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Biomedical subjects

M A Edgar

Publications and source records attributed to M A Edgar.

At least 19 recordsLinked to original sources
PubMed1991

Spinal cord monitoring in scoliosis surgery. Experience with 1168 cases.

Since 1981, during operations for spinal deformity, we have routinely used electrophysiological monitoring of the spinal cord by the epidural measurement of somatosensory evoked potentials (SEPs) in response to stimulation of the posterior tibial nerve. We present the results in 1168 consecutive cases. Decreases in SEP amplitude of more than 50% occurred in 119 patients, of whom 32 had clinically detectable neurological changes postoperatively. In 35 cases the SEP amplitude was rapidly restored, either spontaneously or by repositioning of the recording electrode; they had no postoperative neurological changes. One patient had delayed onset of postoperative symptoms referrable to nerve root lesions without evidence of spinal cord involvement, but there were no false negative cases of intra-operative spinal cord damage. In 52 patients persistent, significant, SEP changes were noted without clinically detectable neurological sequelae. None of the many cases which showed falls in SEP amplitude of less than 50% experienced neurological problems. Neuromuscular scoliosis, the use of sublaminar wires, the magnitude of SEP decrement, and a limited or absent intra-operative recovery of SEP amplitude were identified as factors which increased the risk of postoperative neurological deficit.

Adolescent↗
PubMed1990

Multi-level epidural recordings of spinal SEPs during scoliosis surgery.

Spinal somatosensory evoked potentials were recorded in 35 neurologically normal patients undergoing surgery for scoliosis. The recording electrodes were placed in the dorsal epidural space. Stimulation was of the tibial nerve in the popliteal fossa and the posterior tibial and sural nerves at the ankle. At thoracic levels the response consisted of at least 3 components with different peripheral excitation thresholds and spinal conduction velocities (range 35-85 m/sec). All components were conducted mainly in tracts ipsilateral to the stimulus, component 1 being most laterally located. At low stimulus intensity only the fastest activity was recorded but higher intensities elicited additional, slower conducting components. Component 1 was much less prominent when the posterior tibial nerve was stimulated at the ankle and absent from the (cutaneous) sural nerve response. Component 1 is likely to be due to the stimulation of group 1 muscle afferents which terminate in the dorsal horn and activate second-order neurones, many of whose axons go to form the ipsilateral dorsal spinocerebellar tract. Components 2 and 3 are believed to be largely cutaneous in origin and to be conducted mainly in the dorsal columns.

Electric Stimulation↗
PubMed1989

The economics of mild hypertension programmes.

The recently reported results from several controlled randomised trials of the drug treatment of mild hypertension suggest that such treatment may be expected to exert a small effect toward the primary prevention of stroke disease. In order that the economic implications of these results might be examined, two hypothetical programmes of anticipatory care are considered according to the principles of cost-effectiveness analysis. Each notional 5 year programme is set in a defined population, residents of Stockport, Greater Manchester, aged between 35 and 64 years, and each is addressed toward the detection and treatment of mild hypertension in the community. The programmes differ with respect to their detection processes: one programme is based upon the screening method conducted under the aegis of health visitor staff employed by a District Health Authority, the other upon opportunistic case finding conducted by general practitioners. It is likely that the screening programme would prevent about 13 strokes over a 5 year period; if set in leisure time total programme costs are estimated to be 309,500 pounds at 1986 prices. Discounting future costs and future prevented strokes provides for the development of a present value total cost per prevented stroke of 25,000 pounds. Alternately, the 5 year opportunistic programme, costing 252,650 pounds, would be expected to prevent about 15 strokes at a present value of 17,050 pounds per prevented stroke. The prevention of stroke disease attributable to these programmes can only be achieved in the presence of group compliance to drug treatment. This clearly depends upon the perception of the value of treating hypertension according to each individual subject. The respective merits of the two programmes are examined with particular reference to their sensitivity to this issue, as well as to their likely feasibility and practicability.

Adult↗
PubMed1989

Scoliosis in neurofibromatosis. The natural history with and without operation.

We reviewed 47 patients with neurofibromatosis and dystrophic spinal deformities; 32 of these patients had been untreated for an average of 3.6 years and in them the natural history was studied. The commonest pattern of deformity at the time of presentation was a short angular thoracic scoliosis, but with progression the angle of kyphosis also increased. Deterioration during childhood was usual but its rate was variable. Severe dystrophic changes in the apical vertebrae and in particular anterior scalloping have a poor prognosis for deterioration. The dystrophic spinal deformity of neurofibromatosis requires early surgical stabilisation which should be by combined anterior and posterior fusion if there is an abnormal angle of kyphosis or severely dystrophic apical vertebrae. Some carefully selected patients can be treated by posterior fusion and instrumentation alone.

Adolescent↗
PubMed1988

Long-term follow-up of fused and unfused idiopathic scoliosis.

We reviewed 77 unfused and 91 fused patients with idiopathic scoliosis who first attended between 1949 and 1965. Both groups were re-examined at least 10 years after reaching skeletal maturity, with attention to progression of the Cobb angle, increased in vertebral rotation, back pain and psychosocial problems. We found that spinal fusion protects the scoliotic spine from further deterioration during adult life except for those with severe curves and marked rotation. Fusion also significantly reduced the incidence of severe pain and allowed patients to carry out heavy physical work, but did not confer complete immunity from backache. Surgery improved the appearance, but patients were not always completely satisfied with the cosmetic result.

Adult↗
PubMed1987

Scoliosis in juvenile chronic arthritis.

Structural scoliosis occurs more commonly in patients with juvenile chronic arthritis than in the normal population. We have reviewed 32 patients with both juvenile arthritis and a scoliosis and suggest that structural curves may arise from postural curves associated with asymmetrical involvement of lower limb joints.

Adolescent↗
PubMed1987

The natural history of unfused scoliosis.

Seventy-eight unfused patients with idiopathic scoliosis were followed from skeletal maturity over a mean period of 17 years (range 10 to 27 years) with a mean age at follow up of 33.7 years. The following aspects were investigated: curve deterioration, back pain incidence, and psychosocial details. There was considerable variation in the progression rate of similar deformities but on average significant deterioration occurred when the Cobb angle was over 55 degrees with a maximum deterioration approaching 1.5 degrees per year in the thoracic curves between 90 degrees and 100 degrees mature Cobb angle. Thoracolumbar and lumbar curves were slightly more benign with a maximum progression rate of about 1 degree when the mature angle was 80 degrees to 90 degrees. The thoracic component of double curves progressed least. Rotation increased in proportion to the Cobb angle progression except in some lumbar curves where lateral subluxation occurred with a disproportionate amount of rotation. The incidence of back pain in relation to pain in the general population and in fused patients remains uncertain. Eighty-two percent of patients had married and 87% had job satisfaction; 10% received treatment for depression.

Adult↗
PubMed1985

Backache.

Explore the source record for details and available documents.

Back Pain↗
PubMed1985

Posterior spinal fusion and instrumentation in the treatment of adolescent idiopathic scoliosis.

Three hundred and nineteen patients with adolescent idiopathic scoliosis were treated by posterior spinal fusion over an eight year period. The changes in preoperative correction and surgical techniques are reviewed. The anaesthetic technique using induced hypotension and the postoperative routine are described. The amount of deformity and its correction at operation and postoperatively is discussed by reference to Cobb angles. The early and late complications are reviewed.

Adolescent↗
PubMed1979

The role of NADH-NADPH oxidase activity in the leukocyte function of burned patients.

Irreversible sepsis, in spite of advancements in topical therapy and antimicrobial agents, remains the leading cause of death in major thermal injury. A defect in intracellular bactericidal capacity in leukocytes from severely burned patients appears to correspond with increases in bacterial wound colonization and ultimate sepsis. This leukocyte defect has been demonstrated by abnormally low nitroblue tetrazolium reduction (NBT) and oxygen consumption of white cells in patients with major thermal injury. The subcellular mechanisms responsible for decreased bactericidal capacity were therefore investigated. Nicotinamide-adenine dinucleotide (NADH) and nicotinamide-adenine phosphodinucleotide (NADPH) oxidase activity was measured in patients with major burns, controls (normals), and in patients with nonburn stress or infection. NADH and NADPH oxidase levels in leukocytes from burn patients were not significantly different from those of normal nonchallenged controls but were significantly lower than the leukocyte values found in the patients with nonburn infections or stress. This NADH and NADPH defect in the subcellular leukocyte fraction suggests that it may be a significant factor in the reduced bactericidal function of the intact leukocyte in thermally injured patients.

Burns↗
PubMed1979

Cardiac and respiratory function before and after spinal fusion in adolescent idiopathic scoliosis.

Ten girls with adolescent idiopathic scoliosis were studied before and 17-23 months after spinal fusion. None had any cardiac or respiratory disease complicating the scoliosis. They underwent a range of resting lung function tests and a progressive exercise test. The mean angle of scoliosis decreased from 65.8 to 27.3 degrees after operation but the only significant physiological benefit detected in this study was a decrease in the submaximal minute ventilation. The physiological benefit of spinal fusion was therefore much less prominent than the anatomical improvement of the spinal curvature.

Adolescent↗