Repair of the flexor pollicis longus tendon in children.
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This is a retrospective study of primary repairs of flexor pollicis longus in 16 children under 15 years of age. Patients with injuries to the median or ulnar nerve at the wrist, crush injuries, skin loss or fracture were excluded. Repairs were carried out within 24 hours using a modified Kessler technique. The mean follow-up was for two years. The final results were evaluated using the criteria of Buck-Gramko and Tubiana. They were good or excellent in all except one patient who had a secondary tendon rupture. When compared with the non-injured thumb, however, there was a significant decrease in active interphalangeal flexion (> 30 degrees) in one-third of cases. A new method of assessment is proposed for the recovery of function of the flexor pollicis tendon which is more suitable for children. Postoperative immobilisation using a short splint had a negative effect on outcome. The zone of injury, an early mobilisation programme or concurrent injury to the digital nerve had no significant effect on the final result. (+info)
Tactile apraxia: unimodal apractic disorder of tactile object exploration associated with parietal lobe lesions.
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Tactile apraxia is characterized by an isolated disturbance of hand movements for use of and interaction with an object (transitive movements) in the presence of preserved intransitive movements (movements without use of an object, for example repetitive movements or gestures). It is, however, still unclear whether motor and sensory abnormalities represent causal or associated features of tactile apraxia. To address this question, quantitative kinematic recordings of exploratory finger movements (transitive movements) and rapid alternating finger movements (intransitive movements) were studied in 20 healthy volunteers and 22 patients with focal lesions of the parietal, anterofrontal and motor cortex. The most severe deficits of manual object exploration were found in patients with parietal lesions, using the hand contralateral to the lesion. Patients with lesions of the anterior parietal lobe who exhibited prominent sensory deficits and astereognosia showed a decrease in frequency and regularity of exploratory finger movements and a marked increase in exploration space. Patients with posterior parietal lesions exhibiting severe astereognosia, apraxia and deficits in dexterity had a greater decrease in frequency and regularity of manipulative movements, but a less pronounced increase of exploration space than the patients with anterior parietal lesions. Although the patients with parietal lobe lesions could generate rapid alternating finger movements, the regularity of these movements was also impaired. In comparison, patients with frontal lobe lesions exhibited impaired contralesional manipulatory and rapid alternating finger movements but no sensory abnormalities or astereognosia. We conclude that tactile apraxia represents a deficit in the programming of exploratory finger movements mediated by the parietal lobe. The comparison with lesions of other regions participating in the cortical network for tactile exploration reveals that apraxia of exploratory movements in parietal lobe lesions represents a disturbance distinct from elementary motor or sensory abnormalities, but closely related to stereognostic functioning. (+info)
Effects of age on brain activation during auditory-cued thumb-to-index opposition: A positron emission tomography study.
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BACKGROUND AND PURPOSE: Available data indicate a decline in fine finger movements with aging, suggesting changes in central motor processes. Thus far no functional neuroimaging study has assessed the effect of age on activation patterns during finger movement. METHODS: We used high-resolution perfusion positron emission tomography to study 2 groups of 7 healthy right-handed subjects each: a young group (mean age, 24 years) and an old group (mean age, 60 years). The task was a thumb-to-index tapping, auditory-cued at 1. 26 Hz with a metronome, with either the right or the left hand. The control condition was a resting state with the metronome on. RESULTS: Significant differences between old and young subjects were found, suggesting significant overactivation in older subjects affecting the superior frontal cortex (premotor-prefrontal junction) ipsilateral to the moving fingers, as if the execution of this apparently simple motor task was judged more complex by the aged brain. Similar findings in previous perceptual and cognitive paradigms have been interpreted as a compensation process for the neurobiological changes of aging. Analysis of the control condition data in our sample showed, however, that this prefrontal overactivation in the old group was due at least in part to higher resting perfusion in anterior brain areas in the young subjects. CONCLUSIONS: The changes in brain function observed in this study may underlie the subtle decline in fine motor functions known to occur with normal aging. Our findings emphasize the importance of using an age-matched control group in functional imaging studies of motor recovery after stroke. (+info)
Microstructured magnetic materials for RF flux guides in magnetic resonance imaging.
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Magnetic resonance imaging and spectroscopy systems use coils, either singly or as arrays, to intercept radio-frequency (RF) magnetic flux from regions of interest, often deep within the body. Here, we show that a new magnetic material offers novel possibilities for guiding RF flux to the receiver coil, permitting a clear image to be obtained where none might otherwise be detectable. The new material contains microstructure designed according to concepts taken from the field of photonic band gap materials. In the RF range, it has a magnetic permeability that can be produced to specification while exhibiting negligible direct-current magnetism. The latter property is vital to avoid perturbing the static and audio-frequency magnetic fields needed to obtain image and spectral data. The concept offers a new paradigm for the manipulation of RF flux in all nuclear magnetic resonance systems. (+info)
Dystrophic calcinosis in a child with a thumb sucking habit: case report.
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We present an uncommon case of a 3-year-old boy with a finger sucking habit who developed dystrophic calcification in his left thumb. Two years after excision, there was no recurrence, and the thumb retained full range of motion. We also discuss its probable pathogenesis and present a brief review of the literature about orthopedic complications in the hand due to this habit. (+info)
Percutaneous release of trigger digits.
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We describe a safe and easy percutaneous technique for release of trigger finger using a specially designed knife. The A1 pulley is sectioned by a blade which has a hooked end. We released, percutaneously, 185 trigger fingers, including 62 which were locked using this technique. Satisfactory results were achieved in 173 (93.5%). There were no significant complications. We recommend this as a safe and effective outpatient procedure for those patients who have not responded successfully to conservative treatment, have longstanding symptoms or severe triggering. (+info)
Damping actions of the neuromuscular system with inertial loads: human flexor pollicis longus muscle.
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Our previous work in an animal model showed that neuromuscular damping properties help maintain limb posture by effectively dissipating mechanical energy arising from disturbances. The purpose of this study was to determine whether similar damping properties were expressed in intact, normal human muscles. To review briefly, when the reflexively active soleus muscle in a decerebrate cat is coupled to an inertial load, application of a force impulse to the load results in lightly damped oscillations. By calculating the logarithmic decrement in muscle velocity following the impulse (the decrement being related to the amount of energy dissipated from the inertia), we found that damping increased with oscillation amplitude, a nonlinear property. This nonlinearity represents an automatic compensation for larger perturbations. Our findings in parallel experiments on the interphalangeal joint of the human thumb were that the long thumb flexor, the flexor pollicis longus (FPL), displayed mechanical and reflex behavior closely comparable to that reported earlier for the cat soleus, despite differences in architectural and metabolic properties between these muscles. Specifically, by selecting experimental trials that did not include voluntary interventions, we observed amplitude-dependent differences in damping in which larger amplitude movements elicited larger damping than did smaller movements. In addition, even after accounting for amplitude-dependent differences in damping, damping was found to be larger in later cycles than in the first cycle. This nonlinearity indicates that both mechanical properties of muscle and reflex mechanisms are dependent on prior movement history. We propose that this history-dependent behavior arises from the effects of prior movement on stretch reflex gain, and these effects are mediated primarily via changes in muscle spindle properties. Recordings of electromyographic activity from the FPL, during the first and second cycles of oscillation supported this postulate of a reduced reflex gain following prior motion. The functional significance of these nonlinear damping properties is that during the initial muscle stretch, the stiffness is high, which helps to preserve the initial position (although at the expense of promoting oscillation). Subsequently, the ensuing increase in damping helps suppress continuing oscillation. This sequence of varying mechanical properties is broadly analogous to the features of a predictive, or feed-forward controller, designed to produce a response that initially maintains position, and subsequently dampens oscillations. These results show that the intrinsic properties of muscle and spinal reflexes automatically provide a complex time-varying response, appropriate for maintenance of stable limb posture. (+info)
Thenar muscle blood flow and bone mineral in the forearms of lumberjacks.
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Forty lumberjacks who had used a chain saw for 0-20 years and who had no general disease affecting the bones were studied by measuring the thenar muscle blood flow of both hands by the 133-Xe local clearance method. Bone mineral in the left forearm in the region of cancellous and cortical bone was assessed by the 241-Am gamma ray attenuation method. Virbration was found to decrease the blood flow in the saw-bearing left hand compared with the right hand of the lumberjacks. The bone mineral density (g/vm-3) was lower in the forearm bones of the lumberjacks than in controls of the same age with healthy bones. Moreover the poorer the thenar muscle blood flow, the greater was the decrease in the mineral density of the distal radius. Measurement of the mineral density of the forearm bones by the gramma ray attenuation method can be used for early detection of bone lesions in traumatic vasospastic disease. (+info)