Analysis of the Prechiasmatic Sulcus in Chiari Malformation Type I.

ABSTRACT

OBJECTIVE: To assess morphologic features of the prechiasmatic sulcus (PS) in Chiari malformation type I (CM-I). METHODS: Computed tomography images were obtained in patients with CM-1 (mean age 21.26 ± 16.46 years; sex 25 females and 17 males) and 58 healthy control subjects (mean age 28.12 ± 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. Considering 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 ± 18.21°) compared with the control group (23.05 ± 14.53°) (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 + NFG) PS in the CM-I group was higher than in the control group.