Cervical spine variationsand anomalies

Cervical spine variations and anomaliesThe purpose of this presentation is to allow students to review the essentials of Normal Radiographic Anatomy. The information within is designed to be a supplement to the lecture and lab material. In no way should completely replace those tools. The material presented in the following pages augments the material within the traditional class and lab setting. This presentation should not be used exclusively in the pursuit of testable knowledge for the class.

Created by: Jean-Nicolas Poirier, DC, DACBR

Cervical spine variations and anomalies This presentation was created using information from the excellent reference mentioned above

3 year old girl. The atlas often appears wider than the axis until about 5 years of age. The ossification center at the tip of the odontoid (arrow) typically appears at the age of 2 years and fuses to the odontoid by the age of 12 years.

A. 11 month old girl. The odontoid is not yet fused with the body of C2. It should fuse by 3 years. Vertebral bodies appear flattened. The sagittal spinal diameter is disproportionately wide. C. 5 year old boy. Vertebral bodies are wedge-shaped. E. 11 years old girl. The secondary ring apophyses at the superior and inferior endplates begin to appear at puberty.

G. 15 year old boy. Observe the ring apophyses and scalloped posterior body margins. Note the v-shaped pre-dens space, a normal variant. H. 16 year old girl. The ring apophyses usually fuse with the vertebral bodies by the age of 17 year in girls and 18 years in boys. I. Adult, 43 years old woman. Vertebral bodies are squared. Their anterosuperior margins remain slightly rounded. The C2-C3 facet joints are not well visualized owing to their normal oblique orientation.

27 year old woman with stuttering and loss of memory after motor vehicle accident. Atlanto-axial assimilation (occipitalization) is seen with block vertebrae at C2-C3 and mild basilar impression (protruding odontoid through the foramen magnum kinking the spinomedullary juction).

Complete agenesis of the posterior arch of C1.

Spina bifida occulta of C1 (spondyloschisis). Absence of the spinolaminar junction line at the posterior arch of C1 with midline cleft defect. Note the hypertrophied and sclerotic anterior arch of C1.

Spondyloschisis of C1 with associated enlarged spinous process of C2 (megaspinous) and hypertrophic anterior arch of C1. The presence of an hypertrophied anterior arch of C1 is commonly seen with anomalies of the upper cervical spine, including spondyloschisis, agenesis of the posterior arch and os odontoideum.

Accessory ossicle at the inferior aspect of the anterior arch of C1. This normal variant should not be confused with an anterior arch fracture or hydroxyapatite deposition within the longus colli tendon.

Posterior ponticle (posterior ponticulus, Kimmerles anomaly). Curvilinear osseous bridge joining the posterior arch of C1 to the lateral masses forming a circular opening (arcuate foramen) for the passage of the vertebral artery and the C1 nerve. B. The transverse foramen through the transverse processes of C2 can be seen. Hydroxyapatite crystal deposition can also be seen in the longus colli at the inferior aspect of the anterior arch of C1.

Lateral ponticles. The osseous arches are continuous between the lateral masses and the transverse processes of C1. This anomaly is less frequently observed than the posterior ponticle.

The anterior arch of C1 (or its anterior tubercle) commonly appears sclerotic. Sclerosis of the anterior arch can be associated with another anomaly of the atlanto-axial region or can represent an isolated variation. An incomplete posterior ponticle is also observed.

Asymmetrical atlas. The lateral masses of the atlas have developed asymmetrically simulating a compression fracture of the left lateral mass. Vertebral asymmetry is commonly seen at the transitional regions of the spine.

The apparent fracture of the posterior arch of C1 is created by the overlapping posterior aspect of the lateral mass of C1. Overlapping osseous fractures can often simulate a fracture.

Mach band effect. The radiolucency visualized crossing through the base of the dens can be caused by the inferior edge of the occipital bone (A) or the superior aspect of the posterior arch of the atlas (B,C). It is important to recognize this artifactual summation of shadows as a normal finding and not a type II fracture of the odontoid process.

Bilateral deep paraodontoid notches. A normal variant.

Overlying incisors. A vertical radiolucent shadow overlying the odontoid process results from the space between the two central incisors and should not be mistaken for a split odontoid or vertical fracture.

Os terminale of Bergmann. Small circular ossification center within the radiolucent triangular apex of the odontoid process. The os terminale of Bergmann represents a persistent, ununited secondary growth center at the tip of the odontoid in a patient older than 12 years old. This is of no clinical significance but should be differentiated from a fracture or an os odontoideum.

Os odontoideum. Amputated appearance of the odontoid process. The ossicle is better seen on the lateral projection with associated posterior translation of the atlas. The anterior arch of the atlas is sclerotic and hypertrophic. Lateral flexion radiographs demonstrate clearly the instability.

Posterior inclination of the odontoid process. The presence of a posterior tilt is a common normal variation. An anterior tilt would most likely be secondary to an odontoid fracture

V-shaped predens space (atlantodental interspace). This represents a normal finding. If atlantoaxial instability is suspected, the atlantodental interspace should be measured and compared on flexion and extension projections. The measurement is performed in the central portion of the predens space and should not exceed 3 mm in adults and 5 mm in children.

C1-C2 synostosis. There is congenital fusion of the C1-C2 segments. The lateral masses are fused to the superior articular processes of C2 and the posterior arch of C1 is fused with the spinous process of C2. This appearance leads to the formation of an anomalous foramen, resembling an intervertebral foramen. Note the wasp-waist narrowing at the fusion site.

Anomalous C1-C2 articulation. Unusual articulation between the posterior arch of C1 and the spinous process of C2. Minimal movement is observed between the flexion and extension projections.

C2 pseudosubluxation. Anterior displacement of the C2 vertebral body in relation to C3 in this 5 year old child. This normal variant can be seen up to 8 years of age. Similar findings with less prominence are seen at C3-C4. Note that the atlantodental interspace measures 5 mm (upper limits of normal for a child).

Anomalous C2-C3 articulation. Presence of an unusually bulbous superior articular process of C3 articulating with a concave inferior articular process of C2. This forms a ball-and-socket type of articulation. Note the posterior ponticle at the atlas.

C2-C3 facet joint pseudofusion. Apparent ankylosis of the C2-C3 facet joints caused by a more pronouced normal angulation of the facet joints. As a result, the x-ray beam is not tangent to the articular facet (like C3-C4) and fails to reveal the radiolucent joint space. This should not be mistaken for developmental or acquired ankylosis of the facet joints.

Normal ring apophyses. 16 year old boy. Tiny, linear, partially ossified secondary ossification centers adjacent to the inferior vertebral endplates.

Nuclear impressions. Prominent, broad-based, curvilinear depressions of the superior and inferior vertebral endplates. These indentations are believed to be related to notochordal remnants and represent a normal variant. They should be differentiated from a mid-body compression fracture or the H-type vertebra found in sickle-cell patients.

Anomalous development of C6. The C6 vertebral body appears flattened and the spinous process is thin and elongated. This is a common isolated anomaly.

Elongated anterior tubercles of the transverse processes of C5-C6. Lateral and oblique projections help demonstrate the elongated anterior tubercles of the transverse processes of C5 and C6 with an accessory articulation between them. These elongated transverse processes with accompanying pseudoarthrosis may be a source of anterolateral neck pain and limitation in the normal range of motion.

Articular process notching. Notching of the superior apophyseal joint surface of C7 represents a normal variation that may simulate an erosion or a fracture.

Congenital block vertebrae (developmental synostosis). Non-segmentation of the vertebral bodies with/without ankylosis of the posterior elements. A rudimentary disc can sometime persist (arrow in A). The hallmark of congenital fusion is the hypoplastic appearance of the vertebral bodies, usually more prominent at the intervertebral junction, leading to a wasp-waist appearance. Note the multiple segments affected in C. Degenerative changes are commonly seen adjacent to the block vertebra in older individuals (B).

Klippel-Feil syndrome. This 58 year old man reveals synostosis of the C2-C3 and C5-C7 segments with prominent degenerative changes in the remaining mobile segments of the spine. Stenosis of the spinal canal is better appreciated on T2-weighted sagittal MRI. An omovertebral bone can sometime accompany this syndrome, as seen here in a different patient. Sprengles deformity, not observed on these patients, can also be seen in a quarter of patients with Klippel-Feil syndrome.

Congenital (dysplastic) spondylolisthesis at C6. Spina bifida occulta is observed at C6 with minimal anterior displacement of C6 over C7, mild hypoplasia of the vertebral body of C6 and neural arch defect consisting of of incomplete ossification of the pedicles and articular processes of C6.

Persistent (ununited) secondary growth center at the tip of the transverse process of T1 and the first rib. A failure of the normal fusion of the secondary ossification center can sometimes be seen as a normal variation. This structure normally fuses by the age of 25 years.

Cervical limbus bones. These two triangular opacities represent persistent secondary ossification centers of the vertebral endplates, which should normally fuse to the vertebral body by age 17 or 18. These variations of normal resemble intercalary bones and should be differentiated from teardrop fractures.

Elongated transverse processes of C7 and cervical ribs. The presence of elongated transverse processes of C7 or cervical ribs have been implicated in the mechanism of thoracic outlet syndrome. Note the accessory articulation of the cervical rib in patient B. These represent examples of transitional vertebrae.

Thyroid cartilage and tracheal ring calcification. Prominent ring-like calcification of the tracheal cartilage and thyroid cartilage in this 50 year old woman. Such calcification is common in the elderly and is clinically asymptomatic and insignificant.

Hair artifact. Streaky, vertically oriented lineal opacities commonly encountered representing strands of hair.

Lymph node calcification. Lobulated calcification of the cervical lymph nodes are seen within the paraspinal soft tissues of the neck. These calcification are common residuals of previously healed infections.

Ossification of the stylohyoid ligament. This usually is an incidental finding of no clinical significance. This structure may possess one or more articulations. In a small percentage of patients, it may cause pain, dysphagia and a sensation of lump in the throat (Eagles syndrome).