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At least 1,531 records · Page 85Linked to original sources

PubMed1999

Balloon device for experimental graded spinal cord compression in the rat.

We have developed a balloon device that creates reproducible graded compression of the rat spinal cord. It uses a modified Camino intracranial pressure monitor bolt with a small latex balloon attached to the tip. The device is affixed to the spinous processes of two cervicothoracic vertebrae and positioned directly over an exposed segment of spinal cord. Ten compression balloons were tested and revealed reproducible pressure transmission at expansion volumes from 0.12 to 0.34 cc. Reversible graded spinal cord compression was verified by monitoring cortical somatosensory and motor evoked potentials before, during, and after cord compression. The pathophysiologic changes occurring with graded compression and the effect of therapeutic interventions can be studied in a rat model.

Animals↗

PubMed1999

[Neurovascular compression as a reason for neurogenic hypertension].

30 years ago Janetta proposed neurovascular compression as an etiological factor of trigeminal neuralgia. Neuroanatomical, neurophysiological studies and observations during neurosurgical operations seem to confirm Janetta's suggestion. The conception of neurovascular compression is accepted also as an etiological factor in hemifacial spasm. In literature a neurovascular compression is suspected as an etiological factor in many diseases of unknown etiology. The results of neurovascular decompression performed as initial treatment of these diseases were presented. The methods of contemporary diagnostics of neurovascular compression syndromes and difficulties with correct diagnosis were described. MRI and neurophysiological examinations were pointed out as the most useful in the evaluation of neurovascular compression syndromes.

Humans↗

PubMed2000

Calcium pyrophosphate dihydrate deposition disease causing thoracic cord compression: case report.

OBJECTIVE AND IMPORTANCE: Calcium pyrophosphate dihydrate (CPPD) deposition disease is being increasingly recognized. Spinal involvement in CPPD deposition disease is rare. When involved, the cervical and lumbar regions are commonly affected. We report a rare case of CPPD deposition disease that caused thoracic cord compression. CLINICAL PRESENTATION: A 45-year-old woman presented with clinical features suggestive of thoracic cord compression. Radiographic findings were consistent with calcification of the ligamenta flava in the lower thoracic levels causing cord compression. Calcification of the ligamentum flavum is commonly attributed to CPPD deposition disease. Evaluation for conditions that might be associated with CPPD deposition disease proved to be negative. INTERVENTION: Laminectomy with removal of the calcified ligamenta flava was performed. Histopathological examination of the excised ligaments revealed evidence of CPPD crystals. Postoperatively, the patient's spasticity decreased and sensations improved, with no significant improvement in motor power. CONCLUSION: Calcification of the ligamenta flava due to CPPD deposition disease is a rare cause of thoracic cord compression. CPPD deposition disease should be entertained in the differential diagnosis of thoracic cord compression.

Chondrocalcinosis↗

PubMed1999

[Compression of the deep branch of ulnar nerve at the wrist].

OBJECTIVE: To investigate the compression factor and clinical manifestation of the compression of deep branch of the ulnar nerve at the wrist. METHODS: Anatomic study was done on both sides of 10 cadavers, the deep branch of ulnar nerve, the Guyon's canal and the flexor digiti minimi brevis pedis were observed. Then from Jan. 1990 to Jan. 1997, 5 patients with compression of the deep branch of ulnar nerve at the wrist were treated clinically. Among them, there were 4 males and 1 female, aged from 37 to 48 years and the course of disease ranged from 1 to 5 months. RESULTS: The motor branch of the ulnar nerve passed under the tendinous arcade of flexor digiti minimi brevis pedis. Occasionally, the branch of ulnar artery overpassed the motor branch. Clinically, the tendinous arcade compressed the motor branch was released, and after 2 to 4 years follow-up, the clinical results were satisfactory. CONCLUSION: The main compression factor of the ulnar nerve at the wrist is the tendinous arcade of the flexor digiti minimi brevis pedis, the tendinous arcade should be released sufficiently during the operation.

Adult↗

PubMed2003

Lumbar spine disc heights and curvature: upright posture vs. supine compression harness.

INTRODUCTION: Spinal lengthening in microgravity is thought to cause back pain in astronauts. A spinal compression harness can compress the spine to eliminate lengthening but the loading condition with harness is different than physiologic conditions. Our purpose was to compare the effect of spine compression with a harness in supine position on disk height and spinal curvature in the lumbar spine to that of upright position as measured using a vertically open magnetic resonance imaging system. METHODS: Fifteen healthy subjects volunteered. On day 1, each subject lay supine for an hour and a baseline scan of the lumbar spine was performed. After applying a load of fifty percent of body weight with the harness for thirty minutes, the lumbar spine was scanned again. On day 2, after a baseline scan, a follow up scan was performed after kneeling for thirty minutes within the gap between two vertically oriented magnetic coils. Anterior and posterior disk heights, posterior disk bulging, and spinal curvature were measured from the baseline and follow up scans. RESULTS: Anterior disk heights increased and posterior disk heights decreased compared with baseline scans both after spinal compression with harness and upright posture. The spinal curvature increased by both loading conditions of the spine. DISCUSSION: The spinal compression with specially designed harness has the same effect as the physiologic loading of the spine in the kneeling upright position. The harness shows some promise as a tool to increase the diagnostic capabilities of a conventional MR system.

Adult↗

PubMed2003

How accurate is magnetic resonance angiography in predicting neurovascular compression in patients with trigeminal neuralgia? A prospective, single-blinded comparative study.

Ninety-two patients with trigeminal neuralgia (TGN) were investigated prior to posterior fossa surgery with magnetic resonance imaging (MRI) and contrast-enhanced magnetic resonance angiography (MRA). The preoperative investigation was matched to one consultant neuroradiologist (co-author) who was blinded to the side of symptomotology. The imaging results were compared with the operative findings in all patients. In 76 patients MRA showed present neurovascular compression in accordance with surgical findings. Eight cases had no compression either on MRA or intraoperatively. Eight predictions of no compression were false and there was no false positive. Based on surgical findings, the sensitivity of MRA was 90.5% and the specificity 100%. In 19 cases MRA predicted bilateral compression of the trigeminal nerves. Only two cases had clinically bilateral TGN. We conclude that MRA with gadolinium enhancement is an extremely sensitive and specific method for demonstrating compression in TGN. As a result posterior fossa surgery can be recommended with confidence, and microvascular decompression remains the treatment of choice for TGN at the authors' centre.

Contrast Media↗

PubMed2003

Acute cauda equina compression revealing Hodgkin's disease: a case report.

STUDY DESIGN: This is a case report of a young patient who experienced an acute epidural compression of cauda equina revealing Stage IV Hodgkin's disease. OBJECTIVES: To draw attention to this rare presentation of Hodgkin's disease, and to assess the role of surgery in acute cauda equina compression in a context of a chemosensitive disease. SUMMARY OF BACKGROUND DATA: Lymphomatous tissue in Hodgkin's disease may involve the spine usually in the setting of advanced disease. Initial manifestation of Hodgkin's disease in the spine is rare. The management of this rare presentation may be conservative, but surgery provides the most rapid way of neurologic tissue decompression. METHODS: The case of a 14-year-old patient who experienced an acute epidural compression of cauda equina revealing Stage IV Hodgkin's disease is presented. RESULTS: The patient complained of an increased lower back pain of 1-month duration before he developed lower limbs numbness, loss of perineal sensation, and urinary retention. Sagittal and axial T2-weighted magnetic resonance images of the lumbar spine revealed tumoral invasion of the epidural space compressing the cauda equina. Emergency surgical decompression was performed. In fine, Stage IV Hodgkin's disease revealed by acute epidural cauda equina compression was diagnosed. The patient recovered normal neurologic functions in a few days and then underwent chemotherapy and radiotherapy. CONCLUSION: Although a rare situation, Hodgkin's disease may involve the spinal epidural space at presentation. The management is complex, but surgery provides the most rapid means of diagnosis and neurologic tissue decompression in severely affected patients.

Acute Disease↗

PubMed2003

[Tophaceous gout of the cervical spine, causing cord compression. Case report and review of the literature].

We present the case of a 74-year-old patient with long-standing gout who developed C4-C5 tophaceous gout causing cord compression. The patient had undergone 4 years earlier for a disco-osteophytic cord compression (anterior C4-C5 and C5-C6 discectomy). When admitted, the patient presented quadriparesia which had developed during the previous week in association with acute tophaceous gout on the knees, and the metarsophalangeal articulations, in the context of a bronchial infection. The diagnosis of spondylodiscitis was initially retained because of the clinical features of severe infection and the radiological data (C4-C5 cord compression, with anterior epidural lesions in MRI). The intervention allowed decompression and pathological diagnosis of tophaceous gout. Spinal gout is well-known, and very rarely responsible for cord compression: only 15 cases of cervical gout have been described in the literature. Radiological findings are not specific, and treatment is surgical in the event of medullar compression despite medical treatment.

Aged↗

PubMed2004

Effects of lossy image compression on quantitative image analysis of cell nuclei.

OBJECTIVE: To investigate whether statistically significant changes occur in quantitative image analysis of cell nuclei when lossy image compression techniques are used. STUDY DESIGN: Thirty-five stoichiometric, Feulgen-stained samples of rat hepatocytes, human thyroid and ovarian cancer cell nuclei were used. Image analysis was performed by a computerized system that used AutoCyte LINK V1.1.1.56 software (Burlington, North Carolina, U.S.A.) for image acquisition and Zeiss Vision KS 400 V3.0 software (Oberkochen, Germany) for quantitative image analysis. After lossy JPEG compression of acquired images at different quality levels, some densitometric features were selected and measurements performed. RESULTS: We observed that nearly all the standard densitometric features showed statistically significant changes when images were compressed with the lossy JPEG algorithm. However, most invariant densitometric moment features remained free of statistically significant changes. CONCLUSION: The standard densitometric measurements that we used do not tolerate lossy compression. However, analyses using invariant densitometric features may be performed on images compressed with lossy JPEG, resulting in simpler, less expensive systems demanding less network bandwidth.

Animals↗

PubMedDate not supplied

[Spinal cord compression: an unusual clinical manifestation of retroperitoneal fibrosis].

INTRODUCTION: Retroperitoneal fibrosis is a rare disorder consisted of a periaortic fibrous mass that compresses retroperitoneal organs. CASE REPORT: We report a case of retroperitoneal fibrosis diagnosed after a spinal cord compression. Magnetic resonance imaging scan showed a prevertebral mass which affected a vertebral body. It extended to the epidural space and compressed the spinal cord. The final diagnosis was established through the mass biopsy by means of mediastinoscopy. After prednisone treatment, both clinical remission and mass reduction in the follow-up MRI were observed. CONCLUSIONS: The spinal cord compression is an extremely unusual initial manifestation of retroperitoneal fibrosis. Nevertheless, it should be considered in the differential diagnosis of spinal cord compression syndrome, specially given the possibility of its medical treatment instead of aggressive surgical treatment.

Aged↗

PubMedDate not supplied

MR diffusion tensor imaging and fiber tracking in spinal cord compression.

BACKGROUND AND PURPOSE: Spinal cord damage can result in major functional disability. Alteration of the spinal cord structural integrity can be assessed by using diffusion tensor imaging methods. Our objective is to evaluate the diagnostic accuracy of apparent diffusion coefficient (ADC), fractional anisotropy (FA), and fiber tracking in both acute and slowly progressive spinal cord compressions. METHODS: Fifteen patients with clinical symptoms of acute (n = 2) or slowly progressive (n = 13) spinal cord compression and 11 healthy volunteers were prospectively selected. We performed T2-weighted fast spin echo (FSE) and diffusion tensor imaging by using a 1.5-T MR scanner. ADC and FA maps were computed. Regions of interest were placed at the cervical, upper and lower thoracic cord levels for the healthy subjects and on the area with abnormal T2-weighted signal intensity in the patients with cord compression. In three patients, we used fiber tracking to locate the areas of cord compression precisely. Data were analyzed by using a mixed model. The sensitivity (SE) and specificity (sp) of imaging (T2, ADC, and FA maps) in the detection of spinal cord abnormality were statistically evaluated. RESULTS: For the healthy subjects, averaged ADC values ranged from 0.96 10(-3) mm(2)/s to 1.05 10(-3) mm(2)/s and averaged FA values ranged from 0.745 to 0.751. Ten patients had decreased FA (0.67 +/- 0.087), and one had increased FA values (0.831); only two patients had increased ADC values (1.03 +/- 0.177). There was a statistically significant difference in the FA values between volunteers and patients (P = .012). FA had a much higher sensitivity (SE = 73.3%) and specificity (sp = 100%) in spinal cord abnormalities detection compared with T2-weighted FSE imaging (se = 46.7%, sp = 100%) and ADC (SE = 13.4%, sp = 80%). CONCLUSIONS: FA has the highest sensitivity and specificity in the detection of acute spinal cord abnormalities. Spinal cord fiber tracking is a useful tool to focus measurements on the compressed spinal cord.

Acute Disease↗

PubMed1992

Single- versus double-level nerve root compression. An experimental study on the porcine cauda equina with analyses of nerve impulse conduction properties.

Double-level nerve root compression had a greater effect on nerve impulse conduction, recorded as tail muscle action potential amplitude, than single-level compression at both 10 and 50 mm Hg. If the distance between the two compression sites at 10 mm Hg compression was increased from one vertebral segment (10 mm) to two vertebral segments (30 mm), the reduction of muscle action potential amplitude was further enhanced. These observations may give new insight into the pathophysiology of cauda equina compression in spinal disorders such as stenosis.

Action Potentials↗

PubMedDate not supplied

The effect of compression on clinical diagnosis of glaucoma based on non-analyzed confocal scanning laser ophthalmoscopy images.

BACKGROUND AND OBJECTIVE: To evaluate the effect of different image compression formats of non-analyzed Heidelberg Retina Tomography (HRT; Heidelberg Engineering, Heidelberg, Germany) images on the diagnosis of glaucoma by ophthalmologists. MATERIALS AND METHODS: Thirty-three topographic and reflectance images taken with the HRT representing different levels of disease were transformed using nine different compression formats. Three independent ophthalmologists, masked as to contour line and stereometric parameters, classified the original and compressed HRT images as normal, suspected glaucoma, or glaucoma, and Kappa agreement coefficients were calculated. RESULTS: The Tagged Image File Format had the largest file size and the Joint Photographic Experts Group (JPEG) 2000 format had the smallest size. The highest Kappa coefficient value was 1.00 for all ophthalmologists using the Tagged Image File Format. Kappa values for JPEG formats were all in the range of good to excellent agreement. Kappa values were lower for Portable Network Graphic and Graphics Interchange Format compression formats. CONCLUSION: Image compression with JPEG 2000 at a ratio of 20:1 provided sufficient quality for glaucoma analysis in conjunction with a relatively small image size format, and may prove to be attractive for HRT telemedicine applications. Further clinical studies validating the usefulness of interpreting non-analyzed HRT images are required.

Data Compression↗

PubMed2005

Effects of expiratory rib-cage compression on oxygenation, ventilation, and airway-secretion removal in patients receiving mechanical ventilation.

BACKGROUND: Expiratory rib-cage compression, a chest physiotherapy technique, is well known as the "squeezing" technique in Japan. OBJECTIVE: To determine the effects of rib-cage compression on airway-secretion removal, oxygenation, and ventilation in patients receiving mechanical ventilation. SETTING: An intensive care unit of an emergency and critical care center at a tertiary-care teaching hospital in Tokyo, Japan. METHODS: Thirty-one intubated, mechanically ventilated patients in an intensive care unit were studied in a randomized, crossover trial. The patients received endotracheal suctioning with or without rib-cage compression, with a minimum 3-hour interval between the 2 interventions. Rib-cage compression was performed for 5 min before endotracheal suctioning. Arterial blood gas and respiratory mechanics were measured 5 min before endotracheal suctioning (baseline) and 25 min after suctioning. The 2 measurement periods were carried out on the same day. RESULTS: There were no significant differences in the ratio of arterial partial pressure of oxygen to fraction of inspired oxygen, P(aCO2), or dynamic compliance of the respiratory system between the 2 periods (before and after endotracheal suctioning). Moreover, there were no significant differences in airway-secretion removal between the 2 periods. CONCLUSIONS: This study suggests that rib-cage compression prior to endotracheal suctioning does not improve airway-secretion removal, oxygenation, or ventilation after endotracheal suctioning in this unselected population of mechanically ventilated patients.

Combined Modality Therapy↗

PubMed2005

[Objective retinal nerve fiber laser assessment by scanning laser polarimetry in patients with chiasmal compression].

PURPOSE: To assess the evaluation ability of retinal nerve fiber layer (RNFL) in patients with visual tracts' compression and to assess the correlation between visual field loss and changes in RNFL. MATERIAL AND METHODS: Polarimetric RNFL analysis (scanning laser polarimeter- NFA/GDx, software version 1.0.16, LDT(inc)) and kinetic perimetry were done in 41 eyes with different types of optic chiasma compression and in 40 healthy eyes, age matched controls. RESULTS: In eyes with optic chiasma compression most of the GDx parameters were statistically different from the control group (P<0.05). In eyes with normal visual fields and with optic chiasma compression most of GDx parameters were statistically different from the other analyzed groups. CONCLUSIONS: GDx may be a helpful tool in diagnosis of optic chiasma diseases. GDx is a useful visual prognostic indicator in the preoperative assessment of optic chiasma compression. Objective RNFL assessment is especially important in patients with serious visual field loss and poor visual acuity.

Diagnostic Techniques, Ophthalmological↗

PubMed1991

Aspects on pathophysiology of nerve entrapments and nerve compression injuries.

The microanatomy of the neuron and the peripheral nerve, which is a composite tissue, should be considered when discussing the pathophysiology of nerve compression injuries. Acute and chronic compression of peripheral nerve can induce changes in intraneural microcirculation and nerve fiber structure, increase vascular permeability with subsequent edema formation, and impair anterograde and retrograde axonal transport, which all contribute to the clinical symptoms and deterioration of nerve function. Morphologic and functional changes in the nerve cell bodies can be observed after compression which may be due to inhibition of axonal transport. The latter findings might be a theoretical explanation for double crush syndromes. Diabetes mellitus may confer on the peripheral nerve an increased susceptibility to compression injuries. Clinical stages of compression syndromes, such as carpal tunnel syndrome, may be related to specific pathophysiologic events occurring in the nerve.

Humans↗

PubMed2006

[Rare compression syndromes of the peripheral nerves of the forearm and distal leg].

OBJECTIVES: The study presents results of rare operations of the peripheral nerves compartment syndromes of the forearm and distal leg, completed in our clinic during a 14-year period (1990-2004). SUBJECTS AND METHODS: We completed 25 procedures for 25 compartment syndromes in 25 patients. All patients sufferred from unilateral compartment syndromes. The patients were operated for the first time in our clinic. None of them needed to be re-operated. The clinical pictures of the compartment syndromes were classified (three degrees) according to the Dellon's intensity classification: None of the patients sufferred from the Ist degree compression. The IInd degree occured in 4 patients (16%). The IIIrd degree occured in 21 patients (84%). The surgical procedure's effectiveness was analyzed, taking into consideration the degree of the compression, its duration and the symptoms duration. RESULTS: Excellent and good results were observed in all cases of the IInd degree compression and the symptoms duration up to 12 months. Worse results were recorded in the IIIrd degree compression cases, where excellent and good results were observed in 19 cases (76%). In cases, where the symptoms lasted for over 12 months, no excellent or good results were recorded. CONCLUSION: The decisive factor affecting the procedure's outcome, is the degree of the compression and its duration. The main factors improving the outcome of the procedure are the following: the patient's age up to 30 years of age and the duration of the symptoms up to 1 year, when the defect is not irreversible.

Adult↗

PubMed2006

Mechanical response of polyethylene tibial component using compression loading contact test: experimental and finite element analysis.

An experimental apparatus has been developed to study the mechanical response of Total Knee Replacement (TKR) prosthesis under compression loading test (Tibial HDPE component and femoral Vitallium component). Analysis of experimental results indicates that the load-displacement curve depends on the initial contact location. The position of this curve varies between two curves of lower and higher stiffness. Experimental compression loading curve for femoral part resting on flat HDPE is located between the extreme curves. This result allows us to model load-displacement curve of TKR prosthesis under compression loading using femoral component resting on flat polyethylene surface. For simple contact geometry of spherical cap on flat HDPE specimen, Hertz elastic theory can be used to describe the load displacement curve for loads under 635 N. This value corresponds to the load which induces plastic flow of polyethylene. In the case of femoral component on flat HDPE specimen, Hertz elastic theory can be considered for loads under 800 N. Finite element 2D is also used to model the compression load displacement curve for femoral component resting on flat HDPE specimen. The finite element results are similar to the Hertz elastic theory analysis for compression loading under 1200 N. Damage of tibial component can be related to the critical load which induces plastic flow of polyethylene. This load depends on the contact geometry and can be estimated with the Hertz elastic theory.

Compressive Strength↗