A Traumatic Dislocation of the Atlas from the Axis in a Patient with Atlantooccipital Assimilation

Abstract

Atlantooccipital assimilation is defined as the complete or partial fusion of the caudal portion of the occiput with the cranial portion of the atlas. We report an extremely rare case of a traumatic dislocation of the atlas from the axis (C1 from C2), which lead to internal decapitation in a patient with atlantooccipital assimilation. This report reviews the background of atlantooccipital assimilations and their clinical relevance.

Traumatic posterior dislocation of atlanto-axial joint with anterior arch fracture in the patient of atlanto-occipital assimilation: A case report

“…A previous report on AAD accompanied by AOA included a case reported by Gnanadev et al [ 12 ]. However, unlike this case, it was an anterior AAD, and the patient arrived at the hospital without consciousness or spontaneous breathing.…”

Successful non-operative management for atlanto-occipital dislocation resulting in spinal cord contusion in a patient with atlanto-occipital assimilation and severe Chiari I malformation

“…AOD in patients with AOA is rarely reported. [6,11,26] ere are no good data to suggest whether the altered biomechanics at the CVJ improve or worsen prognosis, and no specific diagnostic criteria exist. In their case of AOD in a patient with AOA, Chaudhary et al [6] postulated that altered biomechanics, such as craniocervical rigidity and decreased size of the foramen magnum, may decrease the force necessary to cause AOD.…”

“…[10,20,29] It is correlated with decreased space available at the CVJ which can predispose to myelopathy and traumatic injury. [10,30] Four patients [6,11,26] are described in the literature with both AOA and AOD, two of whom died. Surgical fixation was performed in all three patients [6,26] who survived past the time of initial injury.…”

“…None of these cases demonstrated concomitant Chiari I malformation (C1M) and skull base anomalies. [6,11,26] We will describe a patient presenting with AOD and spinal cord contusion who had AOA and incidental C1M, platybasia, and basilar invagination. He had an intact neurologic examination, he was treated non-operatively, and he later had near-complete resolution of injury at follow-up.…”