Fig. 4

Receiver Operating Characteristic curve comparing neurophysiological differences (threshold ratio of the filum to motor nerve roots at the same surgical level) between fatty filum and normal filum. The curve represents the relationship between sensitivity and specificity at various threshold ratios of the filum to motor nerve roots. The Area Under the Curve (AUC) is a quantitative measure of the curve’s discriminative ability. The AUC was 0.943 (p < 0.0001), the sensitivity was 100%, and the specificity was 85.71% if the cut-off point was taken as 21.03