Case report. Recovery of shoulder movement in patients with complete axillary nerve palsy.
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Classical anatomical teaching suggests that the deltoid muscle is the main abductor of the shoulder. We present three cases of proven complete paralysis of the deltoid with an almost full range of movement of the shoulder owing to the compensatory action of accessory muscles. The mechanisms by which this occurs are described. (+info)
Acute barium intoxication following ingestion of ceramic glaze.
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A case of deliberate overdose of barium sulphide in a psychiatric setting is presented, with resulting flaccid paralysis, malignant arrhythmia, respiratory arrest and severe hypokalaemia, but ultimately with complete recovery. The degree of paralysis appears to be related directly to serum barium levels. The value of early haemodialysis, particularly with respiratory paralysis and hypokalaemia, is emphasised. (+info)
Patterns of synchronization in the superior colliculus of anesthetized cats.
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Sensorimotor transformations in the mammalian superior colliculus (SC) are mediated by large sets of distributed neurons. For such distributed coding systems, stimulus superposition poses problems attributable to the merging of neural populations coding for different stimuli. Such superposition problems could be overcome by synchronization of neuronal discharges, because it allows the selection of a subset of distributed responses for further joint processing. To assess the putative role of such a temporal binding mechanism in the SC, we have applied correlation analysis to visually evoked collicular activity. We performed recordings of single-unit and multiunit activity in the SC of anesthetized and paralyzed cats with multiple electrodes. Autocorrelation analysis revealed that collicular neurons often discharged in broad (20-100 msec) bursts or with an oscillatory patterning in the alpha- and beta-frequency range. Significantly modulated cross-correlograms were observed in 50% (128 of 258) of the collicular multiunit recording pairs, and for these pairs significant correlations occurred in 44% of the stimulation epochs. For the single-unit pairs, significant interactions were observed in 14 of 48 cases studied (29%). Collicular cross-correlograms were often oscillatory, and these oscillations covered a broad frequency range of up to 100 Hz, with a predominance of oscillation frequencies in the alpha- and beta-range. In the majority of the significant correlograms (64%) the phase lag of the center peak was <5 msec. The probability of collicular synchronization increased with the overlap of the receptive fields and the proximity of the recording sites. Correlations were also observed between cells in the superficial and deep SC layers. Collicular synchronization required activation of the respective cells with a single coherent stimulus and broke down when the neurons were activated with two different stimuli. These data are consistent with the notion that collicular synchrony could define assemblies of functionally related cells. (+info)
Neurotoxicity and behavioral effects of thiram in rats.
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Eight of 24 female rats fed 66.9 mg/kg-day of thiram developed neurotoxicity. The neurotoxic effects were characterized by ataxia and paralysis of the hind legs. There were demyelination, degeneration of the axis cylinders, and presence of macrophages in the nerve bundle of the sciatic nerve. Degeneration in the ventral horn of the lower lumbar region of the spinal cord was evidenced by chromatolysis of motorneurons, pyknosis, and satellitosis. During a second experiment, 4 of 24 females fed 65.8 mg/kg--day also developed ataxia and paralysis. An additional 9 females showed clasping of the hind feet when picked up by the tail. Nerve conduction could not be measured for one severely ataxic rat and the electromyogram indicated a loss of motor unit function. Histopathology of this rat, along with the others, suggests the peripheral nerve as the primary site of the lesion. Thiram also caused behavioral changes in apparently normal rats. The walking pattern of the hind legs was altered with decreases in stride width and the angle between contralateral steps. These rats required significantly more shock-motivations and cleared a lower height in a jump/climb ability test. An open-field study indicated that thiram caused hyperactivity in the nonataxic rats of both sexes. Three of 24 rats fed 95.8 mg/kg-day of ferbam also developed ataxia or paralysis. (+info)
Posterior fossa epithelial cyst: case report and review of the literature.
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A 49-year old woman with progressive cranial nerve signs and hemiparesis was found at MR imaging and at surgery to have a cyst at the foramen magnum. Immunohistochemistry and electron microscopy showed an epithelial cyst of endodermal origin. MR findings were of an extraaxial mass, with short T1 and T2 times. Unless immunohistochemistry and electron microscopy are used in the final diagnosis of such cysts, all posterior fossa cysts lined by a single layer of epithelium should be described simply as epithelial cysts. (+info)
Contractile activity in intestinal muscle evokes action potential discharge in guinea-pig myenteric neurons.
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1. The process by which stretch of the external muscle of the intestine leads to excitation of myenteric neurons was investigated by intracellular recording from neurons in isolated longitudinal muscle-myenteric plexus preparations from the guinea-pig. 2. Intestinal muscle that was stretched by 40 % beyond its resting size in either the longitudinal or circular direction contracted irregularly. Both multipolar, Dogiel type II, neurons and uniaxonal neurons generated action potentials in stretched tissue. Action potentials persisted when the membrane potential was hyperpolarized by passing current through the recording electrode for 10 of 14 Dogiel type II neurons and 1 of 18 uniaxonal neurons, indicating that the action potentials originated in the processes of these neurons. For the remaining four Dogiel type II and 17 uniaxonal neurons, the action potentials were abolished, suggesting that they were the result of synaptic activation of the cell bodies. 3. Neurons did not fire action potentials when the muscle was paralysed by nicardipine (3 microM), even when the preparations were simultaneously stretched by 50 % beyond resting length in longitudinal and circular directions. Spontaneous action potentials were not recorded in unstretched (slack) tissue, but when the L-type calcium channel agonist (-)-Bay K 8644 (1 microM) was added, the muscle contracted and action potentials were observed in Dogiel type II neurons and uniaxonal neurons. 4. The proteolytic enzyme dispase (1 mg ml-1) added to preparations that were stretched 40 % beyond slack width caused the myenteric plexus to lift away from the muscle, but did not prevent muscle contraction. In the presence of dispase, the neurons ceased firing action potentials spontaneously, although action potentials could still be evoked by intracellular current pulses. After the action of dispase, (-)-Bay K 8644 (1 microM) contracted the muscle but did not cause neurons to fire action potentials. 5. Gadolinium ions (1 microM), which block some stretch activated ion channels, stopped muscle contraction and prevented action potential firing in tissue stretched by 40 %. However, when (-)-Bay K 8644 (1 microM) was added in the presence of gadolinium, the muscle again contracted and action potentials were recorded from myenteric neurons. 6. Stretching the tissue 40 % beyond its slack width caused action potential firing in preparations that had been extrinsically denervated and in which time had been allowed for the cut axons to degenerate. 7. The present results lead to the following hypotheses. The neural response to stretching depends on the opening of stretch activated channels in the muscle, muscle contraction in response to this opening, and mechanical communication from the contracting muscle to myenteric neurons. Distortion of sensitive sites in the processes of the neurons opens channels to initiate action potentials that are propagated to the soma, where they are recorded. Neurons are also excited indirectly by slow synaptic transmission from neurons that respond directly to distortion. (+info)
Activities and functional assessment 1 year after spinal fusion for paralytic scoliosis.
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The results of spinal fusion in patients with paralytic deformities are usually presented as the correction of the deformity. When evaluating the surgical results in such patients, it is advantageous to classify the patients into subgroups because of the varying dysfunction and disabilities. The aim of this study was to evaluate the effect of spinal fusion in patients with paralytic scoliosis in relation to function in terms of Impairments, activities in terms of Disabilities, and dependence in terms of Handicaps 1 year postoperatively, with emphasis on subgroups. A total of 94 patients with paralytic scoliosis and 18 different diagnoses were evaluated 1 year after surgery. The patients were classified according to whether or not they could understand verbal instructions. The patients were also grouped according to the Scoliosis Research Society classification of diagnoses. A set of instruments was used with the variables classified according to WHO's International Classification of Impairments, Disabilities, and Handicaps (ICIDH). This consists of the patient's/relative's motives for surgery, persistent skin discoloration, ambulating or use of wheelchair, use of a brace, sitting balance, weight distribution on a sitting surface, angle of scoliosis, reaching, pain estimation, activities of daily living (ADL) Klein and Bell, care given, time spent resting, and seating supports. The set of instrument also included a follow-up questionnaire comprising 12 different areas, where the patients/relatives assessed the results of surgery. The study showed that spinal fusion in paralytic scoliosis led to showed improvements in the whole group of patients at the Impairment level in the angle of scoliosis, sitting balance, weight distribution, and reduced number of patients with persistent skin discoloration, and at the Handicap level in reduced time for resting during the day, reduced number of seating supports in the wheelchair, and in the use of a brace. Most of the parameters were unchanged. The results in the subgroups were almost the same as in the whole group, although pain and reaching at the Impairment level, and ADL at the Disability level, could not be measured in the patients who were unable to understand verbal instructions. The subjectively assessed results showed that seating posture was ranked positively irrespective of the motive for surgery. The study showed that the patients with paralytic scoliosis maintained or improved their function and level of independence in terms of Impairment and Handicap 1 year postoperatively. The subjective results assessed by the patients/relatives also showed a positive outcome of surgery. Weight distribution on a seating surface was improved, but still uneven, and with respect to better sitting balance and increasing time sitting in a wheelchair, this can involve a risk for pressure sores and needs further investigation. When introducing outcomes including the Disability level, one must take the importance of homogeneity in the groups into consideration. (+info)
Hyperkalaemic paralysis--a bizarre presentation of renal failure.
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Paralysis due to hyperkalaemia is rare and the diagnosis may be overlooked in the first instance. However it is rapidly reversible and so long as electro-cardiography and serum potassium measurement are urgently done in all patients presenting with paralysis, it will not be missed. A case of hyperkalaemic paralysis is described and a review of the emergency management discussed. (+info)