Light touch and pin prick disparity in the International Standard for Neurological Classification of Spinal Cord Injury (ISNCSCI)

Abstract

Retrospective review. The International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) assesses cutaneous sensibility through light touch (LT) and sharp-dull discrimination, referred to as pin prick (PP). This project aimed to confirm a tendency for LT to score higher than PP in SCI subjects and discuss possible reasons for such disparity. Single site cohort study, the London Spinal Cord Injury Centre, United Kingdom. A retrospective analysis of LT and PP scores of 99 spinal cord injury subjects at the time of discharge (median 5 months) from acute care and rehabilitation in the London Spinal Cord Injury Centre was conducted. Subjects were aged 10-88 years (median 44 years; 78 men, 74 traumatic, 25 non-traumatic). There were 40 American Spinal Injury Association (ASIA) Impairment Scale (AIS) A, 7 B, 18 C and 34 D subjects. A disparity (P<0.001) was found between LT (64.5±3.2, mean±s.e.) and PP (54.7±2.9) AIS sensory scores. A similar difference in score (LT>PP) was registered both for traumatic and non-traumatic injury, but was greater for incomplete than for complete injury. Despite the difference, LT was well correlated with PP (R=0.87, P<0.001). Spinal segmental level of injury was determined more frequently by PP alone (43 of 99) than by LT (10 of 99) alone. The discrepancies between LT and PP could relate to the greater complexity of the PP test or a difference in the extent of injury to the posterior columns (LT) and spinothalamic (PP) tracts. Further interpretation would benefit from additional electrophysiological sensory tests.