The anorectal exam is unnecessary!

Abstract

The anorectal examination is an unnecessary part of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) in almost all cases. Its requirement in the ISNCSCI is based on limited data and a modification of the "sacral sparing" definition of SCI proposed by Waters [1]. The reliability of deep anal sensation and voluntary anal contraction (VAC) are modest, and the validity of deep anal pressure (DAP) as an indicator of somatic sensation has been questioned. Finally, the pre-dictive validity of "sacral sparing" as defined in the ISNCSCI is limited. The basis of the inclusion of DAP and VAC in the ISNCSCI is said to be from Waters [1], who reported that a change in classification of completeness was unidirectional using his proposed sacral sparing definition, and bidirec-tional using the Frankel scale definition (sparing of sensory or motor function more than three levels below the neuro-logical level of injury, NLI). Waters [1], however, did not include DAP in his definition of sacral sparing, and VAC was not the sole criterion for motor sparing! He defined motor sparing as motor function in the VAC or the toe flexor (TF) muscles. Sensory sacral sparing was defined as "presence of sensation in the perinium at the anal muco-cutaneous junction, glans penis or clitoris [1]." The article did not describe which component(s) were present in persons classified as incomplete by sacral sparing. The value of the anorectal examination in whole or in part has been questioned. The European Multicenter Study on Human Spinal Cord Injury (EM-SCI) group looked at the ability to ambulate at 1 year based on the ISNCSCI sacral sparing definition and components of the sacral exam. They found that the combination of VAC and S4-5 light touch (LT) and pin prick (PP) scores (omitting DAP) was better at predicting ambulation by 1 year than the current definition of incomplete (including DAP) [2]. To be fair, however, the sacral sparing criteria was meant to identify inujries that have no sparing of sensory or motor function from those with some sparing. There was no suggestion that having any sacral sparing would be a good predictor of ambulation. The value of the sacral sparing definition of completeness is not clear, however. There are discrepencies in the description and terminology for the anorectal exam, including whether to apply pressure against the anal sphincter, the rectal wall, or both. Stimulating the rectal wall may activate autonomic pathways and generate a response not based on somatically mediated sensation [3]. Report of a large number of subjects in the control group of a clinical trial converting from complete to incomplete based solely on anorectal sensation [4] highlights the importance of assuring that the test for sacral sensation be done consistently and reflect somatic sensory preservation. Potential alternatives exist for the anorectal exam components , DAP, VAC, and bulbocavernosus reflex. The majority of persons classified as American Spinal Injury Association impairment scale (AIS) B have LT and/or PP preservation. Zariffa looked at patterns of sacral sparing and found that for all exams at all time points in the EMSCI database at the time (n = 3848, NLI C4-T12), only 5% had discrepant DAP and S4-5 LT-PP results [5]. For those classified as AIS B, the rate was higher, 22%, with 12.5% having just DAP and 9.5% just S4-5 sensation. Marino [6] showed that pressure sensation at the S3 sensory point (S3P) may be a good substitute for DAP. Test-retest reliability of S3P was excellent (kappa = 0.98) and agreement between DAP and S3P was 89%, with differences split evenly. S3P was more sensitive than LT or PP at S4-5, present more often, and at a similar frequency as DAP.