An anatomical study of arcuate foramen and its clinical implications: a case report

Abstract

BackgroundThe objective of this paper is to describe the relationship of the vertebral artery (VA) to the Atlas (C1) in the sub-occipital region in the presence of arcuate foramen; and discuss the clinical implications related to manual therapies and surgical implications related to screw placement. This study is an anatomical cadaveric case report of symmetrical bilateral lateral and dorsal arcuate foramina on the C1 dorsal arch. Case PresentationOut of 40 cadavers that were available for use in teaching anatomy in the university setting, three presented with anomalies of the C1 dorsal arch. The sub-occipital regions were skillfully prosected to preserve related structures, especially VAs, sub-occipital and greater occipital nerves. Visual observations, photographs, measurements, and radiographic examinations were performed between January 15, 2014 and August 25, 2014. One cadaver (Specimen A) presented with complete bilateral ossified arcuate foramina, and two presented with partial ossification of the atlanto-occipital membrane. Specimen A presented the bilateral anomaly which is almost symmetrical. The VAs were found passing through double foramina (lateral and dorsal) on each side.ConclusionsArcuate foramina have been shown to be commonly found anomalies with highly variable shapes and sizes, even in the same individual with a bilateral condition. This study found a rare type of the anomaly associated with the C1 dorsal arch, which protected the VA against manual pressure. However, VA, in this case, would be more susceptible to dissection. The presence of the arcuate foramen would also complicate screw placement during surgery. Clinical pre-screening for signs of vertebrobasilar insufficiency is important for chiropractic and manual therapies.

Vertebral artery variations revised: origin, course, branches and embryonic development

“…This foramen, which is formed by the ossification of the altantoccipital membrane, transforms the groove of VA in an osseous tunnel inside of which the artery passes through to the suboccipital region. Among 252 cadavers [3,25,36,46,54] The osseous bridge forming the canal for the VA variant was reported for the first time in the late nineteenth century [32]. According to Manjunath (2001) [32], this variant anatomy was detected on 11.7% of C1 vertebrae observed in 60 southern Indians and was reported to occur in 1.8 to 29.2% of individuals in various geographic locations.…”

Ponticulus posticus in a cohort of orthodontic children and adolescent patients with different sagittal skeletal anomalies: a comparative cone beam computed tomography investigation

“…Ponticulus posticus, meaning "little bony bridge'' in Latin, is described using various names, including arcuate foramen, Kimmerle's anomaly, foramen arcuale, foramen sagittal, foramen atlantoideum posterius, retroarticular vertebral artery and canalis vertebralis [3,4,10,23,29,34]. It has been shown in studies in the literature that PP is of clinical significance and that an understanding of PP is especially important for the management of cervical spine surgery.…”

The Importance of Arcuate Foramen, A Variation of the Atlas: A Microsurgical Cadaveric Study and Review of the Literature

“…In addition, although the dimensions of AF on both sides were larger than the pre-foraminal diameter of VA, V3 compression was observed at the foramen level (Table 3). Tubbs et al (18) also reported compression of VA, however, Afsharpour et al (29) reported that there was no compression of VA at the level of AF. This different result in the second study may be related to the fact that the AF variation in the cases is bilateral (lateral and dorsal) on both sides (29).…”