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Biomedical subjects

E G Dawson

Publications and source records attributed to E G Dawson.

At least 37 records · Page 2Linked to original sources
PubMed1989

Early experience with automated percutaneous lumbar discectomy in the treatment of lumbar disc herniation.

Seventeen patients with symptomatic lumbar disc herniation were treated with automated percutaneous lumbar discectomy employing local anesthetic in an outpatient setting. Operative technique included (1) intravenous sedation and single-dose antibiotics, (2) prone oblique patient positioning for initial needle placement, and (3) postdiscectomy interspace lavage with bupivacaine hydrochloride. There were no postoperative complications and the procedure was well-tolerated by all patients. Although results have thus far been less successful than previously reported, with improved patient selection by means of routine magnetic resonance imaging (or computed tomographic discography in select cases), success rates (nine of 17 patients) might approach those achieved by chemonucleolysis. The successful response of four patients with so-called midline L4-L5 discs has been particularly encouraging, and it may be that percutaneous lumbar discectomy will be an effective and a reasonable treatment alternative for this particular subgroup of patients.

Adult↗
PubMed1988

Cortical evoked potential monitoring during spinal surgery: sensitivity, specificity, reliability, and criteria for alarm.

Cortical somatosensory evoked potentials (EP) were used for intraoperative monitoring of spinal cord integrity during 158 consecutive cases involving surgical correction of spinal deformities. Using a monitoring technique designed to optimize recording, 88% of patients had stable EP results at the time of spinal manipulation. However, five of six patients with preexistent neurological deficits did not have stable EPs. A persistent EP amplitude attenuation of greater than or equal to 40% was a sensitive and specific criterion for alarm. Seven patients had transient attenuations of greater than or equal to 40% after distraction that recovered, so that the distraction instrumentation could be left in place. Overall, this particular cortical somatosensory EP recording technique appears to be appropriate for clinical monitoring. Other recording techniques may be necessary for patients with preexisting neurological deficits.

Adolescent↗
PubMed1986

Bone repair induced by bone morphogenetic protein in ulnar defects in dogs.

In dogs, resection of a length of the ulna equal to twice the diameter of the mid-shaft leaves a defect which consistently fails to unite. In response to an implant of 100 mg of bovine bone morphogenetic protein (BMP), the defect becomes filled by callus consisting of fibrocartilage, cartilage and woven bone within four weeks. The cartilage is resorbed and replaced by new bone in four to eight weeks. Woven bone is then resorbed, colonised by bone marrow cells and remodelled into lamellar bone. Union of the defect is produced by 12 weeks. Control defects filled with autogeneic cortical bone chips unite after the same period. In regeneration induced by bone morphogenetic protein (BMP) and in repair enhanced by bone graft, union depends upon the proliferation of cells within and around the bone ends. Our working hypothesis is that BMP induces the differentiation of perivascular connective tissue cells into chondroblasts and osteoprogenitor cells and thereby augments the process of bone regeneration from the cells already present in the endosteum and periosteum.

Animals↗
PubMed1985

The cephaloscapular projection. A special diagnostic aid.

The cephaloscapular roentgenographic projection is a new projection for diagnosing subluxation about the glenohumeral joint. When properly projected, the acromion, glenoid, humeral head, and coracoid can be seen in independent relief. The relatively radiolucent clavicle overlies the area but does not obscure the landmarks. This view should prove useful in diagnosing a variety of acute and chronic shoulder problems.

Adolescent↗
PubMed1985

A comparison of different methods used to diagnose pseudarthrosis following posterior spinal fusion for scoliosis.

Pseudarthrosis is a recognized complication of posterior spinal fusion for scoliosis, and its early recognition and repair may prevent loss of correction, failure of the instrumentation, or pain. In this study of 200 fusions for scoliosis, we compared the reliability of different methods that are currently used to determine the presence or absence of a pseudarthrosis. Anteroposterior tomography was found to have the highest rate of correlation (96 per cent), as there was only one false-negative study. Other methods of diagnosis--including anteroposterior, lateral, and oblique radiographs and clinical findings such as loss of correction and back pain--were less accurate.

Adolescent↗
PubMed1984

Abdominosacral resection for malignant tumors of the sacrum.

Malignant sacral tumors present unique problems because of their location deep in the pelvis, their juxtaposition to the ureters, rectum, and iliac vessels, and the need to preserve spinal stability and sacral nerve function after resection. The simultaneous abdominosacral resection circumvents many of these problems since it provides good exposure of the intraabdominal structures, allows precise selection of the level of sacral resection, and avoids damage to the sacral nerve roots. Tolerable control of bladder and bowel functions is possible by preservation of the S1 nerve roots, and spinal stability can be maintained with preservation of the body of the S1 vertebra. Because malignant tumors of the sacrum have a high propensity for local recurrence, we believe that the exposure afforded by the sacroabdominal approach provides an opportunity to obtain a wide margin of resection during initial resection of these tumors.

Abdomen↗
PubMed1984

The role of tomography in the evaluation of the postoperative spinal fusion.

Despite the fact that pseudarthrosis is the most common complication after posterior spinal fusion, no reproducible diagnostic method has been established. This study analyzes the accuracy of the anteroposterior trispiral tomography in evaluating the posterior spinal fusion mass. Tomography was shown to be both sensitive and specific in its ability to detect the presence or absence of a pseudarthrosis. Radiation exposure is not increased when tomography is performed in lieu of less accurate diagnostic studies. Anteroposterior trispiral tomography is a useful adjunct in the routine postoperative evaluation of the patient who has undergone a posterior spinal arthrodesis.

Adult↗
PubMed1983

Muscular torticollis. A modified surgical approach.

Since 1967 twelve children with muscular torticollis were treated at the Los Angeles Shriners Hospital for Crippled Children with a modified bipolar release of the sternocleidomastoid muscle. The results of the procedure were compared with the results in twenty-two other patients who had had either conservative treatment or other types of operations and who were seen between 1952 and 1981. The average follow-up was nine years (range, one to thirty-three years). Fourteen patients, most of them less than one year old, were treated non-operatively and had 86 per cent good or excellent results. The bipolar release and z-plasty was performed either when conservative treatment had failed or in older children who had had other operations, and it yielded 92 per cent good or excellent results. Only 15 per cent good and 77 per cent fair results were obtained when surgical procedures other than bipolar release were performed.

Child↗
PubMed1981

Giant cell tumor of the cervicothoracic spine.

Four cases of giant cell tumor of the cervicothoracic spine are reported. All involved women aged 17-20. Current treatment consists of surgical extirpation and radiation therapy; however, carefully monitored cryotherapy of this lesion may be a feasible new therapeutic method. Due to their relatively inaccessible location, giant cell tumors of the spine will be difficult to treat adequately, and can be expected to recur and cause neurologic compromise in a significant proportion of cases. Computed tomography is the imaging method of choice for defining the extent of tumor because it can show bone involvement, spinal canal encroachment, and soft-tissue extension.

Adolescent↗
PubMed1981

Elbow flexorplasty. An analysis of long-term results.

We analyzed the long-term functional results in twenty-five consecutive patients who underwent Steindler elbow flexorplasty between 1952 and 1976. In eighteen patients, the elbow flexorplasty was augmented by a glenohumeral arthrodesis. The mean length of the follow-up was 9.3 years. The mean arc of active flexion following floxorplasty was 95 degrees. The postoperative loss of elbow extension averaged 36 degrees. The mean postoperative active pronation was 79 degrees and supination, 51 degrees. In two patients mild transient ulnar paresthesias developed following flexorplasty. At final evaluation, fourteen patients were judged to have excellent; six, good; four, fair; and one, poor function. All but one patient noted subjective improvement after the procedure.

Adolescent↗
PubMed1981

Twelfth thoracic-first lumbar vertebral mechanical stability of fractures after Harrington-rod instrumentation.

UNLABELLED: Thirteen fresh cadaver spinal segments (fifth thoracic to fifth lumbar vertebra) with a posterior ligamentous defect at the twelfth thoracic-first lumbar level were tested to failure in flexion, creating an unstable fracture at the twelfth thoracic and first lumbar vertebrae. The fractured spines were then instrumented with Harrington distraction rods and retested. Spines instrumented at the eleventh thoracic to second lumbar vertebrae were not significantly stronger than uninstrumented specimens (with a posterior ligamentous defect). Repositioning the upper hook from the eleventh to the tenth thoracic vertebra increased the failure moment by an average of 36 per cent. Instrumentation of the spine at either level protected the spinal column against distraction at the fracture site until a threshold movement was reached. Moving the upper hook from the eleventh up to the tenth thoracic vertebra increased the threshold moment by an average of 65 per cent. Our recommended hook placement at the tenth thoracic and second lumbar vertebrae tends to reduce tilting of the upper vertebra, changing the mode of failure from slip-out of the upper hook (with partial laminar fracture) to total laminar fracture. CLINICAL RELEVANCE: The presence of internal fixation rods in itself does not make the unstable fractured spine stronger in a flexion mode. The level of hook placement above and below the fracture is important in determining with bending strength of the instrumented spine. When the use of Harrington distraction rods is contemplated for internally stabilizing a fractured spine, a specific level of hook placement, three laminae above and two laminae below the point of instability, is recommended. This configuration allows the instrumentation to maintain increased spinal stability in a flexion mode by reducing the tendency for the upper hooks to "back out" and lose their hold secondary to vertebral tilting.

Aged↗
PubMed1978

Scoliosis in arthrogryposis multiplex congenita.

Scoliosis was evident in eighteen of eighty-eight patients with arthrogryposis multiplex congenita. The predominant pattern of spinal deformity was a structural thoracolumbar double curve that extended to the sacrum and was associated with pelvic obliquity and lumbar hyperlordosis. Significant contractures about the hips, dislocation of the hip, or both were present in all patients but one. Most of the curves were progressive and they became rigid and fixed at an early age. There was progression of the pelvic obliquity coincident with progression of the curve. Treatment by corrective casts or a Milwaukee brace was ineffective and if surgical treatment directed at the pelvic obliquity did not correct that deformity, spine fusion to the sacrum appeared necessary.

Adolescent↗
PubMed1977

Methylmethacrylate as an adjunct in spinal instrumentation.

Sixteen patients with scoliosis were treated with Harrington-rod instrumentation supplemented by methylmethacrylate fixation at the distraction sites to reduce the possibility of dislodgement of a hook due to inferior bone stock or the patients' inability to cooperate postoperatively because of mental insufficiency or involuntary-movement disorders. Follow-up ranged from six to thirty-eight months (average, fourteen and one-half months). There were no complications related to the use of methylmethacrylate in these patients.

Casts, Surgical↗
PubMed1976

Solitary bone cyst of the cervical spine.

A histologically proven case of solitary bone cyst of a cervical vertebral body seems not to have been previously reported. Cysts of sufficient size to be a potential source of pathologic fracture should be excised and filled with autologous bone grafts.

Adult↗
PubMed1975

Fiberglass casts.

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Casts, Surgical↗