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At least 127 records · Page 7Linked to original sources
PubMed1997

The intravertebral vacuum phenomenon ("vertebral osteonecrosis"). Migration of intradiscal gas in a fractured vertebral body?

STUDY DESIGN: Retrospective cohort. OBJECTIVES: To compare the prevalence of the association between contiguous intervertebral disc and vertebral collapses with or without an intravertebral vacuum phenomenon. SUMMARY OF BACKGROUND DATA: The mechanism of occasional gas accumulation within some vertebral collapses is poorly known. The current hypothesis is that this phenomenon is indicative of bone ischemia. In fact, avascular necrosis as the main pathologic event remains speculative, and should not explain per se the presence of gas within a vertebral body. METHODS: Comparison of the prevalence of intervertebral disc vacuum phenomenon adjacent to the affected vertebral body in 23 cases of intravertebral vacuum phenomenon in 19 patients (intravertebral vacuum phenomenon group) and in 708 osteoporotic collapses without intravertebral vacuum phenomenon in 199 patients (control group). RESULTS: There were no differences in sex and age between the two groups, and all the patients in the intravertebral vacuum phenomenon group had signs of underlying osteoporosis. A vacuum phenomenon in at least one intervertebral disc adjacent to the collapses on radiographs, conventional tomography, computed tomography, or magnetic resonance imaging was found in 19 cases (83%) in the intravertebral vacuum phenomenon group, compared with 13% in the control group (P < 0.0001). Considering plain radiographs only, this association was found in 50% of the intravertebral vacuum phenomenon group and in 9.7% of the control group (P < 0.0001). The intervertebral and intravertebral gaseous collections were connected through a fractured endplate in six cases. CONCLUSIONS: The high prevalence of the association of contiguous intervertebral and intravertebral vacuum phenomenon could have implications in the pathogenesis of the intravertebral vacuum phenomenon. We hypothesize that the intravertebral vacuum phenomenon could simply be the result of migration of an intradiscal-gaseous collection through the fractured endplate of some osteoporotic collapses.

Aged↗
PubMed1990

[Performance of X-ray absorptiometry in post-menopausal vertebral osteoporosis. Discriminant value of vertebral and femoral measurements, fracture threshold, reproducibility].

The aim of this study was to assess the performance of a new bone densitometry technique, X-ray absorptiometry, in vertebral osteoporosis with fracture(s). Vertebral and femoral (neck, Ward's triangle and trochanter) bone density was measured in 60 women with at least one vertebral compression fracture of osteoporotic origin (mean age: 61), 100 controls of the same age and in 40 young adults (mean age: 30). Osteoporosis patients had significantly (p less than 0.0005) low bone density values in comparison with the young adults: -40 to -50% (T-score -1.9 to -2.3) for the femur and with control subjects of the same age: -20 to -30% (Z-score -2.2 to -2.6) for the spine; -10 to -20 (Z-score -1.1 to -1.3) for the femur. Measurements using the spine and Ward's triangle had the best discriminant values assessed by the ROC (Receiver Operating Characteristics) technique (areas under the curve: 95% and 84% respectively). The fracture threshold was fixed at a vertebral bone density of 0.78 g/cm2, this value giving the best compromise between sensitivity (83%) and specificity (95%) with 91% of subjects appropriately classified. Reproducibility was assessed in the short term in 9 osteoporosis patients. The mean standard deviation of measurements was 0.017 g/cm2 (coefficient of variation: 2.6%) as compared with 0.010 g/cm2 (coefficient of variation: 0.8%) in the young adult. These results emphasise the true advance represented by X-ray absorptiometry in the area of bone densitometry, notably in the assessment and monitoring of demineralisation disorders.

Absorptiometry, Photon↗
PubMed1985

[Another new etiology of vertebral artery insufficiency--a case of dynamic entrapment of the vertebral artery by the cervical nerve].

In the etiology of vertebral artery insufficiency, cervical spondylosis with uncal osteophyte, Power's syndrome, A-V malformation and atheromatous narrowing have been recognized. We recently experienced a patient with episodic vertigo and hyposthenia of the left side of the body on rotational movement of the neck. On surgical exploration of the atlanto-axial area of the vertebral artery where dynamic constriction of the artery could be observed by angiography, we found that the right vertebral artery was entrapped and constricted by the anterior branch of the second cervical nerve with fibrous adhesion after injury. With the release and resection of the injured nerve, the patient became free of any vertigo or hyposthenia. Although this kind of etiology involving entrapment-constriction of the vertebral artery by the cervical nerve after trauma has not been reported at all in the literature, we should always keep this in mind when dealing with patients with cervical vertigo after trauma.

Adult↗
PubMed1986

Percutaneous transluminal angioplasty of the vertebral artery. A therapeutic alternative to operative reconstruction of proximal vertebral artery stenoses.

Percutaneous transluminal angioplasty (PTA) of the proximal vertebral artery was performed in 13 patients with stenosis of the proximal vertebral arteries. All of these patients had symptoms indicating vertebrobasilar insufficiency. PTA was performed only if an extreme reduction of the total diameter of both vertebral arteries was present. Only 13 patients have fulfilled the strict selection criteria in the last 3 years. All patients were monitored during the procedure by means of continuous-wave Doppler ultrasound and electrophysiological techniques. After PTA their neurological and vascular conditions were serially examined. Of the 13 patients, 8 showed marked improvement of both subjective and objective clinical symptoms. During an observation period of 2-25 months (average: 15 months) reocclusion of the angioplasty was observed in only 2 cases, without any additional neurological sequelae. Electrophysiological and Doppler sonographic monitoring during PTA helped to minimize the risk of angioplasty.

Angioplasty, Balloon↗
PubMed1991

Treatment of proximal vertebral artery stenosis. Vertebral to subclavian transposition.

For vascular reconstruction in cases of atherosclerotic stenosis at the origin of the vertebral artery, we use vertebral to subclavian artery transposition. We discuss the advantages and effectiveness of such treatment based on a study of 32 cases. We have experienced neither surgical mortality nor morbidity and the outcome at the time of discharge has been favourable. Follow-up revealed no deaths, however, three cases exhibited symptoms of cerebral ischaemia. One had a supratentorial completed stroke, and the other two hat TIA or RIND, but without any notable lesion in the angiograms. There were no cases of cerebral infarction of the posterior fossa. We believe that this method should be the first choice for treatment of cases without lesions of the subclavian artery for the following reasons: serious operative complications have not been encountered, surgical invasion is minimal, temporary occlusion of the common carotid artery is unnecessary, the operation can be done by occluding only the vertebral artery, and unlike various bypass operations, anastomosis is required at only one location and is consequently technically uncomplicated. Following anastomosis the cerebral blood pathway is physiological.

Adult↗
PubMed1980

Antiquity of the vertebrate pattern of activity metabolism and its possible relation to vertebrate origins.

Vertebrates generally possess well developed capacities for anaerobic metabolism, resulting in formation of lactic acid. Those capacities have traditionally been interpreted in terms of adaptation to hypoxic environments or to special situations such as diving. However, anaerobic metabolsim in striated muscle tissue is frequently a major source of ATP utilized during periods of intense activity. The evolutionary significance of anaerobically supported activity has not been discussed, although the interrelationships of capacities for aerobiosis and activity have received considerable attention. We present here evidence that the pattern of activity metabolism utilized by extant species probably dates back to the earliest vertebrates. It is also postulated that the evolution of extensive capacity for anaerobically supported burst activity may have been closely related to the evolution of vertebrates from invertebrate chordates.

Aerobiosis↗
PubMed1999

Vertebrate MitBASE: a specialised database on vertebrate mitochondrial DNA sequences.

Vertebrate MitBASE is a specialized database where all the vertebrate mitochondrial DNA entries from primary databases are collected, revised and integrated with new information emerging from the literature. Variant sequences are also analyzed, aligned and linked to reference sequences. Data related to the same species and fragment can be viewed over the WWW. The database has a flexible interface and a retrieval system to help non-expert users and contains information not currently available in the primary databases. Vertebrate MitBASE is now available through the MitBASE home page at URL: http://www.ebi.ac.uk/htbin/Mitbase/mitb ase.pl. This work is part of a larger project, MitBASE which is a network of databases covering the full panorama of knowledge on mitochondrial DNA from protists to human sequences.

Animals↗
PubMedDate not supplied

[Spontaneous dissection of carotid and vertebral arteries. II. Vertebral arteries and their branches].

Dissection of the extra- and ntracranial portions of vertebral arteries, as well as basilar artery and their branches are discussed based on the up-to-date literature. Formerly, arterial dissections were found exclusively at necropsy, yet they have currently arisen to the field of interest of not only neurologists but also radiologists, neurosurgeons, and vascular surgeons. Ischemic strokes frequently result from arterial dissection, in particular subintimal dissection (most often in the extracranial portion of vertebral artery), by formation of emboli or reduced perfusion. Conversely, subadventitial and transmedial dissections produce aneurysms (most often in the intracranial portion of vertebral arteries and basilar artery) which may result in subarachnoid or intracerebral hemorrhages. The other possible mechanism of focal lesions is the compression of adjacent structures by dissected artery, most frequently by dolichoectasia of basilar artery which originates from its multiple intramural lesions. The dissections may present with cranial nerve palsies, symptoms of ischemia of cervical spine, cerebellum, and cerebral trunk, as well as occipital lobe syndromes. Arterial dissection may occur in adolescents and young adults. The clinical symptom that should be stressed is headache which precedes the occurrence of stroke for several days. The right diagnosis gives a chance for proper treatment, including operative procedures, and improved prognosis.

Adult↗
PubMed1999

Anomalous origin of the right vertebral artery: review of the literature and case report of right vertebral artery origin distal to the left subclavian artery.

We present the case of a 57-year-old patient who was admitted to the hospital for preoperative cerebral angiography because of an intraspinal mass at the level of C1 and C2. Angiographic examination revealed an abnormal origin of the right vertebral artery, which normally originates from the right subclavian artery. Thus, the right vertebral artery was the last branch of the supraaortic vessels. We also review herein the incidence of the various anomalous origins of the right vertebral artery in the literature and discuss their potential embryologic development and clinical significance.

Cerebral Angiography↗
PubMed1986

Somitic-vertebral correlation and vertebral levels in the human embryo.

Somitic and vertebral interrelationships and levels were studied in 84 human embryos of stages 9-23 (3-8 postovulatory weeks). The first four somites are occipital, the occipitocervical junction is at somites 4/5, and eight somites are involved in the cervical region: X, Y, Z, and C. 3-7. By stage 17 the total number of occipitovertebral "units," namely 38 or 39, is attained. Resegmentation (Neugliederung) of sclerotomes is not supported. A new scheme of somitic/vertebral correlation is proposed in which somites and centra are in register. Differential growth of the regions of the vertebral column was calculated, and it was found that the percentages of the total column occupied by the various regions vary from one stage to another. The cervical and coccygeal regions decrease, the thoracic and lumbar regions increase, and the sacral region remains more or less constant during embryonic development. The following structures descend with reference to the vertebral column during the embryonic period proper: roots of lower limbs, thyroid gland and thymus, tracheal bifurcation, lungs, heart, diaphragm, abdominal arteries, mesonephroi, and suprarenal glands. The gonads may descend slightly. The scapulae and the separation point between the trachea and the esophagus remain at a fairly constant level. The metanephroi ascend. The migration of many of these structures (e.g., the heart, diaphragm, and metanephroi) is much more marked in the embryonic period than later although it continues during the fetal and postnatal periods. The conus medullaris ascends during the fetal period. Anomalies of migration that affect such organs as the thyroid gland, gonads, and metanephroi are discussed.

Embryo, Mammalian↗
PubMed1996

Is there a link between changes in the vertebral "hox code" and the shape of vertebrae? A quantitative study of shape change in the cervical vertebral column of mice.

Homeobox (hox) genes are of considerable importance in the formation of the body axis of invertebrates and vertebrates. The postulation of a hox-code (i.e. the simultaneous activity of a certain subset of hox genes) for structures at different metameric levels and which differ from each other in shape suggests a relationship between hox-code and shape, which is reinforced by the possibility of homeotic transformation when the hox-code is changed experimentally. This paper considers the possible nature of such a relationship between the hox genes governing vertebral formation in the upper part of the mouse vertebral column and the shape of the adult vertebrae formed in this region.

Animals↗
PubMed1975

Relationships between the vertebral parameters C2--C6 during movement of the cervical "vertebral units" in the sagittal plane.

In the paper it is endeavoured to set up objective criteria for the detection of a qualitatively abnormal mobility of the cervical vertebral units. Three scalar parameters were chosed to characterize the position of a cervical vertebra in the sagittal plane. By the aid of the parameters, graphs were drawn illustrating the reciprocal functional dependence of the vertebral parameters. It is stated that a discontinuous variation of the angle between the straight lines shown in the Fig. 4 and 8 and the axis of abscissae can be taken as an objective criterion of a qualitatively abnormal movement of the cervical vertebral units.

Cervical Vertebrae↗
PubMed1991

Screening for vertebral osteoporosis using individual risk factors. The Multicentre Vertebral Fracture Study Group.

Osteoporosis is a major cause of ill health in postmenopausal women. Several risk factors for osteoporosis have been identified, and they have been widely recommended as a means of identifying subgroups of postmenopausal women who might benefit from prophylaxis and therapy. Evidence to support this use of risk factors is currently lacking, however. We have constructed and evaluated a profile of putative risk factors as a means of identifying women attending general practitioners who have sustained vertebral fractures. The overall prevalence of vertebral fractures in the 1012 women (mean age 64.4 years) studied was 7.8%. Women who had sustained vertebral fractures in this population were significantly (p less than 0.05) older and shorter than those without fractures. They reported a significantly (p less than 0.05) earlier menopause, lower parity and a greater prevalence of hyperthyroidism. However, the best screening instrument devised was not sufficiently predictive to warrant widespread use.

Aged↗
PubMed2001

[Biomechanical stability with a new artificial vertebral body implant. 3-dimensional movement analysis of instrumented human vertebral segments].

UNLABELLED: The authors present a new implant for vertebral body replacement in the thoracic and lumbar spine. The titanium implant is designated for reconstruction of the anterior column in injury, posttraumatic kyphosis or tumor of the thoracolumbar spine. The instrumentation has to be supplemented by a stabilizing implant. After positioning, the implant is distracted in situ, through which best contact to adjacent end-plates and 3-dimensional stability should be provided. The possibility of secondary dislocation or loss of correction should thereby be minimized. OBJECTIVES: We investigated the biomechanical 3-dimensional stability in vitro, using Synex in combination with an anteriorly (Ventrofix) or a posteriorly (USS) stabilizing implant. The differences between both stabilizing implants were to be determined. Synex was compared with the "Harms titanium mesh cage" (MOSS) as vertebral body replacement. METHODS: In a 3-dimensional spinal loading simulator, we determined the bisegmental (T12-L2) neutral zone (NZ), elastic zone (EZ), and range of motion (ROM) of 12 human cadaveric spines. After corpectomy of L1 we tested 4 groups of implant combinations: USS/Synex, USS/MOSS, Ventrofix/Synex, Ventrofix/MOSS. We analyzed the differences between each of the instrumentations as well as differences compared to the intact spine. RESULTS: In most directions, significantly higher stability was achieved with USS, compared with Ventrofix and the intact specimen. For axial rotation, with no instrumentation the stability of the intact spine was restored. With Synex a significantly higher stability was noted for extension, lateral bending, and axial rotation in comparison with the Harms cage. A tendency towards more stability for flexion was additionally observed with Synex. When using MOSS in combination with USS, it was necessary to perform a third operative step for induction of intervertebral compression via the posterior fixator. CONCLUSIONS: The posterior fixation was found to offer superior stability compared to the anterior one. Synex was at least comparable to MOSS for suspensory replacement of the vertebral body in the thoracolumbar spine. The evidence of higher biomechanical stability with Synex leads to the probability of a higher rigidity in vivo. Due to the distractability of Synex, a better intervertebral compression was achieved. Therefore, an additional tightening of the posterior fixator after insertion of Synex was not necessary, in contrast to the Harms cage.

Biomechanical Phenomena↗
PubMed2006

Stability of anterior vertebral body screws after kyphoplasty augmentation. An experimental study to compare anterior vertebral body screw fixation in soft and cured kyphoplasty cement.

The goal of this cadaver study was to compare the stability of anterior vertebral body screws after implantation in soft or cured kyphoplasty cement. Anterior vertebral body screws were inserted in a total of 30 thoracolumbar vertebrae of ten different human specimens: ten screws were implanted in non-augmented vertebrae (group 1), ten screws were placed in soft cement (group 2), and ten screws were placed in cured cement (group 3). The screws were then tested for biomechanical axial pullout resistance. Mean axial pullout strength was 192 N (range: 10-430 N) in group 1, 364 N (range: 65-875 N) in group 2, and 271 N (range: 35-625 N) in group 3. The paired Student's t-test demonstrated a significant difference between pullout strength of groups 1 and 2 (p= 0.0475). No significant difference was seen between pullout strength of groups 1 and 3 (p= 0.2646) and between groups 2 and 3 (p= 0.3863). We achieved a 1.9 times higher pullout strength with kyphoplasty augmentation of osteoporotic vertebrae compared with the pullout strength of non-augmented vertebrae. Implantation of anterior vertebral body screws in cured cement is a satisfactory method. With this method we found a 1.4 times higher pullout strength than non-augmented vertebrae.

Bone Cements↗
PubMed2004

The varying distribution of intra- and inter-vertebral height ratios determines the prevalence of vertebral fractures.

Credible inferences regarding the burden of vertebral fractures (VFs) cannot be made without a globally accepted quantitative definition of 'fracture'. Currently, differences in anterior, middle, or posterior vertebral heights (VHs) within a vertebra, or between adjacent vertebrae, are used to define 'fracture'. However, VH differences are essential for the construction of thoracolumbar curves, evolutionary adaptations that provide stability in bipedal stance and gait. As there is no reference standard to distinguish anatomical variation from fracture, approaches to defining a VF use a reference range of VH ratios derived in premenopausal women or derived by trimming, a method that iteratively removes the tails of a distribution of VH ratios to produce a normal distribution. From this, reference ranges of VH ratio means and standard deviations (SDs) are obtained and a nominal deviation of 15% or more, or 3 SD or more is regarded as a 'fracture'. We measured VHs by quantitative vertebral morphometry (QVM) and bone mineral density (BMD) by dual energy X-ray absorptiometry in 697 Lebanese women (age 20-89 years) to compare the prevalence of VF ascertained by published methods and a new method that uses the premenopausal range (without trimming) and requires two VH abnormalities. VF prevalence using published methods reached 60% to 70% in pre- and post-menopausal women, and in women with normal or high BMD because VH ratios were not normally distributed and cut-offs used to define VF fracture fell within the observed distribution of the data. The new method resulted in a VF prevalence of 3.3% in younger and 14% in older women, 7% (high), 10% (middle), and 20% (low) BMD tertiles consistent with the notion that the method detected VF due to bone fragility. We suggest that using a fixed trimming method to define reference range and cut-offs or applying fixed cut-offs to identify VFs in populations, where these ratios are not normally distributed, may result in the capture of anatomical variation, not structural failure. Thus, group differences in the VF prevalence may reflect differences in methodology, not bone fragility. Improved criteria to define VF are needed before credible inferences can be made regarding the burden of VFs in women and men, and between sexes, races, countries, decades, and placebo arms of clinical trials.

Absorptiometry, Photon↗
PubMed1992

Modification of vertebrate and algal prolyl 4-hydroxylases and vertebrate lysyl hydroxylase by diethyl pyrocarbonate. Evidence for histidine residues in the catalytic site of 2-oxoglutarate-coupled dioxygenases.

A search for conserved amino acid residues within the cDNA-derived amino acid sequences of 2-oxoglutarate-coupled dioxygenases revealed the presence of two distinct motifs, spaced 49-71 amino acids apart, toward the C-terminal regions of these proteins. Each of the two common motifs contains an invariant histidine residue at a conserved position. The 2-oxoglutarate-coupled dioxygenases function in diverse processes, including the post-translational hydroxylation of proline and lysine residues in vertebrate collagens and the biosynthesis of microbial cephalosporins, yet they have a common reaction mechanisms, which requires the binding of Fe2+, 2-oxoglutarate, O2 and ascorbate at the catalytic site. The two regions of homology, and specifically the identical histidines, potentially represent functionally important sites related to their catalytic activity. Modification of histidine residues by diethyl pyrocarbonate inactivated vertebrate and algal prolyl 4-hydroxylase and vertebrate lysyl hydroxylase, indicating that histidine residues function in the catalytic site of these 2-oxoglutarate-coupled dioxygenases. Inactivation was prevented by the presence of co-substrates, but not by the peptide substrate. It is proposed that the histidine residues in the conserved motifs may function as Fe(2+)-binding ligands.

Amino Acid Sequence↗