Analysis of the prechiasmatic sulcus in chiari malformation type I

OBJECTIVE: To assess morphologic features of the pre-chiasmatic sulcus (PS) in Chiari malformation type I (CM-I).-METHODS: Computed tomography images were ob-tained in patients with CM-1 (mean age: 21.26 & PLUSMN; 16.46 years; sex: 25 females and 17 males) and 58 healthy control subjects (mean age: 28.12 & PLUSMN; 22.60 years; sex: 29 females and 29 males). The following parameters were measured to determine the anatomy of the PS: planum length, sulcal length, sulcal angle (SA), and interoptic distance. Consid-ering sulcal length and SA measurements, 4 types of PS were identified: narrow-steep-groove (NSG), narrow-flat -groove (NFG), wide-steep-groove, and wide-flat-groove.-RESULTS: SA was greater in the CM-I group (32.80 & PLUSMN; 18.21 & DEG;) compared with the control group (23.05 & PLUSMN; 14.53 & DEG;) (P = 0.004), but the other parameters were similar in both groups. Distribution ranking of PS types was as follows: NFG (31%) > NSG (26.20%) > wide-steep-groove (23.80%) > wide-flat-groove (19%) in the CM-I group; wide-flat-groove (37.90%) > wide-steep-groove (20.70%) = NFG (20.70%) = NSG (20.70%) in the control group. Distribution rate of PS types relative to both groups showed that the classification system was not affected by CM-I (P = 0.226).-CONCLUSIONS: SA value was approximately 25% greater in the CM-I group than in the control group; thus, CM-I patients had more vertical groove. The percentage of narrow-type (NSG D NFG) PS in the CM-I group was higher than in the control group.