Dalfampridine is a lipid-soluble small molecule that more readily crosses the blood-rain barrier and, therefore, its effects on the central nervous system (CNS) have been the subject of greater focus. The initial Phase 2 study determined the safety of escalating doses of dalfampridine in subjects with multiple sclerosis (MS), to explore a number of outcome measures, and examine dose related efficacy. A battery of assessments was performed weekly, including the MS Functional Composite (MSFC), fatigue questionnaires, lower extremity manual muscle testing, and spasticity assessment using the Ashworth scale. The results supported the idea that quantitative functional outcome measures (such as walking speed derived from timed gait and lower extremity muscle testing) were sufficiently sensitive to demonstrate efficacy. Based on evaluation, the US food and drug administration (FDA) approved the extended release (ER) formulation of dalfampridine (daily oral dose of 10 mg BID) for use in MS to improve walking.

Penn and Kroin first described the benefits reporting the treatment of six patients with severe continuing spasticity and spasms resulting from spinal injury or multiple sclerosis. Baclofen is hydrophilic and crosses the blood-brain barrier poorly. Spinal intrathecal administration bypasses the blood-brain barrier, allowing effective treatment of spasticity with a dose range that is 100 to 1000 times smaller than that required for oral treatment. The plasma levels of baclofen in patients undergoing intrathecal infusion have been found to be vanishingly low. Intrathecal baclofen (ITB) reduces spasticity, as clinically assessed using the Ashworth scale. Flexion or extension spasms, more common in the lower limbs, may occur spontaneously or in response to cutaneous stimuli in association with spasticity. The threshold of the electrically induced flexion reflex in the lower limb has been found to be reduced in spinal spasticity and the response amplitude to be increased.

Even today the measurement of spasticity at the level of impairment is probably in its infancy. Due to the lack of treatment or therapy to reduce spasticity, there has been limited development of methods for its measurement. There are four distinct levels of measurement that can be identified hierarchically as follows: nominal, ordinal, interval and ratio levels. Following the original research of Tardieu and colleagues in the early 1950s, a new scale for classifying spasticity based was developed. This scale has since been translated to English and undergone substantial modifications. The Tardieu method of assessment provides a composite measure of spasticity. The quality of the muscle reaction is a categorical level of measurement and therefore can primarily used for classification purposes only. There are two elements to be considered when exploring the reliability of the Tardieu scale.