Functional neurological recovery after spinal cord injury is impaired in patients with infections

Infections are a common threat to patients after spinal cord injury. Furthermore, infections might propagate neuronal death, and consequently contribute to the restriction of neurological recovery. We investigated the association of infections (i.e. pneumonia and/or postoperative wound infections) with functional neurological outcome after acute severe traumatic spinal cord injury. We screened data sets of 24 762 patients enrolled in a prospective cohort study (National Spinal Cord Injury Database, Birmingham, AL, USA). Patients were assessed according to the ASIA classification. ASIA impairment scale-classified A and B patients recruited within 24 h post-trauma (n = 1436) were selected as being a major recruitment population for interventional trials. Patients with documented pneumonia and/or postoperative wound infections (n = 581) were compared with control subjects (non-documented infections, n = 855). The functional neurological outcome parameters (i) upward ASIA impairment scale conversions; (ii) gain of ASIA motor scores; and (iii) gain of motor and sensory levels were consecutively analysed over time up to 1 year after spinal cord injury. The group with pneumonia and/or postoperative wound infections revealed less ASIA impairment scale upward conversions after 1 year than the control group (ASIA impairment scale A: 17.2 versus 23.9%, P = 0.03; ASIA impairment scale B: 57.1 versus 74.7%, P = 0.009). ASIA motor score gain [median (interquartile range)] was lower in patients with infections [ASIA impairment scale A: 8 (4-12) versus 10 (5-17), P = 0.01; ASIA impairment scale B: 19.5 (8-53.5) versus 42 (20.5-64), P = 0.03)]. Analysis of acquired motor/sensory levels supported these findings. In ASIA impairment scale A patients, the gain in motor levels (21.7 versus 33.3%, P = 0.04) and sensory levels (24.4 versus 38 of 102, 37.3%, P = 0.03) was significantly lower in the group with pneumonia and/or postoperative wound infections than in the control group. Multiple regression analysis identified pneumonia and/or postoperative wound infections as independent risk factors for impaired ASIA impairment scale upward conversion (odds ratio: 1.89, 95% confidence interval: 1.36-2.63, P < 0.0005) or lower gain in ASIA motor score (regression coefficient: -8.21, 95% confidence interval: -12.29 to -4.14, P < 0.0005). Infections associated with spinal cord injury, such as pneumonia and/or postoperative wound infections, qualify as independent risk factors for poor neurological outcome after motor complete spinal cord injury. Infections constitute a clinically relevant target for protecting the limited endogenous functional regeneration capacity. Upcoming interventional trials might gain in efficacy with improved patient stratification and might benefit from complementary protection of the intrinsic recovery potential after spinal cord injury.