A case of occipitalization in the human skull

Occipitalization of the atlas is an osseous anomaly of the craniovertebral junction. The aim of this paper is to present an anatomical variant of the fused atlas with the occipital bone and discuss similar cases described in literature. The skull of an adult male analysed in this study belonged to the cranial collection of the Department of Anatomy of the Jagiellonian University, Medical Collage. A tight bony fusion between the anterior arch of the atlas, the left portion of the posterior arch, the lateral masses of the atlas, and the occipital bone was observed. Hence, the left and right superior articular facets of the atlas were fused with the corresponding occipital condyles. The anteroposterior dimension of both inferior articular facets was the same (20 mm), while the transverse diameter of the right one was considerably smaller (12 mm). The transverse diameter of the left inferior articular facets was 17 mm. The right and the left transverse process of the atlas were normally developed, each of them contained transverse foramen, and they were not fused with the occipital bone. The circumference of the foramen magnum was minimally diminished by the osseous structures of the atlas fused to the occipital bone. The sagittal and transverse diameters of the foramen magnum (38 mm x 34 mm) were within the normal range of variation. However, the asymmetrical anatomy of the inferior articular facets of the atlas give rise to speculation that movement in the atlantoaxial joint was disturbed by assimilation with the occipital bone.

[Fibrous dysplasia of the scull discovered accidently on CT from different indication]

Fibrous dysplasia (dysplasia fibrosa -DF) is a local disorder of spongy bone structure caused by local pathological metabolism. Transformation of trabecular bony structure into connective tissue takes place. Inside the transformed bone scattered connective tissue elements, cartilaginous elements and pathological density are found. The disease proliferates either in the medullary bone or in subperiosteal region, and the development of fibrous tissue causes bone expansion with thinning of overlying cortex. The radiological appearance depends on the stage of the disease. The margins of the lesions are usually obscured and gradually turn into pathological tissue of trabeculated appearance.

AIM OF THE STUDY

The aim of the study is to demonstrate fibrous dysplasia that is accidentally found during radiological diagnostics of facial skeleton and stomatological disease, and to describe radiological appearance of the pathological lesions.

MATERIAL AND METHOD

The material included 23 patients (9 males, 14 females), of 24 to 64 years of age, that were directed for the diagnostics of facial skeleton and stomatological disease with the use of multislice computer tomography, because of clinically diagnosed pathologies in the nasal sinuses, temporomandibular joints, pathologies of the mandible and maxillary, and before treatment with prosthetic implants. All the presented fibrous dysplasia cases were diagnosed during the performance of the above examinations. The examinations were performed by the use of spiral CT (Siemens Somatom Sensation 10) with standard parameters. The range of the examination included the nasal sinuses, facial skeleton or the whole scull-configuration of the detectors 10 x 0.75 mm, slice thickness 1 mm, reconstruction gap 0.7 mm, kernel H60s for osseous structure evaluation, and slice thickness 1, 4 do 4 mm, reconstruction gap 4 mm, kernel H31s for soft tissue evaluation. The obtained results were presented sented in the form of figures.

RESULTS

In the analyzed material 23 cases of scull fibrous dysplasia were found. The disease involved 9 males (39.14%) and 14 females (60.86%) from 24 to 64 years of age. Mean age for the whole group was 46.6 years, for males was 50,5 years and for females was 44.4 years. Females with fibrous dysplasia were more numerous (60.86%) than males (39.14%). Monoostotic dysplasia was found in 18 cases (78,89%), polyostotic dysplasia was found in 4 cases (13.05%), the skull-face dysplasia was found in 9 cases (14.07%). The radiological appearance is characterized by lesions that unclearly and gradually turn into pathological tissue with different densities, trabeculated appearance, and sclerotic, lytic or mixed structure. Early lesions usually have lower density than the normal surrounding bone, giving the appearance of translucency.

CONCLUSIONS

Fibrous dysplasia of the facial skeleton is most commonly incidentally found on CT examinations of the head, mandible and nasal sinuses. Diagnosis of fibrous dysplasia is important because of unfavorable influence of the disease on stomatognathic system, laryngological disease, ophthalmic and neurological disease.

[Anatomic variations of the septation within the sphenoid sinus on CT scan images--an initial report]

AIM

The aim of this study was to assess the septation of the sphenoid sinuses and relationship between the number and position of septa in the adult Polish subpopulation.

METHODS

A retrospective study of the CT examination of the paranasal sinuses 207 patients (101 male, 106 female) were performed using spiral multirow CT scanner (Siemens Somatom Sensation 10) with the following parameters: the extent fully covering all paranasal sinuses, detector configuration 10 x 0.75 mm, feed 4.1 mm, reconstruction thickness 1 mm, reconstruction increment 0.7 mm, kernel H60s for bone structures, or reconstruction thickness 4 mm, reconstruction increment 4 mm, kernel H31s for soft tissue structures. Secondary coronal and sagittal MPR's (multiplanar reconstructions) were then generated from original axial slices. No intravenous contrast media was required. Siemens CARE Dose 4D option was used to maximally reduce the X-ray dose. Since the aim of this study was to evaluate anatomical variations of sphenoidal sinuses septation only patients with no diseases within sphenoidal sinuses were included. All the subjects were Polish, with a mean age of 44 years, ranging from 18 to 84 years.

RESULTS

In our study there was only one septum in 41%, two septa in 33%, three septa in 22% and four septa in 4%. The total amount of sinuses depending on total amount of septa (including accessory septa) and it can be different in the anterior and posterior part of the sphenoidal sinus. We also notice that the highest and the broadest septum (main septum) was completely bony in 57% whilst in 47% it was partially membranous.

CONCLUSIONS

Performing CT of paranasal sinuses before surgery is essential to avoid potential complications resulting from anatomical variations.

[Origin of abdominal herniae--anatomical aspects]

Based on anatomical background authors review the current knowledge on mechanisms and anatomical predisposes causing abdominal herniations. They are giving a brief summary of limitations of potential spaces involved into dislocation of abdominal visceral through natural spaces. Authors try to join anatomical knowledge with clinical information what might be useful in understanding of the patomechanism of these surgical disorders.

Bilateral ossification of the stylohyoid ligament

This paper presents the case of an adult male skull with bilateral ossification of the stylohyoid complex. The total length of the stylohyoid complex amounts to 62 mm on the left side and 65 mm on the right side. Visual inspection of the stylohyoid revealed the presence of callosities that are located on both stylohyoid complexes at nearly the same level. These sites are regarded as the ossified attachments of the stylohyoid ligaments to the corresponding styloid processes. The skull studied is an example of extreme development of the stylohyoid complex, which could cause severe pain and a restriction of head and neck movement.

The clinical significance of the petroclinoid ligament

This report describes the topography and structure of the petroclinoid ligament with reference to its clinical significance. Observations of this ligament were performed on 24 sections of human heads. Remnants of the ossified form of this ligament were sought in 73 dry human skulls. It was found that the petroclinoid ligament existed as an anterior and posterior fold of the dura mater and stretched from the petrous apex and the anterior and posterior clinoid process respectively. We assessed the close proximity of this ligament to the oculomotor nerve. In one case we found a partially ossified posterior petroclinoid ligament, which appeared as a bony spike that arose posteriorly and inferiorly from the posterior clinoid process.