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At least 181 records · Page 10Linked to original sources
PubMed2002

Painful osteolytic metastasis of the atlas: treatment with percutaneous vertebroplasty.

STUDY DESIGN: Technical note. OBJECTIVE: To describe a technique for performing percutaneous vertebroplasty of C1 for treatment of osteolytic metastatic disease involving the lateral portions of the atlas in which precautions are taken to protect the vertebrobasilar arterial supply and a posterior access route is used for cement delivery. SUMMARY OF BACKGROUND DATA: Percutaneous vertebroplasty (PVP) has proved to be efficient for the treatment of painful osteolytic vertebral disease. Good clinical experience with this technique suggested its extension to stabilize a painful osteolytic lesion of the atlas. METHODS: A patient with known parotid cancer presented with neck pain refractory to conservative treatment. On computed tomography, osteolytic destruction of the atlas that mainly involved the right lateral mass and surrounded the vertebral artery was found. On digital subtraction angiography, the lesion was shown to be highly vascularized and supplied mainly by direct branches of the ipsilateral vertebral artery. To avoid the risk of cement reflux from the tumor vascular bed to the involved vertebral artery, coil occlusion of the involved V3 segment was performed before vertebroplasty. Percutaneous vertebroplasty was then carried out using a percutaneous posteroanterior direction access route. RESULTS: Satisfactory filling of the osteolytic lesion with cement was achieved radiologically. Three days after the intervention and at a 9-month follow-up examination, the patient was free of pain. CONCLUSIONS: Vertebroplasty used to treat an osteolytic lesion of the atlas involving the lateral mass was performed by a posterior percutaneous approach. To prevent vertebrobasilar embolism, the involved vertebral artery was occluded before polymer injection.

Aged↗
PubMed2003

Morphometric evaluation of screw fixation in atlas via posterior arch and lateral mass.

STUDY DESIGN: This study is a result of manual and radiologic measurements of 50 isolated anatomic specimens of C1 and five patients of atlantoaxial instability treated by screw fixation via posterior arch and lateral mass. OBJECTIVES: To investigate the feasibility of screw placement via posterior arch and lateral mass in atlas. SUMMARY OF BACKGROUND DATA: Several types of posterior approaches have been adopted for stabilization and fusion of atlantoaxial complex. Before this study, Gallie in 1939 gave a report on a posterior wiring technique that depended on a structural bone graft. Since then, double-looped wiring with two bone grafts and Halifax clamp technique had been introduced. A transarticular screw fixation technique was introduced by Magerl and Seeman in 1987, and a C1 lateral mass screw fixation technique was described by Harms in 2001. However, the feasibility of screw fixation in atlas via posterior arch and lateral mass has not been addressed until now. METHODS: Fifty dry samples of atlas were measured manually and radiologically with vernier calipers, protractors, and CT. The parameters of posterior arch, lateral mass, vertebral artery groove, axis length of screw path via posterior arch and lateral mass, the entry point, and screw direction were measured. Five patients of atlantoaxial instability were treated with this technique and the radiographs and CT scans were evaluated after surgery. RESULTS: The longest trajectory distance of the screw path was about 30 mm. The outer thickness at the thinnest part of groove was 4.58 mm, and it was found to be <4 mm in four cases (8%). The entry point is 18-20 mm lateral to the midline and 2 mm superior to the inferior border of posterior arch. The direction of screw placement is perpendicular to the coronal plane and about 5 degrees cephalad to the transverse plane. Ten screws via posterior arch and lateral mass were placed properly, without incidence of nerve or blood vessel injury in clinical practice. CONCLUSION: Atlas is capable for screw fixation via its posterior arch and lateral mass.

Adult↗
PubMed1988

Acute traumatic atlas fractures: management and long term outcome.

Fractures of the 1st cervical vertebra (C1) represent 7% of all acute cervical spine fractures. Isolated atlas fractures are most commonly bilateral or multiple fractures through the ring of C1. Frequently (44% of cases), the atlas will be fractured in combination with the axis. Treatment of isolated C1 fractures should be governed by the rules of Spence. The treatment of combination C1-C2 fractures is dictated by the type and severity of the C2 fracture. Experience with 57 cases of acute atlas fractures is reviewed. Nonoperative external immobilization was used in 53 patients (with 1 failure), and early surgical wiring and fusion were performed in 4 patients. The long term outcome from an atlas fracture is good (median follow-up, 40 months).

Adolescent↗
PubMedDate not supplied

Agenesis of the posterior arch of the atlas.

PURPOSE: To illustrate the radiological findings and review the current literature concerning a rare congenital abnormality of the posterior arch of the atlas. CASE REPORT: An adult female without neurological symptoms presented with an absent posterior arch of the atlas, examined with plain films and helical computerized tomography. Complete agenesis of the posterior arch of the atlas is a rare entity that can be easily identified by means of plain films. Although it is generally asymptomatic, atlantoaxial instability and neurological deficits may occur because of structural instability. Computerized tomography provides a means of assessing the extent of this abnormality and can help evaluate the integrity of neural structures. Although considered to be rare entities, defects of the posterior arch of the atlas may be discovered as incidental asymptomatic findings in routine cervical radiographs. Familiarity with this abnormality may aid medical professionals in the correct management of these cases.

Adult↗
PubMed2000

Quantitative anatomy of the lateral masses of the atlas and axis vertebrae.

The study was carried out to determine the safe site of entry and the appropriate trajectory of the screw implantation in the lateral masses of atlas (Cl) and axis (C2) during their fixation using the plate and screw technique. Fifty dried specimens of atlas and axis vertebrae were studied. Various dimensions of the lateral masses were quantitatively measured, laying stress on their relationship with the vertebral artery foramen. As the vertebral artery foramen was present entirely in the transverse process in all specimens, screw implantation in the facet of atlas was relatively safe. Best direction of screw implantation in the facet of atlas was observed to be 15 degrees medial to sagittal plane and 15 degrees superior to axial plane. It should be implanted from the middle of the posterior surface of facet. Vertebral artery foramen formed a deep groove in the undersurface of a majority of superior facets of axis. In 15% facets, vertebral artery foramen occupied the entire undersurface of the superior facet. Safe angle for screw implantation in the facet of axis through its pedicle was seen to be 40 degrees medial to sagittal plane and 20 degrees superior to axial plane. Safe site of screw entry in the axis was superior and medial third of the posterior surface of the pedicle. Quality of cancellous bone in the lateral masses in the proposed trajectory of screw in Cl and C2 was good, providing an excellent purchase of the screw.

Axis, Cervical Vertebra↗
PubMed2000

Analytical static stress analysis of first cervical vertebra (atlas).

INTRODUCTION: Fracture of the atlas was first described by Jefferson (1920). He theorised a bursting mechanism of fracture as the occipital condyles were driven into the atlas. Experimental studies by Hays and Alker (1988) and Panjabi et al (1991) were also conducted to explain the injury mechanisms. Injury mechanisms and fracture patterns are important in the clinical evaluation of spinal injuries. Recognition and interpretation of the fracture patterns help to determine the spinal instability and consequently the choice of treatment. Although the fracture mechanics of the atlas have received much attention, it has not been investigated using theoretical modelling. MATERIALS AND METHODS: A high-definition digitiser was used to obtain the geometrical data for the finite element mesh generation. Contrary to the widely used method, such as computed tomography scan for geometric extraction, the direct digitising process of the dried specimen reliably preserves the accurate topography of up to 0.1-mm interval of the original structure. The finite element model was exercised under an axial compressive mode of pressure loading to investigate the sites of failure reported in vivo and in vitro. RESULTS: Using material properties from literature, the predicted results from the 7808-finite element model demonstrate high concentration of localised stress at the anterior and posterior arch of the atlas, which agrees well with those reported in the literature. Furthermore, our results are also in good agreement with the findings reported by Panjabi et al (1991), which show that the groove of the posterior arch is subjected to enormous bending moment under simulated hyperextension conditions. CONCLUSIONS: The close agreement of the failure location provided confidence to perform further analysis and in vitro experiments. The predicted results from finite element analysis may be potentially used to supplement experimental research in understanding the clinical biomechanics of the C1.

Aged↗
PubMed2001

Ethics and access to teaching materials in the medical library: the case of the Pernkopf atlas.

Conflicts can occur between the principle of freedom of information treasured by librarians and ethical standards of scientific research involving the propriety of using data derived from immoral or dishonorable experimentation. A prime example of this conflict was brought to the attention of the medical and library communities in 1995 when articles claiming that the subjects of the illustrations in the classic anatomy atlas, Eduard Pernkopf's Topographische Anatomie des Menschen, were victims of the Nazi holocaust. While few have disputed the accuracy, artistic, or educational value of the Pernkopf atlas, some have argued that the use of such subjects violates standards of medical ethics involving inhuman and degrading treatment of subjects or disrespect of a human corpse. Efforts were made to remove the book from medical libraries. In this article, the history of the Pernkopf atlas and the controversy surrounding it are reviewed. The results of a survey of academic medical libraries concerning their treatment of the Pernkopf atlas are reported, and the ethical implications of these issues as they affect the responsibilities of librarians is discussed.

Anatomy, Artistic↗
PubMedDate not supplied

[Associations among non-metric features of the atlas in the human species].

Six non-metrical variants has been studied in a series of 500 human atlases. A bipartition of the superior articular facet has been observed in 20.8% of cases, a posterior ponticulus in 14.2% of cases, a retrotransverse ponticulus in 14.2% of cases, an anterior dehiscence of the foramen tranversarium in 10.2% of cases, a dehiscence of the posterior arch in 2.8% of cases, and a lateral ponticulus in 1.8% of cases. Bilateral occurrence has been noted in 42.2 to 46.2% of cases for the anterior dehiscence of the foramen transversarium, the posterior ponticulus, and the bipartition of the superior articular facet. Bilateral occurrence is less frequent for the retrotransverse ponticulus (29.6%), and particularly for the lateral ponticulus (11.1%). The incidence of a given lateral character according to the side has been found identical or similar on the left and on the right sides. In the present series, 51.6% of the atlases showed none of the six variants studied; 46.8% of the atlases showed one or two variants; and only 1.6% of the atlases showed more than two variants; any cases with more than four variants were observed. The most interesting association observed is the association of the lateral ponticulus with the posterior ponticulus.

Cervical Atlas↗
PubMed2004

Variants and deformities of atlas vertebrae in Eastern Anatolian people.

OBJECTIVE: At the craniocervical junction, developmental anomalies of the atlas may produce clinical symptoms by compressing on the vertebral artery, particularly during extreme rotational movements of the cervical spine. The aim of the present study was to investigate several varieties and deformities of the atlas vertebra from the skeletal specimens of Eastern Anatolian people. METHODS: This study was carried out over a 3-year period, 2000 through to 2002 in the Department of Anatomy, Firat, Yuzuncu Yil and Ataturk University, Turkey. Developmental anomalies and the variants of the first vertebrae were investigated on 86 atlas. RESULTS: Ponticulus posterior was observed with a low frequency on right as 2.3%. The bilateral localization was 10.5% and the left-side localization was 9.3%. Ponticulus lateralis showed an equal localization as 1.2% on the right, 1.2% on the left and 1.2% bilateral. In the present study, a complete subdivision of the joint surface was observed in 11 atlases (12.8%). Processus infratransversarius atlantis with a frequency between 1.2-7%, arthrotic formation and corona atlantis peridentals in 8 cases (9.3%) were also found. CONCLUSION: The low frequency for fonticulus posterior might be peculiar to the population living in this area.

Atlanto-Axial Joint↗
PubMed2004

[Experimental study of posterior pedicle screw placement on atlas].

OBJECTIVE: To assess the possibility of placing the posterior pedicle screw on atlas. METHODS: Twenty human cadaver specimens were used to insert pedicle screws in atlas, through the posterior arch or the pedicle of C1 into the lateral mass. The screw entry point was on the posterior surface of C1 posterior arch and at the intersection of the vertical line through the center of C2 inferior articular process and the horizontal line at least 3 mm below the superior rim of the C1 lamina. The screw of 3.5 mm in diameter was placed in a direction of 10 degrees medial angle and 5 dgrees upward angle. After placement of C1 pedicle screw, the distance from C1 screw entry point to the medial-lateral midpoint of C1 pedicle, the maximum length of screw trajectory and the actual screw trajectory angles were measured. The direction of screw penetrating through the cortical of C1 pedicle or lateral mass and the injuries to the vertebral artery and spinal cord were observed. RESULTS: Forty pedicle screws were placed on atlas, the mean distance from C1 screw entry point to the medial-lateral midpoint of C1 pedicle was (2.20 +/- 0.42)mm, the maximum length of screw trajectory averaged (30.51 +/- 1.59)mm, and the actual screw trajectory angle measured (9.7 +/- 0.67)degrees in a medial direction and (4.6 +/- 0.59)degrees in a upward direction. Only 1 screw penetrated the upper cortical bone of the atlas pedicle because the upward angle was too large, and 8 screws were inserted so deep that the inferior cortical bone of the C1 lateral mass was penetrated. But no injuries to the vertebral artery and spinal cord were observed. CONCLUSION: C1 posterior pedicle screw fixation is quite accessible and safe, but the surgeons should pay attention to the angle and the depth of the screw placement.

Adult↗
PubMed2006

[C1 lateral mass-C2 pedicle screws and crosslink compression fixation for instable atlas fracture].

OBJECTIVES: To evaluate the feasibility and reliability of C(1) lateral-mass screw-C(2) pedicle screw and crosslink compression fixation for Jefferson fracture. METHODS: Seventeen patients with atlas fracture, 12 males and 5 females, aged 42.5 (25 - 67), 4 of which with unstable atlas fracture, were treated. 11 cases underwent C(1) lateral mass and C(2) pedicle screws and crosslink fixation, 6 of which had axial instability and rupture of atlas transverse ligament, 1 had C(2) luminal fracture, and the other 4 had axial instability. With the assistant of regional anatomy study and fluoroscopy the C(1) lateral mass screw and C(2) pedicle screw were inserted properly. Connecting rods were applied into the two screws on each side. Crosslink between the two rods were applied, compressing to achieve the realignment of the C(1) lateral mass fracture and C(0)-C(1)-C(2) into anatomical position. C(1)-C(2) fusions with posterior bone graft were performed in the patients with axial instability or transverse ligament discontinuity. RESULTS: The operative time ranged from 90 to 176 min with an average of 124 min. The intra-operative blood loss ranged from 270 to 1200 ml with an average of 432 ml. Fluoroscopic examination was used for 18 seconds on average. There were no neurological deficits, vertebral artery related complications or other complications in all the patients. No neurological deficit was aggravated after the patient's mobilization with brace 5 days after operation. One case of vertebral artery rupture happened because of the use of electrocautery. The bleeding was stopped by the use of hemostatic sponge and bone cement without causing cerebral hemodynamic deficit. X-ray examination showed bone fusion and stability in all the patients three months after the operation. The restoration of the C(2) fracture was confirmed by CT scan. CONCLUSION: Osteosynthesis of the atlas by C(1) lateral-mass screw-C(2) pedicle screw and crosslink compression fixation is an ideal option for C(1) burst fracture with or without rupture of transverse ligament. The procedure allows a physiological reconstruction of the C(0)-C(1)-C(2) joint and short segmental solid fusion for Jefferson fracture.

Adult↗
PubMed1989

[Isolated fracture of the lateral mass of the atlas: a case report].

Isolated fracture of the lateral mass of the atlas is extremely rare. The authors report such a case because of its rarity and to emphasize the usefulness of computed tomography (CT) for its diagnosis. The case was that of a 63-year-old male, who had been hit on his left parietal region by a board falling from behind, and which forced him to hyperflex his neck. He complained of neck pain on arrival at our hospital without any resulting neurological deficits. Routine plain cervical spine films were normal, but CT scan revealed a vertical fracture of the lateral mass of the atlas. He was placed in a Halo brace for several months, and after 3 months the fracture was seen, by CT scan, to have healed without complications. Fractures of the atlas are uncommon. They comprise 2-13% of all fractures of the cervical spine, and about 1.3% of the fractures of the entire spinal column. An isolated fracture of the lateral mass of the atlas has been reported only in seven cases including our case previously and this is the first case in which CT scan could make the diagnosis. We emphasize that CT scan is a most useful tool for the diagnosis of the fracture.

Braces↗
PubMed1982

Roentgenographic measurement of atlas laterality and rotation: a retrospective pre- and post-manipulation study.

Case records (523) were chosen at random from the files of J.F. Grostic, D.C. (deceased) for retrospective determination of the effects of chiropractic adjustments on atlas positioning relative to the occiput and axis. For each patient the recorded degrees of (1) atlas rotation and (2) laterality, both before and soon after spinal manipulative therapy, were extracted from the x-ray reports. Frequency histograms were made of pre- and post-adjustment degrees of laterality and rotation and the relative change of values analyzed statistically. Before manipulation, nine patients had zero atlas rotation and none were zero with respect to laterality. The mean deviation from zero degrees of "misalignment," was 2.75 and 2.63 respectively for rotation and laterality. After manipulation the corresponding values were 1.43 and 140, which is a statistically significant change. The numbers of patients who had zero rotations and laterality after adjustment were 156 and 151 respectively. In 63 patients the post-adjustment values were zero for both parameters. Under the circumstances presented in this retrospective study, these data tend to show that spinal manipulative therapy altered the position of atlas in the postulated direction.

Atlanto-Occipital Joint↗
PubMed1994

Congenital defects of the posterior arch of the atlas: a report of seven cases including an affected mother and son.

PURPOSE: To describe our experience with congenital anomalies of the posterior arch of the atlas, with a review and classification of these defects and a note on their clinical significance. METHODS: We report six children and one adult, the mother of one of the children, with an anomalous posterior arch of the atlas. The diagnosis was made on lateral films of the neck. Three patients also had axial CT of the cervical spine. RESULTS: The anomalies encountered in the seven patients were absence of the posterior arch of the atlas (four patients), bilateral clefts (two patients), and unilateral cleft (one patient). In three patients the anomaly was discovered as an incidental asymptomatic finding; three other patients presented with transient neck pain or transient neurologic symptoms after head and neck trauma, and one patient (an adult woman) described neck symptoms of 1-year duration. CONCLUSIONS: On the basis of these seven cases we conclude that congenital defects of the posterior arch of the atlas may be discovered as incidental asymptomatic findings, but symptoms occurring after trauma to the head and neck or spontaneously also may be encountered.

Adult↗
PubMed2000

Mathematical/computational challenges in creating deformable and probabilistic atlases of the human brain.

Striking variations in brain structure, especially in the gyral patterns of the human cortex, present fundamental challenges in human brain mapping. Probabilistic brain atlases, which encode information on structural and functional variability in large human populations, are powerful research tools with broad applications. Knowledge-based imaging algorithms can also leverage atlased information on anatomic variation. Applications include automated image labeling, pathology detection in individuals or groups, and investigating how regional anatomy is altered in disease, and with age, gender, handedness and other clinical or genetic factors. In this report, we illustrate some of the mathematical challenges involved in constructing population-based brain atlases. A disease-specific atlas is constructed to represent the human brain in Alzheimer's disease (AD). Specialized strategies are developed for population-based averaging of anatomy. Sets of high-dimensional elastic mappings, based on the principles of continuum mechanics, reconfigure the anatomy of a large number of subjects in an anatomic image database. These mappings generate a local encoding of anatomic variability and are used to create a crisp anatomical image template with highly resolved structures in their mean spatial location. Specialized approaches are also developed to average cortical topography. Since cortical patterns are altered in a variety of diseases, gyral pattern matching is used to encode the magnitude and principal directions of local cortical variation. In the resulting cortical templates, subtle features emerge. Regional asymmetries appear that are not apparent in individual anatomies. Population-based maps of cortical variation reveal a mosaic of variability patterns that segregate sharply according to functional specialization and cytoarchitectonic boundaries.

Aged↗
PubMed1999

Exploring spatial patterns of mortality: the new atlas of United States mortality.

The National Center for Health Statistics, CDC, has produced an Atlas of United States Mortality which includes maps of rates for the leading causes of death in the United States for the period 1988-1992. As part of this project, many aspects of statistical mapping have been re-examined to maximize the atlas's effectiveness in conveying accurate mortality patterns to epidemiologists and public health practitioners. Because recent cognitive research demonstrated that no one map style is optimal for answering many different map questions, maps and graphs of several different mortality statistics are included for each cause of death. New mixed effects models were developed to provide predicted rates and improved variance estimates. Results from these models were smoothed using a weighted head-banging algorithm to produce maps of general spatial trends free of background noise. Maps of White female lung cancer rates from the new atlas are presented here to illustrate how this innovative combination of maps and graphs permits greater exploration of the underlying mortality data than is possible from previous single-map atlas designs. Published in 1999 by John Wiley & Sons, Ltd. This article is a U.S. Government work and is in the public domain in the United States.

Adult↗
PubMed2001

Three-dimensional digital mouse atlas using high-resolution MRI.

We present an archetypal digital atlas of the mouse embryo based on microscopic magnetic resonance imaging. The atlas is composed of three modules: (1) images of fixed embryos 6 to 15.5 days postconception (dpc) [Theiler Stages (TS) 8 to 24]; (2) an annotated atlas of the anterior portion of a 13.5 dpc (TS 22) mouse with anatomical structures delineated and linked to explanatory files; and (3) three-dimensional renderings of the entire 13.5 dpc embryo and specific organ systems. The explanatory files include brief descriptions of the structure at each volume element in the image and links to 3D reconstructions, allowing visualization of the shape of the isolated structures. These files can also contain or be linked to other types of information and data including detailed anatomical and physiological information about structures with pointers to online references, relationships between structures, temporal characteristics (cell lineage patterns, size, and shape changes), and gene expression patterns (both spatial and temporal). As an example, we have "painted" in the expression pattern of Dlx5/Dlx6 genes. This digital atlas provides a means to put specific data within the context of normal specimen anatomy, to analyze the information in 3D, and to examine relationships between different types of information.

Animals↗
PubMed1994

Mouse lemur microscopic MRI brain atlas.

We present a three-dimensional (3D) digital atlas of a mouse lemur head at 60-micron cubic voxel isotropic resolution. It was constructed from a 3D proton magnetic resonance image (MRI) acquired at 500 MHz. It shows views of 3D volume-rendering and movies of contiguous 2D plane cuts in three orthogonal directions. This MR data set was acquired using a spin-echo pulse sequence under conditions of strong T2 and significant diffusion weighting. Experimental parameters were optimized to provide strong intrinsic contrast between gray and white matter. Familiar anatomical structures are clearly identifiable. Fine fiber tracts, laminations of cortices, details of the inner ears, and layering in the lateral geniculate nuclei are all visible. Anatomical identifications of structures in representative slices selected from the atlas are presented. We also describe some difficulties and trade-offs encountered in microscopic resolution MRI. We note that this type of atlas does not suffer from the spatial distortions and slice registration problems introduced by standard histological techniques. Future in vivo longitudinal studies will provide atlases describing in detail the development of the primate brain.

Animals↗