Cerebellar ataxia cases with ICBs have threefold higher total preliminary CIA scores than those without ICBs (12.06 ± 5.96 vs. 4.68 ± 3.50, p = 0.038). Cronbach's alpha revealed good internal consistency across all items (α > 0.70). By performing the test–retest reliability and inter-rater reliability on the preliminary version of CIA, we excluded seven questions (r < 0.70) and generated the final version of CIA. Based on the ROC, a score of 8.0 in CIA was chosen as the cut-off for ICBs in individuals with cerebellar ataxia with 81% sensitivity and 81% specificity.