The 3 "A"s of EPM (Equine Protozoal Myeloencephalitis) are: Ataxia (unsteady), Asymmetry (the symptoms are not equal on both sides) and Atrophy (patches of muscle wasting).
Here's a great article on EPM.
Murrieta Valley Equine Practice, Inc.
Medicine - Dentistry - Preventive Care - Lameness
Medicine - Dentistry - Preventive Care - Lameness