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At least 127 records · Page 7Linked to original sources
PubMed1975

Lesions of the atlas and axis.

The atlas and axis support the head on the lower cervical spine while providing for considerable mobility in flexion, extension, rotation and lateral bending. The first two vertebrae also function as conduits for the cervical cord and vertebral arteries. Lesions of the atlas and axis, therefore, can cause instability with loss of support and encroachment on the upper cord and vertebral arteries, or less often stiffness with restricted motion. Congenital lesions of the occipito-cervical spine such as occipitalization of the atlas or accessory occipital vertebrae can constrict the upper cord with osseous, dural, or fibrous compression. Such encroachment on the cord at this level produces a varying array of clinical complaints and findings frequently difficult to interpret. Instability of the upper cervical spine can result from congenital, traumatic, inflammatory or neoplastic disruptions of the interlocking mechanism of the atlas and axis. Such factors as the loss of structural integrity of the dens or stretching or tearing of the transverse ligament can permit instability with cord involvement. Because of the serious potential of these lesions, patients with abnormalities of the atlas and axis require prompt recognition and treatment.

Adolescent↗
PubMed2001

Cervical myelopathy and congenital stenosis from hypoplasia of the atlas: report of three cases and literature review.

STUDY DESIGN: Case reports of patients with cervical myelopathy to hypoplasia of the atlas. OBJECTIVES: To report cases of cervical myelopathy due to congenital hypoplasia of the atlas and to review the literature. SUMMARY OF BACKGROUND DATA: Six previously documented cases of congenital hypoplasia of the atlas as a cause of cervical myelopathy are reported in the literature. METHODS: Three patient's clinical record and radiologic imaging studies as well as a thorough literature search are reported. Plain radiographs, computed tomography scans, magnetic resonance images, as well as somatosensory-evoked potential changes are displayed. RESULTS: Cervical myelopathy developed in three patients who were found to have congenital hypoplasia of the atlas. Laminectomy of C1 provided neurologic improvement in all three patients presented. CONCLUSION: Congenital hypoplasia of the atlas is a rare cause of cervical myelopathy. This report should broaden the radiographic differential diagnosis when seeking an explanation for the signs and symptoms of cervical myelopathy.

Adult↗
PubMed2004

Bipartite atlas with os odontoideum: case report.

STUDY DESIGN: A case report of bipartite atlas associated with os odontoideum and review of the pertinent literature are presented. OBJECTIVE: To illustrate an unusual association of bipartite atlas and os odontoideum and explain the embryological basis. SUMMARY OF BACKGROUND DATA: To the authors' knowledge, only one case of bipartite atlas with os odontoideum had been reported previously. Most of the previously reported cases of bipartite atlas are asymptomatic. METHODS: A 16-year-old boy presented with a 2-month history of weakness and numbness of all four limbs after sustaining a minor head trauma. Radiographs of cervical spine revealed aplasia of anterior arch of atlas, ventral displacement of C1 over C2 on flexion, which reduced on extension. CT scan showed anterior arch aplasia, posterior arch midline defect, and os odontoideum, which had a small projection on the anterior surface at the level of anterior arch. MRI demonstrated increased cord signal at C1-C2 levels on T2-weighted image. Transoral odontoidectomy and posterior fixation of occiput with C2-C3 spinous processes was performed. RESULTS: The patient had significant improvement over next 3 months. CONCLUSIONS: We described a rare association of an anterior arch aplasia, posterior arch defect and os odontoideum. The natural history of patients with os odontoideum suggests that these people have a potentially precarious existence.

Adolescent↗
PubMed2004

Eosinophilic granuloma of the atlas presenting as torticollis in a child.

STUDY DESIGN: This report describes a case of successful surgical treatment of eosinophilic granuloma of the atlas in a 3.5-year-old boy who presented with torticollis. OBJECTIVE: The purpose of this report was to illustrate the rare clinical presentation of eosinophilic granuloma in the atlas. SUMMARY OF BACKGROUND DATA: Eosinophilic granuloma, a benign solitary lesion that commonly affects children, has a variable clinical course. Although eosinophilic granuloma has been reported to occur in the cervical spine, there have been only five reported cases of eosinophilic granuloma affecting the atlas. The management of eosinophilic granuloma ranges from observation and immobilization of the cervical spine to surgical excision. METHODS: The tumor was located on the left lateral mass of the atlas. Biopsy and curettage were performed through an oblique incision through the posterior border of the sternocleidomastoid muscle. A histopathologic evaluation confirmed the diagnosis of eosinophilic granuloma. RESULTS: The patient tolerated the procedure with no complications, and his torticollis has completely resolved. CONCLUSION: Eosinophilic granuloma of the atlas initially presented in this patient as torticollis. Biopsy for confirmation of diagnosis and curettage for treatment provided a successful outcome in this patient. We suggest biopsy of the lesion and histopathologic evaluation to confirm the diagnosis in atypical cases.

Cefazolin↗
PubMed2004

Mobile and reducible atlantoaxial dislocation in presence of occipitalized atlas: report on treatment of eight cases by direct lateral mass plate and screw fixation.

STUDY DESIGN: This is a retrospective review on the application of the authors' technique of atlantoaxial lateral mass plate and screw fixation on a rare subset of patients having mobile and reducible atlantoaxial subluxation in the presence of occipitalized atlas. OBJECTIVE: Mobile and reducible atlantoaxial dislocation in the presence of an occipitalized atlas is extremely rare. We retrospectively analyzed the management of eight such patients who were treated by lateral mass plate and screw fixation. SUMMARY OF BACKGROUND DATA: The authors report their experience with a rare congenital craniovertebral anomaly where there was a mobile and reducible atlantoaxial dislocation in the presence of the occipitalized atlas. The cases were treated by lateral mass plate and screw method of treatment described by the authors in 1994. METHODS: Eight patients with occipitalized atlas had a mobile and completely reducible atlantoaxial dislocation. These patients were treated between the years 1996 to 2003 and underwent a direct atlantoaxial lateral mass fixation. The follow-up ranges from 4 months to 6 years (average, 48 months). RESULTS: All patients underwent a successful fixation and ultimately achieved a solid bony fusion. There were no intraoperative or postoperative complications. CONCLUSIONS: Although lateral mass plate and screw fixation in the presence of occipitalized atlas is technically a relatively difficult and anatomically a precise surgical procedure, the firm and segmental stabilization that it provides offers an optimum situation for bony fusion.

Adolescent↗
PubMed2004

A case of Collet-Sicard syndrome associated with traumatic atlas fractures and congenital basilar invagination.

An 18 year old man with congenital basilar invagination developed multiple lower cranial nerve (CN) palsies including CN IX to XII after a traffic accident. Computed tomography of his skull base revealed a two part atlas Jefferson fracture. Normally, lower cranial nerves (CN IX-XII) pass through a space between the styloid process and the atlas transverse process. Atlas burst fractures rarely cause neurological deficits because of a greater transverse and sagittal diameter of the spinal canal at the atlas, and a tendency of the lateral masses to slide away from the cord after injury. However, when associated with a rare condition-congenital basilar invagination-atlas fractures can compromise the space and make CN IX-XII more vulnerable to compression injury. This report discusses the correlation between the anatomical lesions and clinical features of this patient.

Accidents, Traffic↗
PubMed2003

The informatics of a C57BL/6J mouse brain atlas.

The Mouse Atlas Project (MAP) aims to produce a framework for organizing and analyzing the large volumes of neuroscientific data produced by the proliferation of genetically modified animals. Atlases provide an invaluable aid in understanding the impact of genetic manipulations by providing a standard for comparison. We use a digital atlas as the hub of an informatics network, correlating imaging data, such as structural imaging and histology, with text-based data, such as nomenclature, connections, and references. We generated brain volumes using magnetic resonance microscopy (MRM), classical histology, and immunohistochemistry, and registered them into a common and defined coordinate system. Specially designed viewers were developed in order to visualize multiple datasets simultaneously and to coordinate between textual and image data. Researchers can navigate through the brain interchangeably, in either a text-based or image-based representation that automatically updates information as they move. The atlas also allows the independent entry of other types of data, the facile retrieval of information, and the straight-forward display of images. In conjunction with centralized servers, image and text data can be kept current and can decrease the burden on individual researchers' computers. A comprehensive framework that encompasses many forms of information in the context of anatomic imaging holds tremendous promise for producing new insights. The atlas and associated tools can be found at http://www.loni.ucla.edu/MAP.

Anatomy, Artistic↗
PubMed2001

Atlas hypoplasia manifesting as myelopathy in a child--case report.

A 14-year-old Japanese boy presented with myelopathy due to atlas hypoplasia with complete posterior arch. Decompressive laminectomy of the atlas produced good neurological recovery, and follow-up T2-weighted magnetic resonance imaging showed disappearance of spinal cord edema. Congenital atlas stenosis may be symptomatic even in children, with no accompanying cervical spondylotic change. Such cases have previously occurred only in Asian adults. A radiological study of the patient's brother showed median cleft formation of the posterior arch of atlas, indicative of a wide spectrum of atlas anomalies and a possible genetic relationship between these anomalies.

Adolescent↗
PubMed2003

Cervical myelopathy caused by hypoplasia of the atlas and ossification of the transverse ligament--case report.

A 79-year-old Japanese female presented with symptomatic cervical myelopathy caused by a hypoplastic posterior arch of the atlas and ossification of the transverse ligament. Neuroradiological examination demonstrated a hypoplastic posterior arch of the atlas and ossification of the transverse ligament. The cervical spinal cord was compressed at the level of the atlas by both the hypoplastic posterior arch of the atlas and the ossification of the transverse ligament. The patient underwent C-1 laminectomy, which arrested the progressive myelopathy and resulted in a good recovery. Atlas hypoplasia with ossification of the transverse ligament may be associated with Asian ethnicity.

Aged↗
PubMed2002

[Atlas burst fracture (Jefferson fracture) requiring surgical treatment after conservative treatment--report of two cases].

Most cases of atlas burst fracture do not require surgical stabilization, because they can be successfully treated with external immobilization. The authors present two cases of atlas burst fracture in which surgical stabilization was required after external immobilization. The first patient was a 50-year-old male and the second patient was a 34-year-old male. Both presented with neck pain without neurological symptoms after a traffic accident. Neuroradiological examinations revealed atlas burst fracture in both patients. They were initially treated with conservative treatment; one with a rigid collar and the other with a halo vest. However, lateral offset of the atlas on the axis increased and atlanto-axial instability became evident three months later in both patients. They underwent upper cervical arthrodesis with satisfactory results. The authors review surgical indication and its timing in patients with atlas burst fracture.

Adult↗
PubMed2004

[Isolated fractures of the atlas].

PURPOSE OF THE STUDY: To present the current tends in the diagnosis and management of isolated atlas fractures based on the retrospectively evaluated group of patients with this trauma. MATERIAL: In the period from 1995 to 2002, we treated 486 injuries to the cervical spine at our department. Out of these, 19 patients sustained an isolated fracture of the first cervical vertebra. This group consisted of 12 men and seven women; the average age was 46.6 years. Neurological findings in 18 patients were classified as Frankel E and, in one, as Frankel A. The causes of injury included a fall from height in five patient, a fall in the street in five pedestrians, a car accident in five patients, a dive into shallow water in three and a shooting injury in one patient. METHODS: We treated 16 patients conservatively, using a halo-vest in eight patients and a Philadelphia collar also in eight patients. In two patients with unstable atlas injury, we carried out C1-C2 transarticular stabilization according to Magerl. In the patient who had been shot, we removed the bullet transorally. RESULTS: All patients healed completely without signs of instability. One patient with postraumatic pentaplegia, who died within 24 h of surgery due to septic shock, had not been included in the follow-up. Two patients reported neck pain at rest, three after exercise and 13 were without any pain. The patient after C1-C2 transarticular stabilization had a significant restriction of the range of motion in the cervical spine; the rest of the patients were without limitation. None of the patients showed any deterioration of neurological findings during the treatment, nor was any post-traumatic atlantoaxial instability recorded after the therapy was completed. DISCUSSION: Isolated fractures of the atlas account for 1 to 2% of all spinal fractures. Many fractures may remain unnoticed and, therefore, it is important to X-ray patients with a symptomatic injury to the cervical spine in three standard projection planes (anteroposterior, lateral and transoral). When a fracture of the atlas is suspected, it is necessary to examine them by computed tomography to obtain a more accurate presentation of fracture lines. Views on the method of treating isolated fractures of the atlas, particularly unstable ones, are not consistent. CONCLUSIONS: Isolated fractures of the first cervical vertebra, in terms of therapy, are stable and unstable. Stable fractures heal within 8 to 12 weeks. A Philadelphia collar or halo-vest provide sufficient immobilization. Surgical stabilization or a halo-vest immobilization for a period of 12 weeks are recommended in unstable injuries that are characterized by the lateral mass displacement of more than 7 mm or extension of the space before the dens (predental space) by more than 3 mm, or in which magnetic resonance imaging demonstrated injury to the transverse ligament. After the halo-vest removal, it is necessary to perform functional examination of the cervical spine for detection of potential atlantoaxial instability.

Adolescent↗
PubMed2006

[Reliability of direct probing isthmus of axial vertebrae to defining the screw path in atlas during Magerl technique].

OBJECTIVE: To evaluate the accuracy and reliability of atlantoaxial transarticular screw insertion (Magerl's technique) in atlas under lateral fluoroscopic monitoring without anteroposterior view. METHOD: Seventy-five consecutive patients with atlantoaxial instability, 48 males and 27 females, aged 35.1, were treated by Magerl's technique. The screw path in atlas was achieved by direct probing the isthmus of axial vertebrae then identifying its position through the atlantoaxial joint correlation. Postoperative transoral X ray and CT film were used for analysis of the position of the 150 screws in the mass of atlas. Three areas were delimitated in and around the lateral mass of atlas: area A (inside the joint face), area: B (outside the joint face but still in lateral mass), and area C area (outside the lateral mass) so as to analyze the location of screws. RESULTS: Among the 150 screws 139 (92.7%) were located in area A, 8 in area B(1) and 3 in area B(2) (7.3%), and none in area C. All cases got atlantoaxial union 3 months after operation. CONCLUSION: The method of "direct probing" is reliable for identifying the path of screw in atlas.

Adolescent↗
PubMedDate not supplied

Unstable Jefferson variant atlas fractures: an unrecognized cervical injury.

We retrospectively reviewed the plain films and CT scans of 11 unstable atlas fractures from a series of 72 atlas fractures to better characterize these injuries and to determine if the correct diagnosis could have been made. These 11 atlas fractures were unstable because either the anterior bony ring was disrupted (six cases), the posterior longitudinal ligament was torn (one case), or both the anterior bony ring and the posterior longitudinal ligament were disrupted (four cases), allowing C1-C2 subluxation to occur. Although all the fractures were potentially unstable, only eight demonstrated subluxation on the lateral radiography. Despite the abnormal open mouth view in all cases, the plain films showed minimal abnormalities, requiring CT for definitive diagnosis. Less than half (five of 11) of the patients had other levels of spine injury or associated transverse ligament tear. Three of the 11 patients were quadriplegic, and two died as a result of their spinal cord injury. These unstable atlas fractures were similar to the classical Jefferson fracture in appearance and mechanism, except that they had fewer than four breaks in the atlas ring and were associated with severe neurologic injury and lower level spine injuries. The pattern of bilateral anterior arch fractures was associated more often with neurologic injury. Because of these differences, we chose to refer to them as Jefferson variant fractures to distinguish them from the classical Jefferson fracture and to emphasize the seriousness of this injury.

Cervical Atlas↗
PubMed1998

The effect of atlas anterior translation and rotation on axis canal size. A computer-assisted anatomic study.

Eighteen adult paired atlas and axis specimens were used in conjunction with computer analysis to determine the average transverse canal area of the axis after different degrees of anterior translation and three types of rotation of the atlas. After each displacement, the remaining transverse canal area of the axis was calculated. The data showed that the mean transverse canal area of the axis was 351.5 +/- 8.8 mm2 for males and 276.9 +/- 8.6 mm2 for females, respectively. After a 3-, 4-, and 5-mm anterior translation of the atlas, the mean transverse canal area of the axis decreased to 300.4 +/- 5.1 mm2 (85.5%) for males and 238.0 +/- 2.1 mm2 (85.9%) for females, 283.9 +/- 5.9 mm2 (80.8%) for males and 228.5 +/- 3.1 mm2 (82.5%) for females, and 260.4 +/- 4.2 mm2 (74.1%) for males and 216.4 +/- 2.8 mm2 (78.2%) for females, respectively. After a 40 degree rotation, 40 degree rotation with 4-mm anterior translation, and 40 degree rotation with 8-mm anterior translation of the atlas, the mean transverse canal area of the axis for both sexes decreased approximately to 58%, 42%, and 23%, respectively. This study confirmed that the size of the transverse canal area of the axis was consistently correlated with the degrees of the anterior translation and rotation of the atlas.

Adult↗
PubMed2005

Three-dimensional average-shape atlas of the honeybee brain and its applications.

The anatomical substrates of neural nets are usually composed from reconstructions of neurons that were stained in different preparations. Realistic models of the structural relationships between neurons require a common framework. Here we present 3-D reconstructions of single projection neurons (PN) connecting the antennal lobe (AL) with the mushroom body (MB) and lateral horn, groups of intrinsic mushroom body neurons (type 5 Kenyon cells), and a single mushroom body extrinsic neuron (PE1), aiming to compose components of the olfactory pathway in the honeybee. To do so, we constructed a digital standard atlas of the bee brain. The standard atlas was created as an average-shape atlas of 22 neuropils, calculated from 20 individual immunostained whole-mount bee brains. After correction for global size and positioning differences by repeatedly applying an intensity-based nonrigid registration algorithm, a sequence of average label images was created. The results were qualitatively evaluated by generating average gray-value images corresponding to the average label images and judging the level of detail within the labeled regions. We found that the first affine registration step in the sequence results in a blurred image because of considerable local shape differences. However, already the first nonrigid iteration in the sequence corrected for most of the shape differences among individuals, resulting in images rich in internal detail. A second iteration improved on that somewhat and was selected as the standard. Registering neurons from different preparations into the standard atlas reveals 1) that the m-ACT neuron occupies the entire glomerulus (cortex and core) and overlaps with a local interneuron in the cortical layer; 2) that, in the MB calyces and the lateral horn of the protocerebral lobe, the axon terminals of two identified m-ACT neurons arborize in separate but close areas of the neuropil; and 3) that MB-intrinsic clawed Kenyon cells (type 5), with somata outside the calycal cups, project to the peduncle and lobe output system of the MB and contact (proximate) the dendritic tree of the PE1 neuron at the base of the vertical lobe. Thus the standard atlas and the procedures applied for registration serve the function of creating realistic neuroanatomical models of parts of a neural net. The Honeybee Standard Brain is accessible at www.neurobiologie.fu-berlin.de/beebrain.

Anatomy, Artistic↗
PubMed2005

Automated atlas-based clustering of white matter fiber tracts from DTMRI.

A new framework is presented for clustering fiber tracts into anatomically known bundles. This work is motivated by medical applications in which variation analysis of known bundles of fiber tracts in the human brain is desired. To include the anatomical knowledge in the clustering, we invoke an atlas of fiber tracts, labeled by the number of bundles of interest. In this work, we construct such an atlas and use it to cluster all fiber tracts in the white matter. To build the atlas, we start with a set of labeled ROIs specified by an expert and extract the fiber tracts initiating from each ROI. Affine registration is used to project the extracted fiber tracts of each subject to the atlas, whereas their B-spline representation is used to efficiently compare them to the fiber tracts in the atlas and assign cluster labels. Expert visual inspection of the result confirms that the proposed method is very promising and efficient in clustering of the known bundles of fiber tracts.

Algorithms↗
PubMed2005

Construction of a 4D statistical atlas of the cardiac anatomy and its use in classification.

In this paper we present a novel method for building a 4D statistical atlas describing the cardiac anatomy and how the cardiac anatomy changes during the cardiac cycle. The method divides the distribution space of cardiac shapes into two subspaces. One distribution subspace accounts for changes in cardiac shape caused by inter-subject variability. The second distribution subspace accounts for changes in cardiac shape caused by deformation during the cardiac cycle (i.e. intra-subject variability). Principal component analysis (PCA) have been performed in order to calculate the most significant modes of variation of each distribution subspace. During the construction of the statistical atlas we eliminate the need for manual landmarking of the cardiac images by using a non-rigid surface registration algorithm to propagate a set of pseudo-landmarks from an automatically landmarked atlas to each frame of all the image sequences. In order to build the atlas we have used 26 cardiac image sequences from healthy volunteers. We show how the resulting statistical atlas can be used to differentiate between cardiac image sequences from patients with hypertrophic cardiomyopathy and normal subjects.

Algorithms↗
PubMed1995

An elastic computerized brain atlas for the analysis of clinical PET/SPET data.

An elastic computerized brain atlas was developed for the analysis of positron emission tomography/single-photon emission tomography (PET/SPET) data. It consists of a set of digital anatomical contours and a template of regions of interest, schematically describing the brain, derived from a currently used anatomical/functional brain atlas. A warping algorithm, matching equivalent contours, was implemented to elastically fit the atlas to individual brain images. The elastic computerized brain atlas was applied to representative magnetic resonance imaging (MRI)-PET/SPET studies, MRI providing the anatomical information used by the matching procedure. The atlas is suited for clinical use in a nuclear medicine environment.

Brain↗