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Congenital clefts and other developmental anomalies of the atlas vertebra are rarely encountered. They are incidental findings discovered while investigating the cervical spine following trauma. Differentiation of developmental variants of the atlas from the burst fracture of Jefferson is essential to prevent unnecessary medical intervention.
The fracture of the Atlas is a serious trauma, associated with important diagnostic traps. Whether operative or noninvasive treatment should be used depends on the type of fracture. Paralysis of brain nerves are exceptionally rare. We present a case in which fracture of the atlas was associated with paralysis of the 9th through 12th brain nerves, to which differential diagnostic considerations are discussed.
Although ossification of the posterior longitudinal ligament and ligamentum flavum are well known, ossification of the transverse ligament of the atlas is extremely rare. We present the case of a 79-year-old man who developed a gradually progressive spastic quadriparesis caused by upper cervical canal stenosis due to ossification of the transverse ligament of the atlas together with ligamentum flavum hypertrophy.
Anterior atlas clefts (AACs) are rare developmental variants that may mimic fractures. Due to the potential severe implications of craniocervical junction trauma, expeditious differentiation between a Jefferson burst fracture and a congenital cleft is essential in trauma patients. Three cases of AAC are presented. Two cases demonstrated incidental AACs; the third case was associated with a Jefferson burst injury. Computed tomography is most helpful in evaluating the integrity of the atlas; however, plain radiography or pluridirectional tomography are best for evaluating displacement of the lateral masses of C1 in relation to C2.
STANDARDS: There is insufficient evidence to support treatment standards. GUIDELINES: There is insufficient evidence to support treatment guidelines. OPTIONS: Treatment of atlas-axis combination fractures based primarily on the specific characteristics of the axis fracture is recommended. External immobilization of most C1--C2 combination fractures is recommended. C1--Type II odontoid combination fractures with an atlantodens interval of 5 mm or more and C1--hangman's combination fractures with C2--C3 angulation of 11 degrees or more should be considered for surgical stabilization and fusion. In some cases, the surgical technique must be modified as a result of loss of the integrity of the ring of the atlas.
The presence of a bifid posterior arch of the atlas has been regarded as a contraindication to the wiring of C1-2 for atlantoaxial arthrodesis. Three cases with C1 posterior spondyloschisis are presented with successful atlantoaxial arthrodesis using laterally placed wires to avoid the midline defect of the atlas. An experimental study of the efficacy of three different wiring constructs by computerized tomography showed that there is little difference between midline versus lateral wiring in restricting rotation of C1-2.
STUDY DESIGN: This study is based on direct quantitative caliper measurements of 88 isolated anatomic specimens of the C1 vertebra. OBJECTIVES: The study was undertaken to establish the range and variability of the external dimensions of the atlas and to describe the cortical thicknesses and trabecular distribution of this unique vertebra. SUMMARY OF BACKGROUND DATA: Before this study, Francis in 1952 reported the total anterior and posterior diameter of 285 atlas vertebrae. Liu et al reported detailed external dimensions and facet joint surface morphologies on a total of three C1 vertebrae. METHODS: Measurements were made of overall dimensions, canal diameters, and the dimensions of the anterior and posterior arches of 88 dried human C1 vertebrae. Eight specimens were sectioned in the frontal plane, eight in the sagittal plane, and four in the coronal plane. The anatomy of these sections was documented by radiographic imaging. Cortical thicknesses on the sections were then obtained by direct measurement. RESULTS: The canal diameter ranged from 32 mm (SD 2 mm) in the sagittal plane, and 29 mm (SD 2 mm) in the lateral dimension. The mean thickness of the anterior ring was 6 mm (SD 1 mm) and posteriorly was 8 mm (SD 2 mm). Cortical bone was thinnest posteriorly. CONCLUSIONS: These measurements indicated remarkably constant dimensions for the ring itself, suggesting there may be significant functional restraints on the canal size of this unique vertebra. In contrast, a significant variability was noted in objective measurements of lateral mass height and sagittal plane widths of the entire bone.
STUDY DESIGN: This was a retrospective review of a new surgical technique. OBJECTIVES: To describe a new method of fixation augmentation in posterior C1-C2 spondylodesis. SUMMARY OF BACKGROUND DATA: Posterior atlantoaxial spondylodesis using transarticular screws is often supplemented with sublaminar wires to enhance stability. This technique is not possible if the arch of C1 is deficient. A method of stabilizing the segment and the graft was developed, and the early results were reviewed. METHODS: Five patients with a deficient posterior arch of the atlas, who also needed atlantoaxial spondylodesis, were reviewed. In each patient, fixation was augmented with translaminar screws that attached the graft to the arch of C1. RESULTS: In all five patients, solid arthrodesis was achieved, and all had substantial relief of pain. There were no neurologic complications or failures of fixation. CONCLUSIONS: The method of fixation of graft to the atlas using translaminar screws is a safe and reasonable alternative to external halo immobilization or more extensive surgery, such as occiput to C2 fusion.
This article describes how a team from the Virginia Department of Health (VDH) and the Virginia Center for Healthy Communities (VCHC) attended the UNC Management Academy for Public Health to learn skills to address Virginia's commitment to using technology to improve the public's health. After creating a business plan for a food-safety information Web site, team members used that experience as well as Management Academy training in information technology, the management of data and finances, and strategic partnering to create a comprehensive tool with which to place customizable population data in the hands of anyone interested in pursuing population health improvement. The Virginia Atlas of Community Health, launched through the VCHC in 2003, places clear, compelling data in the hands of those who can influence decisions at the local level and create the most impact for health. Since the program's inception, more than 2,000 individuals have registered as ongoing users of the Virginia Atlas. Initially funded by a Turning Point grant from the Robert Wood Johnson Foundation, the program is sustained through a series of smaller grants and funding from the VDH.
OBJECTIVE: A prospective review of a clinical series was performed. The treatment features of atlas fractures with and without associated axis injuries were investigated. METHODS: Twenty-nine patients were investigated. RESULTS: No displaced fractures were treated with a cervical orthosis. Patients with displaced fractures were managed with a halo vest immobilization; 96.4% patients had a solid fusion at their last follow-up evaluations. CONCLUSIONS: Isolated not displaced or combined with not displaced axis fractures atlas fractures can be treated effectively with a rigid cervical collar alone. Isolated displaced fractures or not displaced but with concurrent displaced axis fractures require immobilization by the halo vest.
The atlas of a 52-year-old male Japanese cadaver, which had been removed and macerated, presented a bilateral unknown bone bridge forming a foramen (Case 1). The bone bridge connected the ponticulus lateralis (PL) and posterior (PP) to form an oval foramen between the superior roots of both ponticuli. The atlas of a 69-year-old male Japanese cadaver was found to have similar variations in situ (Case 2). In this case, the right bone bridge connected the superior root of the incomplete PL and the inferior root of the also incomplete PP to form a long ellipsoid foramen opening medially. The medial opening of the foramen was closed by a ligamentous connective tissue in situ. The condylar emissary vein passed this complete foramen to join the cervical epidural venous plexus. The similar bilateral foramen in case 1 was supposed to pass the same vein as in case 2. The bone bridge between the two ponticuli and the resulting foramen mentioned above have not been described previously, as far as we know. We propose that these structures be called the ponticulus interponticularis atlantis and the foramen atlantoideum interponticulare, respectively.
Occipitalization of the atlas is an important congenital malformation of the craniovertebral region because of the proximity to the spinomedullary region. In a sample of 109 human adult skulls of Asian origin examined for evidence of atlanto-occipital fusion, only one specimen exhibited this type of anomaly, in which the atlas was totally synostosed with the occipital bone with multiple bony defects. The embryological basis of this congenital abnormality is discussed.
The consecutive steps of a seizure with leftward versive movements of the head and eyes were analyzed after video monitoring and correlated with findings on single photon emission computed tomography (SPECT) using [99m Tc] hexamethyl propylene amine oxime (HM-PAO). Evaluation included reconstruction of subtraction images from the early postictal state, obtained immediately after the video-monitored seizure, and the interictal baseline. Based on normalized perfusion indexes within voxels of Talairach space, we concluded that the primary epileptogenic focus was in the premotor cortex of the contralateral hemisphere. We then placed the functional data in an anatomic context by adapting a dedicated computerized brain atlas (CBA) to the patient's brain with the aid of magnetic resonance imaging (MRI) slices. By inverse transformation, the patient's data were aligned with the standard geometry of the brain atlas for comparison purposes with data from the literature. The validated activation field projected exactly onto the right precentral sulcus with the anterior border zone including the right frontal eye field.
OBJECTIVE: To investigate markers that predict modes of death in patients with chronic heart failure. DESIGN: Randomised, double blind, three period, comparative, parallel group study (ATLAS, assessment of treatment with lisinopril and survival). PATIENTS: 3164 patients with mild, moderate, or severe chronic heart failure (New York Heart Association functional class II-IV). INTERVENTIONS: High dose (32.5 or 35 mg) or low dose (2.5 or 5 mg) lisinopril once daily for a median of 46 months. MAIN OUTCOME MEASURES: All cause mortality, cardiovascular mortality, sudden death, and chronic heart failure death related to prognostic factors using competing risks analysis. Mode of death was classified by trialists and by an independent end point committee. RESULTS: Age, male sex, pre-existing ischaemic heart disease, increasing heart rate, creatinine concentration, and certain drugs taken at randomisation were markers of increased risk of all cause mortality and cardiovascular death. There were risk markers for sudden death that were different from the risk markers for death from chronic heart failure. Low systolic blood pressure at baseline, raised creatinine, reduced serum sodium or haemoglobin, and increased heart rate were associated with chronic heart failure death. Use of beta blockers or antiarrhythmic agents (mainly amiodarone) was associated with a reduced risk of sudden death, whereas long acting nitrates and previous use of angiotensin converting enzyme inhibitors were markers for increased risk. CONCLUSIONS: The use of competing risks analysis on the data from the ATLAS study has identified variables associated with certain modes of death in heart failure patients. This approach to analysing outcomes may make it possible to predict which patients might benefit most from particular therapeutic interventions.
Symptomatic canal stenosis at the level of atlas (C1) without atlantoaxial dislocation is thought to be very rare in children. Though common, anomalies of the arch of atlas are generally incidental findings in X-rays. High cord compression due to a narrow canal from a bifid posterior arch, or an absent posterior arch, is a very rare condition. We report 5 children with high cord compression from stenosis of C1 arch.
Six hundred and seventy-two atlas vertebrae of 6 population groups were examined for the presence of a posterior and/or lateral bridge. Of these, 174 (25.9%) presented with partial posterior bridge formation and 53 (7.9%) with a complete bridge. Twenty-six (3.8%) showed some form of lateral bridging. Although controversy exists as to the origin of atlas bridging, the findings of the present study show that aging could be a factor predisposing to complete bridge formation. The clinical significance of bridge formation is discussed with reference to their possible effect on normal vertebral artery function, particularly in rotation.
Anatomical texts allude to many variations in the foramen transversarium of the seventh cervical vertebra, including its absence, but absent foramen transversarium of the atlas vertebra has not been mentioned. This is the case report of an atlas vertebra, the transverse process of which did not exhibit this foramen on the left side. However, the groove for the vertebral artery was present bilaterally on the posterior arch. The possible factors responsible for this interesting variant are discussed.
The occurrence of a retrotransverse foramen of the atlas has been investigated in a series of 409 nonhuman primates representative of 40 genera, and in a series of 500 human atlases (dried bones). In nonhuman primates, no retrotransverse foramen was found in any of the individuals studied. In humans, the retrotransverse foramen was observed in 71 cases (14.2%). It was present bilaterally in 21 cases (29.6% of the 71 foramina), and unilaterally in 50 cases (70.4%). The foramen was present in 44 cases on the right side, and 48 on the left side. The character was noted as present only if it was complete; partial forms were not recorded. Various aspects of the retrotransverse foramen were observed. The present observations suggest that the retrotransverse foramen is a uniquely derived trait (autapomorphy) within primates which is restricted to some individuals in Homo sapiens. Appearance of this foramen in human evolution can be related to the acquisition of the erect posture and bipedal locomotion, and consecutive modifications of the regional venous circulation.