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PubMedDate not supplied

[Rhabdomyolysis and truncular sciatica. 2 cases studied by MRI].

We report two cases of acute rhabdomyolysis in pelvic girdle muscles with sciatic palsy secondary to compression of the sciatic nerve trunk, with clinical and MRI correlation. The diagnosis of rhabdomyolysis is based on clinical and biological data, but diagnosis of compression complications secondary to swelling of the muscles, especially the compression of nerve trunk, is done by imaging. T2 weighted images give a definite anatomical evaluation. They show enlarged high signal intensity muscles and anatomic relationship with the sciatic nerve from its emergence out of pelvis, giving a good correlation between rhabdomyolysis and the compressed nervous trunk. It helps for planning a possible surgical fasciotomy. However, MRI provides only morphological informations, but not differentiates edema from necrosis in involved muscles.

Acute Disease↗
PubMed1996

Wavelet compression of medical imagery.

Wavelet compression is a transform-based compression technique recently shown to provide diagnostic-quality images at compression ratios as great as 30:1. Based on a recently developed field of applied mathematics, wavelet compression has found success in compression applications from digital fingerprints to seismic data. The underlying strength of the method is attributable in large part to the efficient representation of image data by the wavelet transform. This efficient or sparse representation forms the basis for high-quality image compression by providing subsequent steps of the compression scheme with data likely to result in long runs of zero. These long runs of zero in turn compress very efficiently, allowing wavelet compression to deliver substantially better performance than existing Fourier-based methods. Although the lack of standardization has historically been an impediment to widespread adoption of wavelet compression, this situation may begin to change as the operational benefits of the technology become better known.

Diagnostic Imaging↗
PubMed1998

The value of somatosensory and motor evoked evoked potentials in pre-clinical spondylotic cervical cord compression.

Previous studies have yielded conflicting data concerning the value of evoked potential parameters in the assessment of clinical relevance of cervical cord compression in clinically "silent" cases. The aim of this study was to assess the value of somatosensory (SEP) and motor evoked potentials (MEP) in the evaluation and prediction of the clinical course, by means of a 2-year follow-up prospective electrophysiological and clinical study performed in patients with clinically "silent" spondylotic cervical cord compression. Thirty patients with MR signs of spondylotic cervical cord compression but without clinical signs of myelopathy were evaluated clinically and using SEPs and MEPs during a 2-year period. The results of the study showed that SEPs and MEPs documented subclinical involvement of cervical cord in 50% of patients with clinically "silent" spondylotic cervical cord compression. During the 2-year period clinical signs of cervical myelopathy were observed in one-third of patients with entry EP abnormality in comparison with no patients with normal EP tests. Combined SEPs and MEPs proved to be a valuable tool in the assessment of the functional relevance of subclinical spondylotic cervical cord compression. Normal EP findings predict a favourable 2-year clinical outcome.

Case-Control Studies↗
PubMed1997

Depth-dependent confined compression modulus of full-thickness bovine articular cartilage.

The objective of this study was to determine the equilibrium confined compression modulus of bovine articular cartilage as it varies with depth from the articular surface. Osteochondral samples were compressed by 8, 16, 24, and 32% of the cartilage thickness and allowed to equilibrate. Intratissue displacement within the cartilage was measured with use of fluorescently labeled chondrocyte nuclei as intrinsic, fiducial markers. Axial strain was then calculated in nine sequential 125 microns thick cartilage layers comprising the superficial 1,125 microns and in a 250 microns thick layer of cartilage adjacent to the cartilage-bone interface. Adjacent osteochondral cores were also tested in confined compression to determine the equilibrium stresses required to achieve the same levels of compression. Stress-strain data for each layer of each sample were fit to a finite deformation stress-strain relation to determine the equilibrium confined compression modulus in each tissue layer. The compressive modulus increased significantly with depth from the articular surface and ranged from 0.079 +/- 0.039 MPa in the superficial layer to 1.14 +/- 0.44 MPa in the ninth layer. The deepest layer 250 microns thick, had a modulus of 2.10 +/- 2.69 MPa. These moduli were markedly different from the apparent "homogeneous" modulus for full-thickness cartilage (0.38 +/- 0.12 MPa) and ranged from 21 to 560% of that value. The relatively low moduli and the compression-induced stiffening of the superficial layers suggest that these layers greatly affect the biomechanical behavior of cartilage, such as during confined compression testing. The delineation of the depth-dependent modulus provides a basis for detailed study of the relationship between the composition, structure, and function of cartilage in such processes as aging, repair, and degeneration.

Animals↗
PubMedDate not supplied

Skin tensile strength modulation by compressive garments in burn patients. A pilot study.

Compression therapy is frequently used to prevent hypertrophy of post-burn scars. This pilot study was performed in 6 patients to assess non-invasive changes induced in the tensile strength of the skin before any clinical improvement can be perceived. Assessments were performed using a computerized suction device delivering three 5 s cycles of 500 mbar depression. Measurements were made at one-month intervals for three months after initiating the garment compression therapy. Comparisons were made between the intact skin, the ungrafted and grafted post-burn scars and the graft donor sites. Data show that garment compression therapy alters the tensile strength in the skin of all test sites. The most reliable variations consist of an increase in both the extensibility and elasticity of the tissues submitted to traction.

Bandages↗
PubMed2006

Lipoma due to chronic intermittent compression as an occupational disease.

A total of 15 coppersmiths who do the job as a traditional profession in Kahramanmaras Province were retrospectively analyzed for revealing a possible relationship of lipoma formation and chronic compression, as the work characteristic related to mechanical pressure to the right thoracal and shoulder region. The workers were examined and their historical data were noted. Chronic compression sites in the patients were also evaluated by magnetic resonance imaging and ultrasonography. The ages were between 30 and 52 years. Body mass index ranged from 18.6 to 38.8. Five were operated for visible lipomatous masses at their injured sites. All of the specimens were reported as containing mature adipocytes. An increased subcutaneous fat thickness at the injured sides of the patients was seen when compared with the uninjured contralateral sides using ultrasonography. At the magnetic resonance images, no capsule intensity was observed in the lipomatose masses. Subcutaneous fat of injured right mammarial regions was thicker than the other contralateral sides in all of the cases. The most prominent lipomas were seen in obese workers, and strong evidence for chronic trauma and lipoma formation as an occupational disease was obtained from the study.

Adult↗
PubMed2003

A systematic review of pneumatic compression for treatment of chronic venous insufficiency and venous ulcers.

INTRODUCTION: As part of a reconsideration of coverage policy, the Centers for Medicare and Medicaid Services requested a systematic review of the evidence on the use of pneumatic compression devices in the home environment for treatment of chronic venous insufficiency (CVI) and venous ulcers. METHODS: Articles were found with a systematic literature search of MEDLINE, EMBASE, and AMED (Allied and Complementary Medicine) databases, hand searches of reference lists, and suggestions of experts. RESULTS: Eight trials that met the inclusion criteria, including several randomized control trials, were found. Most studies were small and may have been underpowered. However, several were well-designed randomized controlled trials. Three studies showed that the devices could alleviate symptoms of CVI. No studies directly measured whether the devices could prevent the occurrence of venous ulcers. Some studies on the treatment of venous ulcers did not show a benefit for pneumatic compression, but other studies showed a benefit for the devices in healing long-standing chronic ulcers that had not healed with other methods. No studies directly compared single-chamber and multiple-chamber devices or studied whether the effectiveness of the pump was dependent on types of treatment used concurrently with the pump. Few adverse events were reported in the trials. Patients generally expressed satisfaction with the pneumatic compression devices, and several studies reported higher compliance than with other compression methods. CONCLUSION: The available data cannot be relied on to inform the optimal choice of compression therapy or optimal protocol for patients with CVI or venous ulcers. Methodologically rigorous research designed to answer these questions would be useful for treatment decisions. The Centers for Medicare and Medicaid Services considered the results of this study and issued a decision that pneumatic compression will only be covered for patients with refractory edema with significant ulceration of the lower extremities after a 6-month trial of standard therapies, such as compression stockings, has failed.

Chronic Disease↗
PubMed1998

L5 root compression caused by degenerative spinal stenosis of the L1-L2 and L2-L3 spaces.

STUDY DESIGN: A severe bilateral L5 root lesion associated with spinal stenosis at L1-L2 and L2-L3 is described. OBJECTIVE: To describe clinical findings and the difficulty in obtaining a correct diagnosis of L5 Root Compression. SUMMARY OF BACKGROUND DATA: The disorder reported in this study has not been reported previously. Only one similar case has been described in the literature: an L5 root compression at L1-L2 caused by disc herniation. METHODS: Diagnosis was obtained by using computed tomography scanning, magnetic resonance imaging, and computed tomography myelography. The findings at L5-S1 were minimal to justify the patient's clinical symptoms, but a detailed study of the upper levels revealed spinal stenosis at L1-L2 and L2-L3, which could have been causing L5 and S1 root compression. A decompressive laminectomy and partial facetectomy in both levels were performed. RESULTS: The patient's pain and claudication disappeared, and clinical symptoms associated with the right L5 root improved. The left L5 root deficit remained stable. CONCLUSION: An unusual case of L5 root compression caused by degenerative stenosis of L1-L2 and L2-L3 is described.

Aged↗
PubMed1996

Axon and ganglion cell injury in rabbits after percutaneous trigeminal balloon compression.

New Zealand white rabbits were used to determine whether the changes in the Vth cranial nerve sensory root after compression were associated with the loss of a specific subclass of Vth cranial nerve ganglion cells, the disappearance of a distinct subset of primary afferent terminals in Vth cranial nerve nucleus caudalis, and/or injury to a specific axonal fiber type. There was no significant difference in the size of surviving ganglion cells after Vth cranial nerve compression, as measured 2 to 3 months after injury (P > 0.5, n = 4). Densitometric analysis of the nerves of rabbits that survived > 2 months after compression showed no significant difference in the immunoreactivity of substance P and calcitonin gene-reactive protein between compressed and control sides (P > 0.1, n = 4). Fink-Heimer staining of the Vth cranial nerve subnucleus caudalis revealed that transganglionic degeneration was most dense in the deeper layers, which are the sites of termination of large myelinated fibers. Ultrastructural evaluation of the type of myelinated axons injured by Vth cranial nerve compression in rabbits killed 7, 14, 37, and 270 days after injury was studied, and morphometric analysis was performed. The frequency distribution of axon diameters was significantly different for injured and control areas. The injured areas had higher ratios of small (< 3-microns diameter) to large-diameter axons compared to control distribution. These data indicate that balloon compression results in loss of fibers from the Vth cranial nerve sensory root and extensive transganglionic degeneration in the Vth cranial nerve brain stem complex. Cell size measurements and immunocytochemical data suggest that there is no specific loss of small ganglion cells or fine-caliber primary afferents. These experiments suggest that balloon compression relieves trigeminal pain by injuring the myelinated axons involved in the sensory trigger to the pain.

Afferent Pathways↗
PubMed2003

Unique roles of a data and safety monitoring board in vaccine safety trials with compressed timelines and urgent implications.

Studies with urgent implications for public policy and programs represent a special case for monitoring boards, whose responsibilities must include ensuring applicability to policy making and timely communication of results as well as data and safety monitoring. We recently conducted two preseason evaluations of an influenza vaccine, results of which would influence the supply of vaccine for the Canadian annual program. Only 12 weeks were available for planning the studies and 6 weeks for fieldwork and data analysis. The enlisted board played key roles in determining appropriate study design, setting and enforcing rules for study initiation and early termination, monitoring safety, and encouraging timely dissemination of results. An extended role in data monitoring would have been desirable. Providing a safety valve for inevitable tensions between investigators and sponsor was an understated but significant role. Lessons from our experience will be particularly pertinent to future studies of pandemic influenza vaccines.

Canada↗
PubMed1992

Os calcis fractures: a randomized trial comparing conservative treatment with impulse compression of the foot.

Published data suggest that soft tissue involvement plays a role in the aetiology of residual symptoms following fractures of the os calcis. This randomized study involved 23 patients with 24 intra-articular fractures of the calcaneum. It was designed to evaluate the efficacy of a pneumatic plantar impulse device in reducing pain, associated morbidity and convalescent time. The results show a significant improvement in subtalar range of movement in the pumped group at 3 months, with pain significantly reduced at 6 months and at 1 year. There was no difference in weight bearing or walking distance between the pumped and control groups. The time from date of injury to return to work was significantly reduced in the pumped group by an average of 3 months.

Adult↗
PubMed1982

[Clinico-electromyographic characteristics of discogenic lumbosacral vascular compression radiculomyeloischemia].

Clinical and electromyographic data obtained from 50 patients who were in the late period of discogenic lumbosacral radiculoischemias were compared. A group of patients was differentiated in whom the clinical findings did not correlate with the electromyographic ones. These patients showed subclinical electromyographic symptoms pointing to an involvement of the segmental apparatus of the spinal cord. The differentiation of the above group of the patients is especially important for the practice of estimating the working capacity, since in cases of a physical overstrain or action of additional adverse factors the process may be decompensated.

Adult↗
PubMed2004

Nonlinear wavelet compression of ion mobility spectra from ion mobility spectrometers mounted in an unmanned aerial vehicle.

Linear and nonlinear wavelet compression of ion mobility spectrometry (IMS) data are compared and evaluated. IMS provides low detection limits and rapid response for many compounds. Nonlinear wavelet compression of ion mobility spectra reduced the data to 4-5% of its original size, while eliminating artifacts in the reconstructed spectra that occur with linear compression, and the root-mean-square reconstruction error was 0.17-0.20% of the maximum intensity of the uncompressed spectra. Furthermore, nonlinear wavelet compression precisely preserves the peak location (i.e., drift time). Small variations in peak location may occur in the reconstructed spectra that were linearly compressed. A method was developed and evaluated for optimizing the compression. The compression method was evaluated with in-flight data recorded from ion mobility spectrometers mounted in an unmanned aerial vehicle (UAV). Plumes of dimethyl methylphosphonate were disseminated for interrogation by the UAV-mounted IMS system. The daublet 8 wavelet filter exhibited the best performance for these evaluations.

Journal Article↗
PubMedDate not supplied

Confocal microscopic image sequence compression using vector quantization and three-dimensional pyramid.

The three-dimensional (3-D) pyramid compressor project at the University of Glasgow has developed a compressor for images obtained from confocal laser scanning microscopy (CLSM) device. The proposed method using a combination of image pyramid coder and vector quantization techniques has good performance at compressing confocal volume image data. An experiment was conducted on several kinds of CLSM data using the presented compressor compared with other well-known volume data compressors, such as MPEG-1. The results showed that the 3-D pyramid compressor gave a higher subjective and objective image quality of reconstructed images at the same compression ratio, and presented more acceptable results when applying image processing filters on reconstructed images.

Animals↗
PubMedDate not supplied

Mammography with breast cushions.

OBJECTIVE: We conducted a randomized clinical trial to determine the impact on pain and image quality when breast cushions were used to pad the surfaces of the mammography equipment during film-screen mammography. METHODS: We recruited a consecutive volunteer sample of 394 participants. Breast cushions were used for only one breast, with laterality and sequence of use assigned randomly. Data collected from participants included demographic data, rating of pain from previous mammography, and rating of pain from present mammography using both a numeric rating scale and a visual analogue scale. Research assistants also collected breast compression and radiation exposure data. Radiologists were blinded to the laterality of cushion assignment while reading the mammograms and assessing image quality. RESULTS: Participants were primarily white women (75.3%), mean age 55.4 years. Most (94.4%) reported having previous mammography. Eight percent (n = 32) of those surveyed had thought about skipping or delaying mammography because of the pain involved. The pain associated with mammography was significantly (p < .001) less during oblique and craniocaudal views when breast cushions were used during the procedure. Retakes were required for 2% of the 1576 views with the most common reason being positioning (53%). CONCLUSION: The use of breast cushions significantly reduced the pain during film-screen mammography. Image quality with the cushions was reduced in a very small subset of women probably due to the difficulty in positioning the breast without visual clues. More research needs to be done prior to the routine use of these cushions in clinical practice.

Adult↗
PubMed2004

Cerebrospinal fluid biomarkers in experimental spinal nerve root injury.

STUDY DESIGN: Cerebrospinal fluid biomarkers were evaluated in a setup using established pig models to mimic clinical disc herniation. OBJECTIVES: To investigate biomarkers for nerve tissue injury, inflammation, and pain in cerebrospinal fluid after mechanical compression and/or nucleus pulposus application to spinal nerve roots. SUMMARY OF BACKGROUND DATA: The association between mechanical compression, biochemical effects of nucleus pulposus, and nerve root injury in degenerative disc disorders is incompletely investigated. METHODS: The unilateral S1 nerve root was exposed in 20 pigs. The animals were divided into four groups (n = 5 each): 1) slow-onset mechanical compression with an ameroid constrictor; 2) autologous nucleus pulposus application; 3) mechanical compression plus nucleus pulposus; and 4) sham operation. After 1 week, 6 mL of cerebrospinal fluid was collected, and four structural nerve proteins, neurofilaments, S-100, glial fibrillary acidic protein, neuron-specific enolase, the proinflammatory cytokine interleukin-8, the neurotransmitter nociceptin, and substance P endopeptidase activity were analyzed using immunoassays. RESULTS: The concentration of neurofilament was increased in the mechanical compression group (17.0 microg/L +/- 5.0) and in the mechanical compression plus nucleus pulposus group (19.8 +/- 12.1 microg/L) compared with the sham group (0.9 +/- 0.9 microg/L) and the nucleus pulposus group (0.4 +/- 0.1 microg/L) (P < 0.01 for both). The concentration of nociceptin was increased significantly in the mechanical compression group (24.0 +/- 8.6 fm/mL) and in the mechanical compression plus nucleus pulposus group (31.2 +/- 6.6 fm/mL) compared with the sham group (7.0 +/- 1.3 fm/mL) (P < 0.05 and P < 0.01, respectively). A correlation was found between concentrations of neurofilament and nociceptin (r = 0.50, P < 0.05). There were no intergroup differences regarding glial fibrillary acidic protein, neuron-specific enolase, S-100, interleukin-8, or substance P endopeptidase activity. CONCLUSIONS: The present study demonstrates increased concentrations of neurofilament and nociceptin in cerebrospinal fluid after nerve root compression. A simultaneous application of nucleus pulposus did not increase the response.

Animals↗
PubMed1991

Design and implementation of full-frame, bit-allocation image-compression hardware module. Work in progress.

A hardware module was designed and built to implement the full-frame, bit-allocation image-compression algorithm in a clinical setting. The algorithm transforms an entire image without prepartitioning into small subimages. This adaptation eliminates block artifacts at subimage borders that can mimic relevant pathologic conditions. The quality of 1,024- and 2,048-pixel images compressed at a rate up to 10:1 with a custom-designed processor board (which contains four digital signal processors that transform and quantize separate rows and columns of an image independently with a two-pass cosine transform) and a 16-Mbyte frame buffer was found to be diagnostically acceptable in preliminary receiver operating characteristic studies. The module can compress a 1,024-pixel image in 4 seconds in a general-purpose computer system; images can be compressed in 1 second with the addition of a custom-designed data transporter. Copies of the compression module are being installed in the authors' department and in collaborating hospitals for laboratory and clinical evaluation.

Computers↗
PubMed2004

Use of FemoStop system for arterial puncture site closure after coronary angioplasty.

Different protocols exist concerning the method and timing of post-coronary angioplasty arterial puncture site closure. Easy handling and good effectiveness are well-documented for the Femostop femoral artery compression system; however, no hard data exist concerning the relationship between heparin anticoagulation level and femoral artery compression time (FSCT). Thus, we prospectively randomized 267 patients after elective percutaneous transluminal coronary angioplasty (PTCA) into two groups [group A (n=137) had early sheath removal 6 to 8 hours after PTCA; group B (n=130) had late sheath removal 14 to 16 hours after PTCA] and analyzed the dependence of the FSCT on the heparin anticoagulation level (aPTT) and the incidence of vagal reactions and puncture site complications. FSCT was significantly longer in group A (69+/-27 minutes versus 45+/-15 minutes; p<0.001) with high heparin anticoagulation level (aPTT, 88+/-46 seconds) in comparison to group B with low heparinization (aPTT, 59+/-34 seconds). Vagal reactions occurred more frequently in group A (15.3% versus 10.0%; p<0.01) and the incidence of minor hemorrhage at the arterial puncture site was also increased (9.5% versus 3.1%; p<0.05). In the clinical setting of intensive heparin anticoagulation and early sheath removal after PTCA (<8 hours), the FemoStop system cannot be recommended due to prolonged femoral artery compression times.

Angioplasty, Balloon, Coronary↗