Occipitalization of the atlas: its incidence and clinical implications

Khamanarong, Kimaporn; Woraputtaporn, Worawut; Ratanasuwan, Somsiri; Namking, Malivalaya; Chaijaroonkhanarak, Wunnee; Sae-Jung, Surachai

doi:10.5644/ama2006-124.69

Cited by 17 publications

(13 citation statements)

References 8 publications

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“…Congenital assimilation of the atlas is caused by failure of segmentation between the last occipital and first cervical sclerotome during the early fetal development [5,6]. It is described in the literature as the most common anomaly of the craniocervical junction with an incidence of 0.75%-3% and a male to female ratio of 5 : 1 [7][8][9]. Complete and partial assimilation have been described.…”

Section: Discussionmentioning

confidence: 99%

Traumatic Craniocervical Dissociation in Patients with Congenital Assimilation of the Atlas to the Occiput

Tavolaro

Pulido

Bransford

et al. 2019

Case Reports in Orthopedics

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Traumatic atlantooccipital dissociation (AOD) is a severe and usually fatal injury. Patients with assimilation of the atlas to the skull are exposed to a higher risk of injury and delay diagnosis due to the abnormal anatomy. We report two cases of acute traumatic craniocervical dislocation in patients with baseline congenital assimilation of the atlas to the skull. Computer tomography (CT) was used to identify the injury. Computer tomography angiography (CTA) showed variations of the vertebral arteries’ location on both patients. Assimilation of the atlas was complete in patient one and partial in patient two. Emergent surgical instrumentation and fusion were performed with a very careful and meticulous posterior dissection. As general rule, most of the patients with CCD will undergo occiput to C2 posterior segmental instrumentation and fusion. In the presented cases, a more extensive fusion was necessary based on the type and severity of the CCJ injury and the anatomical anomalies associated. Postoperatively, patient one remained neurologically intact and patient two died. Alternative fixation techniques should be used to minimize risk of VA injury during the surgical procedures.

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Section: Discussionmentioning

confidence: 99%

Traumatic Craniocervical Dissociation in Patients with Congenital Assimilation of the Atlas to the Occiput

Tavolaro

Pulido

Bransford

et al. 2019

Case Reports in Orthopedics

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“…AO has been documented in human remains from archaeological sites across the world over the last few millennia [2][3][4][5][6][7][8][9][10][11][12]. AO occurs in around 1% of prehistoric populations [5] and in 0.03-3.6% of contemporary populations [13][14][15]. AO is often asymptomatic, but when symptoms do appear, they usually do so after the young adult years [16].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, because the atlas plays a key role in transmitting the weight of the head to the rest of the vertebral column [1], the restriction of head movement associated with ACM may contribute to morphological changes like AO by changing how the atlas bears this weight. Given that fusion of the atlas with the occipital bone can be localized or extensive, including multiple variations of partial AO that involve some degree of atlanto-occipital articulation [15], it is also possible that ACM could influence the expression of this anomaly even in cases of a congenital origin.…”

Section: Introductionmentioning

confidence: 99%

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Population-level assessment of atlas occipitalization in artificially modified crania from pre-Hispanic Peru

et al. 2020

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Atlas occipitalization (AO) is a spinal anomaly, characterized by the fusion of the first cervical vertebra and occipital bone, with a complex etiology that can arise from congenital and environmental causes. AO has been reported in three regions of pre-Hispanic Peru in skeletal remains with artificial cranial modification (ACM), which involves the use of compression devices to permanently alter cranial shape and may have affected the fusion of the atlas and occipital bone. The aims of this study were to gain insights into AO's etiology by testing correlations between AO and ACM presence/type and geographic region as well as to characterize morphological variation associated with AO. We investigated the geographic distribution of AO and its potential relationship to ACM in a large sample of human crania from eight coastal and highland regions of pre-Hispanic Peru, held at the Smithsonian's National Museum of Natural History (n = 608, 1300-1500 CE). Eleven cases of AO were observed in three coastal regions-including two previously unreported regions-at an overall frequency of 1.8%. The frequency of AO did not differ significantly between crania with and without ACM, in general or by type, suggesting that ACM is not an etiological factor that influences AO in this sample. AO was observed at a significantly higher rate in the southern coastal region of Arequipa than in any other region. Genetic, dietary, and epidemiological conditions are evaluated as factors possibly shaping the geographic distribution of AO along the central and southern coasts of Peru.

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“…Atlantal Occipitalization may be congenital or acquired. Because of its proximity to the spinomedullary region, congenital malformation of the cervico-occipital region is of considerable consequence as it can produce wide range of symptoms of neurovascular and skeletal conditions [3]. Neurological signs and symptoms associated with Occipitalization vary from transitory headache to neurological syndrome.…”

Section: Introductionmentioning

confidence: 99%

Occipitalization of Atlas

Walia¹,

Modi²,

Puri³

et al. 2014

IJAR

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Occipitalization of atlas is an osseous anomaly of the craniovertebral junction which occurs at the base of the skull in the region of the foramen magnum. The knowledge of such a fusion is important because skeletal abnormalities at the craniocervical junction may result in sudden death. During bone cleaning procedure and routine undergraduate osteology teaching, three skulls with Occipitalization of atlas were encountered in the department of Anatomy at MMIMSR, Mullana, India. In one skull, both anterior and posterior arch were completely fused with occipital bone while the transverse process on the right side was not fused whereas left transverse process was fused with occipital bone. Both anterior and posterior arch were completely fused whereas transverse process on both sides were not fused in other skull. In another skull, partial and asymmetrical Occipitalization of atlas vertebra with occipital bone was found with bifid posterior arch of atlas at the level of posterior tubercle. Anterior arch was completely fused with basilar part of occipital bone but both the transverse processes were not fused. Reduced diameter of foramen magnum due to the atlanto-occipital fusion might cause neurological complications due to compression of spinal cord or medulla oblongata, vertebral vessels, 1st cervical nerve, thus, knowledge of occipitalization of the atlas may be of substantial importance to orthopaedicians, neurosurgeons, physicians and radiologists dealing with abnormalities of the cervical spine.

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Occipitalization of the atlas: its incidence and clinical implications

Cited by 17 publications

References 8 publications

Traumatic Craniocervical Dissociation in Patients with Congenital Assimilation of the Atlas to the Occiput

Traumatic Craniocervical Dissociation in Patients with Congenital Assimilation of the Atlas to the Occiput

Population-level assessment of atlas occipitalization in artificially modified crania from pre-Hispanic Peru

Occipitalization of Atlas

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