The frequency and clinical significance of XXXX of the posterior and anterior arch of the atlas.

@entity1 @entity154 @entity6746 @entity51 @entity6127
OBJECT: In this study the authors investigated the anatomical, clinical, and imaging features as well as incidence of @entity154 of the @entity6746 arch. METHODS: The records of 1104 @entity1 who presented with various medical problems during the time between January 2006 and December 2006 were reviewed retrospectively. The craniocervical computed tomography (CT) scans obtained in these @entity1 were evaluated to define the incidence of @entity154 of the posterior arch of @entity6746 . In addition, 166 dried @entity6746 specimens and 84 fresh @entity1 cadaveric cervical spine segments were evaluated for anomalies of the @entity6746 arch. RESULTS: Altogether, 40 anomalies (2.95%) were found in 1354 evaluated cases. Of the 1104 @entity1 in whom CT scans were acquired, 37 (3.35%) had @entity154 of the posterior arch of the atlas. The incidence of @entity154 was as follows: Type A, 29 (2.6%); Type B, six (0.54%); and Type E, two (0.18%). There were no Type C or D defects. One @entity1 (0.09%) had an anterior arch cleft. None of the reviewed @entity1 had @entity51 or required surgical intervention for their anomalies. Three cases of Type A @entity6127 were present in the cadaveric specimens. CONCLUSIONS: Most @entity154 of the atlantal arch are found incidentally in asymptomatic @entity1 . @entity154 of the posterior arch are more common than defects of the anterior arch.
