Predicting the Risk for Central Pain Using the Sensory Components of the International Standards for Neurological Classification of Spinal Cord Injury

Central neuropathic pain (CP) after spinal cord injury (SCI) is excruciating and difficult to manage. Pre-emptive treatment could be initiated in patients at risk for CP providing that it can be predicted. A combination of psychophysical tests could predict CP, but the process necessitates sophisticated equipment and constant monitoring. A simple predictive tool for CP is required. The aim of this study was to test the predictability for CP of the sensory component of the International Standards for Neurological Classification of Spinal Cord Injury (SC-ISNCSCI), routinely performed on all SCI patients. In an historical-prospective study, the SC-ISNCSCI and background variables were extracted from medical records of 115 SCI patients. In a prospective study, 20 SCI patients underwent the SC-ISNCSCI at admission and were followed-up for 12 months. In both studies, pinprick (PP) and light touch (LT) scores from the SC-ISNCSCI and the difference between them (LT-PP) were compared between those who eventually developed CP and those who did not. Heat-pain and touch thresholds were measured and correlated with the SC-ISNCSCI to test its validity. In both studies, patients who developed CP had, prior to CP, lower PP than LT scores, and lower PP scores than those who did not develop CP. At-level delta LT-PP score>1 best predicted CP; the odds of developing CP with LT-PP>1 was 24.4 times that of the reverse category (LT-PP<1). Heat-pain and touch thresholds significantly correlated with PP and LT. We conclude that the SC-ISNCSCI can be used as a clinical biomarker of CP with high probability.