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PubMedDate not supplied

Bony anomalies of the craniocervical junction.

A review of the literature on bony anomalies of the craniovertebral junction was carried out with emphasis on anomalous manifestations associated with the occipital bone, atlas and axis vertebrae. A summary of the evolution and normal development of the above bony structures and the embryological structures contributing to the bony anomalies is presented. In addition the diagnostic measurements used for the diagnosis of the bony anomalies of the craniocervical junction and their clinical presentation were summarised. This review was prepared with the aim of providing reference material for neurosurgeons and radiologists.

Atlanto-Axial Joint↗

PubMed1975

Surgical treatment of the symptomatic unstable cervical spine in rheumatoid arthritis.

In rheumatoid arthritis spontaneous subluxation of cervical vertebrae is not infrequent and can usually be managed by conservative treatment. Surgical treatment, however, is necessary when there is neural involvement. Of twelve patients who had spine fusion for atlanto-axial subluxation only six had solid union. When conservative treatment fails, reduction by halo traction and arthrodesis of the cervical spine is the method recommended, but the best method of post-operative care remains uncertain. In these patients postoperative immobilization was provided by various methods, including a halo cast or brace, but no method appeared to be superior.

Adolescent↗

PubMed2003

Functional-adaptive anatomy of the axial skeleton of some extant marsupials and the paleobiology of the paleocene marsupials Mayulestes ferox and Pucadelphys andinus.

In this study, the axial skeletons of two Early Paleocene marsupials, Mayulestes ferox and Pucadelphys andinus, were analyzed functionally and compared to that of six South American and three Australian species of extant marsupials. In the case of the South American opossums, myological data of the epaxial musculature were collected and analyzed and osteological-myological associations were related to locomotor behavior. Various features of the vertebral column that relate to diet or to locomotor or postural patterns were pointed out. These features include: the craniocaudal development of the neural process of the axis; the position of the anticlinal vertebra; the morphology of the neural processes of the thoracolumbar vertebrae (orientation, length, and craniocaudal width); the length, orientation, and curvature of the transverse processes of the lumbar vertebrae; and the length and robustness of the caudal vertebrae. In both fossil forms the vertebral column is mobile and allows a great range of flexion and extension of the spine, more so than in most of the living didelphids. It is emphasized here that the analysis of the axial skeleton complements and improves the conclusions provided by the forelimb and hindlimb analyses. It is proposed that Mayulestes and Pucadelphys represent an ancestral morphotype suggesting that the generalized type of locomotion of Paleocene marsupials was partly terrestrial with some climbing ability.

Adaptation, Physiological↗

PubMed1989

Hangman's fracture in head injury.

Five patients with fracture of pedicle of axis vertebra as a complication of head injury are reported. The ages of the patients ranged from 16-25 years and all of them were victims of road traffic accidents. The head injuries were moderately severe requiring admission. The average Glasgow Coma Scale sum on admission was 11. Simple non-operative management in a well padded stiff collar with sand bags supporting the head in a neutral position in bed resulted in full recovery without complication after an average of 4 weeks recumbency.

Accidents, Traffic↗

PubMed2000

Morphologic considerations of C2 isthmus dimensions for the placement of transarticular screws.

STUDY DESIGN: This study examines the C2 vertebrae using both direct anatomic and computed tomographic measurements. OBJECTIVE: To define the relation of the C2 vertebrae bony elements to the vertebral artery and the spinal canal, to determine individuals at risk for vertebral artery injury during C1-C2 transarticular screw placement. SUMMARY OF BACKGROUND DATA: Recent literature assessing the safety of upper cervical spine transarticular screws has concentrated on technique, including the optimal point of entry and path projection of the screw. The actual dimensions of the C2 isthmus of the pars interarticularis has not been examined in a large number of specimens. METHODS: C2 isthmus width and height measurements were made on 205 human cadaveric C2 vertebrae. Vertebrae predicted to be at risk for vertebral arterial injury were imaged by computed tomography. RESULTS: There were 102 female and 103 male specimens with mean isthmus widths of 8.2 +/- 1.5 mm and 7.2 +/- 1.3 mm, respectively. Five specimens (2.4%) had an isthmus width less than 5 mm. The mean isthmus heights were 8.6 +/- 2.0 mm and 6.9 +/- 1.5 mm for male and female specimens, respectively. In twenty-four specimens (11.7%), one or both isthmi had a height of less than 5 mm. Six of these specimens were male and 18 were female. The right C2 isthmus was generally smaller than the left. Computed tomographic measurements closely approximated those of the actual dimensions of the isthmi. CONCLUSIONS: Placing a 3.5 mm screw in a patient with narrow C2 isthmus dimensions (smaller than 5 mm in either the height or width) is technically difficult. Because of narrow C2 isthmus width and/or height, approximately 10% of patients may be at risk for a vertebral artery injury with placement of C1-C2 transarticular screws.

Adolescent↗

PubMed1975

[Dorsal stabilization in dislocated fractures of C-1 and C-2 vertebrae with Palacos and wiring].

During 1 year 6 patients with dislocated fractures of C-1 and C-2 vertebrae (fractures of the odontoid process) and 1 patient with a pseudarthrosis of the odontoid process have been treated. 6 patients have been treated surgically by internal fixation of the arch of C-1 and C-2 spinous process by wiring and plastic material (Palacos). No complications occurred. The advantage of the method was early mobilization of the patients and reduction of hospitalization. Clinical and radiographic follow-up studies showed stable fusion on Flexion-extension X-rays and boney union of the fracture of the odontoid process.

Adolescent↗

PubMedDate not supplied

[Intraoral surgical approach to tumors destroying the axis. Report of three cases].

Primary and metastatic tumours of the axis vertebra are difficult surgical problems. The authors report 3 patients with axis tumours who underwent surgery in 1993 and 1994. Clinical symptoms and signs included pain in three, myelopathy in two, vertebrobasilar circulatory insufficiency and cranial nerve lesions in two patients. Tumours have been resected through transoral and posterior pharyngeal wall approach. The purpose of surgery was decompression of nervous and vascular structures, and histological verification of the tumour. Tumour pathology was diverse and included: multiple myeloma, chordoma and metastatic tumour from stomach. There were no postoperative complications and improvement of neurological conditions was observed.

Adolescent↗

PubMed1994

Morphology and kinematics of the baboon upper cervical spine. A model of the atlantoaxial complex.

STUDY DESIGN: Quantitative and qualitative analyses were performed to compare the anatomy and biomechanics of baboon and human upper cervical spines. OBJECTIVES: This study examined the baboon as a potential model for in vivo and in vitro atlantoaxial research. SUMMARY OF BACKGROUND DATA: A variety of animal models have been used for spine research; however, no species have been used for C1-C2 research. Most species have remarkably different C1-C2 morphology compared with that of humans. METHODS: Twenty baboon and seven human normal adult cadaveric upper cervical spines were studied morphologically. C1-C2 motion segments were analyzed biomechanically using a flexibility method of testing with physiologic range, nondestructive loading. Motion and load-deformation relationships were studied during flexion, extension, bilateral lateral bending, and bilateral axial rotation. RESULTS: The bones and ligaments of the baboon and human upper cervical vertebrae have similarly proportioned structures, identical individual components, and similar geometric configurations. The average size of the baboon vertebrae was 50% to 60% of the human specimens. There were several minor anatomical differences. Baboons had more horizontal C2-C3 facet joints and more vertical C1-C2 articular surfaces; the vertebral arteries were encased in a continuous bony canal in C1. Biomechanical testing demonstrated that baboons and humans had similarly proportioned neutral zones and elastic zones. Compared with humans, baboons had a 2 degrees to 9 degrees wider range of motion in all directions. CONCLUSIONS: The baboon and human upper cervical anatomy and biomechanics are similar. The baboon may be useful to study atlantoaxial biomechanics and pathology.

Adult↗

PubMed1983

The radiology of chronic neck pain: sequelae of occult traumatic lesions.

Occult traumatic lesions of the cervical spine usually involve the smaller, posterior elements of the vertebrae. Chronic neck pain associated with these lesions is intermittent and of variable severity, but with patterns that are fairly characteristic of the osseous lesions. Similarly, the long-term radiographic sequelae occur in fairly predictable patterns. The original osseous injury characteristically involves a fracture deformity and frequently some instability. There is a closed five point suspension system at each of the levels of the lower cervical spine, so that each of these five points is stressed whenever any one of them is deformed. Thus there follows bilateral hypertrophic changes and disc deterioration. Satellite changes also occur. The original deformity usually leads to rotation at the level of the lesion, cervical malalignment, and muscle imbalance. Therefrom the osseous and disc changes associated with chronic torticollis may occur, as well as distant instabilities.

Accidents, Traffic↗

PubMed2001

The location of the pedicle and pars interarticularis in the axis.

STUDY DESIGN: This is an anatomic and radiologic study on the lateral mass of the C2 vertebra. OBJECTIVES: To define the location of the pedicle and pars interarticularis in the C2 vertebra. SUMMARY OF BACKGROUND DATA: Transpedicular screw fixation of the C2 has been addressed in the literature. However, the use of the anatomic terminology of the pedicle or pars interarticularis (isthmus) in C2 is confusing in most of orthopaedic and neurosurgical literature since C2 is considered a transitional vertebra. METHODS: Twenty dry C2 vertebrae were obtained for observation of the external anatomy of the C2 from superior, lateral, and inferior views. Six C2 vertebrae were harvested from cadavers and sectioned in the sagittal, horizontal, and coronal planes to observe the internal structures of the lateral mass using high resolution radiographs. RESULTS: Based on observation, the pedicle of the C2 vertebra is defined as the portion beneath the superior facet and anteromedial to the transverse foramen. The pars interarticularis or isthmus is defined as the narrower portion between the superior and inferior facets. No remarkable difference in bone density and trabecular bone orientation between the pedicle and pars interarticularis was noted. CONCLUSIONS: It is still more appropriate to call this procedure "transpedicular screw fixation" in the C2 to avoid confusion, although this technique requires placing a screw from the posterior aspect of the inferior articular process through the isthmus and pedicle into the vertebral body.

Aged↗

PubMed2005

Anatomic considerations for the pedicle screw placement in the first cervical vertebra.

STUDY DESIGN: Anatomic bony measurements were manually performed on 50 dry atlantoaxial vertebral complexes with an electronic digital caliper, and a reliable landmark for insertion of a pedicle screw in C1 vertebra was described and evaluated. OBJECTIVES: To investigate the feasibility of placing a screw in the C1 pedicle and evaluate the reliability of the C2 lateral mass as a landmark for determining the optimal site of screw entry. SUMMARY OF BACKGROUND DATA: The use of C1-C2 pedicle screws with the additional rods or plates has been an alternative method of stabilization for patients who are unsuitable for C1-C2 transarticular screw stabilization. However, the optimal portal of entry for the C1 pedicle screw is difficult to determine during surgery in the absence of reliable reference landmarks and sufficient relevant anatomic studies. METHODS: We manually measured 11 linear anatomic parameters related to the C1 lateral mass, its pedicle and posterior arch under the groove on 50 pairs of dry C1-C2 complexes harvested from cadavers. We also treated five patients with atlantoaxial instability with C1 and C2 pedicle screw fixation; the entry point of the C1 pedicle screw was ascertained by using C2 lateral mass as a landmark, and the position of the C1 pedicle screws in each case was evaluated with postoperative radiographs and computed tomography scans. RESULTS: The mean mediolateral width and rostrocaudal height of C1 pedicle were 8.57 and 5.83 mm, respectively. The mean rostrocaudal height of C1 posterior lamina at the reference entry point for the screw was 4.59 mm. The mean rostrocaudal height of the C1 posterior arch under the vertebral artery groove was 3.88 mm at its medial one-third and 4.25 mm at its lateral one-third. The thinnest external diameter of the screw tract that was recorded was <4 mm in six (12%) specimens of C1 vertebrae. The center of C2 lateral mass was 1.51 mm lateral to the sagittal plane of the mediolateral midpoint of the C1 pedicle. The distance from the suggested screw entry point to C1 posterior tubercle was 22.15 mm, and the mean length of the screw tract was 28.55 mm. Ten C1 pedicle screws were placed exactly, without neural or vascular injury in all five patients. CONCLUSION: The heights of the C1 pedicle, the posterior arch under the groove and the posterior lamina at the screw entry point are the major determinants for the possibility of placing pedicle screws in C1 of a given patient. This study indicates that it is feasible to place a 3.5-mm pedicle screw safely in C1 in most patients, and the lateral mass of C2 is a reliable anatomic landmark that can be easily identified to help the surgeon determine the optimal screw entry portal conveniently during surgery.

Adult↗

PubMed1991

Superior facet fractures of the axis vertebra.

Nine cases of superior facet fractures of the axis vertebra are reported. In seven cases, there were associated odontoid fractures. These fractures can occur in a coronal or sagittal direction, shearing off the anterior or lateral plateau of the facet. In addition, the lateral mass of the atlas may sublux into the depressed facet fracture. The fracture complex should be well documented with conventional radiography and tomography. Computerized tomographic scanning has been found to be particularly helpful in diagnosing these fractures and other injuries about the axis or atlas. Patients with undisplaced or well-reduced facet fractures can be managed satisfactorily by conservative means, but surgery (posterior atlantoaxial fusion) should be considered for unreduced fractures in order to prevent long-term instability, nonunion, malunion, and degenerative arthritis.

Axis, Cervical Vertebra↗

PubMed1993

[Comparative computerized tomography cephalometric and pharyngometric studies of patients with severe and mild sleep apnea, and in a control group].

116 males were examined. Of these, 52 belonged to a control group, whereas 40 had severe obstructive sleep apnoea (apnoea index > 20 + clinical symptoms) and 24 mild obstructive sleep apnoea (apnoea index 5-20 + clinical symptoms) (in the following, OSA signifies obstructive sleep apnoea). Cephalometry and planimetric examinations of the pharynx were performed in recumbent position with the head in neutral position and with shallow respiration. The narrowest passage of the pharynx was measured; other measured sites were the areas of the nasopharynx, oropharynx (at the level of the tip of the palatine uvula) and of the hypopharynx (at the level of the base of the tongue). The sum of all the measured cross-sections was obtained. The cephalogram was evaluated to obtain the length and thickness of the soft palate, the distance between the mandible and hyoid bone, the posterior airspace (PAS), the nuchal subcutaneous fatty tissue at the level of the spine of the second cervical vertebra (also known as axis), the thickness of the posterior pharyngeal wall at the level of the second cervical vertebra, or axis, and the angles between the sella, nasion and superior maxilla and between the sella, nasion and mandible (SNA and SNB, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

Cervical vertebral anomalies in cleft lip and palate.

A survey was made of the upper cervical vertebrae in children with cleft lip and palate in order to determine the prevalence of cervical vertebral anomalies. The cleft sample consisted of 105 patients attending for orthodontic treatment. It was subdivided into cleft lip (CL), cleft palate (CP), unilateral cleft lip and palate (UCLP) and bilateral cleft lip and palate (BCLP) subgroups. A control was comprised of 120 orthodontic patients. The cervical vertebral anomalies were classified into two types, posterior arch deficiency (PAD) and fusion anomalies (FUS). The results confirmed that the cervical vertebral anomalies occurred significantly more often in the cleft sample (13%) than in the controls (0.8%), p less than 0.001. The total prevalence of cervical vertebral anomalies was similar in the four cleft sub-samples, but the occurrence of each of the two types of cervical vertebral anomalies showed a more differentiated pattern. Posterior arch deficiency occurred significantly more often in cleft palate (CP), (16%) than in controls p less than 0.001, but fusions did not occur more frequently in any cleft groups than in controls.

Axis, Cervical Vertebra↗

PubMed1998

Spinal canal capacity in simulated displacements of the atlantoaxial segment: a skeletal study.

In normal, physiological circumstances there is ample room in the spinal canal to accommodate the spinal cord. Our study aimed to identify the degree of compromise of the spinal canal which could be anticipated in various atlantoaxial pathological states. We examined paired atlas and axis vertebrae using high-definition radiography and simultaneous photography in both normal and simulated pathological orientations in order to measure the resultant dimension of the spinal canal and its percentage occlusion. At the extreme of physiological axial rotation (47 degrees) the spinal canal is reduced to 61% of its cross-sectional area in neutral rotation. The spinal cord is thus safe from compromise. Atlantoaxial subluxation of up to 9 mm reduces the area of the spinal canal, in neutral rotation, to 60% with no cord compromise. Any rotation is, however, likely to cause cord compression. The mechanism of fixation in atlantoaxial rotatory subluxation could be explained by bony interlocking of the facet joint, reproducible in dry bones.

Atlanto-Axial Joint↗

PubMed2004

Measurement of occipitocervical angle.

STUDY DESIGN: This study compared the reliability of 3 techniques used to measure alignment between the occiput and cervical spine. OBJECTIVES: Intraobserver and interobserver intraclass correlation coefficient were computed to determine the most reliable method to measure occipitocervical angle. SUMMARY OF BACKGROUND DATA: No studies have been performed comparing occipitocervical angle measurement techniques. METHODS: The angles between the inferior endplate of second cervical vertebrae and the occiput line using the Chamberlain line, McRae line, and McGregor line were measured from lateral cervical radiographs of 30 healthy volunteers. Five spine surgeons made measurements. RESULTS: Mean intraobserver variances of the angles using Chamberlain line, McRae line, and McGregor line were 2.0 degrees (ranging from 0 degrees-15 degrees), 4.7 degrees (from 0 degrees-28 degrees), and 1.5 degrees (from 0 degrees-9 degrees), respectively; intraobserver intraclass correlation coefficients of the angles were 0.956, 0.835, and 0.975. Mean interobserver variances of the angles using Chamberlain line, McRae line, and McGregor line were 2.3 degrees (from 0.4 degrees-6.4 degrees), 5.0 degrees (from 1.8 degrees-11.9 degrees), and 1.4 degrees (from 0 degrees-4.5 degrees), respectively; interobserver intraclass correlation coefficients were 0.939, 0.802, and 0.972. The highest reliability indexes were obtained for McGregor line. CONCLUSIONS: The McGregor line is the most reproducible and reliable method for measurement of the occipitocervical angle.

Anthropometry↗

PubMed1986

Radiology of postnatal skeletal development. XIII. C1-C2 interrelationships.

Composites of C1 and C2 were analyzed in various roentgenographic projections to elucidate osseous interrelationships and the effect of overlap of different portions of these two vertebrae in standard radiographic projections during differing stages of postnatal chondro-osseous transformation. In anteroposterior projections the dentocentral synchrondroses of C2 normally was located below the inferior rim of the C1 anterior ossification center. The upper extent of the dens ossification center was behind this anterior C1 center. The overlap made visualization of the ossiculum terminale difficult. The spinous process of C1 could be confused with the ossiculum. In transverse projections, the normal laxity characteristic of young children allowed considerable variation in rotational interrelationships. Various degrees of such instability are illustrated. In lateral views variation of the anterior contour of the dens was significant. Such variation must be considered developmental due to the location and direction of growth of the chondrum terminale and interactive modeling between C1 and C2 to allow extension at this particular joint.

Axis, Cervical Vertebra↗

PubMed2000

Hangman's fracture: the relationship between asymmetry and instability.

There is ambiguity concerning the nomenclature and classification of fractures of the ring of the second cervical vertebra (C2). Disruption of the pars interarticularis which defines true traumatic spondylolisthesis of C2, is often wrongly called a pedicle fracture. Our aim in this study was to assess the influence of asymmetry on the anatomical and functional outcome and to evaluate the criteria of instability established by Roy-Camille et al. We studied the plain radiographs and CT scans of 24 patients: 13 were judged to be asymmetrical, ten were considered unstable and 14 stable. Treatment was with a Minerva jacket in 15 fractures and by operation in nine. Surgery was undertaken in patients with severe C2 to C3 sprains. One patient with an unstable lesion refused operation and was treated conservatively with a poor radiological result. Our study showed that asymmetry of the fracture did not affect the outcomes of treatment and should not therefore influence decisions in treatment. The criteria of Roy-Camille seem to be reliable and useful. We prefer the posterior approach to the cervical spine, which allows both stabilisation of the fracture and correction of a local kyphosis.

Adolescent↗