Sacral sparing in SCI: beyond the S4-S5 and anorectal examination

There are close relationships between functional sparing at different sacral segments. These relationships can be used to estimate AIS grades when complete information about the anorectal and S4-S5 examination is not available. The accuracy of the classification remains stable over time, while the increased variability in lower levels of SCI, that is, lumbar injuries, emphasizes the importance of careful sacral examinations. The highly reliable predictive values of S1-S3 segments can complement conclusions from anorectal examinations if the latter are considered to be confounded or incomplete.