The commonly used examination procedures of the upper cervical spine depend upon the symmetry for comparison and interpretation of joint functions. If symmetry is not normal, then these assessments may mislead the examiners, allowing them implementation of incorrect treatment plans. Objectives of this study are to explore the possibility that asymmetry is more common than symmetry and, if it is true, to find out the effects of asymmetry on the biomechanics of these joints. The study was carried out on 30 atlas vertebrae of cadavers of Indian origin. The different intra-atlas distances were measured on both sides by digital vernier calliper. All the parameters studied showed statistically significant differences between the right and left side i.e. a p value of < 0.05. The anteroposterior diameter of the foramen transversarium, the transverse diameter of the foramen transversarium, the distance from the midline to medial edge of the vertebral artery groove (inner as well as outer cortex) and the length of the superior articular facets were more on the right side as compared to the left side. The breadth as well as the length of the inferior articular facet, the breadth of the superior articular facet and the difference of posterior arch thickness at the site of vertebral artery groove were more on the left side as compared to the right side. These differences may be explained by the handedness of an individual, which influences the intra-osteal asymmetry in a characteristically distinct manner, which needs to be confirmed or refuted in a further study.
Cervical Atlas

STUDY DESIGN: Retrospective radiological study. PURPOSE: We aimed to determine the prevalence of ponticulus posticus (PP) and high-riding vertebral artery (HRVA) occurring simultaneously on the same side (PP+HRVA) and in cases of PP+HRVA, to assess C2 radio-anatomical measurements for C2 pars length, pedicle width, and laminar thickness. OVERVIEW OF LITERATURE: PP and HRVA predispose individuals to vertebral artery injuries during atlantoaxial fixation. In cases of PP+HRVA, the construct options thus become limited. METHODS: Consecutive computed tomography scans (n=210) were reviewed for PP and HRVA (defined as an internal height of <2 mm and an isthmus height of <5 mm). In scans with PP+HRVA, we measured the ipsilateral pedicle width, pars length, and laminar thickness and compared them with controls (those without PP or HRVA). RESULTS: PP was present in 14.76% and HRVA in 20% of scans. Of the 420 sides in 210 scans, PP+HRVA was present on 13 sides (seven right and six left). In scans with PP+HRVA, the C2 pars length was shorter compared with controls (13.69 mm in PP+HRVA vs. 20.65 mm in controls, p<0.001). The mean C2 pedicle width was 2.53 mm in scans with PP+HRVA vs. 5.83 mm in controls (p<0.001). The mean laminar thickness was 4.92 and 5.48 mm in scans with PP+HRVA and controls, respectively (p=0.209). CONCLUSIONS: The prevalence of PP+HRVA was approximately 3% in the present study. Our data suggest that, in such situations, C2 pedicle width and pars length create important safety limitations for a proposed screw, whereas the translaminar thickness appears safe for a proposed screw.
Axis, Cervical Vertebra ; Cervical Atlas ; Prevalence ; Retrospective Studies ; Vertebral Artery

Cervical stenosis, especially of the upper cervical spine, is quite rare which can be developmental or acquired. Clefts or aplasias of anterior and posterior arches of atlas, ossification of the transverse atlantal ligament, hypertrophy of the dens and os odontoideum are rare conditions causing cervical myelopathy reported either singly or in combination. Hypertrophy of the posterior arch of atlas in the absence of any ring hypoplasia as a cause of cervical myelopathy has not been reported earlier. The authors report a case of cervical myelopathy in a 26-year-old female due to hypertrophied posterior arch of atlas which was preoperatively diagnosed as a bony tumor. Being aware of such an entity may avoid diagnostic surprises and facilitate patient prognostication and management.
Adult ; Cervical Atlas ; Constriction, Pathologic ; Female ; Humans ; Hypertrophy ; Ligaments ; Spinal Cord Diseases ; Spine

OBJECTIVETo observe and measure specimen of Chinese atlas to obtain morphological parameter, providing anatomic data for designing bionic plating of anterior arch of atlas.

METHODSThe anatomic parameters of 48 sets of fresh Chinese adults' atlas specimens were measured with a electric digital caliper and a goniometer, including width of anterior arch of atlas (AW), thickness of atlas at the junction of anterior arch and lateral mass (AD), thickness and height of anterior tubercle of atlas (AT and AH), middle height, length and width of the lateral mass (MHL, L and LW), the extraversion angle of lateral mass of atlas (alpha degrees) and so on. The data were statistically analyzed in order to ascertain the range of morphological parameter of bionic plating of anterior arch of atlas.

RESULTSThe measurement results showed that AW was (20.68 +/- 1.38) mm, AD was (3.86 +/- 1.42) mm, AT was (8.65 +/- 1.88) mm, AH was (10.36 +/- 1.49) mm, MHL was (12.82 +/- 1.76) mm, LW was (12.86 +/- 1.63) mm, the extraversion angle of lateral mass of atlas (alpha degrees) was (13.84 +/- 1.73) degrees. The plating was composed of connecting plate of anterior arch of atlas and fixing plate of atlas lateral mass in bilateral.

CONCLUSIONThe designation of bionic plating of anterior arch of atlas is feasible on morphology. The bionic plating of anterior arch of atlas can not only rebuild the stability of atlas, but also reserve the rotation function between atlas and axis. The plating could be used for patient suffering from instability of upper cervical because of atlas affection.

Adult ; Aged ; Bone Plates ; Cervical Atlas ; anatomy & histology ; surgery ; Female ; Humans ; Male ; Middle Aged

Partial or complete absence of the posterior arch of the atlas is a well-documented anomaly but a relatively rare condition. This condition is usually asymptomatic so most are diagnosed incidentally. There have been a few documented cases of congenital defects of the posterior arch of the atlas combined with atlantoaxial subluxation. We report a very rare case of congenital anomaly of the atlas combined with atlantoaxial subluxation, that can be misdiagnosed as posterior arch fracture.
Adult ; Cervical Atlas/*abnormalities ; Diagnosis, Differential ; Female ; Humans ; Spinal Diseases/*diagnosis

Cervical Atlas ; blood supply ; Humans ; Male ; Middle Aged ; Vertebral Artery ; abnormalities

Atlas fracture accounts for 1% to 3% of all spinal column injuries and 10% of cervical spine fractures, and is most frequently caused by motor vehicle accidents and falls. Only a few cases involving complications after surgical treatment have been reported. We present a case of anterior atlas arch stress fracture accompanied by worsening neurologic symptoms following atlas posterior arch resection for cervical myelopathy with retro-odontoid pseudotumor.
Cervical Atlas ; Fractures, Stress* ; Motor Vehicles ; Neurologic Manifestations ; Spinal Cord Diseases* ; Spine

OBJECTIVETo investigate the feasibility of posterior fixation with 3.5-mm pedicle screws in the atlantoaxial vertebrae of children.

METHODSIn this study, atlantoaxial vertebrae specimens were obtained from 10 cadavers of children aged 6-8 years. We measured the height and width of the C(1) pedicle and the midportion of C(1) lateral mass; the width of C(1) posterior arch under the vertebral artery groove and the height of the external and internal one-third of this part; the external, internal height and the superior, middle, inferior width of the C(2) pedicle (transverse foramen). Furthermore, computed tomography (CT) axial scan was performed on 20 age-matched volunteers to obtain relative data of their atlantoaxial vertebrae. We measured the length and width of the C(1) and C(2) pedicles in the atlantoaxial cross-sectional plane. On CT workstation, we also measured the angles between the longitudinal axes of the atlantoaxial pedicles and the midsagittal plane.

RESULTSFor the cadaveric specimen group, the height and width of the C1 pedicle were (5.26+/-0.44) mm and (6.26+/-0.75) mm respectively. The height of the medial one-third of the C1 posterior arch under the vertebral artery groove was (4.07+/-0.24) mm. The external, internal height and superior, middle, inferior width of the C2 pedicle was (6.86+/-0.48) mm, (6.67+/-0.49) mm, (6.63+/-0.61) mm, (5.41+/-0.39) mm and (3.71+/-0.30) mm, respectively. For the volunteer group measured by CT scan, the height and width of the C(1) pedicle were (5.47+/-0.34) mm and (6.63+/-0.54) mm respectively, while (6.59+/-0.51) mm and (5.13+/-0.42) mm of the C2 pedicle. The angles between the atlas, axis pedicles and the midsagittal plane were (9.60+/-1.32) degree and (27.80+/-2.22) degree respectively.

CONCLUSIONIt is feasible to place a 3.5-mm pedicle screw in the C(1) and C(2) pedicles of children aged 6-8 years old.

Axis, Cervical Vertebra ; anatomy & histology ; diagnostic imaging ; surgery ; Bone Screws ; Cervical Atlas ; anatomy & histology ; diagnostic imaging ; surgery ; Child ; Humans ; Radiography

OBJECTIVETo study the relevant position of the pedicle of C1 to the lateral mass of C(2-4), set up an identification technique for the entry point decision of C1 pedicle screw by using the lateral mass of C(2-4) as anatomic landmarks.

METHODSTwenty cadaver specimens were used to measure the distance from the sagittal midline of spine to the medial border, the midpoint and the lateral border of C1 pedicle or the lateral mass of C2, C3 or C4. The anatomic relation between the measurements data of C1 pedicle and that of the lateral masses of the cervical vertebrae were analyzed, and the technique of C1 pedicle screw fixation was established.

RESULTSThe average medial border of the lateral mass of C2, C3 and C4 was 0.37 mm, 0.27 mm and 0.24 mm lateral to that of C1 pedicle, the average midpoint of the lateral mass of C2, C3 and C4 was 1.18 mm, 1.41 mm and 1.74 mm lateral to that of C1 pedicle, and the average lateral border of the lateral mass of C2, C3 and C4 was 1.96 mm, 2.54 mm and 3.24 mm lateral to that of C1 pedicle, respectively.

CONCLUSIONThere is a steady anatomic location relation between C1 pedicle and the lateral mass of C2, C3 or C4. As well as the lateral mass of C2, the lateral mass of C3 or that of C4 could be convenient anatomic landmarks to determine the location of C1 pedicle and the position of C1 pedicle screw entry point.

Adult ; Cadaver ; Cervical Atlas ; anatomy & histology ; surgery ; Cervical Vertebrae ; anatomy & histology ; surgery ; Female ; Humans ; Male ; Spinal Fusion ; methods

In this report we describe a patient with an unstable Jefferson fracture who was treated by occipitocervical fusion and later reported sustained postoperative occipital neuralgia. A 70-year-old male was admitted to our center with a Jefferson fracture induced by a car accident. Preoperative lateral X-ray revealed an atlanto-dens interval of 4.8mm and a C1 canal anterior-posterior diameter of 19.94mm. We performed fusion surgery from the occiput to C5 without decompression of C1. The patient reported sustained continuous pain throughout the following year despite strong analgesics. The pain dermatome was located mainly in the great occipital nerve territory and posterior neck. Magnetic resonance images revealed no evidence of cord compression, however a C1 lamina compressed dural sac and C2 root compression could not be excluded. We performed bilateral C2 root decompression via a C1 laminectomy. After decompression, bilateral C2 root redundancy was identified by palpation. After decompression surgery, pain was reduced. This case indicates that occipital neuralgia, suggesting the need for diagnostic block, should be considered in the differential diagnosis of patients with sustained occipital headache after occipitocervical fusion surgery.
Analgesics ; Cervical Atlas ; Decompression ; Diagnosis, Differential ; Headache ; Humans ; Laminectomy ; Magnetic Resonance Spectroscopy ; Male ; Neck ; Neuralgia ; Palpation ; Radiculopathy ; Spinal Fractures