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Biomedical subjects

A C Eliasson

Publications and source records attributed to A C Eliasson.

At least 19 recordsLinked to original sources
PubMed2007

Goal-directed training: linking theories of treatment to clinical practice for improved functional activities in daily life.

BACKGROUND: Goal-directed training is an activity-based approach to therapy. Meaningful, client-selected goals are used to provide opportunities for problem solving and to indirectly drive the movements required to successfully meet the task demands. This is in contrast to interventions that focus on changing body functions. Here, the principles of goal-directed training will be studied through two case studies with the aim of linking theories of treatment to clinical practice. PRINCIPLES ILLUSTRATED: The approach is based on the dynamic systems motor control theory and occupation-based therapy models, which suggest that movement patterns emerge from the interaction between the person's abilities, environment and the goal. Motor learning principles are applied to structure and schedule practice. THEORY IN PRACTICE: Four components provide the basis for goal-directed training: (1) selection of a meaningful goal; (2) analysis of baseline performance; (3) intervention/ practice regime; and (4) evaluation of outcome. Two individuals with acquired brain injury practised self-care tasks: eating and tying hair into a ponytail. Intensive training was undertaken over four weeks and the intervention outcome measured using the Goal Attainment Scale. CONCLUSIONS: The positive achievements in the self-care tasks illustrated that theories of motor control and motor learning can be applied to goal-directed training. The examples demonstrated that the approach could be applied to individuals with a range of abilities.

Activities of Daily Living↗
PubMed2005

Psychosocial adjustment in Swedish children with upper-limb reduction deficiency and a myoelectric prosthetic hand.

AIM: To study psychosocial adjustment and mental health in children with upper-limb reduction deficiency and a myoelectric prosthetic hand. METHODS: Sixty-two parents of children aged 8 to 18 y old answered a questionnaire concerning competence and behaviour/emotional problems in their children. Of the 62 children, 37 adolescents aged 11 to 18 y old answered questionnaires concerning competence, problems and mood state. The results were compared with Swedish normative data. The children were divided into five groups based on degree of myoelectric prosthetic use. RESULTS: Children with upper-limb reduction deficiency and a myoelectric prosthetic hand showed social competence and behaviour/emotional problems similar to Swedish standardized norms. However, withdrawn behaviour was significantly higher in all children, social competence was significantly lower in girls, and social activities were significantly lower in older children with upper-limb reduction deficiency. There was a significant difference between prosthetic use groups. Non-users had significantly more delinquent behaviour problems than full-time users. There was an interaction between gender and prosthetic use in their affect on competence and behaviour/emotional problems, yielding two contrasting patterns. CONCLUSION: Children with upper-limb reduction deficiency and a myoelectric prosthetic hand are as well adjusted psychosocially as their able-bodied peers. There are indications, however, of social stigmata related to the deficiency, which have to be considered differently in boys and girls.

Adolescent↗
PubMed2000

Impaired force coordination during object release in children with hemiplegic cerebral palsy.

Recent studies on hand motor control in children with cerebral palsy (CP) have focused on the coordination of fingertip forces during the grasping and lifting of objects. However, little is known about the ability to replace and release an object from grasp, a function that is just as important for fine dexterity. The present study examines the coordination of fingertip forces during the replacement and release of an object (either 200 g or 400 g) from grasp in 14 children (aged between 7 and 13 years) with hemiplegic CP and in 14 age-matched typically developing children. The results indicate that children with hemiplegic CP abruptly replaced the object but had a prolonged and uncoordinated release of the grasp. Unlike what was seen in the control children, the grip and load forces decreased sequentially in the children with CP. However, all the children could appropriately scale the rate of force decrease based on somatosensory weight-related information from the ongoing lift. The results provide further information about the impaired hand skills in children with hemiplegic CP.

Adolescent↗
PubMed2000

Detrimental neural control of precision grip lifts in children with ADHD.

The aim was to investigate the performance of children with attention-deficit-hyperactivity disorder (ADHD) in tasks involving motor-memory representations. A special grip object recorded forces generated by the fingertips during a precision grip-lift task. Common objects were lifted from a linear scale. Twenty-five boys with ADHD were evaluated and grouped according to the presence (ADHD+) or absence (ADHD) of movement dysfunction using the Movement Assessment Battery for Children (Henderson and Sugden 1992). Mean group ages were 11.4 years (range 9.0 to 11.0 years) and 11.7 years (9.0 to 15.6 years), respectively. They were compared to a control group of 25 age-matched boys, mean group age 11.8 years (range 9.0 to 13.0 years). Variability of motor performance was predominant in the ADHD+ group. Several of these participants presented a higher grip-force output during the gripping movement. They also had difficulties in adapting the motor output to target different weights, suggesting deficient anticipatory parameter control based on memory representations. The results suggest that in some children motor problems are due to detrimental neural control functions rather than core symptoms of ADHD.

Adolescent↗
PubMed2000

Quantitative assessment of mirror movements in children and adolescents with hemiplegic cerebral palsy.

Mirror movements in individuals with hemiplegic cerebral palsy (CP) may result from a reorganization of the central sensorimotor system. Motor performances of both hands were measured to characterize mirror activity (or mirroring) and hand functions in 22 participants (6 to 18 years) with hemiplegic CP and in 17 control participants. During a unimanual repetitive squeezing task, contractions of the active hand and fingertip forces of the opposite hand were recorded simultaneously. In the control group, slight mirror activity (or mirroring) was found that decreased with age. In participants with CP, mirror activity was 15 times stronger than in the control group, and was found at all age levels. Mirroring was more prominent in the unaffected hand of the CP group. The amount of mirror activity was not related to the degree of hemiplegia, which was assessed with measures of spasticity, strength, and dexterity. Mirror movements disturbed functional bimanual skills, although to some extent they could be suppressed by voluntary effort.

Adolescent↗
PubMed2000

An examination of the possibility of lowering the glycemic index of oat and barley flakes by minimal processing.

Differences in glycemic responses to various starchy foods are related to differences in the rate of starch digestion and absorption. In this study, the importance of the degree of gelatinization and the product thickness for postprandial glycemic and insulinemic responses to rolled oats and barley were studied in healthy subjects (5 men and 5 women). Thick (1.0 mm) rolled oats were made from raw or preheated (roasted or steamed) kernels. In addition, thin (0.5 mm) rolled oats were made from roasted or roasted and steamed (processed under conditions simulating commercial production) oat kernels. Finally, steamed rolled barley kernels (0.5 or 1.0 mm) were prepared. All thin flakes elicited high glucose and insulin responses [glycemic index (GI), 88-118; insulinemic index (II), 84-102], not significantly different from white wheat bread (P: > 0.05). In contrast, all varieties of thick oat flakes gave significantly lower metabolic responses (GI, 70-78; II, 58-77) than the reference bread (P: < 0.05). Thick barley flakes, however, gave high glucose and insulin responses (GI, 94; II, 84), probably because the botanical structure underwent more destruction than the corresponding oat flakes. We conclude that minimal processing of oat and barley flakes had a relatively minor effect on GI features compared with the more extensive commercial processing. One exception was thick oat flakes, which in contrast to the corresponding barley flakes, had a low GI.

Adult↗
PubMed1999

Identification of microphases in mixed alpha- and omega-gliadin protein films investigated by atomic force microscopy.

Pure and mixed films of alpha- and omega-gliadins were studied by tapping mode atomic force microscopy (AFM). The technique was sensitive to the chemistry of the surface properties of the films, allowing imaging of the mixed gliadin phases at different ratios. In addition to the study of the phases at the micrometer level, higher resolution images allowed visualization of the protein films at the molecular level. These studies may have relevance to the formation of phases in developing protein bodies in grain, where gliadins and glutenins are deposited together. It has been assumed that the protein bodies consist of a random network of proteins; these studies indicate that microphases could be present in protein bodies. The technique provides novel methods for studying mixed biopolymer systems.

Gliadin↗
PubMed1999

Impaired grip-lift synergy in children with unilateral brain lesions.

Children with spastic hemiplegia have impaired dexterity in the affected extremity. The purpose of the present study was to investigate whether the force co-ordination pattern during precision grip in 13 children between 4 and 10 years of age with predominant unilateral brain lesions is related to manual dexterity and to the location and size of the brain lesion. The force co-ordination pattern was investigated by means of a specially designed object that monitored the isometric fingertip forces applied to the contact surfaces during precision grip. Hand function was measured by means of neurological examination, functional hand-grips and dexterity. Brain lesions were identified by series of ultrasound and MRI scans. Normally, the fingertip forces are applied to the object in the initial phase of the lift in an invariant force co-ordination pattern (i.e. grip-lift synergy), in which the grip and load forces are initiated simultaneously and increase in parallel with unimodal force rate trajectories. A majority of children with unilateral brain lesions had not developed the force co-ordination pattern typical for their age, but produced an immature or a pathological pattern. The developmental level of the grip-lift synergy was determined and quantified according to criteria derived from earlier studies on normally developed children. There was a clear relationship between the developmental level of the grip-lift synergy and impaired dexterity, indicating that proper development of the force co-ordination pattern is important for skilled hand function. The grip-lift synergy correlated with the total extent of lesions in the contralateral cortex and white matter and with lesions in the thalamus/basal ganglia, while no correlation was found for isolated cortical lesions. The results suggest that the neural circuits involved in the control of the precision grip are organized in a parallel and distributed system in the hemispheres, and that the basal ganglia are important during the formation of these circuits. Perinatal lesions in specific cortical motor areas may be compensated for by circuits elsewhere in the grip-lift motor system, while large lesions exclude this possibility.

Brain↗
PubMed1998

Obstetric brachial plexus injuries: assessment protocol and functional outcome at age 5 years.

One hundred and five children with the whole spectrum of obstetric brachial plexus (OBP) injuries, from severe to full recovery, were examined at the age of 5 years with regard to motor and sensory functions as well as to use of the affected limb. Since root involvement level does not fully reflect the degree of disability, a classification based on range of motion and grip-strength was formulated and found to correspond well with functional abilities. The results from this study indicate that the eventual outcome in upper-plexus lesions is more complex than is commonly believed. Hand function is affected due to the effect of limited shoulder movements on hand positioning. Grip strength was also reduced in many of these children. All the children with total-plexus lesions had diminished grip strength and half of them had impaired tactile sensibility. In most children with total-plexus lesions, performance of activities in daily life was affected as were bimanual activities requiring use of the involved limb. Hand preference was affected in children with a right-sided injury. From a clinical perspective, as well as for research, it is important to describe OBP injuries not only in terms of impairment but also of disability.

Activities of Daily Living↗
PubMed1998

Hand function in children with cerebral palsy after upper-limb tendon transfer and muscle release.

Thirty-two children with hand dysfunction due to cerebral palsy were examined before tendon transfer and muscle release, and 9 months postoperatively. All children improved their performance regardless of the degree of impaired hand function. The main advantage of surgery was a more functional position of the hand with increased wrist extension and forearm supination. There were also increased functionality of handgrips, grip strength, and dexterity. Impaired sensibility before surgery did not influence the outcome. Individual goals were set preoperatively. Individual functional goals outlined before surgery were met by most children. Children identified as having mild impairments gained new functional skills related to everyday activity (self-care and leisure), while children with severely impaired hand function demonstrated enhanced grasping ability, as well as a better cosmetic appearance.

Adolescent↗
PubMed1995

Development of human precision grip. V. anticipatory and triggered grip actions during sudden loading.

When an object held by a precision gripis subjected to an abrupt vertical load perturbation, somatosensory input from the digits triggers an increase in grip force to restore an adequate safety margin, preventing frictional slips. In adults the response occurs after a latency of 60-80 ms. In the present study, children from 2 years old upward and adults grasped and lifted an object using a precision grip. Sudden, unpredicted increases in load force (tangential to the grip surfaces) were induced by the experimenter by dropping a small disc on to a receptacle attached to the object. The impact elicited a grip force response which in young children had a longer latency and a smaller amplitude than was seen in adults. The grip response latency gradually become shorter and its amplitude increased with increasing age, reaching adult values at 6-10 years. The muscle activity underlying the response could have several bursts. The adults showed one brisk response, appearing 40-50 ms after impact, in extrinsic and intrinsic hand muscles, while younger children also exhibited a short-latency burst, appearing about 20 ms after impact. It is suggested that the short-latency response was mediated via spinal pathways, and that these pathways are disengaged by supraspinal centers during development. In a predictable loading situation, when subjects dropped the disc themselves into the receptable using the contralateral hand, they changed strategy. Adults induced a well-timed anticipatory grip force increase prior to the impact that was scaled to the weight of the object. The youngest children did not time the force increase properly in relation to the impact. Yet, they could scale their anticipatory grip force increase with respect to the weight of the dropped disc. This suggests a well-developed capacity to use information about the weight of objects held by one hand to parameterize a programmed force output to the other hand.

Child↗
PubMed1995

Development of human precision grip. IV. Tactile adaptation of isometric finger forces to the frictional condition.

The adaptation of the grip forces to the frictional condition between the digits and an object relies on feedforward sensorimotor mechanisms that use tactile afferent input to intermittently update a sensorimotor memory that controls the force coordination, i.e., the ratio between grip force (normal to the grip surface) and load force (tangential to the grip surface). The present study addressed the development of these mechanisms. Eighty-nine children and 15 adults lifted an instrumented object with exchangeable grip surfaces measuring the grip and load forces. Particularly in trials with high friction (sandpaper), the youngest children used a high grip force to load force ratio. Although this large safety margin against slips indicated an immature capacity to adapt to the frictional condition, higher grip forces were produced for more slippery material (silk versus sandpaper). The safety margin decreased during the first 5 years of age, in parallel with a lower variability in the grip force and a better adaptation to the current frictional condition. The youngest children (18 months) could adapt the grip force to load force ratio to the frictional condition in a series of lifts when the same surface structure was presented in blocks of trials, but failed when the surface structure was unpredictably changed between subsequent lifts. The need for repetitive presentation suggests a poor capacity to form a sensorimotor memory representation of the friction or an immature capacity to control the employed ratio from this representation. The memory effects, reflected by the influences of the frictional condition in the previous trial, gradually increased with age. Older children required a few lifts and adults only one lift to update their force coordination to a new friction. Hence, the present finding suggests that young children use excessive grip force, a strategy to avoid frictional slips, to compensate for an immature tactile control of the precision grip.

Adolescent↗
PubMed1995

Tactile control of isometric fingertip forces during grasping in children with cerebral palsy.

Sensory mechanisms and sensorimotor integration have often been thought to be disturbed in children with cerebral palsy (CP). The authors investigated the influence of tactile information from the fingertips on the isometric force regulation during the lift of a small object with the precision grip in children with CP and controls. Children with CP were able to modify their grip force according to friction between the fingertips and the object and could use tactile information for anticipatory control of the force-scaling of the precision grip, but they seemed to need predictable conditions and successive lifts to build up memory representation of an object's friction.

Case-Control Studies↗
PubMed1992

Development of human precision grip. II. Anticipatory control of isometric forces targeted for object's weight.

The development of anticipatory control during lifts with the precision grip was examined in 100 children aged 1 to 15 years and in 15 adults. The children were instructed to lift an instrumented test object by using the precision grip between the thumb and index finger. The employed grip force, load force (vertical lifting force), vertical position and their corresponding time derivatives (i.e., grip and load force rates and acceleration) were recorded. The weight of the object was varied between trials to access the influence of the object's weight in the previous trial on the isometric force output. Already by the second year, children began to use information pertaining to the object's weight in the previous lift, i.e., they began to use an anticipatory control strategy. This occurred concomitant to the development of mainly bell shaped force rate profiles (Forssberg et al. 1991). The succeeding development of a more mature anticipatory control was gradual and adult-like capacity was not reached until 8-11 years of age.

Adolescent↗
PubMed1992

Development of human precision grip. III. Integration of visual size cues during the programming of isometric forces.

Recent evidence has shown that visual and haptical size information can be used by adults to estimate the weight of the object, forming the basis of the force programming during precision grip (Gordon et al. 1991a, b,). The present study examined the development of the capacity to use visual size information. In the first experiment, 30 children (age 1-7 years) and 10 adults performed a series of lifts with two boxes presented in an unpredictable order. The boxes were equal in weight but unequal in size and were attached to an instrumented grip handle which measured the employed grip force, load force, position and their corresponding time derivatives. The isometric force development was not influenced by the box size before the age of 3. However, the children aged 3 years and older demonstrated greater visual influences on the force programming than adults. To determine more precisely when children began to use visual size information, a second experiment in which the size and weight covaried was performed on 15 children. Children still did not use the size information during the force programming until the later half of the third year. It is concluded that this ability, probably involving associative transformations between the size and weight of objects, emerges around one year after anticipatory control based on somatosensory information pertaining to the weight of the object.

Adolescent↗
PubMed1992

Impaired anticipatory control of isometric forces during grasping by children with cerebral palsy.

The authors examined the force regulation during prehension of 12 children with cerebral palsy (CP) and an age-matched control group. The control group appropriately scaled the isometric force output in one force-rate pulse toward the weight of the previously lifted object, but children with CP exhibited stepwise increases in force in which the force amplitudes were not influenced by the object's weight. When the object was held in the air, most children with CP were able to modify their force output according to the object's weight, using sensory feedback, but their forces were more variable than those of the control group and less influenced by the object's weight. Although children with CP have disturbed sensory feedback--likely to lead to an indistinct internal representation of an object's physical properties--their main disability stems from impaired central co-ordination of motor activity.

Biomechanical Phenomena↗
PubMed1991

Development of human precision grip. I: Basic coordination of force.

The coordination of manipulative forces was examined while children and adults repeatedly lifted a small object between the thumb and index finger. Grip force, load force (vertical lifting force), grip force rate and the vertical position of the test object were continuously measured. In adults, the force generation was highly automatized and was nearly invariant between trials. After a preload phase in which the grip was established, the grip and load forces increased in parallel under isometric conditions until the load force overcame the force of gravity and the object started to move. During this loading phase, the force rate profiles were essentially bell shaped and single peaked, suggesting that the force increases were programmed as one coordinated event. Children below the age of two exhibited a prolonged preload phase and a loading phase during which the grip and load forces did not increase in parallel. A major increase in grip force preceded the increase in load force, and at the start of the loading phase, the grip force was usually several Newtons (N). The force rate profiles were multi peaked with stepwise force increases most likely allowing peripheral feedback to play an important role in the control of the forces. After the age of two, the grip force increased less during the preload phase. The loading phase was more regularly characterized by a parallel increase of the grip force and load force and the duration of the various phases decreased. The older children programmed the forces in one force rate pulse indicating the emergence of an anticipatory strategy. Yet, the mature coordination of forces was not fully developed until several years later.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗