Short and Long Term Multiple Outcomes in Persons With Multiple Sclerosis Treated by Fampridine.

Multiple sclerosis (MS) is a chronic neurological disorder affecting young and middle-aged adults with a female to male ratio of more than 3:1. The cause of MS is unknown although it involves genetic susceptibility and environmental exposure. Since there is no known cure for MS, the main goals of treatment is to delay progression of the disease and to improve health-related quality of life (HRQoL) by masking patients' symptoms. Among several symptoms of MS (e.g., motor and cognitive impairments, optic neuritis, fatigue, pain, urinary dysfunction), gait impairment, defined as an activity limitation by the International Classification of Functioning Disability and Health, is one of the most common and disabling dysfunction in Persons with Multiple Sclerosis PwMS. Studies have reported that approximately 75 % of individuals with MS experience clinically significant walking disturbances. Likewise, fatigue, impairment of information-processing speed (IPS), attention, working memory and executive functions can occur in MS and can worsen during the evolution of the disease. Studies have shown that MS symptomatic treatment by fampridine (4-aminopyridine) is associated with improvements in walking and muscle strength and possibly with cognition, vision, fatigue and spasticity. Indeed, fampridine is a potassium channel blocker which reduces the leakage of ionic current through these channels, prolonging repolarization and thus, enhancing action-potential formation in demyelinated axons. Presumably, by enhancing action-potential formation, more impulses might be conducted in the central nervous system (CNS) and neurological functions could be ameliorated. In recent phase III studies, Goodman et al. investigated the fampridine effect on the walk of individuals with MS during a timed 25-foot walk test (T25FW). Improvement in walking velocity (≈25 % from baseline) was found for 35-43 % of the individuals in the interventional group. However, improvement in neuronal conduction induced by fampridine might not be limited to short distances of gait or even to motor functions and might also improve long distance ambulation or cognitive functions. Different assessments have been used for measuring gait impairments in multiple sclerosis, including the Timed 25-Foot Walk (T25FW), Six-Minute Walk Test (6MWT), spatio-temporal gait parameters measured with an instrumented walkway or the Timed Up and Go test (TUG). These different assessments can be performed at different conditions: simple task, fast speed or dual task. In this last case, the gait is associated with a cognitive or another motor task. For cognitive assessments, Symbol Digit Modalities Test (SDMT) and verbal fluencies have been used in previous studies. The aimed of the study was to evaluate the impact of fampridine in gait evaluating by long distance tests and to evaluate the impact of fampridine in fatigue and cognition. Assessments of patients were performed 7 days before fampridine treatment initiation (Pre 1), on the day of fampridine treatment initiation (Pre 2), 14 and 21 days after fampridine treatment initiation, respectively Post 1 and Post 2. Gait evaluations were assessed at Pre 1, Pre 2 and Post 1. The first two assessments were intended to evaluate the variability of measurement without any treatment. A measurement of activity was performed by accelerometer during the period covering the first two assessments. The third assessment was intend to measure clinical improvements. The fourth seeks to show a potentially delayed action of fampridine on cognition.