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Biomedical subjects

R B Delamarter

Publications and source records attributed to R B Delamarter.

36 records · Page 2Linked to original sources
PubMed1995

Percutaneous lumbar discectomy. Preoperative and postoperative magnetic resonance imaging.

We evaluated magnetic resonance imaging studies of thirty patients before and after a contained herniation of a lumbar disc was treated with a percutaneous lumbar discectomy. The imaging studies were evaluated to determine whether the preoperative appearance of the herniated disc was predictive of the outcome of percutaneous discectomy and also to determine a possible mechanism of action of the procedure in the relief of symptoms. The index operation was successful in seventeen (57 per cent) of the thirty patients. The preoperative imaging studies showed no differences in the appearance of the discs that went on to have a successful result and those that went on to have an unsuccessful result. Imaging studies made four to six weeks after the operation showed no measurable changes in the morphology of the disc. Imaging studies made a mean of fourteen months after the operation showed no changes in the morphology of the disc in twenty-four (80 per cent) of the patients, irrespective of the clinical outcome. Only three of the seventeen patients who had a successful result had a reduction of more than two millimeters in the size of the herniated segment, and two of the thirteen patients who had an unsuccessful result had an increase of more than one millimeter in the size of the herniated segment. We found that preoperative imaging studies cannot predict the clinical outcome of percutaneous lumbar discectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Pathophysiology of spinal cord injury. Recovery after immediate and delayed decompression.

We evaluated the effect of the timing of decompression of the spinal cord after compression of 50 per cent of the diameter of the spinal cord at the fourth lumbar level in thirty purebred dogs. The dogs were divided into five groups of six dogs each on the basis of the duration of the compression. Decompression was performed immediately (Group I), one hour (Group II), six hours (Group III), twenty-four hours (Group IV), or one week (Group V) after the compression. Monitoring of somatosensory evoked potentials, daily neurological examinations, and histological and electron microscopic studies at the time of the autopsy were performed for all of the dogs. Initially, all of the dogs were paraplegic after the compression of the spinal cord. The dogs that had immediate decompression or decompression after one hour of compression recovered the ability to walk (grades 4 and 5, according to Tarlov's system) as well as control of the bowel and bladder, and the somatosensory evoked potentials improved an average of 85 and 72 per cent, respectively. However, when compression lasted six hours or more, there was no neurological recovery and there was progressive necrosis of the spinal cord. Somatosensory evoked potentials improved 29 per cent in Group III, 26 per cent in Group IV, and 10 per cent in Group V. The percentage of recovery of the somatosensory evoked potentials by six weeks after the decompression was significantly related to the duration of the compression (p < 0.0008).

Animals↗
PubMed1994

Postmortem osseous and neuropathologic analysis of the rheumatoid cervical spine.

METHODS: Eleven patients with paralysis, secondary to rheumatoid arthritis of the cervical spine were analyzed postmortem. Neurologic classification (Ranawat) included one Class 2, four Class IIIA, and six Class IIIB. Rheumatologic changes included atlantoaxial subluxation, basilar invagination, and subaxial subluxation. During autopsy the entire cervical spine was removed, including the occiput and foramen magnum. The spinal cord and medulla oblongata were removed en toto and examined histologically by a neuropathologist. RESULTS: Nine of the eleven cases revealed abnormal histology of the spinal cord, and in two patients, the spinal cords were normal. Three histologic types of spinal cord compression were identified. In Type 1 (four cases) severe chronic mechanical compression revealed marked mechanical distortion, flattening, and destruction of the cord with secondary Wallerian degeneration of the ascending and descending tracts without anoxicischemic neuron changes. In Type 2 (three cases), there was vascular compression showing ischemic damage to the cord with necrosis of the lateral columns in the ischemic watershed regions supplied by anterior and posterior spinal arteries. In Type 3 (two cases), there was mild mechanical compression showing focal gliosis at the site of compression without ascending or descending tract injury. Two of the eleven cases had thrombosis of the vertebral arteries. Of the eleven cases analyzed, two had normal spinal cords. CONCLUSION: This autopsy analysis of rheumatoid cervical spine suggests that paralysis can be due to both mechanical neural compression and/or vascular impairment.

Aged↗
PubMed1994

Hyponatremia and syndrome of inappropriate antidiuretic hormone secretion in adult spinal surgery.

STUDY DESIGN: Patients undergoing spinal surgery were monitored for sodium balance, fluid type, and volume input and output during surgery and for the first 3 postoperative days. OBJECTIVE: To prospectively document the true incidence of the syndrome of inappropriate antidiuretic hormone secretion and hyponatremia, and identify risk and protective factors for the development of the syndrome of inappropriate antidiuretic hormone secretion after spinal surgery. METHODS: Data on medical history, surgical procedure, estimated blood loss, and volumes and types of intraoperative and postoperative fluids were collected on 116 consecutive spinal surgery patients during March to July 1992. RESULTS: One hundred one spinal operations in 96 patients were evaluated. There were 48 males and 48 females, with a mean age of 52 years (range, 16 to 90 years). Hyponatremia developed in 45 (44.6%) patients. The etiology of hyponatremia was the syndrome of inappropriate antidiuretic hormone secretion in seven patients (6.9%), hypovolemia in 19 patients (18%), and other causes in six patients. CONCLUSIONS: Spine patients are at risk for hyponatremia and the syndrome of inappropriate antidiuretic hormone secretion. The incidence of the syndrome of inappropriate antidiuretic hormone secretion was 6.9%. Serum sodium should be monitored postoperatively. Patients who undergo a revision operation have an approximately two to four times greater risk of being affected by the syndrome of inappropriate antidiuretic hormone secretion than those who have primary surgery.

Blood Loss, Surgical↗
PubMed1994

Anterior decompression for late pain and paralysis after fractures of the thoracolumbar spine.

Anterior decompression of the thoracic and lumbar spine is indicated for patients with trauma, infection, or tumor that causes compression of the neural tissues, resulting in an incomplete neurologic deficit. The complication of chronic pain, with or without paralysis, that results from fractures with canal compromise has received little attention. This study involved 45 patients who had anterior decompression for chronic pain or paralysis at an average of 4.5 years after having thoracolumbar fractures. Pain was improved in 41 of 45 patients, with complete relief in 30 and partial relief in 11. In 25 patients with neurologic deficit, 21 noted improvement, 14 of which improved one or more grades of the Eismont classification. No patient had an increase in pain or loss of neurologic function. Complications were few. Anterior decompression of the thoracolumbar spine for chronic pain after thoracolumbar fractures is a safe and effective treatment for patients with this uncommon and difficult problem.

Adolescent↗
PubMed1993

Lumbar spine following successful surgical discectomy. Magnetic resonance imaging features and implications.

In an attempt to determine the expected long-term appearance of the lumbar spine in patients who have undergone successful lumbar discectomy, follow-up magnetic resonance (MR) examinations were performed on 23 patients (26 levels). All patients in the study had undergone at surgery at least one year prior to the study. All patients met rigorous criteria for a successful outcome. In nine cases, the postoperative study indicated a virtually total resolution of the previously identified disc herniations. In 13 cases, the study noted moderate, persistent posterior contour defects in the disc that contributed to persistent mass effect on the thecal sac or corresponding nerve root. In the remaining four cases, the postoperative study indicated virtually no change in the apparent contour of the posterior disc margin. Gadolinium contrast examinations demonstrated enhancement of the persistent contour abnormalities in 18 of 19 disc levels, suggesting the common presence of fibrosis, which was at times "mass-like," in these successful patients. These findings suggest that localized discal contour abnormalities morphologically simulating recurrent disc herniations and variably contributing to mass effect, may be commonly encountered in long-term follow-up imaging studies of successful discectomy patients.

Adult↗
PubMed1993

Lumbar spinal stenosis secondary to calcium pyrophosphate crystal deposition (pseudogout).

A 62-year-old man demonstrated symptoms, signs, and radiographic evidence of lumbar spinal stenosis and intraoperative pathologic findings of tophaceous deposition in the ligamentum flavum. Although there have been reports of cervical calcium pyrophosphate dihydrate crystal deposition (CPPD) with neurologic compression, this report appears to be the first case of lumbar spinal stenosis secondary to CPPD. Cervical calcium pyrophosphate dihydrate crystal deposition should be added to the differential diagnosis of spinal stenosis.

Arthrodesis↗
PubMed1991

1991 Volvo Award in experimental studies. Cauda equina syndrome: neurologic recovery following immediate, early, or late decompression.

An animal model of cauda equina syndrome was developed. Neurologic recovery was analyzed following immediate, early, and delayed decompression. Five experimental groups, each containing six dogs, were studied. Compression of the cauda equina was performed in all 30 dogs following an L6-7 laminectomy. The cauda equina was constricted by 75% in each group. The first group was constricted and immediately decompressed. The remaining groups were constricted for 1 hour, 6 hours, 24 hours, and 1 week, respectively, before being decompressed. Somatosensory evoked potentials were performed before and after surgery, before and immediately after decompression, and 6 weeks following decompression. Daily neurologic exams using the Tarlov grading scale were performed. At 6 weeks postdecompression, all dogs were killed, and the neural elements analyzed histologically. Following compression, all 30 dogs had significant lower extremity weakness, tail paralysis, and urinary incontinence. All dogs recovered significant motor function 6 weeks following decompression. The dogs with immediate decompression generally recovered neurologic function within 2-5 days. The dogs receiving 1-hour and 6-hour compression recovered within 5-7 days. The dogs receiving 24-hour compression remained paraparetic 5-7 days, with bladder dysfunction for 7-10 days and tail dysfunction persisting for 4 weeks. The dogs with compression for 1 week were paraparetic (Tarlov Grade 2 or 3) and incontinent during the duration of cauda equina compression. They recovered to walking by 1 week and Tarlov Grade 5 with bladder and tail control at the time of euthanasia. Immediately after compression, all five groups demonstrated at least 50% deterioration of the posterior tibial nerve evoked potential amplitudes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Urologic changes after cauda equina compression in dogs.

Relative degrees (25%, 50% or 75%) of constriction of the entire cauda equina at the seventh lumbar level were performed on eighteen pure bred female beagle hounds by surgically implanting a circular polyethylene loop with an imbedded stainless steel wire. The wire was mechanically constricted by external control and the degree of compression was confirmed by pre- and postoperative magnetic resonance imaging or computed tomography scanning. A control group of two dogs had laminectomy only. Neurologic function was evaluated daily. Cystometrics were performed on each dog after constriction had been present for three months. Cortical evoked potentials (CEPs) were obtained on all dogs preoperatively, immediately following constriction and at monthly intervals for three months. Dogs were sacrificed at three months and the cauda equina and spinal cord were examined histopathologically. Cystometric tracings were noted to become a flat line with 75% compression of the cord. Less compression had minimal effect on the cystometric curves. The mean latency, determined by cortical evoked potentials, was noted to increase by 3.2%, 7.8%, and 17.2% immediately after 25%, 50% and 75% constriction, respectively. Histologic changes ranged from occasional enlargement of the axons on the periphery of the cauda equina with 25% constriction to severe loss of all axons and atrophic roots at the level of the constricting band with 75% constriction.

Animals↗
PubMed1990

Diagnosis of lumbar arachnoiditis by magnetic resonance imaging.

Twenty-four cases of lumbar arachnoiditis were evaluated by magnetic resonance (MR) imaging. The morphologic changes of arachnoiditis by MR were compared in 20 cases with CT myelography (CTM) and plain film myelography (PFM). An abnormal configuration of nerve roots was seen by MR. Three anatomic groups were identified. Group 1 showed conglomerations of adherent nerve roots residing centrally within the thecal sac. Group 2 demonstrated nerve roots adherent peripherally to the meninges, giving rise to an "empty sac" appearance. Group 3 showed a soft tissue mass replacing the subarachnoid space. Magnetic resonance imaging resulted in accurate diagnosis, and had excellent correlation with CT myelography and plain film myelographic findings in the diagnosis of lumbar arachnoiditis.

Arachnoiditis↗
PubMed1990

Urologic function after experimental cauda equina compression. Cystometrograms versus cortical-evoked potentials.

Twenty female beagle dogs underwent an L6-7 laminectomy and six dogs each had 25, 50 or 75% constriction of the cauda equina and 2 control dogs had laminectomy only. Cystometrograms were performed pre- and post-operatively and three months after constriction. Cortical evoked potentials were monitored pre- and post-operatively and monthly for three months. After three months of constriction, the cauda equina of these dogs in each group was examined histologically and vascular circulation was examined by latex and India ink injection (Spalteholz technique). The control dogs had normal CMGs and CEPs. Twenty-five percent constriction caused no CMG changes and mild CEP changes. Fifty percent constriction caused no statistically significant CMG changes, major CEP changes and venous congestion of the nerve roots and dorsal root ganglia. Seventy-five percent constriction produced severe CMG changes with detrusor areflexia, increased bladder capacity and clinical incontinence. CEPs also had marked deterioration. Vascular analysis revealed severe arterial narrowing at the level of constriction and venous congestion of the nerve roots and dorsal root ganglia. Blockage of axoplasmic flow and nerve root atrophy was seen in all dogs with 75% constriction. Cortical evoked potentials were the most sensitive predictor of neural compression. CMGs were not sensitive until severe compression was achieved. Bladder dysfunction, i.e., detrusor areflexia, appears to occur with blockage of axoplasmic flow and early sensory changes occur with neurovenous congestion.

Animals↗
PubMed1990

Primary neoplasms of the thoracic and lumbar spine. An analysis of 29 consecutive cases.

Primary osseous neoplasms of the thoracic and lumbar spine are uncommon lesions. Between 1965 and 1982, of 1971 patients with musculoskeletal neoplasms, only 29 (1.5%) had primary osseous tumors in these locations. There were eight children and 21 adults. Back pain was the most common complaint in 25 patients (86%), and neurologic symptoms or deficits were present in 16 patients (55%). All lesions were visible on routine spine roentgenograms, while computed tomography and myelography demonstrated spinal canal encroachment and extradural spinal cord compression in 19 patients (66%). The histologic diagnoses included 11 benign and 18 malignant lesions. Benign lesions occurred predominantly in children and malignant tumors in adults. Treatment was individualized, based on the histologic diagnoses. Twenty-two patients had surgical resection of their lesions. Laminectomy without stabilization and arthrodesis resulted in late instability and neurologic deterioration in three of seven patients (43%) with malignant lesions. Resection and decompression combined with arthrodesis did not predispose to late instability. Twenty-one patients were followed for a mean of 4.1 years (range, two to 14 years). Eight patients died from malignant disease between one month and seven years after diagnosis.

Adolescent↗
PubMed1990

HTLV-I viral-associated myelopathy after blood transfusion in a multiple trauma patient.

This may be the first documented case in the United States and in the orthopedic literature of transfusion-transmitted human T-cell leukemia virus Type I (HTLV-I)-associated myelopathy (HAM). Progressive myelopathy occurred in a 58-year-old white man with serologic and molecular evidence of HTLV-I infection after multiple trauma and subsequent transfusion with multiple units of banked blood products. Symptoms of myelopathy occurred 15 months after the transfusions. Myelopathy from HTLV-I infection simulates a disorder of orthopedic interest. Physicians should be aware of the symptoms of HAM and unexplained myelopathy.

HTLV-I Antibodies↗
PubMed1990

Ligament injuries associated with tibial plateau fractures.

Thirty-nine patients with tibial plateau fractures and concomitant ligament injury were evaluated at least one year after injury. Ligamentous injury was determined by stress roentgenograms, plain roentgenograms, operative findings, and Pelle-grini-Stieda's ossification. There were 22 isolated medial collateral, eight lateral collateral, one isolated anterior cruciate, and eight combined ligament injuries. All types of tibial plateau fractures were associated with ligamentous injury, although split compression and local compression were most common. Twenty patients (Group 1) did not have operative repair of the injured ligaments, and 19 patients (Group 2) had primary repair of the injured ligaments. Open reduction and internal fixation of the plateau fracture(s) were performed in 13 patients in Group 1 and 19 patients in Group 2. Follow-up evaluation (100-point scale), including subjective, functional, and anatomic factors, revealed 12 excellent and good, four fair, and three poor results in the 19 patients with ligamentous repair. There were ten excellent and good, two fair, and eight poor results in those without ligament repair. Ten of the 12 patients with 10 degrees or more of instability had poor results. These poor results included five unrepaired medial collateral ligaments, two unrepaired lateral collateral ligaments, and three patients with cruciate ligament injury. This study confirms the view that instability is a major cause of unacceptable results in tibial plateau fractures. Operative repair of medial and lateral collateral ligaments, with appropriate treatment of the bony plateau fracture, may reduce late instability and may improve overall morbidity in these concomitant injuries. Cruciate ligament injury associated with a tibial plateau fracture carries a poor prognosis.

Adolescent↗
PubMed1990

Experimental lumbar spinal stenosis. Analysis of the cortical evoked potentials, microvasculature, and histopathology.

An animal model of lumbar spinal stenosis was developed in which the pathophysiology of this condition could be examined. Four experimental groups, each containing six dogs, were studied. One group had a laminectomy of the sixth and seventh lumbar vertebrae only; these animals served as controls. In the three other groups, a laminectomy was performed and the cauda equina was constricted by 25, 50, or 75 per cent to produce chronic compression. Cortical evoked potentials were recorded preoperatively, immediately after constriction, and at one, two, and three months postoperatively. Daily neurological examinations were carried out, and the neurological deficits were graded using the Tarlov system. After three months of constriction, the cauda equina of three dogs in each group was examined histologically, and the vascular circulation was examined by latex and India-ink injection with a modification of the Spalteholz technique. The animals in the control group showed no neurological abnormalities, no changes in cortical evoked potentials, normal microvascularity, and no histopathological changes in the nerve roots or the spinal cord. The dogs in which the cauda equina had been constricted 25 per cent had no neurological deficits, mild changes in cortical evoked potentials, slight histological changes, and venous congestion of the root and dorsal root ganglion of the seventh lumbar nerve. The dogs in which the cauda equina had been constricted 50 per cent had mild initial motor weakness, major changes in cortical evoked potentials, edema and loss of myelin in the root of the seventh lumbar nerve, and moderate or severe venous congestion of the root and dorsal root ganglion of the seventh lumbar nerve. The dogs in which the cauda equina had been constricted 75 per cent had significant weakness, paralysis of the tail, and urinary incontinence; two dogs recovered by the third month, but all had neurogenic claudication for three months. All six dogs had dramatic changes in cortical evoked potentials and had complete nerve-root atrophy at the level of the constriction. There was blockage of axoplasmic flow and wallerian degeneration of the motor nerve roots distal to the constriction and of the sensory roots proximal to the constriction, as well as degeneration of the posterior column. Severe arterial narrowing at the level of the constriction and venous congestion of the roots and dorsal root ganglia of the seventh lumbar and first sacral nerves were also present. Cortical evoked potentials revealed neurological abnormalities before the appearance of neurological signs and symptoms.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Lumbar spine: postoperative MR imaging with Gd-DTPA.

Thirty patients with failed back surgery syndrome were studied to evaluate the effectiveness of magnetic resonance (MR) imaging with gadolinium-diethylenetriaminepentaacetic acid/dimeglumine (Gd-DTPA) in differentiating postoperative epidural fibrosis (scar) from recurrent disk herniation. Pre- and postcontrast MR images were interpreted without access to other diagnostic, surgical, or pathologic findings. Seventeen patients had surgical and pathologic correlation of the MR findings at 19 disk levels. The precontrast studies had a sensitivity, specificity, and accuracy of 100%, 71%, and 89%, respectively. The enhanced MR studies correctly depicted the character of abnormal epidural soft tissue in 17 patients at all 19 levels. Scar showed heterogeneous enhancement on the early T1-weighted spin-echo images obtained within 10 minutes after contrast material administration. Herniated disk did not show significant enhancement on the early studies but showed variable degrees of enhancement on delayed images in nine of 12 cases. Other criteria were found to be less useful than the pattern of enhancement. Results indicate that precontrast and early postcontrast T1-weighted spin-echo studies are highly accurate in separating epidural fibrosis from herniated disk.

Adult↗
PubMedDate not supplied

Acute management of spinal cord injury.

Demographic trends in the occurrence of injury and improvements in the early management of spinal trauma are changing the long-term profile of patients with spinal cord injuries. More patients are surviving the initial injury, and proportionately fewer patients are sustaining complete injuries. While preventive efforts to reduce the overall incidence of spinal cord injury are important, a number of steps can be taken to minimize secondary injury once the initial trauma has occurred. Recent efforts have focused on understanding the biochemical basis of secondary injury and developing pharmacologic agents to intervene in the progression of neurologic deterioration. The Third National Acute Spinal Cord Injury Study investigators concluded that methylprednisolone improves neurologic recovery after acute spinal cord injury and recommended that patients who receive methylprednisolone within 3 hours of injury should be maintained on the treatment regimen for 24 hours. When methylprednisolone therapy is initiated 3 to 8 hours after injury, it should continue for 48 hours. In addition to the adoption of the guidelines of that study, rapid reduction and stabilization of injuries causing spinal cord compression are critical steps in optimizing patients' long-term neurologic and functional outcomes.

Chemoprevention↗