Spasticity in spinal cord injured persons: quantitative effects of baclofen and placebo treatments. Spasticity commonly occurs after a spinal cord injury and is characterized by increased resistance to passive movement of peripheral joints. This study examined the effect of an antispasticity medication on stiffness from the myotatic reflex response generated by passive sinusoidal ankle motion. A repeated measures, multiple base-line, single-subject, double-blind design was employed. The independent variable was spasticity medication treatment, where the levels were 40 mg/day and 80 mg/day of baclofen v placebo treatment. Viscous and elastic stiffness measurements were taken at the ankle joint during a placebo base-line phase and during treatment with baclofen for five adult males with traumatic spinal cord injuries. Ankle sinusoidal oscillation frequencies were from 3 to 12 Hz during test sessions. Mean viscous and elastic stiffness scores for all frequencies were calculated for each phase of the study. Randomization tests of mean changes in stiffness measurements between each treatment phase of the study failed to provide any convincing evidence of a significant treatment effect for reduction of spasticity in the traumatic spinal cord injured subjects studied. Further testing is needed to exclude potential confounding factors before this conclusion can be confirmed. The results suggest that baclofen is not a universal treatment of choice for all individuals with spasticity resulting from traumatic spinal cord injury. 