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 28,634 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The importance of nasal airflow resistance in the pathogenesis of obstructive sleep apnea syndrome (OSAS) remains contentious. We performed formal nocturnal polysomnography (PSG) on OSAS patients under conditions of baseline and reduced nasal resistance to answer two main questions. First, to what degree does baseline nasal airflow resistance influence upper airway collapse in OSAS patients? Second, in what proportion of the OSAS population is baseline nasal resistance contributing to the pathogenesis of upper airway collapse? Our study group consisted of 10 patients with a wide range of OSAS severity. Six of these patients had symptoms and clinical evidence of chronic nasal obstruction which, in some, was associated with markedly elevated nasal resistance. A placebo (normal saline) was instilled in the nose of each patient on the night of baseline data collection. On the treatment night of the study, nasal resistance was reduced by application of topical vasoconstrictor and insertion of vestibular stents designed to dilate the area of the nasal valve. Posterior rhinomanometry was used to measure resistance to nasal airflow immediately before and after each PSG study. Although treatment was associated with a subjective improvement in sleep quality and mean drop in nasal resistance of 73% (P less than 0.001), there was no significant improvement in sleep architecture, nocturnal oxygenation, or the amount of apnea experienced by patients. The most significant improvement was a reduced number of arousals/hour from 52.4 +/- 12.4 on placebo to 43.7 +/- 10.2 on treatment (P less than 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The importance of nasal resistance in obstructive sleep apnea syndrome. 140 70

The treatment of syringomyelia includes many surgical options. We report a retrospective study of 65 patients with cavitary lesions of the spinal cord in whom the results of magnetic resonance imaging were used to develop specific treatment strategies. Intramedullary cavities were classified into three general types: 1) communicating syrinxes, which occurred with hydrocephalus and were anatomically continuous with the 4th ventricle (9 patients); 2) noncommunicating syrinxes, which were separated from the 4th ventricle by a syrinx-free segment of spinal cord (42 patients); and 3) atrophic syrinxes, which occurred with myelomalacia (14 patients). Noncommunicating syrinxes were further subdivided according to type: Chiari II malformations with hydrocephalus (5 patients), Chiari I malformations without hydrocephalus (11 patients), extramedullary compressive lesions (12 patients), spinal cord trauma (6 patients), intramedullary tumors and infections (6 patients), and multiple sclerosis (2 patients). Of the 65 patients, 39 underwent surgical treatment for progressive symptoms. Syrinxes occurring with hydrocephalus were treated empirically with a ventriculoperitoneal shunt. Excellent results were achieved in 7 of 7 patients with communicating syrinxes and in all 5 patients with Chiari II malformations. Two approaches were used in the treatment of syrinxes occurring with Chiari I malformations: Posterior fossa decompression improved symptoms but did not reduce syrinx size in 2 of 3 patients. In the third patient and in 3 patients who were not treated with decompression, shunting from the syrinx to the cerebellopontine angle cistern collapsed the cavity and resolved symptoms over the interval of follow-up (average follow-up, 1.5 years). Excision of extramedullary obstructions at the rostral end of noncommunicating syrinxes resulted in collapse or disappearance of the cavity in 6 of 7 patients. The remaining patient was treated effectively by a syringocisternal shunt. In all 4 patients with posttraumatic syringomyelia, good results were achieved by a spinal or syringocisternal shunt. Syrinxes associated with intramedullary masses were managed by biopsy or excision of the causal lesion and appropriate adjunctive therapy (6 patients). Patients with atrophic syrinxes were not operated upon except to relieve symptoms referrable to the causal lesion (4 patients). Recurrent syrinxes were not encountered in the 35 surviving patients over an average follow-up of 2.5 years. It is concluded that syringomyelia is a complex pathological disorder with several mechanisms of pathogenesis that requires a number of different treatment strategies.
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PMID:Surgical treatment of syringomyelia based on magnetic resonance imaging criteria. 841 93

It is important to remember that ESCC is a complication of systemic malignancy and usually denotes disseminated disease with poor survival rates. Early diagnosis is crucial. The initial symptom is almost always back pain, which is local, radicular, or both. Following neurologic examination and radiography, MRI scanning or myelography/CT is immediately indicated if radiculopathy or myelopathy is present or if the radiographs of the spine are abnormal. In cancer patients with local back pain and normal findings on neurologic examination and radiography of the spine, there is still a probability of 0.1 of significant ESCC. Therefore, urgent CT/MRI scanning is justified. At present, the best treatment for ESCC remains unknown. In the majority of patients, radiotherapy is the most readily available and appropriate option because it is equal in effect to posterior decompressive laminectomy in both radiosensitive and radioresistant tumors. In patients with posterior epidural disease without tissue diagnosis, laminectomy with or without stabilization should be performed. Posterior decompressive laminectomy alone is contraindicated in patients with vertebral collapse. In selected instances of anterior epidural compression without tissue diagnosis or after failure of radiotherapy, an anterior surgical approach or synchronous vertebral decompression with posterior stabilization may be indicated. In the future, after appropriate clinical trials, vertebral body resection may be the optimal approach in de novo selected patients with ESCC with radioresistant tumors and limited systemic spread of the disease.
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PMID:Metastatic epidural spinal cord compression. 175 28

Membranes from posterior and anterior thirds of the chick optic tectum were added to explants from nasal and temporal retina. Posterior membranes, and to a lesser extent anterior membranes, cause temporal growth cones to collapse and their axonal processes to retract. Neither tectal source has an effect on nasal growth cones. We interpret these results to mean that there is a tectal activity, stronger in the posterior than the anterior region of the tectum, which helps guide growth cones during the development of the retinotectal map. We believe that in vivo this activity helps to steer temporal growth cones away from the posterior tectum. Nasal growth cones, which must map to the posterior tectum, are resistant to it. In vitro, when posterior membranes contact temporal growth cones over their surface, filopodia and lamellipodia withdraw rapidly. This leads to loss of contact between the growth cone and the substrate, followed by collapse.
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PMID:Axonal guidance in the chick visual system: posterior tectal membranes induce collapse of growth cones from the temporal retina. 231 May 73

We are reporting our experience in 23 patients with tumors of the thoracic or lumbar vertebrae treated via surgical anterior decompression and stabilization. Seventeen patients had metastatic disease and were treated with vertebral body resection followed by stabilization with anterior polymethylmethacrylate and threaded Harrington rods with sacral distraction hooks. Six patients had primary tumors and, following tumor resection and partial vertebral body resection, had autogenous bone graft struts placed anteriorly as well as posterior instrumentation. Posterior instrumentation was transpedicular one level above and below in the lumbar spine, and segmental hooks and rods three levels above and below in the thoracic spine. Nineteen patients presented with severe unremitting pain, and 16 had neurologic deficits, including 7 who were unable to ambulate. Radiation therapy was used as an additional treatment and routinely begun 2 weeks postoperatively. All patients survived the surgery, and none had neurologic deterioration immediately postoperatively. Eight patients had died at the time of review. The mean survival was 14 months and ranged from 6 to 38 months. Of the surviving patients, follow-up ranged from 24 to 40 months with an average follow-up of 30 months. Pain relief was excellent in all but two patients (93%). Motor recovery occurred to some extent in all patients, and only one remained nonambulatory. Complications were minor in three patients (13%) and major in one (4%). Tumor recurrence with neurologic deterioration occurred in two patients. We are very encouraged by these results, and we recommend that patients with tumors of the vertebral body with neurologic deficit or severe unremitting pain be studied with MRI and/or myelography and CT. The patients with gross vertebral destruction and greater than 50% collapse of the vertebral body, those in need of a tissue diagnosis, or those with major neurologic deficit can be effectively treated by anterior decompression and stabilization.
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PMID:Tumors of the thoracic and lumbar spine: surgical treatment via the anterior approach. 252 70

The posterior Bite Collapse is a sequelae of advanced break down. The presence of periodontal inflammation and loss of osseous support can induce teeth migration in a direction partially imposed by occlusal forces. Posterior Bite Collapse often causes mesial drifting of the posterior teeth and flaring of the anterior segments. It may be aggravated by early loss of teeth that are not replaced, by malocclusion or by a neuro muscular disorder.
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PMID:[Posterior bite collapse. 1. Etiology and diagnosis]. 263 88

Maxillary alveolar arch morphology was studied from birth to palate repair at the age of 19 months in 24 children with complete unilateral cleft lip and palate (UCLP) treated with passive orthopaedic plates (treated children). 18 children with the same defect, who received no orthopaedic treatment, served as controls. The surgical procedures and the age at lip and palate repair were similar. Maxillary alveolar arch morphology was described by 15 linear and five angular measurements. No significant difference was found in total alveolar crest length neither between the cleft and the non-cleft maxillae nor between the treated children and the controls. Anterior alveolar arch width was significantly larger in the treated children at lip repair and at palate repair. Posterior alveolar arch width was significantly larger in the treated children at lip repair only. There was no significant difference in alveolar cleft width between the treated children and the controls at lip or at palate repair. Palatal cleft width decreased significantly in the treated children only. Medial rotation of both the cleft and the non-cleft maxillae was observed in both groups. The main difference was the absence of arch collapse in the treated children. At palate repair the relationship between the two maxillae was more favourable in the treated children for the development of the occlusion. The occlusion of the mixed dentition will be subject of a subsequent follow-up.
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PMID:[The effect of passive plates on the arrangement of the alveolar arch segments in unilateral total cheilognathopalatoschisis]. 292 36

The diagnosis of scleral perforation of the globe following ocular trauma is often obvious on physical examination, but occult perforations occur frequently. In addition to locating intraorbital foreign bodies and associated facial bone fractures, computed tomography of the orbit can suggest an occult scleral rupture. Posterior collapse of the sclera causes flattening of the posterior contour of the globe, the "flat tire" sign. Other associated findings that are suggestive of scleral rupture are intraocular foreign body or gas, thickening of the sclera posteriorly, and a blood-vitreous fluid-fluid level.
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PMID:Value of computed tomography for the diagnosis of a ruptured eye. 688 40

Perioperative irradiation is often used with anterior decompression and vertebral interbody fusion for the treatment of spinal neoplasms, yet little is known regarding the healing potential of these grafts. This review of 25 patients with neoplasm who had anterior vertebrectomy, bone strut insertion, and perioperative irradiation was performed to look specifically for evidence of radiographic fusion as determined by plain radiographs, tomograms, or computed tomography reconstruction. Four of 25 patients (16%) were judged to have a pseudarthrosis. All four pseudarthrosis patients but only four of 21 fusion patients had 4000 cg or more of irradiation, a statistically significant difference. There was a trend for lumbar lesions to have a higher risk for nonunion. Concomitant posterior stabilization did not necessarily prevent pseudarthrosis. Two iliac strut grafts with a pseudoarthrosis developed late fracture and one went on to collapse into kyphosis. The pseudarthrosis rate of anterior vertebral strut grafts in the face of irradiation for tumor is relatively high, and late graft fracture can occur if pseudarthrosis develops. Probable risk factors include irradiation greater than 4000 cg and lumbar lesions. Posterior stabilization to protect the graft may be warranted in the highest-risk patients.
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PMID:The fate of anterior vertebral bone grafts in patients irradiated for neoplasm. 813 37

Topographic projections of the nervous system are essential to numerous brain functions. They arise during development as a result of encounters between projecting growth cones and particular target cells. Cellular localization of guidance cues can indicate the sequential processes involved in establishment of such topography. The map formed by retinal ganglion cells on their target nuclei has served widely as a model system to investigate mechanisms underlying the highly precise and stereotypic connectivity of the nervous system. To investigate cellular localization of guidance cues in the developing retinotectal system, a three-compartment chamber was created to delimit areas where cultured embryonic chick retinal ganglion axons and tectal cells encounter one another and guidance behavior could be readily assessed. Whereas explants from nasal retinae extended fibers across their natural target population, fibers from temporal regions of retinae failed to invade areas of growing posterior tectal cells. This preservation of relevant guidance information on living cell populations enabled an evaluation of retinal ganglion cell growth cone behavior after encounter with individual tectal cells. Posterior tectal neurons appeared selectively repulsive for temporal retinal ganglion cell growth cones, causing growth cone collapse and retraction. On the contrary, neuroepithelial cells from all regions of the tectum attenuated retinal ganglion axon extension, without inducing sudden retraction. Nasal growth cones traversed or tracked more often along neuroepithelial cells from their natural target area, potentially indicating a second set of guidance cues possibly localized to posterior glia. Together, these differential interactions suggest that development of retinotectal topography critically depends on cell-specific cues, which are distributed selectively on particular populations of target cells.
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PMID:Cellular localization of guidance cues in the establishment of retinotectal topography. 860 52


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