Analysis of the Prechiasmatic Sulcus in Chiari Malformation Type I

Abstract

This study aimed to assess morphological features of the prechiasmatic sulcus (PS) in Chiari Malformation Type I (CM-I). The study population consisted of computed tomography images of 42 CM-I patients (average age: 21.26±16.46 years; sex: 25 females and 17 males) and 58 normal subjects (average age: 28.12±22.60 years; sex: 29 females and 29 males). The measured parameters to determine the anatomy of PS were as follows: the planum length (PL), sulcal length (SL), sulcal angle (SA), and interoptic distance (IOD). Considering SL and SA measurements, PS was identified as four types: the narrow-steep-groove (NSG), narrow-flat-groove (NFG), wide-steep-groove (WSG), and wide-flat-groove (WFG). SA was greater in CM-I (32.80±18.21°) compared to the control group (23.05±14.53°) (p=0.004), but the others were similar in both groups. Distribution ranking of PS types was found as NFG (31%) > NSG (26.20%) > WSG (23.80%) > WFG (19%) in CM-I group, while as WFG (37.90%) > WSG (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). SA value is approximately 25% greater in CM-I than the control; thus, CM-I subjects have more vertical groove. The percentage of narrow-type (NSG + NFG) in CM-I was higher than in the control group.