Reliability of S3 pressure sensation and voluntary hip adduction/ toe flexion and agreement with deep anal pressure and voluntary anal contraction in classifying persons with traumatic spinal cord injury

Context/Objective: The sacral examination components of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), namely deep anal pressure (DAP) and voluntary anal sphincter contraction (VAC), are often difficult to perform. We evaluated whether pressure sensation at the S3 dermatome (S3P), and voluntary hip adductor or toe flexor contraction (VHTC) are tenable alternatives. Here we report test-retest reliability and agreement of these components at 1 month after spinal cord injury (SCI), and impact of disagreement on American Spinal Injury Association (ASIA) Impairment Scale (AIS) grades. Design: Longitudinal cohort. ISNCSCI examination, S3P and VHTC conducted at 1-month post-injury; retest of the sacral exam, S3P and VHTC within 3 days. Follow-up examinations performed at 3, 6, and 12 months. Setting: Five Spinal Cord Injury Model System Centers. Participants: Subjects with acute traumatic SCI, neurological levels T12 and above, AIS grades A-C. Interventions: None. Outcome Measures: ISNCSCI exam, AIS grades. Results: Fifty-one subjects had 1-month data, and 39 had at least one follow-up examination. Test-retest reliability indicated perfect agreement (kappa = 1.0) for all data except S3P (kappa = 0.96). The agreement was almost perfect between S3P and DAP (kappa = 0.84) and between VHTC and VAC (kappa = 0.81). VHTC and VAC differed more often with neurologic levels below T10, possibly due to root escape in conus medullaris injuries. Conclusion: S3P and VHTC show promise as alternatives to DAP and VAC for determining sacral sparing in persons with neurologic levels T10 and above. Reliability and agreement should be evaluated at earlier timepoints and in children with SCI.