• Journal of Veterinary Clinics
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• v.26 no.5
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• pp.490-494
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• 2009

A 2-year-old Maltese and a 5-month-old Yorkshire terrier were presented with ataxia. Tetraparesis was observed in a 9-year -old Yorkshire terrier. The localizations of the lesions suggested brain or cervical spinal cord by the neurological examination, and the following images was achieved: radiography, axial images of computed tomography (CT), reconstruction image of CT such as multi-planar reformation(MPR) and 3-dimensional(3D) reconstruction and magnetic resonance imaging (MRI). On radiography, the misalignment between atlas (C1) and axis (C2), absent dens of axis, and increased space between the dorsal arch of C1 and spinous process of C2 were found. The discontinuation between dens and body of C2 was identified through axial CT images, and the fragmentation of dens separated from axis was observed through MPR and 3D image in all case. The hyperintense lesions and the spinal cord compression on T2-weighted MR images were represented in a dog with tetraparesis, the others represented only spinal cord compression. Three dogs were diagnosed as atlantoaxial instability (AAI) by dens fracture of C2. The dog with tetraparesis was euthanized due to guarded prognosis. The others were recovered completely. It is difficult to differentiate dens fracture of C2 from abnormal dens such as agenesis and hypoplasia. We thought that CT is very useful to evaluate the dens of C2 and differentiate the causes of AAI, and the reconstruction images of CT such as MPR and 3D make the translation of the fragmented dens or axis of AAI more precisely evaluate.

• Korean Journal of Veterinary Research
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• v.35 no.1
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• pp.19-28
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• 1995

The histological and histochemical study of the axis body of piglet was performed in order to clarify the ossification process. These experimental animals collected from after birth to 52 days were used for this study. The results were summarized as follows; 1. The epiphysis, the intercentrum 2 and the centrum of proatlas were appeared in the axis body and dens of piglet after birth. 2. In 39 days of age piglet, the ossification of the intercentrum 2 was first observed but the epiphysis was already initiated. The centrum of proatlas was observed cranioventral part of the dens of the 52 days piglet axis. 3. The notochordal remnants revealed distinctively in the part between the centrum 1 and the centrum2, in the apical cartilaginous tissue of dens and in the caudal cartilaginous part of body of axis. 4. Intramembranous ossification occurred in the adjacent area of perichondrium of centrum 2. These ossified trabeculae show the woven bone configuration.

• Radiation Oncology Journal
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• v.29 no.2
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• pp.107-114
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• 2011

Purpose: To assess the degree and clinical impact of location error of the dens on the X-axis during radiotherapy to brain and head and neck tumors. Materials and Methods: Twenty-one patients with brain tumors or head and neck tumors who received three-dimensional conformal radiation therapy or intensity-modulated radiation therapy from January 2009 to June 2010 were included in this study. In comparison two-dimensional verification portal images with initial simulation images, location error of the nasal septum and the dens on the X-axis was measured. The effect of set-up errors of the dens was simulated in the planning system and analyzed with physical dose parameters. Results: A total of 402 portal images were reviewed. The mean location error at the nasal septum was 0.16 mm and at the dens was 0.33 mm (absolute value). Location errors of more than 3 mm were recorded in 43 cases (10.7%) at the nasal septum, compared to 133 cases (33.1%) at the dens. There was no case with a location error more than 5 mm at the nasal septum, compared to 11 cases (2.7%) at the dens. In a dosimetric simulation, a location error more than 5 mm at the dens could induce a reduction in the clinical target volume 1 coverage (V95: 100%${\rightarrow}$87.2%) and overdosing to a critical normal organ (Spinal cord V45: <0.1%${\rightarrow}$12.6%). Conclusion: In both brain and head and neck radiotherapy, a relatively larger set-up error was detected at the dens than the nasal septum when using an electronic portal imaging device. Consideration of the location error of the dens is necessary at the time of the precise radiation beam delivery in two-dimensional verification systems.

• Journal of Korean Neurosurgical Society
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• v.55 no.4
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• pp.212-214
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• 2014

The synchondrosis between the dens and the body of axis normally fuses between 5 and 7 years of age. Until this age, synchondrosis fractures can occur in children. Most synchondrosis fractures are conventionally treated by external immobilization alone. We report a 10-year-old child with odontoid synchondrosis fracture who was treated by C1 lateral mass and C2 pars screw rod fixation with a successful outcome and discuss the possible reasons for occurrence of odontoid synchondrosis fracture in this older child as well as the indications for surgery in this condition.

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2009.04a
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• pp.225-225
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• 2009

• Journal of TMJ Balancing Medicine
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• v.2 no.1
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• pp.13-16
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• 2012

Objectives: The quadrant theorem is a theorem proposed by C. M. Guzay in the field of functional, holistic dentistry. There are not much of scientific literature on the quadrant theorem. This study briefly reviewed basic concepts of quadrant theorem. Methods: A publication by Guzay and research articles were searched and reviewed. The quadrant theorem is depicted as a series of illustrations and accompanied explanations. Results: The primary concept of the quadrant theorem was presented in 1952. Based on geometric biophysics of the occlusion and related anatomical functions, physiological pivotal axis of the mandible is analyzed to occurs at the dens (the sub-atlas area). Composite muscular activity links the mandibular posture with C1-C2, which is then linked with the spinal posture. Twenty illustrations are progressively presented on the physiognomy, occlusion, and analysis of anatomical functions. The balanced distribution of the forces gives the durability of the functions in life. Conclusions: The quadrant theorem provides a functional linkage between the mandibular posture and the upper cervical vertebrae.

• Journal of Oral Medicine and Pain
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• v.21 no.1
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• pp.197-206
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• 1996

This study ws performed to investigate the relationship between cervical curvature and the spatial position of the posterior part of the atlas imaged in the lateral cephalograph. Sixty six patients with temporomandibular disorders(TMD) and twenty dental students were selected for patients group and control group, respectively. The average age of patients group was 26.3 years, and 24.9 years in control group. Measured variables were cervical depth, upper space between the atlas and the base of the occiput, lower space between the atlas and the spinous process of the axis, rea of the posterior part of the atlas imaged in the lateral cephalograph, and the cervical curvature passing through the uppermost point in dorsal side of Dens of the Axis to the lowermost and rearmost point of the 5th cervical vertebra. The reliability of the method used for measuring cervical curvature with curved ruler was also tested. The results obtained were as follows : 1. Cervical depth of patients group was 122.9mm and significantly shorter than that of control group, in which cervical depth was 131.9mm, and cervical depth was significantly correlated with other variables in all subjects. 2. Upper space was greater in patients group, but total space including upper and lower space showed no difference between the two groups. The average value of total space was 26.5mm. 3. Area of the posterior part of the atlas was 168.2$\textrm{mm}^2$ in patients group, and 186.5$\textrm{mm}^2$ in control group with significant difference between the two groups. 4. Average range of radius of cervical curvature were 33-40cm and there was no difference between the two groups. 5. There was no significant correlation between the cervical curvature and the area of the posterior arch of the atlas. 6. The method using curved ruler for measuring cervical curvature could be accepted as a reliable method.

• Journal of Korean Neurosurgical Society
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• v.58 no.5
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• pp.454-461
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• 2015

Objective : In this study, we aimed to investigate the underlying ethiological factors in chiari malformation (CM) type-I (CMI) via performing volumetric and morphometric length-angle measurements. Methods : A total of 66 individuals [33 patients (20-65 years) with CMI and 33 control subjects] were included in this study. In sagittal MR images, tonsillar herniation length and concurrent anomalies were evaluated. Supratentorial, infratentorial, and total intracranial volumes were measured using Cavalieri method. Various cranial distances and angles were used to evaluate the platybasia and posterior cranial fossa (PCF) development. Results : Tonsillar herniation length was measured $9.09{\pm}3.39mm$ below foramen magnum in CM group. Tonsillar herniation/concurrent syringomyelia, concavity/defect of clivus, herniation of bulbus and fourth ventricle, basilar invagination and craniovertebral junction abnormality rates were 30.3, 27, 18, 2, 3, and 3 percent, respectively. Absence of cisterna magna was encountered in 87.9% of the patients. Total, IT and ST volumes and distance between Chamberlain line and tip of dens axis, Klaus index, clivus length, distance between internal occipital protuberance and opisthion were significantly decreased in patient group. Also in patient group, it was found that Welcher basal angle/Boogard angle increased and tentorial slope angle decreased. Conclusion : Mean cranial volume and length-angle measurement values significantly decreased and there was a congenital abnormality association in nearly 81.5 percent of the CM cases. As a result, it was concluded that CM ethiology can be attributed to multifactorial causes. Moreover, congenital defects can also give rise to this condition.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.3 no.1
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• pp.1-7
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• 2008

Objectives : The os odontoideum is an uncommon abnormality which is due to non fusion of axis and odontoid process that exists as a separate ossicle apart from a hypoplastic dens. Its clinical significance lies in its potential to produce serious neurologic symptoms after cervical Chuna Manipulation Treatment. We experienced a patient diagnosed as os odontoideum which corresponds to absolute contra-indications of chuna manipulation treatment and report it. Methods : The patient was diagnosed as os odontoideum through cervical spine CT and MRI. Results and Conclusion : During cervical physical examination, we encountered L'hermitte's phenomenon from the patient and suspected one of contra-indications of chuna manipulation treatment. We could diagnose the patient as os odontoideum through cervical spine CT, MRI and prevent him from severe sequelae caused by chuna manipulation treatment.