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Fractures of the Odontoid Process of the Axis*
Published in Alexander R. Vaccaro, Charles G. Fisher, Jefferson R. Wilson, 50 Landmark Papers, 2018
Joseph S. Butler, Andrew P. White
This early study examining the treatment and outcome of fractures of the odontoid process of the axis has a number of significant limitations that must be considered. The retrospective design likely has several inherent flaws, such as selection bias, misclassification and information bias, leading to inaccuracies in establishing the true incidence and mortality rates for this particular injury. The inclusion of patients 3–6 years of age with those greater than 65 years of age is inappropriate, due to differing physiology and coexisting morbidities affecting clinical decision making. The assessment of fracture union based solely on dynamic radiographic imaging, as opposed to the current gold standard of computed tomography (CT) scanning, is a significant weakness when drawing conclusions for current treatment strategies. The lack of standardization of the surgical and conservative management approaches makes it difficult to draw treatment-specific conclusions, and the lack of an agreed bracing protocol also raises concerns about treatment duration and compliance. The surgical decision making in this series appears to be based on individual surgeon preference as opposed to an agreed rationale. Furthermore, the neurological involvement is poorly delineated, with a lack of objective clinical and functional data or use of validated scoring systems. The lack of modern imaging modalities, such as magnetic resonance imaging (MRI), also weakens the relevance to modern practice, particularly since treatment decisions were made with the goal of preventing late myelopathy.
Back and central nervous system
Published in Aida Lai, Essential Concepts in Anatomy and Pathology for Undergraduate Revision, 2018
Cervical vertebrae (7)– secondary curvature (concave post.)– C1 (atlas): X body, accommodates odontoid process of C2– C2 (axis): has odontoid process (dens) for rotation of head– C7: has palpable spinous process (vertebra prominens)– small and wide vertebral body– short, bifid spinous process– transverse process contains foramina– triangular-shaped vertebral canal– greatest range of movement in spine (flexion, extension, lat. flexion and rotation)
Epid. 1–7 (ἐπιδημιῶν, epidemiarum)
Published in Elizabeth M. Craik, The ‘Hippocratic’ Corpus, 2014
There is a strong anatomical element in Epidemics 2. Some passages may be dismissed as speculative rather than informed, but all display intellectual curiosity directed at the acquisition and presentation of fundamental knowledge about the body. Two long passages, one (2. 4. 1) on the course of the blood vessels and the other (2. 4. 2) on the course of the bands in the body (τόνοι), have attracted most attention. In addition to these, several passages refer to the pulse: the question is raised as to what kind of throbbings (διασφύξιες) are shared in the blood vessels (2. 1. 8); a kind of haemorrhage which throbs is recognised (2. 3. 14); the temperament of one with a throbbing vessel at the elbow is described and contrasted to that of one with a still vessel (2. 5. 16); the throbbing of the blood vessels at the wrist is treated as a significant indicator in disease (2. 6. 5). The attention paid to osteology (ὀστέων φύσις ‘the nature of bones’ 2. 3. 12) suggests greater knowledge than here presented. There is awareness of the presence of, and nomenclature for, the vertebral odontoid process (2. 2. 4); there is awareness of potential problems arising from deleterious deposits at the joints, as in podagra (2. 3. 12). Glandular problems too are prominent in the case histories and some understanding of glandular malfunction is evident (2. 2. 5; 2. 2. 15; 2. 2. 24; 2. 3. 5). The visionary suggestion is made that certain areas of the body operate in conjunction with one another (2. 1. 11; 2. 5. 4; 2. 5. 8; 2. 5. 11).
Possible predictive clinical and radiological markers in decision making for surgical intervention in patients with Chiari Malformation type 1
Published in Neurological Research, 2022
Ulaş Yuksel, Veysel Burulday, Suleyman Akkaya, Selcuk Baser, Mustafa Ogden, Aslihan Alhan, Bulent Bakar
Interestingly, the severity of the symptoms was related to the syrinx and cerebellum height values. In addition, the tonsillar herniation risk was associated with the McRae and Chamberlain line values, cerebellum height, and posterior fossa area values measured behind the brainstem. These findings suggested that the cerebellum height value was the most important parameter for the prediction of the severity of the symptoms and the risk of tonsillar herniation >10 mm. Although the total area of the posterior fossa was observed to be similar between the control group individuals and the CM type I patients, the McRae line value could be measured longer, the posterior fossa area measured behind the brainstem could be larger, and cerebellum height could be higher in the CM type I patients than in the control group individuals. It was also observed that the odontoid process could be shorter in these patients. In contrast, the McRae and Chamberlain line values were found to be longer and cerebellum heights could be higher in patients with tonsillar herniation >10 mm. Based on these findings, it was thought that the McRae and Chamberlain lines might be longer due to the shorter odontoid process and higher cerebellum height may cause a tonsillar herniation.
Micro-architecture study of the normal odontoid with micro-computed tomography
Published in The Journal of Spinal Cord Medicine, 2020
Wei Wang, Zhijun Li, Yingna Qi, Lianxiang Chen, Ping Yi, Feng Yang, Xiangsheng Tang, Mingsheng Tan
This similarity suggests that the characteristics is occurring in ossification centers of the odontoid. Development of the axis involves ossification of four ossification centers consisting of the vertebral body and the odontoid. The odontoid process fuses to the vertebral body at 3–6 years of age. As even normal odontoid ossification centers may not be completely fused until young adolescence, however, normal areas of incomplete fusion may be mistaken for fractures.18 We also noted, with micro-CT, that the ossification center formed a trabecular cavity in one of the specimens. The micro-architecture of the ossification center of the odontoid was thus markedly altered compared with normal trabeculae bone (Fig. 4). The ossification center was interspersed with areas devoid of the trabecular cavity that had lower bone volume fractions and thus represented weak points in the structure. Because of an absence of the range of completed trabeculae due to resorption in the ossification center, the base of the odontoid-responsible for its load-bearing capacity-might thus have been weakened.
Craniometrical imaging and clinical findings of adult Chiari malformation type 1 before and after posterior fossa decompression surgery with duraplasty
Published in British Journal of Neurosurgery, 2019
Mehdi Nikoobakht, Hamidreza Shojaei, Peter C. Gerszten, Seyedeh Fahimeh Shojaei, Reza Mollahoseini, Maziar Azar
In recent years, there has been a growing emphasis on assessment of odontoid process and skull base parameters in Chiari malformation patients. In the current study, pre-surgical measurements included a mean odontoid height of 18.35 mm, mean odontoid retroflexion of 82.80°, odontoid retroversion of 79.1°, and mean pB-C2 line distance of 7.48 mm. Khaleel and colleagues13 studied odontoid process height, posterior inclination and pB-C2 line in 125 normal patients and estimated the mean odontoid height as a 22 ± 1.8 mm, mean odontoid retroflexion 79.3 ± 4.9, mean odontoid retroversion 71.9 ± 5.3, and pB-C2 line distance 6.5 ± 2.1 mm. This signifies that the patients in our cohort had a mean odontoid height and posterior inclination lower than the normal population but pB-C2 line distance seems to be higher than expected.