Respiratory functional and motor control deficits in children with spinal cord injury.

Children with spinal cord injury (SCI) are at high risk for developing complications due to respiratory motor control deficits. However, underlying mechanisms of these abnormalities with respect to age, development, and injury characteristics are unclear. To evaluate the effect of SCI and age on respiratory motor control in children with SCI, we compared pulmonary function and respiratory motor control outcome measures in healthy typically developing (TD) children to age-matched children with chronic SCI. We hypothesized that the deficits in respiratory functional performance in children with SCI are due to the abnormal and age-dependent respiratory muscle activation patterns. Fourteen TD (age 7±2 yrs., Mean±SD) and twelve children with SCI (age 6±1 yrs.) were evaluated by assessing Forced Vital Capacity (FVC); Forced Expiratory Volume in 1sec (FEV1); and respiratory electromyographic activity during maximum inspiratory and maximum expiratory airway pressure measurements (PImax and PEmax). The results indicate a significant reduction (p<.01) of FVC, FEV1 and PEmax values in children with SCI compared to TD controls. During PEmax assessment, children with SCI produced significantly decreased (p<.01) activation of respiratory muscles below the neurological level of injury (rectus abdominous and external oblique muscles). In addition, children with SCI had significantly increased (p<.05) compensatory muscle activation above the level of injury (upper trapezius muscle). In the TD group, age, height, and weight significantly (p<.05) contributed towards increase in FVC and FEV1. In children with SCI, only age was significantly (p<.05) correlated with FVC and FEV1 values. These findings indicate the degree of SCI-induced respiratory functional and motor control deficits in children are age-dependent.