SEARCH · PubMed Health

Results for “COMPRESSION”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources

PubMed2005

Treating osteoporotic and neoplastic vertebral compression fractures with vertebroplasty and kyphoplasty.

BACKGROUND: Compression fractures are common in patients with osteoporosis and cancer. In particular, vertebral compression fractures are crippling, and pose an additional risk of cord compression. Although a number of nonmedical options such as bracing and exercise programs may help these patients, the combination of constant, severe pain and spinal instability was until recently almost invariably synonymous with painful gradual deterioration and a poor quality of life. Vertebroplasty, and more recently kyphoplasty, are minimally invasive procedures that aim at limiting or reversing painful collapse of the vertebrae, while providing stability to the treated segment of the spine. As these new options are highly effective and involve minimal risk, it is important that physicians be familiar with them. OBJECTIVE: This paper reviews the demographics of vertebral compression fractures, both osteoporotic and neoplastic, the technical aspects of vertebroplasty and kyphoplasty, and current results and outcomes. RESULTS: Pain relief rates in excess of 90% have been reported with both vertebroplasty and kyphoplasty in patients with vertebral compression fractures. Procedural complication rates should be very low, in the 1%-2% range at most with proper technique. CONCLUSIONS: Until the advent of vertebroplasty, almost no effective therapeutic option could be offered to patients suffering from neoplastic or osteoporotic vertebral compression fractures, which are relatively common and often crippling. The technical feasibility of these procedures is high, the risk low, and the effectiveness high. Therefore, it is important that physicians consider vertebroplasty and kyphoplasty as viable and strong options.

Fractures, Compression↗

PubMed1990

Neuropathological changes and neurological function after spinal cord compression in the rat.

As part of a series of experimental investigations of the effects of various pharmacological agents on the outcome of compressive spinal cord trauma in the rat, the time course of the cell changes in the cord at the site of and distal to the compression was studied at the light microscopic level. The degree of compression used with the present model results in a transient paraparesis that recovers almost completely over a period of 3 weeks as judged by the inclined plane technique. The most significant morphological findings were as follows. Initially (1 and 24 h after the impact) there was pronounced swelling and hemorrhage at the compression site, chiefly in the gray matter of the cord. On day 4 there was severe necrosis in the same region, with numerous macrophages and leukocytes. Rats killed after 21 days showed either minor residual signs of necrosis or essentially normal tissue architecture. Surprisingly, necrosis with delayed onset also developed in the dorsal columns, involving the pyramidal tracts. This necrosis was detected in animals killed after 9 and 21 days but not in those observed after 4 days or earlier. The longitudinal tracts of the white matter showed reduced staining in paraffin sections of the compression site. Epon sections revealed splits in the myelin sheaths and enlarged periaxonal spaces as early as 1 h after the impact. The alterations in the longitudinal tracts persisted throughout the 21-day observation period and extended down to L2-L4. There was gradual functional recovery, documented by the inclined plane test. Preinjury values were almost reached on day 21, although the cord still showed some morphological damage. In individual animals, no relation was found between degree of function as tested by inclined plane and extent of morphologic injury. Additional functional and morphological methods obviously are needed in future investigations of the effects of treatments on the outcome of compressive spinal cord injury.

Animals↗

PubMed2000

Eccentric compression of the spinal canal causing dominantly contralateral-side symptoms.

In this retrospective study, five patients are described in whom the dural sac at the thoracic and lumbar spine was compressed by a herniated disk or stenosis, located eccentrically in the spinal canal. In all of them, the symptoms or neurologic findings were dominantly in the limb contralateral to the side of compression. All five patients were operated on and the compressing disk or lamina was removed, resulting in immediate improvement of symptoms. In only one of the patients was the compression at the common level of L4-L5. In the remaining four patients, compression was at the low thoracic or upper lumbar spine. With the exception of one patient, the area of canal compression was greater than 50%.

Adult↗

PubMed1987

Experimental neoplastic spinal cord compression: evoked potentials, edema, prostaglandins, and light and electron microscopy.

Spinal cord compression was induced in Fischer rats by percutaneous inoculation of 10(6) cells of malignant fibrous histiocytoma anterior to the T13 vertebral body. Paraplegia and incontinence occurred in all animals after 14-27 days (median, 23 +/- 3.0 days). Autonomic dysfunction and a measurable increase in tumor volume were documented with the use of computer tomography. The tumor penetrated the vertebral bone, invaded the epidural space, and gradually compressed the lumbar spinal segments. Electron-microscopic examination revealed dilated intermyelin spaces containing exuded homogenous material and extravasated leukocytes and erythrocytes. Myelin breakdown was accompanied by the presence of lipid-laden macrophages. Sequential recording of somatosensory evoked potentials (SEP) revealed a progressive increase in the latency of the cervical responses, which preceded the onset of clinical signs. In the presence of paraplegia, spinal cord conductivity was abolished. The levels of the prostaglandins TXB2, 6-keto-PGF1 alpha, and PGE2 were measured in the compressed and remote spinal cord segments during the presymptomatic and symptomatic periods. Only PGE2 was significantly elevated (P less than 0.001) in the paraplegic rats, all along the spinal cord segments. A significant increase in water content was measured in the compressed lumbar segments in the presymptomatic period, and when paralysis set in it was increased in the adjacent low thoracic area as well. Tissue specific gravity was significantly increased only in paraplegic rats in the compressed (P less than 0.01) and the adjacent low thoracic areas (P less than 0.05) but no significant change occurred during the presymptomatic period. Multiple mechanisms play a role in the pathogenesis of neurologic symptoms in neoplastic spinal cord compression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Neuropeptide changes in compressed spinal nerve roots.

STUDY DESIGN: Compression-induced changes in the concentration of substance P and VIP (vasoactive intestinal polypeptide), in spinal nerve roots and dorsal root ganglia were studied in an experimental nerve root compression model in pigs. OBJECTIVES: To analyze by radioimmunoassay the concentration of the neuropeptides substance P and VIP in a model for experimental chronic nerve root compression. SUMMARY OF BACKGROUND DATA: Neuropeptides such as substance P and VIP seem to be involved in the transmission of pain and changes in the levels of these neuropeptides have been described in models where peripheral or spinal nerve injury was induced. METHODS: An ameroid constrictor was applied on a spinal nerve root just cranial to the dorsal root ganglion. The inner diameter of this constrictor is gradually reduced. After 1 or 4 weeks, tissue samples were taken from the nerve root cranial to the constrictor and from the dorsal root ganglion for measurement of substance P and VIP concentrations. RESULTS: There was a statistically significant increase in substance P concentrations in the compressed dorsal root ganglia when compared to the noncompressed dorsal root ganglia at both 1 and 4 weeks. Substance P concentration was also significantly increased in the nerve root after 1 but not after 4 weeks. The VIP levels were not significantly changed in either tissue. CONCLUSIONS: The results of the study indicates an increase in substance P levels in the dorsal root ganglion (after 1 and 4 weeks) and in the nerve root (after 1 week) in a model for chronic nerve root compression in pigs. There were no significant differences in the VIP concentrations. The study thus indicates that changes in substance P are related to experimental chronic nerve root compression.

Animals↗

PubMed1995

Can we distinguish between benign versus malignant compression fractures of the spine by magnetic resonance imaging?

STUDY DESIGN: The authors investigate the usefulness of magnetic resonance imaging in differentiating benign versus malignant compression fractures by reviewing patients and a fracture model in a canine model. OBJECTIVES: To determine the sensitivity and specificity of magnetic resonance imaging in differentiating benign versus malignant compression fractures of the spine and to obtain distinguishing features in magnetic resonance imaging. SUMMARY OF BACKGROUND DATA: The differentiation between benign and abnormal compression fractures of the thoracolumbar spine has important implications regarding patient treatment and prognosis. Plain radiographs, bone scans, and computed tomography are not accurate imaging modalities for this purpose. METHODS: Magnetic resonance imaging scans of 22 patients with confirmed lesions of the thoracolumbar spine were studied. There were 11 malignant and 11 benign lesions. Two experienced neuroradiologists blindly reviewed the magnetic resonance imaging scans and determined benign or malignant lesions. A canine study was performed to simulate a compression fracture model with a vertebral osteotomy in two dogs, and serial contrast-enhanced magnetic resonance imaging scans were performed 15, 30, 60 and 90 days after surgery. RESULTS: The correct interpretation between two neuroradiologists was 77% and 95%. The combined sensitivity rate was 88.5%, and the specificity rate was 89.5%. Magnetic resonance imaging reliably distinguished benign versus malignant lesions based on the anatomic distribution and intensity of signal changes of bone and adjacent tissues, contrast enhancement characteristics, and changes over time. Only one malignant lesion was misinterpreted by both neuroradiologists as benign, whereas there was one additional missed malignant lesion and three misinterpreted benign lesions by one radiologist. In the canine study, signal changes and enhancement were found 60 days after surgery, but no signal changes or enhancement were noted on the scan 90 days after surgery. CONCLUSIONS: Magnetic resonance imaging scans can detect malignant vertebral lesions early, but acute healing compression fractures may mimic the findings of metastatic lesions. The use of contrast-enhanced magnetic resonance imaging scans and serial magnetic resonance imagings are helpful for additional differentiation between benign and malignant compression fractures. In addition to magnetic resonance imaging scans, other diagnostic tests and clinical findings should be correlated before biopsy or surgery of the suspected lesion.

Adult↗

PubMed1997

Histologic analysis of the lumbosacral nerve roots after compression in young and aged rabbits.

STUDY DESIGN: The histologic changes in the lumbosacral nerve roots of aged rabbits because of chronic (graded) and acute compression were compared with those seen in young rabbits. OBJECTIVES: To study differences in the process of recovery from nerve compression between the aged and the young. SUMMARY OF BACKGROUND DATA: Clinical findings often differ between nerve compressive lesions in young and aged patients. Little has been reported on the pathologic basis of this difference. METHODS: Forty-five Japanese white rabbits were used. The cauda equina and spinal nerve root were compressed with a device specifically designed for this purpose. Nerve compression was applied to the dura mater and nerve roots after partial laminectomy. The specimens were sampled at 1 month or 3 months after acute or graded nerve compression. RESULTS: An increase in small myelinated fibers, consistent with the process of regeneration, was observed by light microscopy; this difference was greater in the young group than in the aged group. Reactive degenerative changes, as seen by electron microscopy, were more often observed in the aged group than in the young group. CONCLUSIONS: These findings demonstrate the suppression of regeneration and the latent fragility of the aged neural tissue. This may explain the clinical findings observed in aged patients with degenerative lumbar lesions.

Age Factors↗

PubMed1999

The optimal radiologic method for assessing spinal canal compromise and cord compression in patients with cervical spinal cord injury. Part I: An evidence-based analysis of the published literature.

STUDY DESIGN: An evidence-based analysis of published radiologic criteria for assessing spinal canal compromise and cord compression in patients with acute cervical spinal cord injury. OBJECTIVES: This study was conducted to determine whether literature-based guidelines could be established for accurate and objective assessment of spinal canal compromise and spinal cord compression after cervical spinal cord injury. SUMMARY OF BACKGROUND DATA: Before conducting multicenter trials to determine the efficacy of surgical decompression in cervical spinal cord injury, reliable and objective radiographic criteria to define and quantify spinal cord compression must be established. METHODS: A computer-based search of the published English, German, and French language literature from 1966 through 1997 was performed using MEDLINE (U.S. National Library of Medicine database) to identify studies in which cervical spinal canal and cord size were radiographically assessed in a quantitative manner. Thirty-seven references were included for critical analysis. RESULTS: Most studies dealt with degenerative disease, spondylosis, and stenosis; only 13 included patients with acute cervical spinal cord injury. Standard lateral radiographs were the most frequent imaging method used (23 studies). T1- and T2-weighted magnetic resonance imaging were used to assess spinal cord compression in only 7 and 4 studies, respectively. Spinal cord size or compression were not precisely measured in any of the cervical trauma studies. Interobserver or intraobserver reliability of the radiologic measurements was assessed in only 7 (19%) of the 37 studies. CONCLUSIONS: To date, there are few quantitative, reliable radiologic outcome measures for assessing spinal canal compromise or cord compression in patients with acute cervical spinal cord injury.

Cervical Vertebrae↗

PubMed1999

Surface strain distribution on thoracic and lumbar vertebrae under axial compression. The role in burst fractures.

STUDY DESIGN: The surface strain distribution on the thoracic and lumbar vertebrae during axial compressive loading was examined. OBJECTIVES: To examine the general mechanical behavior of the thoracic and lumbar vertebrae to evaluate their role in burst fractures. SUMMARY OF BACKGROUND DATA: Burst fractures are generally characterized by injury to the middle column and fracturing of the superior endplate. However, results in previous biomechanical investigations have not shown how these fractures are initiated during compression. METHODS: Twenty-one thoracic and lumbar vertebrae (5 T10, 10 L1, and 6 L4) with upper and lower vertebrae were studied. Three-axis rosette strain gauges were cemented to 11 sites on the vertebral surface. An axial compressive load was applied, and the strain was measured in each specimen. The strain recorded by each rosette gauge was converted into a tensile, compressive, and shear component. RESULTS: The highest tensile and compressive strain was recorded at the base of the pedicle. Shear strain in the vertebral body was significantly higher than that in the lamina at all three spinal levels. At L1 and L4, the tensile strain at the superior vertebral rim was higher than that at the inferior rim. CONCLUSIONS: The high tensile and compressive strains found at the base of the pedicle of T10, L1, and L4 indicate that the base of the pedicle is the site of fracture initiation. The higher tensile strain at the superior vertebral rim of L1 and L4 supports the clinical observation of the thoracolumbar burst fractures.

Aged↗

PubMed2000

Effects of core body temperature on changes in spinal somatosensory-evoked potential in acute spinal cord compression injury: an experimental study in the rat.

STUDY DESIGN: Acute spinal cord injury was induced by a clip compression model in rats to approximate spinal cord injury encountered in spinal surgery. Spinal somatosensory-evoked potential neuromonitoring was used to study the electrophysiologic change. OBJECTIVES: To compare and correlate changes in evoked potential after acute compression at different core temperatures with postoperative neurologic function and histologic change, to evaluate current intraoperative neuromonitoring warning criteria for neural damage, and to confirm the protective effect of hypothermia in acute spinal cord compression injury by electrophysiologic, histologic, and clinical observation. SUMMARY OF BACKGROUND DATA: With the increase in aggressive correction of spinal deformities, and the invasiveness of surgical instruments, the incidence of neurologic complication appears to have increased despite the availability of sensitive intraoperative neuromonitoring techniques designed to alert surgeons to impending neural damage. Many reasons have been given for the frequent failures of neuromonitoring, but the influence of temperature-a very important and frequently encountered factor-on evoked potential has not been well documented. Specifically, decrease in amplitude and elongation of latency seem not to have been sufficiently taken into account when intraoperative neuromonitoring levels were interpreted and when acceptable intraoperative warning criteria were determined. METHODS: Experimental acute spinal cord injury was induced in rats by clip compression for two different intervals and at three different core temperatures. Spinal somatosensory-evoked potential, elicited by stimulating the median nerve and recorded from the cervical interspinous C2-C3, was monitored immediately before and after compression, and at 15-minute intervals for 1 hour. RESULTS: Spinal somatosensory-evoked potential change is almost parallel to temperature-based amplitude reduction and latency elongation. Significant neurologic damage induced by acute compression of the cervical spinal cord produced a degree of effect on the amplitude of spinal somatosensory-evoked potential in normothermic conditions that differed from the effect in moderately hypothermic conditions. Using the same electromonitoring criteria,moderately hypothermic groups showed a significantly higher false-negative rate statistically (35%) than normothermic groups (10%). CONCLUSIONS: Systemic cooling may protect against the detrimental effects of aggressive spinal surgical procedures. There is still not enough published information available to establish statistically and ethically acceptable intraoperative neuromonitoring warning and intervention criteria conclusively. Therefore, an urgent need exists for further investigation. Although a reduction of more than 50% in evoked potential still seems acceptable as an indicator of impending neural function loss, maintenance of more than 50% of baseline evoked potential is no guarantee of normal postoperative neural function, especially at lower than normal temperatures.

Acute Disease↗

PubMed2001

Correlation between operative outcomes of cervical compression myelopathy and mri of the spinal cord.

STUDY DESIGN: Magnetic resonance images of cervical compression myelopathy were retrospectively analyzed in comparison with surgical outcomes. OBJECTIVES: To investigate which magnetic resonance findings in patients with cervical compression myelopathy reflect the clinical symptoms and prognosis, and to determine the radiographic and clinical factors that correlate with the prognosis. SUMMARY OF BACKGROUND DATA: Signal intensity changes of the spinal cord on magnetic resonance imaging in chronic cervical myelopathy are thought to be indicative of the prognosis. However, the prognostic significance of signal intensity change remains controversial. METHODS: The participants in this study were 73 patients who underwent cervical expansive laminoplasty for cervical compression myelopathy. Their mean age was 64 years, and the mean postoperative follow-up period was 3.4 years. The pathologic conditions were cervical spondylotic myelopathy in 42 patients and ossification of the posterior longitudinal ligament in 31 patients. Magnetic resonance imaging (spin-echo sequence) was performed in all the patients. The transverse area of the spinal cord at the site of maximal compression was computed, and spinal cord signal intensity changes were evaluated before and after surgery. Three patterns of spinal cord signal intensity changes on T1-weighted sequences/T2-weighted sequences were detected as follows: normal/normal, normal/high-signal intensity changes, and low-signal/high-signal intensity changes. Surgical outcomes were compared among these three groups. The most useful combination of parameters for predicting prognosis was determined using a stepwise regression analysis. RESULTS: The findings showed 2 patients with normal/normal, 67 patients with normal/high-signal, and 4 patients with low-signal/high-signal change patterns before surgery. Regarding postoperative recovery, the preoperative low-signal/high-signal group was significantly inferior to the preoperative normal/high-signal group. There was no significant difference between the transverse area of the spinal cord at the site of maximal compression in the normal/high-signal group and the low-signal/high-signal group. A stepwise regression analysis showed that the best combination of surgical outcome predictors included age (correlation coefficient R = -0.348), preoperative signal pattern, and duration of symptoms (correlation coefficient R = -0.231). CONCLUSIONS: The low-signal intensity changes on T1-weighted sequences indicated a poor prognosis. The authors speculate that high-signal intensity changes on T2 weighted images include a broad spectrum of compressive myelomalacic pathologies and reflect a broad spectrum of spinal cord recuperative potentials. Predictors of surgical outcomes are preoperative signal intensity change pattern of the spinal cord on radiologic evaluations, age at the time of surgery, and chronicity of the disease.

Adult↗

PubMed2002

Detection of lumbosacral nerve root compression with a novel composite nerve conduction measurement.

STUDY DESIGN: Multivariate logistic regression techniques were used to develop a composite nerve conduction measurement that detects lumbosacral (L5, S1, or both) nerve root compression. OBJECTIVES: To evaluate the diagnostic efficacy of a composite nerve conduction measurement for detection of lumbosacral nerve root compression. SUMMARY OF BACKGROUND DATA: Nerve root involvement is characterized by clinical abnormalities and confirmed by radiologic and electrodiagnostic studies. Imaging studies visualize structural abnormalities; however, they are associated with high false-positive rates. Electrodiagnostic methods assess the physiologic integrity of the nerve roots. One form of electrodiagnostic testing, nerve conduction studies, is widely used for evaluation of musculoskeletal and neuromuscular complaints. Although similar clinical value is expected for the evaluation of nerve root compromise, prior applications of nerve conduction studies have yielded widely varying results. METHODS: Two groups of subjects were compared. The L5-S1 compression group was composed of 25 patients with magnetic resonance imaging-confirmed lumbosacral (L5, S1, or both) nerve root compression and symptoms in the appropriate segmental distribution. The majority of subjects (22) had at least one of the following findings on physical examination: positive straight-leg raise test, diminished ankle reflexes, sensory loss, or weakness. The control group consisted of 35 asymptomatic individuals with no history of radiculopathy or potentially confounding neuropathology. The posterior tibial and deep peroneal nerves were evaluated bilaterally in all study subjects using standard nerve conduction procedures, which consisted of the measurement of distal motor latencies and F-wave latencies that assess nerve root pathophysiology. A composite nerve conduction measurement was determined using multivariate logistic regression analysis. The efficacy of the composite measurement was assessed by receiver operating characteristic curve analysis and by the diagnostic sensitivity and specificity. RESULTS: Five F-wave latency parameters (peroneal mean F-wave latency, odds ratio = 0.42; peroneal seventh F-wave latency decile, odds ratio = 2.71; tibial mean F-wave latency, odds ratio = 8.90; tibial first F-wave latency decile, odds ratio = 0.47; tibial maximum F-wave latency, odds ratio = 0.44) were found to be predictive of nerve root compression. A composite nerve conduction measurement, NC composite, constructed from these five parameters (NC composite = exp(phi)/(1 + exp(phi)), phi = -31.2 + 1.0 * Per7 Decile - 0.88 * PerMean + 2.2 * TibMean - 0.88 * Tib1 Decile - 0.83 * TibMax) yielded an area under the receiver operating characteristic curve of 0.91. At a threshold of 0.20, NC composite had a diagnostic specificity of 84.3% and a sensitivity of 83.3%. CONCLUSION: This preliminary study suggests that a novel composite nerve conduction measurement, based on F-wave latency parameters, may be highly effective at detecting magnetic resonance imaging-confirmed lumbosacral nerve root compression. Because these measurements provide objective evidence of functional nerve root compromise and are noninvasive, they may be of diagnostic value to clinicians evaluating patients presenting with low back and leg pain.

Adult↗

PubMed2005

Understanding the biology of compressive neuropathies.

Compressive neuropathies are highly prevalent, debilitating conditions with variable functional recovery after surgical decompression. Chronic nerve compression injury induces concurrent Schwann cell proliferation and apoptosis in the early stages of the disorder, independent of axonal injury. These proliferating Schwann cells locally demyelinate and remyelinate in the region of injury. Furthermore, Schwann cells upregulate vascular endothelial growth factor secondary to chronic nerve compression injury and induce neovascularization to facilitate the recruitment of macrophages. In contrast to Wallerian degeneration, macrophage recruitment occurs gradually with chronic nerve compression injury and continues for a longer time. Schwann cells change their gene and protein expression in response to mechanical stimuli as shear stress decreases the expression of myelin associated glycoprotein and myelin basic protein mRNA and protein for in vitro promyelinating Schwann cells. The local down-regulation of myelin associated glycoprotein in the region of compression injury creates an environment allowing axonal sprouting that may be reversed with intraneural injections of purified myelin associated glycoprotein. These studies suggest that while the reciprocal relationship between neurons and glial cells is maintained, chronic nerve compression injury is a Schwann cell-mediated disease.

Awards and Prizes↗

PubMed2004

Presymptomatic spondylotic cervical cord compression.

STUDY DESIGN: We conducted a cohort study of clinically asymptomatic spondylotic cervical cord compression cases with the primary end point of the development of clinical signs of cervical myelopathy. OBJECTIVES: To investigate whether various demographic, clinical, radiologic, and electrophysiological parameters could predict progression from clinically asymptomatic (preclinical) spondylotic cervical cord compression to symptomatic myelopathy. SUMMARY OF BACKGROUND DATA: The data available on the prediction of the outcome in surgical and conservative treatment of spondylotic cervical myelopathy are controversial. Little is known about the clinical natural history of asymptomatic magnetic resonance image-detected spondylotic cervical cord compression and/or changes of signal intensity. METHODS: A group of 66 patients (32 women, 34 men, median age 50 years) with magnetic resonance signs of spondylotic cervical cord compression but without clear clinical signs of myelopathy was followed prospectively for at least 2 years (range, 2-8 years; median, 4 years). Various demographic, clinical, imaging, and electrophysiological parameters were correlated with clinical outcome. RESULTS: Clinical signs of myelopathy during the follow-up period were detected in 13 patients (19.7%). The only variables significantly associated with the development of clinically symptomatic spondylotic cervical myelopathy (SCM) were the presence of symptomatic cervical radiculopathy, electromyographic signs of anterior horn lesion, and abnormal somatosensory-evoked potentials. A multivariate logistic regression model based on these variables correctly classified 90% of cases into 2 subgroups: a group with development of symptomatic SCM and that without clinical manifestation of subclinical cervical cord compression. CONCLUSIONS: Electrophysiological abnormalities together with clinical signs of cervical radiculopathy could predict clinical manifestation of preclinical spondylotic cervical cord compression.

Adult↗

PubMed2006

Targeted retrograde transfection of adenovirus vector carrying brain-derived neurotrophic factor gene prevents loss of mouse (twy/twy) anterior horn neurons in vivo sustaining mechanical compression.

STUDY DESIGN: Immunohistochemical analysis after adenovirus (AdV)-mediated BDNF gene transfer in and around the area of mechanical compression in the cervical spinal cord of the hyperostotic mouse (twy/twy). OBJECTIVE: To investigate the neuroprotective effect of targeted AdV-BDNF gene transfection in the twy mouse with spontaneous chronic compression of the spinal cord motoneurons. SUMMARY OF BACKGROUND DATA: Several studies reported the neuroprotective effects of neurotrophins on injured spinal cord. However, no report has described the effect of targeted retrograde neurotrophic gene delivery on motoneuron survival in chronic compression lesions of the cervical spinal cord resembling lesions of myelopathy. METHODS: LacZ marker gene using adenoviral vector (AdV-LacZ) was used to evaluate retrograde delivery from the sternomastoid muscle in adult twy mice (16-week-old) and (control). Four weeks after the AdV-LacZ or AdV-BDNF injection, the compressed cervical spinal cord was removed en bloc for immunohistologic investigation of b-galactosidase activity and immunoreactivity and immunoblot analyses of BDNF. The number of anterior horn neurons was counted using Nissl, ChAT and AChE staining. RESULTS: Spinal accessory motoneurons between C1 and C3 segments were successfully transfected by AdV-LacZ in both twy and ICR mice after targeted intramuscular injection. Immunoreactivity to BDNF was significantly stronger in AdV-BDNF-gene transfected twy mice than in AdV-LacZ-gene transfected mice. At the cord level showing the maximum compression in AdV-BDNF-transfected twy mice, the number of anterior horn neurons was sinificantly higher in the topographic neuronal cell counting of Nissl-, ChAT-, and AChE-stained samples than in AdV-LacZ-injected twy mice. CONCLUSION: Targeted AdV-BDNF-gene delivery significantly increased Nissl-stained anterior horn neurons and enhanced cholinergic enzyme activities in the twy. Our results suggest that targeted retrograde AdV-BDNF-gene in vivo delivery may enhance neuronal survival even under chronic mechanical compression.

Adenoviridae↗

PubMed2006

Posterior spinal cord compression: outcome and results.

STUDY DESIGN: Prospective, comparative study of neurologic outcome in patients with posterior extradural cord compression. OBJECTIVE: To compare the results of surgical decompression in patients presenting with neurologic deficit due to posterior element tuberculosis with those due to other causes. SUMMARY OF BACKGROUND DATA: Posterior cord compression is a relatively uncommon entity with not much literature published on it. METHODS: Over a period of 5 years, 14 patients with extradural posterior cord compression with neurologic deficit were divided into two etiologic groups: 9 patients had Koch's and 5 had other pathologies. All these cases were surgically decompressed posteriorly and the results compared. RESULTS: While results of surgery in patients with Koch's were good, with 7 of the 9 patients showing full recovery, outcome in patients with compression due to other causes (tumor/pyogenic infection) was not very satisfactory even after adequate mechanical decompression, with 3 of the 5 cases remaining paraplegic even after surgery. CONCLUSION: Posterior cord compression due to nontuberculous causes frequently mimics the picture of Koch's both clinically and radiologically. Prognosis of surgical decompression is good in tuberculous compression but not in other cases.

Abscess↗

PubMed2005

Compound image compression for real-time computer screen image transmission.

We present a compound image compression algorithm for real-time applications of computer screen image transmission. It is called shape primitive extraction and coding (SPEC). Real-time image transmission requires that the compression algorithm should not only achieve high compression ratio, but also have low complexity and provide excellent visual quality. SPEC first segments a compound image into text/graphics pixels and pictorial pixels, and then compresses the text/graphics pixels with a new lossless coding algorithm and the pictorial pixels with the standard lossy JPEG, respectively. The segmentation first classifies image blocks into picture and text/graphics blocks by thresholding the number of colors of each block, then extracts shape primitives of text/graphics from picture blocks. Dynamic color palette that tracks recent text/graphics colors is used to separate small shape primitives of text/graphics from pictorial pixels. Shape primitives are also extracted from text/graphics blocks. All shape primitives from both block types are losslessly compressed by using a combined shape-based and palette-based coding algorithm. Then, the losslessly coded bitstream is fed into a LZW coder. Experimental results show that the SPEC has very low complexity and provides visually lossless quality while keeping competitive compression ratios.

Algorithms↗

PubMed2006

Video compression using spatiotemporal regularity flow.

We propose a new framework in wavelet video coding to improve the compression rate by exploiting the spatiotemporal regularity of the data. A sequence of images creates a spatiotemporal volume. This volume is said to be regular along the directions in which the pixels vary the least, hence the entropy is the lowest. The wavelet decomposition of regularized data results in a fewer number of significant coefficients, thus yielding a higher compression rate. The directions of regularity of an image sequence depend on both its motion content and spatial structure. We propose the representation of these directions by a 3-D vector field, which we refer to as the spatiotemporal regularity flow (SPREF). SPREF uses splines to approximate the directions of regularity. The compactness of the spline representation results in a low storage overhead for SPREF, which is a desired property in compression applications. Once SPREF directions are known, they can be converted into actual paths along which the data is regular. Directional decomposition of the data along these paths can be further improved by using a special class of wavelet basis called the 3-D orthonormal bandelet basis. SPREF -based video compression not only removes the temporal redundancy, but it also compensates for the spatial redundancy. Our experiments on several standard video sequences demonstrate that the proposed method results in higher compression rates as compared to the standard wavelet based compression.

Algorithms↗