Atlas-dens interval (ADI) in children: a survey based on 200 normal cervical spines.
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Axis, Cervical Vertebra↗
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[Axial mesenchyme structure in the anlage of the human vertebral column. Light microscopy study of a human embryo of 9 mm CRL (Carnegie stage 16)].
The anlage of the cervical vertebral column of a human embryo has been investigated (9 mm CRL, Carnegie stage 16). The nuclear density in the axial mesenchyme increases rhythmically from cranial to caudal. This phenomenon superimposes a metameric pattern on the blastema. Furthermore, cell formations are shaped by the orientation of the mesenchymal cells. The name 'formationes quasi distensae' is proposed for this system. The anlage of the atlas shows a distinct mesenchymal anlage of a vertebral body. The conclusion is drawn that the dens axis is predominantly formed out of the anlage of the atlas body. The opinion that man does not show an anlage of the atlas body can no longer be sustained.
Cervical Vertebrae↗
The odontoid process in children--is it hypoplastic?
An analysis of the cervical spine of 508 normal children aged between 3 and 18.9 years provided data for the normal development of the odontoid process and its relationship to the anterior arch of the atlas. In normal children under the age of 9 years, the tip of the odontoid may fall well short of the upper margin of the anterior arch of the atlas. This has important implications for the assessment of atlanto-axial instability in children with Down's syndrome.
Adolescent↗
[Atlas displacement as he result of inflammatory changes or surgery of the nasopharynx. Clinical picture based on Grisel and Hadley].
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Adolescent↗
[X-ray studies of the brain as a basis for stereotaxy (author's transl)].
All attempts to reconstruct the topography of the brain in the living from studies of animal material are handicapped by technical difficulties. The best method is to compare exact X-ray pictures, which have been taken under stereotactic conditions. From a large collection of such X-rays the authors have composed contours of the internal table of the skull and of the ventricles, which best match the brains, selected for the Schaltenbrand-Bailey sterotactic atlas. For practical purposes these contours were combined with the transparent overlays for the nomenclature and the border lines of the different parts of the basal ganglia, which have been used in the myelin sections part of the atlas. A comparison of our sagittal series with the new X-ray findings shows, that the sagittal schemata of the atlas represent an extreme variation in the position of the Meynert axis and of the contours of the 4th ventricle. We have chosen a new axis system for the hindbrain, which corresponds to the average of our brains in constructing a new set of typical overlays for the atlas. The contour of the posterior fossa had to be completed. An independent axis system dor the structures of the 4th ventricle was developed, consisting of the base of the 4th ventricle, and a tangent, to the upper contour of the pons. In sterotactic procedures the axis systems for the forebrain and the hindbrain should be used independently. The results obtained are the basis for a new series of lantern slides which can be projected against the X-ray pictures with the Würzburg stereotactic equipment. In the course of this investigation we discovered a source of error. When air enters the puncture hole of the dura, the brain may sink back, so with the patient lying on his back, all structures may shift a few millimeters towards the occipital region. When the patient is lying on his side, as during an approach to the amygdala through the planum temporale, the ventricular system may collapse, so that almost no air is visible in the ventricles and the 3rd ventricle may appear to be in the lower hemisphere, the dislocation being more than 5-8 mm. But filling the ventricle with air through the ventricular catheter is sufficient to blow up the brain and to restore the normal topography.
Brain↗
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↗
Associations between atlantoaxial and craniomandibular anatomy.
Roentgen-cephalometric studies have shown that anatomical features of the craniocervical junction are associated with head posture, cranial base angulation, and mandibular shape and growth. The aim of the present work was to study relationships between atlantoaxial and craniofacial morphology based on macroscopical observations of skeletal material derived from 38 prehistoric Polynesian and 53 prehistoric Thai people. The two uppermost cervical vertebrae and the mandible of each individual were studied macroscopically and each skull base was analyzed on cephalometric X-rays in lateral projection. The height of the atlantal anterior and posterior arches displayed a significant negative correlation with the cranial base angulation, in that the higher the arches the steeper the flexure between the sphenoidal/clival and clival/foraminal planes. None of the axial variables were associated with the cranial base angulation. The height of the atlantal posterior arch was also associated with the mandibular length, ramal height and gonial angle. Thus, in general, a high arch was seen in conjunction with a long, high and square shaped mandible, whereas a low arch was usually found together with a short and low mandible characterized by an obtuse jaw angle. The anterior height of the axis (vertebral mass + dens) was significantly associated with mandibular length and ramal height. It is suggested that these results are evidence of the intimate ontogenetic development of the atlas and the cranial base, and a reflection of the functional relationship between atlas and cranium.
Anthropology↗
Skeletal aspects of the atlanto-occipital fusion in a Japanese brown calf.
Atlanto-occipital fusion in a Japanese Brown calf was examined morphologically, paying special attention to skeletal changes. At the craniovertebral junction, the basal occipital bone fused to the cranial extremity of the ventral arch of the atlas with the rudiment of the atlantal centrum. The dens was not formed at the axis. These changes suggest that a hypocentrum and a centrum of the atlas derived from the first cervical sclerotome had failed to separate the occipital base from the proatlantal sclerotome including the apical element of the dens. Although a developmental disturbance at the cervical and thoracic vertebrae was also associated, critical neurological signs such as ataxia and paralysis were absent.
Animals↗
[Different images of the atlanto-axial joint based on lateral flexion].
If lateral flexion results in narrowing of one of the two atlas/dens axis articulations, then this is exclusively due to a (facultative) rotation of the atlas. In this case the massa lateralis atlantis of that side displays the usual pattern associated with rotation. Narrowing of the articular cavity is entirely due to projection and definitely not pathological. Rotation of the dens axis, being obligatory in lateral flexion, does not affect the width of the articular cavities of the atlas/dens axis articulations. Both facts can be verified without leaving any doubt, by x-ray film. Ventral or dorsal "tipping" of the dens axis or lateral "tipping" of the atlas is anatomically impossible. In our daily routine diagnosis of lateral flexion x-ray films we never found any sign pointing to such movement.
Atlanto-Axial Joint↗
Congenital atlantoaxial fusion. A case report.
An adult patient, after a minor fall, had a painful neck, and roentgenograms of the affected area showed a separate odontoid with the remnant fused to the anterior ring of the atlas. The multiple nature of the anomalies, coupled with the lack of significant trauma, indicated that the finding was that of congenital atlantoaxial fusion.
Abnormalities, Multiple↗
Fractures of the dens in adult patients.
The series involves 42 consecutive acute fractures of the dens, of which 41 were treated nonoperatively. There were 26 Type II and 16 Type III fractures, as classified by Anderson and D'Alonzo. All Type III fractures and undisplaced or anteriorly displaced Type II fractures united. Posteriorly displaced Type II fractures had an overall nonunion rate of 50%, which increased to 75% if displacement was more than 5 mm. Eight patients died within 40 days after sustaining their fracture; seven had Type II fractures with an average of 10-mm posterior displacement. Seven patients with a Type II fracture had an associated atlas fracture; five of these patients died early. In Type II fractures, posterior displacement is an important prognostic factor for union and possibly for early mortality of elderly patients. In Type II fractures with an associated atlas fracture, the mortality rate is high. Nonoperative management, preferably halo-thoracic immobilization, is successful in all acute fractures of dens, except posteriorly displaced Type II fractures.
Axis, Cervical Vertebra↗
Sagittal kinematics of the cervical spine--how constant are the motor axes?
The aim of this study was to establish whether or not the axes of cervical spine movement in the sagittal plane are constant (an impression conveyed by the literature). Based on 60 functional radiographs (of which 24 showed degenerative discopathy or atlas subluxations), the axes of seven motor segments (C1-D1) were determined geometrically. The axes of the segments C5/C6 proved to scatter least; the further the distance of a segment is to the latter, the larger the tendency of scattering appears. Hence, the axes are neither constant in time nor in location and thus only convey the momentary kinematic situation of the cervical spine. Clearly pathologic axis positions could not be found, except in the case of an extreme atlas subluxation.
Adolescent↗
Functional neuroanatomy of visual object naming: a PET study.
BACKGROUND: The ability to name objects depends partly on visual perception. We used positron emission tomography (PET) to measure activity-related changes in regional cerebral blood flow (r-CBF) in order to identify regions of the brain activated during visual object naming. METHODS: Four right-handed volunteers were recruited. Following an intravenous injection of 15O-labeled water, r-CBF was measured during visual object naming, counting numbers, and resting. PET and MRI images were coregistered, the size of the brain was proportionally adjusted in each axis to Talairach's and Tournoux's atlas, and the comparison of stimulated versus resting blood flow images revealed activated brain regions. RESULTS: In the subtraction of resting from naming, activation was observed in the bilateral primary visual cortex, bilateral fusiform gyrus, left lingual gyrus, bilateral inferotemporal cortex, bilateral inferior frontal gyrus, bilateral precentral gyrus, anterior cingulate gyrus, left parietal operculum, and left putamen. In the subtraction of counting from naming, most of the those areas were activated, but no significant activity was observed in the left lingual gyrus, left parietal operculum, or bilateral precentral gyrus (motor cortex). The areas activated with the paradigm included those dedicated to visual perception (primary and associate visual cortex), visual recognition (inferior temporal cortex), and phonological output (Broca's area). CONCLUSION: Our results indicated that the major neural network from occipital lobe to frontal cortex, which is mainly involved in the ventral visual pathway, demonstrated activation in these tasks. Result of this study will serve as base line data for analyzing the findings in patients with impaired visual perception.
Adult↗
Screw implantation in spinous process for occipitoaxial fixation.
The feasibility of direct implantation of screws into the spinous process of the axis for fixation of plates in occipitoaxial stabilization is discussed. The method was used in 11 cases of congenital craniovertebral anomalies. The relatively strong and stubby spinous process of the axis in cases with occipitalization of the atlas facilitated screw implantation. In three cases two screws were implanted into the spinous process. The follow-up ranged from 3 to 43 months, the average being 26 months. During the period of follow-up one screw backed out from the spinous process. In the rest of the cases the screw in the spinous process satisfactorily fixed the axial end of the plate and stabilized the region.
Bone Screws↗
Multiple unstable cervical fractures with cord compromise treated nonoperatively: a case report.
STUDY DESIGN: The case of a 17-year-old boy who sustained an unusual pattern of multiple unstable cervical spine fractures with a spinal cord injury is presented. OBJECTIVE: To review the management and treatment of multiple unstable cervical spine fractures. SUMMARY OF BACKGROUND DATA.: Combined unstable cervical spine injuries are uncommon. Treatment of multiple-level cervical spine fractures remains controversial. METHODS: The case of a 17-year-old boy who sustained a ring fracture of the atlas, an atypical traumatic spondylolisthesis of the axis, bilateral pedicle fractures of C3 with significant anterior subluxation of C3 on C4, a C6 burst fracture, compression fractures of C7 and T1, and significant cord compression as the result of a motor vehicle accident is presented. RESULTS: The patient was successfully treated with an initial closed reduction using cervical traction for 1 week followed by placement of a cervical halo vest. The fractures healed successfully, and the patient regained near-normal neurologic function. CONCLUSIONS: Despite advances in the surgical treatment of cervical fractures and dislocations, nonoperative treatment with halo immobilization remains a viable option for selected complex injury patterns.
Adolescent↗
Anatomic validation of spatial normalization methods for PET.
UNLABELLED: Spatial normalization methods, which are indispensable for intersubject analysis in current PET studies, have been improved in many aspects. These methods have not necessarily been evaluated as anatomic normalization methods because PET images are functional images. However, in view of the close relation between brain function and morphology, it is very intriguing how precisely normalized brains coincide with each other. In this report, the anatomic precision of spatial normalization is validated with three different methods. METHODS: Four PET centers in Japan participated in this study. In each center, six normal subjects were recruited for both H2(15)O-PET and high-resolution MRI studies. Variations in the location of the anterior commissure (AC) and size and contours of the brain and the courses of major sulci were measured in spatially normalized MR images for each method. Spatial normalization was performed as follows. (a) Linear: The AC-posterior commissure and midsagittal plane were identified on MRI and the size of the brain was adjusted to the Talairach space in each axis using linear parameters. (b) Human brain atlas (HBA): Atlas structures were manually adjusted to MRI to determine linear and nonlinear transformation parameters and then MRI was transformed with the inverse of these parameters. (c) Statistical parametric mapping (SPM) 95: PET images were transformed into the template PET image with linear and nonlinear parameters in a least-squares manner. Then, coregistered MR images were transformed with the same parameters used for the PET transformation. RESULTS: The AC was well registered in all methods. The size of the brain normalized with SPM95 varied to a greater extent than with other approaches. Larger variance in contours was observed with the linear method. Only SPM95 showed significant superiority to the linear method when the courses of major sulci were compared. CONCLUSION: The results of this study indicate that SPM95 is as effective a spatial normalization as HBA, although it does not use anatomic images. Large variance in structures other than the AC and size of the brain in the linear method suggests the necessity of nonlinear transformations for effective spatial normalization. Operator dependency of HBA also must be considered.
Brain↗
Fusion of the anterior arch of the atlas and dens.
Seven cases of fusion of the anterior arch of the atlas to the dens have been described in the English literature. This anomaly alone is stable. A new case of this rare anomaly incidentally discovered in a patient examined for trauma is presented.
Adolescent↗
Evaluation of the craniocervical junction in Down syndrome: correlation of measurements obtained with radiography and MR imaging.
Measurement of the atlas-dens interval is the radiographic standard for identification of patients with Down syndrome at high risk for neurologic injury from spinal cord compression. In 17 pediatric patients with Down syndrome, measurements of the atlas-dens interval, distance between the clivus and posterior odontoid process, and width of the neural canal obtained with plain radiographs were compared to predict the width of the subarachnoid space on magnetic resonance (MR) images. In all patients, cervical radiography and craniocervical MR imaging were prospectively performed during lateral flexion and extension. The width of the subarachnoid space was measured with MR imaging. When the 95% confidence interval for correlation coefficients of regression was used, subarachnoid space width on MR images correlated with neural canal width on radiographs better than with either atlas-dens interval or clivus-posterior odontoid process distance (P = .05). Measurement of neural canal width is a better predictor of potential spinal cord compression than the atlas-dens interval or clivus-posterior odontoid process distance and should be emphasized in screening examinations performed with plain radiography.
Adolescent↗