Most patients whose first symptoms are ocular eventually develop muscular weakness symptoms within a couple of years. The next most common symptoms include muscle weakness in the pharynx, a passageway at the back of the mouth and nose through which both air from the nose and food from the mouth travel. This means that the person may have difficulties swallowing, chewing, or breathing, and their speech may be slurred. A person's speech may sound nasal, especially after eating or after talking for a long period. Sometimes a person with these symptoms might have some facial weakness as well.
Patients often have trouble moving their neck forward, resulting in the head dropping back.
The arms are usually weaker than the legs. However, any of the limbs can be affected. Usually the weakness progresses throughout the day, especially after a person has been using their muscles for a long period of time. The symptoms often fluctuate, so a person will have periods of weakness mixed with periods of normal health. When appropriately treated, the periods of weakness may disappear altogether.