Some people with MS have improved walking using the drug fampridine. Phase III research had studied 301 patients, half were given a placebo and half were given fampridine. The doctors evaluated walking ability after 2, 6, 10, and 14 weeks.
35% of those given fampridine and only 8% of those given the placebo showed improvement in walking speed and those given the drug showed increases in leg strength.
The problem is that 5 % of those given the drug had to stop taking the drug because of side effects, namely severe anxiety and seizures.
Doctors are encouraged but hesitant because of adverse effects the drug may have, aside from the many usual side effects that are possible.