neck-shoulder pain (NS). The degree of reduced acuity was shown to correlate with self-ratings of various health concepts, functioning and pain. A conspicuous finding was that there was lack of correlation between short and long target errors, along with the fact that associations between repositioning acuity and symptoms and self-rated characteristics was primarily found for the short target position. To further investigate the possible mechanisms underlying the disassociation between long and short target movement control, the association pattern between the outcome of several variants of ipsilateral position matching and velocity-discrimination tests, were studied. It was found that the perception of limb position in position-matching of short target locations appears to be predominantly based on movement velocity, whereas perception of limb position in movements to longer target locations may rely on a location-based perception mechanism. To extend the research on reduced upper extremity proprioception in neck-shoulder pain to a more natural movement situation, acuity of goal-directed pointing including full vision and 3D multi-joint movements was investigated in WAD, NS and healthy controls subjects. The results revealed a reduced acuity for both neck-pain groups. Moreover, distinct associations between end-point acuity and neck movement problems, limitations of some physical functions and, in WAD; some aspects of pain, were revealed. The findings demonstrate that the precision of upper limb movements can be reduced in chronic neck-shoulder pain. Substantial associations with symptoms and self-rated functioning suggest a clinical relevance of acuity measures of goal-directed arm movements. The findings indicate that tests of sensorimotor control can provide objective measures that may be useful in biopsychosocial profiling and characterization of subgroups of patients with chronic neck-shoulder pain, and that training target control of goal-directed movements should be considered in rehabilitation programs of people with these disorders.
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| 2. |
- Björklund, Martin, 1961-
(author)
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Effects of repetitive work on proprioception and of stretching on sensory mechanisms : implications for work-related neuromuscular disorders
- 2004
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Doctoral thesis (other academic/artistic)abstract
- The aims of the thesis were (i) to investigate the impact of repetitive low-intensity work exposure on proprioception and (ii) to examine effects of muscle stretching (especially sensory effects and effects on muscle nociception) and to relate its application to the prevention, alleviation and/or treatment of work-related neuromuscular disorders. The effects of low-intensity repetitive work on the shoulder proprioception were tested in healthy subjects. The effect of working time on the retention of subjective fatigue and their relation to changes in proprioception, and the immediate effect of stretching on shoulder proprioception were investigated. A new method to test the stretchability of the rectus femoris muscle was investigated for reliability and validity and used to assess the effects of a two-week stretching regimen on range of motion and on subjective stretch sensation. Finally, the interactions between innocuous muscle stretch and nociceptive chemical stimulation on discharge behavior of nociceptive dorsal horn neurons in the feline spinal cord were explored. The main findings were as follows: 1) The repetitive low-intensity work to fatigue diminished the shoulder proprioception; the working time as well as the retention of subjective fatigue were partly related to the extent of changed proprioception. 2) There was no effect of acute muscle stretching on the proprioception. 3) The new method for testing muscle stretchability proved valid and reliable. A two-week stretching regimen increased the tolerance to stretch torque, but the range of motion remained unchanged. 4) Half of the nociceptive dorsal horn neurons that responded to close arterial injections of bradykinin were modulated by muscle stretching applied directly after the injections. Altogether, the results give credence to the hypothesis of an involvement of sensory information distortion due to repetitive low-intensity work exposure in the development of work-related neuromuscular disorders. Increased tolerance to stretch torque may be an important mechanism in explaining improvements following stretch treatment. The spinal interactions between innocuous stretch and nociceptive muscle afferent inputs indicate a possible mechanism involved in stretching-induced pain alleviation.
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| 3. |
- Larsson, Hans-Olov, 1947-
(author)
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Quantitative morphological studies of the parathyroid gland
- 1983
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Doctoral thesis (other academic/artistic)abstract
- This work is based upon a series of quantitative morphological studies of the parathyroid glands of Mongolian gerbils and rats. Standard stereological methods were used on light and electron microscopical levels.Subclassification of the chief cells based on the staining affinity and electron density of the cytoplasm was not correlated with contents (volume and surface densities) of organelles.Compared to fixation by immersion, fixation by perfusion caused a remarkable reduction in the number of light chief cells and atrophic cells, indicating that the occurrence of those kind of cells is dependent on factors of artifactual nature.The early response of the parathyroid gland to altered concentrations of extracellular calcium was studied in vitro. At six hours of "incubation, enlargement of the Golgi zone (Golgi complex and presecretory granules), but unaltered endoplasmic reticulum, was seen in glands incubated in low (0,5 mM) compared to those incubated in high (3,0 mM) calcium concentrations.Prolonged hypocalcemia induced in vivo by intraperitoneal injections of ethylenediaminetetraacetate and calcium deficient diet for eight days, did not give rise to any major quantitative morphological changes in the individual parathyroid cell, and furthermore, the quantitative morphology of the parathyroid cell was unchanged in experimentally induced hyperparathyroidism (calcium deficient diet for 16 weeks).The morphological data do not support the opinion of a functional cycle in the parathyroid chief cell, but suggest that the early response of this cell to altered extracellular calcium may be funtional activities associated with the Golgi zone.
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| 4. |
- Pettersson, Ulrika, 1970-
(author)
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Bone mass in the young athlete
- 1999
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Doctoral thesis (other academic/artistic)abstract
- Bone mass and bone size accumulate during childhood and adolescence and peak in the twenties. The obtained peak bone mass has been suggested to be a major determinant of bone mass even in the very elderly. Although, genetic factors are the main determinants, environmental and lifestyle factors also play a crucial role in modulating maximal bone mass. Assessing these lifestyle factors would be of great importance for the intervention strategies against osteoporosis. The first aim of this thesis was to compare the bone mass and bone size in male and female young adults on a high level of physical activity with males or females on a low level of physical activity. Furthermore, it also aimed to investigate the influence of pubertal maturity, menstrual disturbances, and different body constitutional factors on bone mass and size during adolescence and young adulthood. The female activity groups consisted of cross-county skiers, soccer players, and rope skippers. Compared to their age-matched inactive controls, all these athletic groups demonstrated a significantly higher bone mineral density (BMD) at those sites subjected to the sport-specific loading. Rope-skipping, a very high impact activity was associated with a higher bone size, preferentially in the lower extremity, suggesting an effect of weight-bearing activity also on bone geometry. The effect of menstrual disturbances was evaluated in a group of long-distance runners, where amenorrheic runners had significantly lower BMD in both trabecular and also cortical bone in the lower extremity compared to eumenorrheic runners, suggesting that weight-bearing activity cannot compensate for the shortfall of reduced estrogen levels. The male activity groups consisted of ice hockey players and badminton players. Compared to their age-matched controls, both athletic groups demonstrated a significantly higher BMD at those sites subjected to the sport-specific loading. Especially badminton was associated with a high BMD, suggesting that physical activity, including jumps in unusual directions has a great osteogenic potential. The main determinants of BMD in both male and females were, except for type of physical activity, activity, muscle strength, height, and different body constitutional factors. However, the relationships with muscle strength and body constitution were somewhat weaker in the athletic groups, especially in the males, indicating that impact forces may be of greater importance in regulating bone mass in highly trained athletes. Yet bone size was largely determined by parameters related to body size and less strongly to physical activity. In a prospective study on adolescent boys, the changes in bone mass during late puberty were mainly accounted for by growth and development, including height and pubertal maturation, and less to physical activity level. Thus, the osteogenic effect from physical activity seems to be of importance for bone mass achievement predominantly before late puberty.
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