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Biomedical subjects

G F Tuite

Publications and source records attributed to G F Tuite.

15 recordsLinked to original sources
PubMed1999

Signals for proinflammatory cytokine secretion by human Schwann cells.

Wallerian degeneration is a post-traumatic process of the peripheral nervous system whereby damaged axons and their surrounding myelin sheaths are phagocytosed by infiltrating leukocytes. Our studies indicate that Schwann cells could initiate the process of Wallerian degeneration by releasing proinflammatory cytokines involved in leukocyte recruitment and differentiation including IL-1beta, MCP-1, IL-8 and IL-6. A comparison of the secretory pattern between nerve explants and cultured Schwann cells showed that each cytokine was differentially regulated by growth factor deprivation or axonal membrane fragments. Since Wallerian-like degeneration occurs in a wide variety of peripheral neuropathies, Schwann cell-mediated cytokine production may play an important role in many disease processes.

Cells, Cultured↗
PubMed1997

Computer-assisted measurement of lumbar spine radiographs.

RATIONALE AND OBJECTIVES: The authors evaluated a method for obtaining reproducible, reliable measurements from standard lumbar spine radiographs for determining the degree of spondylolisthesis, vertebral body height, intervertebral disk space height, disk space angle, and degree of vertebral body wedging. MATERIALS AND METHODS: Four to six easily defined points were identified on each vertebral body on anteroposterior and lateral plain radiographs of the lumbosacral spine of patients. From these points, the degree of spondylolisthesis, the vertebral body height, the intervertebral disk space height, the disk space angle, and the degree of vertebral body wedging were easily calculated by using well-known geometric relationships. This method requires the use of a personal computer and a standard spreadsheet program but does not require the use of any other specialized radiographic equipment, computer hardware, or custom software. RESULTS: Calculations of intra- and interobserver variability for the measurement of spondylolisthesis, disk space height, disk space angle, and vertebral body height measurement showed that the technique is extremely reproducible. CONCLUSION: This technique may prove useful in the prospective evaluation of potential candidates for lumbar spinal stenosis surgery.

Humans↗
PubMed1997

Dural inversion procedure for moyamoya disease. Technical note.

A variety of surgical procedures have been proposed for the treatment of moyamoya disease, but few have used the potential of the middle meningeal artery to any great extent. During the period of spontaneous collateral formation, patients with this disease are at risk for the development of transient ischemic attacks and strokes. Surgical treatments aimed at increasing collateral flow to the brain from the external carotid system have included both direct and indirect anastomotic methods. In this report, the authors describe a technique that used the middle meningeal artery circulation as a source of collateral blood supply by inverting dural flaps that are located on a large meningeal vessel, allowing the richly vascularized outer dural surface to contact a large surface area of the ischemic cortex. An extensive degree of revascularization was observed.

Anatomy, Artistic↗
PubMed1996

The effectiveness of papilledema as an indicator of raised intracranial pressure in children with craniosynostosis.

Craniosynostosis management partially depends on the detection and treatment of elevated intracranial pressure (ICP). Examination for papilledema is considered to be the most reliable screening method for identifying raised ICP, but its effectiveness has not been defined. One hundred and twenty-two children with craniosynostosis who underwent funduscopic examinations and then Camino ICP monitoring were studied. All eye examinations were performed by an ophthalmologist after pharmacological pupillary dilation. Fifteen patients (12%) had papilledema. Subsequent ICP monitoring showed that the median ICP was 12.7 mm Hg, with 41 patients (34%) having elevated ICPs (> 15 mm Hg). Those with papilledema had higher ICPs (17.5 +/- 3.2 versus 12.7 +/- 5.5 mm Hg), were older (5.9 +/- 4.7 versus 1.9 +/- 2.6 years), and were more likely to have craniofacial syndromes (73 versus 41%) than those without papilledema (P < 0.05). Patients with both elevated ICPs and papilledema were older (5.9 +/- 4.7 versus 1.6 +/- 1.4 years) and more likely to have multiple-suture synostosis (92 versus 61%) than those with elevated ICPs and no papilledema (P < 0.05). The presence of papilledema was a specific (98%) indicator of raised ICP, but its sensitivity was age-dependent. It was 100% sensitive in children older than 8 years, but it indicated elevated ICP in only 22% of younger patients. These results suggest that ICP monitoring to document elevated ICP is unnecessary in children older than 8 years who have detailed ophthalmological examinations. In the younger child, the presence of papilledema reliably indicates elevated ICP but its absence does not rule out elevated ICP; formal ICP measurement has a greater role in detecting elevated ICP in these patients.

Adolescent↗
PubMed1996

The beaten copper cranium: a correlation between intracranial pressure, cranial radiographs, and computed tomographic scans in children with craniosynostosis.

OBJECTIVE: The beaten copper appearance of the cranium, as well as other cranial radiographic and computed tomographic findings in children with craniosynostosis, is often interpreted by clinicians as evidence of elevated intracranial pressure (ICP). However, a correlation between radiological findings and ICP measurements has not been previously demonstrated, and their usefulness in detecting elevated ICP has not been defined. METHODS: To address those issues, 123 children with craniosynostosis who had cranial radiographs and ICP monitoring were studied. To assess the specificity of certain radiological findings to patients with craniosynostosis, cranial radiographs of patients with craniosynostosis were compared to those of age- and sex-matched controls. In patients with craniosynostosis, findings on cranial radiographs were compared to computed tomographic scans of the brain. Radiographic findings were then correlated with ICP measurements obtained while the patient was sleeping, which was measured using a Camino fiberoptic ICP monitor (Camino Laboratories, San Diego, CA). All radiographs were independently analyzed by two radiologists who were blinded to clinical and ICP data. RESULTS: A diffuse beaten copper pattern, erosion of the dorsum sellar, and suture diastasis were seen more commonly in patients with craniosynostosis than in controls (P < 0.05), but the presence of the beaten copper pattern was no more common in children with craniosynostosis. ICP was greater when a diffuse beaten copper pattern, dorsum sellar erosion, suture diastasis, or narrowing of basal cisterns was present (P < 0.05). CONCLUSION: Although this study demonstrates that some cranial radiographic and computed tomographic findings do correlate with elevated ICP, the sensitivity of radiological methods for detecting elevated ICP is universally low and they are not recommended to screen for elevated ICP in children with craniosynostosis.

Child↗
PubMed1996

Pediatric transoral surgery: indications, complications, and long-term outcome.

Knowledge of the role and hazards of transoral surgery has expanded rapidly, but the application of this technique in children has been limited. To assess its usefulness, 27 pediatric patients who underwent transoral surgery between 1985 and 1994 were studied. Transoral surgery was performed for irreducible anterior neuraxial compression at the craniovertebral junction caused by basilar impression, atlantoaxial subluxation with pseudotumor, or chordoma. The patients ranged in age from 3 to 17 years. Symptomatic presentation varied widely, but 89% had significant neurological deficits before surgery. No patient with normal strength deteriorated after surgery. Of the 16 patients with a preoperative motor deficit, nine improved rapidly, three were unchanged, and four significantly worsened in the perioperative period. Those with mobile atlantoaxial subluxation were most vulnerable to surgically related neurological morbidity. Twenty-four patients were alive for long-term follow-up study (average 5.7 years, range 1-9.2 years). Of those with preoperative weakness, nine improved one Frankel grade, four remained the same, and one deteriorated from Frankel Grade D to C. Swallowing and speech worsened in five patients; this occurred only after resection of lesions above the foramen magnum (p<0.05) when rostral pharyngeal disruption resulted in velopharyngeal dysfunction. This study, unlike previous reviews of pediatric transoral operations, leads the authors to suggest that although transoral surgery can be effective, it also carries a significant risk of neurological injury in patients with symptomatic spinal cord compression and it is also associated with long-term swallowing and speech difficulties.

Adolescent↗
PubMed1996

Use of an adjustable, transportable, radiolucent spinal immobilization device in the comprehensive management of cervical spine instability. Technical note.

In this report the authors describe a device that consists of a transportable, radiolucent board that couples to a standard halo head ring. The board provides continuous cervical spine immobilization during all phases of acute medical treatment of cervical spine instability, including closed reduction, transport, radiographic imaging, and operative procedures. By combining the advantages of several existing systems, this immobilization device facilitates and improves the safety of comprehensive acute management of cervical spinal instability by eliminating the need for patient transfer from stretcher to radiography machine to operating table. Its radiolucent construction and its compatibility with standard operating tables allow unencumbered surgical access and ample room for biplanar fluoroscopy, thereby also facilitating operative procedures, particularly the placement of internal spinal fixation.

Cervical Vertebrae↗
PubMed1995

Vertebral artery dissection related to basilar impression: case report.

A 50-year-old man with myelopathy secondary to basilar impression developed bilateral vertebral artery dissection after undergoing treatment with 8 pounds of cervical traction. The vertebral artery dissection resulted in vertebrobasilar insufficiency and posterior circulation stroke. In this report, the current management philosophies in the treatment of basilar impression are discussed, and the pertinent neurovascular anatomy is illustrated. This report suggests that vertebral artery injury may result from attempted reduction of severe basilar impression. Regardless of the cause of cranial settling, the risk of vertebral artery injury with cervical traction should be considered in patients with severe basilar impression.

Aortic Dissection↗
PubMed1994

Sources of human Schwann cells and the influence of donor age.

We evaluated several tissues as possible sources for culturing human Schwann cells. The average cell yield (total cell number/mg of nerve fascicle) obtained from adult autopsy cases and transplant organ donors was similar (2 x 10(4) and 2.9 x 10(4), respectively), but significantly higher yields were obtained from dorsal roots of pediatric patients undergoing selective dorsal rhizotomy (6.1 x 10(4)). Fresh tissue was not essential since cells isolated from 0 to 20 h postmortem were equally viable. However, we found evidence that donor age affects the intrinsic growth rate of Schwann cells and perineurial fibroblasts in culture.

Adult↗
PubMed1994

Outcome after laminectomy for lumbar spinal stenosis. Part I: Clinical correlations.

All patients who underwent decompressive lumbar laminectomy in the Washtenaw County, Michigan metropolitan area during a 7-year period were studied for the purpose of defining long-term outcome, clinical correlations, and the need for subsequent fusion. Outcome was determined by questionnaire and physical examination from a cohort of 119 patients with an average follow-up evaluation interval of 4.6 years. Patients graded their outcome as much improved (37%), somewhat improved (29%), unchanged (17%), somewhat worse (5%), and much worse (12%) compared to their condition before surgery. Poor outcome correlated with the need for additional surgery, but there were few additional significant correlations. No patient had a lumbar fusion during the study interval. The outcome after laminectomy was found to be less favorable than previously reported, based on a patient questionnaire administered to an unbiased patient population. Further randomized, controlled trials are therefore necessary to determine the efficacy of lumbar fusion as an adjunct to decompressive lumbar laminectomy.

Adult↗
PubMed1994

Outcome after laminectomy for lumbar spinal stenosis. Part II: Radiographic changes and clinical correlations.

The pre- and postoperative lumbar spine radiographs of 119 patients who underwent decompressive lumbar laminectomy were studied to evaluate radiographic changes and to correlate them with clinical outcome. An accurate and reproducible method was used for measuring pre- and postoperative radiographs that were separated by an average interval of 4.6 years. Levels of the spine that underwent laminectomy showed greater change in spondylolisthesis, disc space angle, and disc space height than unoperated levels. Outcome correlated with radiographic changes at operated and unoperated levels. This study demonstrates that radiographic changes are greater at operated than at unoperated levels and that some postoperative symptoms do correlate with these changes. Lumbar fusion should be considered in some patients who undergo decompressive laminectomy. The efficacy of and unequivocal indications for lumbar fusion can only be determined from randomized, prospective, controlled trials, however, and these studies have not yet been undertaken.

Age Factors↗
PubMed1993

Lumbar disk disease: pathophysiology, management and prevention.

Patients with symptomatic lumbar disk disease may present with back pain, referred leg pain, radicular leg pain, sensory changes and leg weakness. Because neurologic deficits are commonly localized to the L5 or S1 nerve roots, evaluation of patients with such symptoms should focus on these dermatomes and muscle groups. Myelography, computed tomography, postmyelogram computed tomography and magnetic resonance imaging are the most valuable diagnostic studies. Initial management consists of physical therapy and reduced activity, followed by gradually increasing mobilization and exercise. Conservative treatment is effective for most patients. Surgical treatment is reserved for patients who have failed to improve with conservative therapy or those who present with a profound neurologic deficit. Prevention of recurrent symptoms centers on patient education and reassurance. A program of weight control, regular exercise and posture correction may reduce the frequency and severity of recurrent disk herniation and pain.

Humans↗
PubMed1992

Caspar plate fixation for the treatment of complex hangman's fractures.

This report details our recent experience with the surgical treatment of complex hangman's fractures after failure of closed reduction and immobilization in external orthosis. We have successfully treated hangman's fractures in 5 patients with anterior Caspar plate stabilization and C2-C3 interbody fusion. The specific anatomical features of these fractures were complex, rendering the spines of the patients highly unstable. The patients were considered surgical candidates when reduction could not be achieved or maintained with axial traction or halo immobilization. Each patient underwent anterior C2-C3 interbody bone fusion and Caspar plating from C2 to C3. All patients achieved adequate intraoperative reduction and were immobilized postoperatively with a halo vest. The follow-up period ranged from 3 to 28 months and provided a 100% fusion rate with no complications related to plating or nonunion. Our initial experience indicates that anterior C2-C3 interbody bone fusion and Caspar plate fixation is a suitable treatment option for patients with complex hangman's fractures who are not successfully managed nonoperatively.

Adolescent↗
PubMed1988

Histology and angiography in a bifurcation aneurysm model.

Laser-sealed arteriotomy has recently been shown to produce a reliable saccular aneurysm model. By applying this method to the rat abdominal aorta and performing serial angiography, the behavior of this aneurysm model at an arterial bifurcation has been studied for the first time. Three days after laser-sealed arteriotomy, no aneurysms were found, but in animals studied 7, 14, 21, and 28 days after laser-sealed arteriotomy, a 100% (17/17) aneurysm formation rate was achieved. Serial angiography did not demonstrate significant changes in size when performed at 2-week intervals, but angiography significantly underestimated true aneurysm size (p less than 0.001) as a function of increasing aneurysm diameter (p less than 0.001). By light-microscopic analysis, these aneurysms were similar to human cerebral saccular aneurysms. This saccular aneurysm model could be used to study various surgical and interventional radiology techniques in experimental animals.

Angiography↗