Men appear to be more susceptible to the development of chordoma than women (ratio 2:1), and lesions typically arise in the sacrococcygeal area (29-57%), sphenooccipital
area (27-35%), and vertebrae (10-33%) [1, 6, 9, 10].
These are: (1) the Kerckring ossicle (ko), (2) posterior intraoccipital synchondrosis (pio), (3) anterior intraoccipital synchondrosis (aio), (4) sphenooccipital synchondrosis (sos), (5) petrooccipital fissure (pof) and (6) occipitomastoid suture (oms).
The sphenooccipital suture showed CT evidence of the beginning of fusion at a mean age of 7.5 years in 136 cases (68%) and reached complete fusion in all cases by the age of 15 years (Figure 4, 5).
The sphenooccipital synchondrosis showed wide variation in the age demonstrating initial CT evidence of fusion (grade 2), ranging from 4-10 years with the mean age of 7.5 years in 68% of cases, and reached grade 4 at a mean age of 15 years.