Table 1.

Important finding of the Os odontoideum-related article.

First author, year	Title	Important finding
J.W. Fielding, 1980	Os Odontoideum	9/35 cases of Os odontoideum had normal odontoid process prior to the development of the os odontoideum Only one-third of the patients had symptoms of neural deficits
H.G. French, 1987	Upper Cervical Ossicles in Down Syndrome	6/184 patients with Down syndrome had abnormal ossicles of the dens. Only one patient had AAI
A.H. Menezes, 1992	Craniovertebral Abnormalities in Down's Syndrome	Os odontoideum was seen in 3/18 patients with craniovertebral abnormalities.
E.H. Harley, 1994	Neurologic Sequelae Secondary to Atlantoaxial Instability in Down Syndrome: Implications in Otolaryngologic Surgery	10 % to 20 % of children with DS have AAI. Up to 1.5 % of these patients will exhibit neurologic symptoms.
M. Watanabe, 1996	Atlantoaxial Instability in Os Odontoideum With Myelopathy	If the patient has either a sagittal plane rotation angle of more than 20° or an Instability Index of more than 40 %, he or she is likely to have the cord signs
O.M. Sergeenko, 2020	Atlantoaxial dislocation due to os odontoideum in patients with Down's syndrome: literature review and case reports	Most patients with DS and OsO had AAI (80 %). The appropriate treatment in such cases is posterior screw fixation