Reliability and Validity of S3 Pressure Sensation as an Alternative to Deep Anal Pressure in Neurologic Classification of Persons With Spinal Cord Injury

Ralph J. Marino, Mary Schmidt-Read, Steven C. Kirshblum, Trevor A. Dyson-Hudson, Keith Tansey, Leslie R. Morse, Daniel E. Graves

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Objective: To determine whether pressure sensation at the S3 dermatome (a new test) could be used in place of deep anal pressure (DAP) to determine completeness of injury as part of the International Standards for Neurological Classification of Spinal Cord Injury. Design: Prospective, multicenter observational study. Setting: U.S. Spinal Cord Injury Model Systems. Participants: Persons (N=125) with acute traumatic spinal cord injury (SCI), neurologic levels T12 and above, were serially examined at 1 month (baseline), 3, 6, and 12 months postinjury. There were 80 subjects with tetraplegia and 45 with paraplegia. Interventions: S3 pressure sensation at all time points, with a retest at the 1-month time point. Main Outcome Measures: Test-retest reliability and agreement (κ), sensitivity, specificity, positive and negative predictive values. Results: Test-retest reliability of S3 pressure at 1 month was almost perfect (κ=.98). Agreement of S3 pressure with DAP was substantial both at 1 month (κ=.73) and for all time points combined (κ=.76). The positive predictive value of S3 pressure for DAP was 89.3% at baseline and 90.3% for all time points. No pattern in outcomes was seen in those cases where S3 pressure and DAP differed at 1 month. Conclusions: S3 pressure sensation is reliable and has substantial agreement with DAP in persons with SCI at least 1 month postinjury. We suggest S3 pressure as an alternative test of sensory sacral sparing for supraconus SCI, at least in cases where DAP cannot be tested. Further research is needed to determine whether S3 pressure could replace DAP for classification of SCI.

Original languageEnglish (US)
Pages (from-to)1642-1646
Number of pages5
JournalArchives of Physical Medicine and Rehabilitation
Issue number10
StatePublished - Oct 2016
Externally publishedYes

Bibliographical note

Funding Information:
The contents of this report were developed under a grant from the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR grant nos. 90SI5012, 90SI5011, 90SI5007, 90SI5004, 90SI5002). NIDILRR is a Center within the Administration for Community Living (ACL), Department of Health and Human Services (HHS). The contents of this report do not necessarily represent the policy of NIDILRR, ACL, HHS, and you should not assume endorsement by the Federal Government.


  • Classification
  • Rehabilitation
  • Reproducibility of results
  • Sensitivity and specificity
  • Spinal cord injuries

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