Ampyra (dalfampridine) hasn't been included on this treatment list because it's a different type of MS drug from the disease-modifying FDA-approved drugs on the list. However, since there are actually 12 FDA-approved MS drugs including Ampyra, it is now being listed, but at the bottom of the list, to set it apart from the others.
The MS Society has information about Ampyra, which has improved walking in some persons with MS:
http://www.nationalmssociety.org/Treating-MS/Medications/Ampyra