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PubMed1993

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↗
PubMed1995

Substantial head trauma: value of routine CT examination of the cervicocranium.

PURPOSE: To evaluate the usefulness of routine performance of computed tomography (CT) of the craniocervical junction in unconscious patients with substantial head injury. MATERIALS AND METHODS: In a prospective study, CT of the head and the cervicocranium was performed in 202 patients with substantial cranial trauma (Glasgow Coma Scale scores of 3-6). Plain radiography was performed in all patients. Radiographs and CT scans were then blindly interpreted. RESULTS: Twenty-eight patients (13.9%) had C-1 or C-2 fractures; plain radiographs did not demonstrate cervical fractures in 11 of these patients. Nine patients (4.4%) had fractures of the occipital condyles; plain radiographs did not demonstrate occipital condyle fractures in eight of these patients. CONCLUSION: Because 5.4% of all patients had fractures of either C-1 or C-2 and 4.0% had occipital condyle fractures not seen at plain radiography, routine additional performance of CT of the craniocervical junction is useful in patients with substantial cranial trauma.

Adolescent↗
PubMed2001

The cervicocranium: its radiographic assessment.

Acute injuries of the cervicocranium (from the occiput to the second cervical intervertebral disk) may be radiographically obscure due to minimal displacement of fracture fragments, minor alterations of normal anatomic relationships (occipitoatlantal subluxation), or superimposition of normal skeletal structures. With the nasooropharynx adequately distended with air, the normal cervicocranial prevertebral soft-tissue contour is congruent with the anterior cortical margin of the cervicocranium; namely, concave above, convex anterior to, and concave below the anterior tubercle of C1. Alterations of the normal cervicocranial prevertebral soft-tissue contour due to hemorrhage into the retropharyngeal fascial space from subtle fractures or ligamentous injuries should prompt further assessment of the cervicocranium by means of computed tomography (CT). Cervicocranial CT prompted by an abnormal cervicocranial prevertebral soft-tissue contour has yielded a 16% positive injury rate, approximately three times the rate of acute cervical spine injuries reported in the literature.

Adult↗
PubMed1984

Brain stem reticular influences on lumbar axial muscle activity. I. Effective sites.

Lumbar axial muscle responses to electrical stimulation of the brain stem reticular formation were used to characterize reticular influences on these muscles. Electromyographic recordings were obtained from the transversospinalis, medial longissimus, and lateral longissimus systems in the urethan-anesthetized rat. Ipsilateral stimulation of the pontomedullary reticular formation evoked excitatory responses in these muscles. Trains of pulses were required, but currents as low as 15 microA were effective. Contralateral reticular stimulation with currents similar to those that elicited activation during ipsilateral stimulation at the same brain stem levels could inhibit lumbar electromyographic activity. The results suggest that the motoneurons innervating the lumbar axial musculature in the rat receive strong reticulospinal influences that could be important for postural maintenance and the expression of certain behaviors.

Animals↗
PubMed1984

Brain stem reticular influences on lumbar axial muscle activity. II. Temporal aspects.

Epaxial muscle electromyographic (EMG) responses to electrical stimulation of the pontomedullary reticular formation were analyzed for temporal patterns in the urethan-anesthetized rat. Recordings were obtained from the transversospinalis, medial longissimus, and lateral longissimus groups of back muscles. In response to a series of repetitive stimulus trains, the latency of muscle activation decreased with successive trains. Typically a 10-fold decrease in latency required eight to nine stimulus trains (5 trains/s, 25 pulses/train) with currents of 25-30 microA. Individual pulses within long stimulus trains evoked muscle spike potentials at low probability but with short latencies (population range 4-7 ms). The results suggest that whereas influences on lumbar axial musculature from brain stem reticular formation were not powerful enough to evoke muscle spikes with single-pulse stimulation at currents applied in this study, they can yield short, relatively fixed EMG onset latencies in response to individual pulses within stimulus trains once a potentiation phenomenon has occurred.

Animals↗
PubMed1977

Congenital anomaly of the odontoid in children. A report of four cases.

The embryologic origins of congenital abnormalities of the odontoid process are reviewed. Four cases of odontoid dysgenesis in childhood are presented. All of our cases were associated with a head injury, which subsequently led to the diagnosis. Pain was the most common presenting complaint in our patients. Decreased cervical mobility was the most consistent physcial finding. There was no major neurological defect implicating spinal cord compression in any of our patients. This is not true of adults with congenital abnormalities of the odontoid, particularly those with atlantoaxial instability. The diagnosis of odontoid dysgenesis is a radiographic one. Flexion-extension films, tomograms and cineradiograms are often required to make the diagnosis. C1-C2 subluxation, either anterior or posterior is often found. Prompt posterior cervical fusion is recommended as the treatment of choice.

Axis, Cervical Vertebra↗
PubMed1975

Morphofunctional peculiarities of the transverse processes of the axis, considerations on their pathogenetic significance.

The transverse process C2 plays an important role in the stabilization of the vertebral unit C2/C3 and the protection of the vertebral artery and the cervical spinal cord. The anatomical disposition of the transverse processes C2 and especially the lateral processes may be different from one subject to another. Certain anatomical variants of the transverse process can exert a negative effect on the stabilizing and protective function of the same. Our observations suggest that a maldevelopment or a lesion of the transverse process of the axis may induce extra stresses in the vertebral unit C2/C3 with subsequent development of a zygapophyseal arthrosis at this level. Any zygapophyseal arthrosis (uni- or bilaterally) should lead us to think of this possibility too.

Axis, Cervical Vertebra↗
PubMed1991

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↗
PubMedDate not supplied

Transpalatal excision of the odontoid process.

A patient with platybasia of the skull and temporomandibular joint ankylosis is presented. Relief of brain stem compression by the impingement of the odontoid through a soft, hypoplastic clivus was done by first doing a mandibular condylectomy to open the mouth. A transoral-transpharyngeal route was then employed to excise the odontoid process.

Adult↗
PubMedDate not supplied

Axial loading injuries to the middle cervical spine segment. An analysis and classification of twenty-five cases.

Injuries to the cervical spine at the C3-C4 level involving the bony elements, intervertebral disks, and ligamentous structures are rare. We present 25 cases of traumatic C3-C4 injuries sustained by young athletes and documented by the National Football Head and Neck Injury Registry. Review of the cases reveals that the response of energy inputs at the C3-C4 level differ from those involving the upper (C1-C2) and lower (C4-C5-C6-C7) cervical segments. Specifically, the C3-C4 lesions appear to be unique with regard to the infrequency of bony fracture, difficulty in effecting and maintaining reduction, and a more favorable recovery following early, aggressive treatment. In the majority of instances, injury at this level results from axial loading of the cervical spine. Lesions were distributed into specific categories: 1) acute intervertebral disc herniation (N = 4), 2) anterior subluxation of C3 on C4 (N = 4), 3) unilateral facet dislocation (N = 6), 4) bilateral facet dislocation (N = 7), and 5) fracture of vertebral body C4 (N = 4). Analysis of these 25 cases suggests that traumatic lesions of the cervical spine in general can be classified as involving the upper (C1-C2), middle (C3-C4), or lower (C4-C7) segments. This is based on our observations from this series that C3-C4 lesions 1) generally do not involve fracture of the bony elements; 2) acute intervertebral disc herniations are frequently associated with transient quadriplegia; 3) reduction of anterior subluxation of C3 on C4 is difficult to maintain; 4) reduction of unilateral facet dislocation is difficult to obtain by skeletal traction and is best managed by closed manipulation and reduction under general anesthesia; and 5) reduction of bilateral facet dislocation is difficult to obtain by skeletal traction and is best managed by open methods. The more favorable results observed in this series of immediate reduction of both unilateral and bilateral facet dislocations deserves emphasis. In two cases of unilateral facet dislocation reduced within 3 hours of injury and subsequently fused anteriorly, significant neurologic recovery occurred. The other four patients, two who underwent an open reduction and laminectomy and two treated closed with skeletal traction, remained quadriplegic. In the four instances of bilateral facet dislocation where reduction was achieved by either closed or open methods, although there was no neurologic recovery, all four patients survived their injuries. However, the three patients who were not successfully reduced died.

Adolescent↗
PubMed1996

Semi-automated positional analysis using laser scanning microscopy of cells transfected in a regenerating newt limb.

Limb regeneration in urodele amphibians such as the newt is a key system for investigating the positional identity of cells. The regenerate arises locally from blastemal cells, mesenchymal progenitors that normally give rise to structures distal to the amputation plane but which can be respecified (proximalized) by treatment with retinoic acid (RA) such that proximal structures are formed. To establish an assay for positional identity, cells of distal and RA-treated distal blastemas are labeled by transfection with an alkaline phosphatase marker gene using particle bombardment (biolistics). After grafting the distal blastema to a proximal stump, a context known as intercalary regeneration, the proximodistal distribution of labeled cells in the resulting regenerate is an index of positional identity. We use enzyme-labeled fluorescence (ELF) in conjunction with laser scanning microscopy to detect transfected cells within a section of the entire regenerate. A semi-automated analysis of the positional distribution of marked cells along the proximal-distal axis demonstrates that cells from both distal and RA-treated blastemas contribute to the regenerate. This procedure provides an efficient and accurate tool for positional analysis of transfected cells, and should be applicable for studying genes that play a role in specifying cell position during morphogenesis.

Alkaline Phosphatase↗
PubMed2005

Does head posture have a significant effect on the hyoid bone position and sternocleidomastoid electromyographic activity in young adults?

The aim of this study was to evaluate the associations between head posture (head extension, normal head posture, and head flexion) and anteroposterior head position, hyoid bone position, and the sternocleidomastoid integrated electromyographic (IEMG) activity in a sample of young adults. The study included 50 individuals with natural dentition and bilateral molar support. A lateral craniocervical radiograph was taken for each subject and a cephalometric analysis was performed. Head posture was measured by means of the craniovertebral angle formed by the MacGregor plane and the odontoid plane. According to the value of this angle, the sample was divided into the following three groups: head extension (less than 95 degrees); normal head posture (between 95 degrees and 106 degrees); and head flexion (more than 106 degrees). The following cephalometric measurements were taken to compare the three groups: anteroposterior head position (true vertical plane/pterygoid distance), anteroposterior hyoid bone position (true vertical plane-Ha distance), vertical hyoid bone position (H-H' distance in the hyoid triangle), and CO-C2 distance. In the three groups, IEMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing bipolar surface electrodes on the right and left sternocleidomastoid muscles. In addition, the condition with/without craniomandibular dysfunction (CMD) in each group was also assessed. Head posture showed no significant association with anteroposterior head position, anteroposterior hyoid bone position, vertical hyoid bone position, or sternocleidomastoid IEMG activity. There was no association to head posture with/without the condition of CMD. Clinical relevance of the results is discussed.

Adult↗
PubMed2005

Evaluation of cervical posture of children in skeletal class I, II, and III.

Previous studies on the relationship between morphological structure of the face and cervical posture have predominantly focused on vertical dimensions of the face. The aim of this study was to investigate whether there are significant differences in cervical posture in subjects with a different sagittal morphology of the face, i.e., a different skeletal class. One hundred twenty (120) children (60 males and 60 females, average age 9.5 yrs., SD+/-0.5) were admitted for orthodontic treatment. Selection criteria was: European ethnic origin, date of birth, considerable skeletal growth potential remaining and an absence of temporomandibular joint dysfunction (TMD). Lateral skull radiographs were taken in mirror position. Subjects were divided into three groups based on their skeletal class. The cephalometric tracings included postural variables. The most interesting findings were: 1. children in skeletal class III showed a significantly lower cervical lordosis angle (p<0.001) than the children in skeletal class I and skeletal class II; 2. children in skeletal class II showed a significantly higher extension of the head upon the spinal column compared to children in skeletal class I and skeletal class III (p<0.001 and p<0.01, respectively). This is probably because the lower part of their spinal column was straighter than those of subjects in skeletal class I and II (p<0.01 and p<0.001, respectively). Significant differences among the three groups were also observed in the inclination of maxillary and mandibular bases to the spinal column. The posture of the neck seems to be strongly associated with the sagittal as well as the vertical structure of the face.

Axis, Cervical Vertebra↗
PubMed2006

Genomic analysis of Xenopus organizer function.

BACKGROUND: Studies of the Xenopus organizer have laid the foundation for our understanding of the conserved signaling pathways that pattern vertebrate embryos during gastrulation. The two primary activities of the organizer, BMP and Wnt inhibition, can regulate a spectrum of genes that pattern essentially all aspects of the embryo during gastrulation. As our knowledge of organizer signaling grows, it is imperative that we begin knitting together our gene-level knowledge into genome-level signaling models. The goal of this paper was to identify complete lists of genes regulated by different aspects of organizer signaling, thereby providing a deeper understanding of the genomic mechanisms that underlie these complex and fundamental signaling events. RESULTS: To this end, we ectopically overexpress Noggin and Dkk-1, inhibitors of the BMP and Wnt pathways, respectively, within ventral tissues. After isolating embryonic ventral halves at early and late gastrulation, we analyze the transcriptional response to these molecules within the generated ectopic organizers using oligonucleotide microarrays. An efficient statistical analysis scheme, combined with a new Gene Ontology biological process annotation of the Xenopus genome, allows reliable and faithful clustering of molecules based upon their roles during gastrulation. From this data, we identify new organizer-related expression patterns for 19 genes. Moreover, our data sub-divides organizer genes into separate head and trunk organizing groups, which each show distinct responses to Noggin and Dkk-1 activity during gastrulation. CONCLUSION: Our data provides a genomic view of the cohorts of genes that respond to Noggin and Dkk-1 activity, allowing us to separate the role of each in organizer function. These patterns demonstrate a model where BMP inhibition plays a largely inductive role during early developmental stages, thereby initiating the suites of genes needed to pattern dorsal tissues. Meanwhile, Wnt inhibition acts later during gastrulation, and is essential for maintenance of organizer gene expression throughout gastrulation, a role which may depend on its ability to block the expression of a host of ventral, posterior, and lateral fate-specifying factors.

Animals↗