The first thing to understand about ALS is that it affects every patient differently. Early symptoms, location of the symptoms, how severe the symptoms are, and the speed of progression can vary from patient to patient. However, there are trends that help doctors identify and diagnose ALS patients.
The first sign of ALS is usually muscle weakness, which happens when the motor neurons (that help the brain communicate with your muscles) are damaged. The location of that early muscle weakness depends on which motor neurons are damaged first. At first, the muscle weakness may be very subtle, but you shouldn’t mistake general clumsiness for this relatively rare disease.
In most patients (about 60% of cases), muscle weakness first happens in arms and legs, which is known as “limb-onset” ALS. People with limb-onset ALS might have difficulty doing tasks that require fine motor control, such as buttoning buttons, or they may experience difficulty walking, finding themselves tripping over even the smallest obstacles, like carpet edges, or nothing at all. They may also find it difficult to lift and grasp items.
In other cases, muscle deterioration occurs first in the muscles of the throat and tongue, which makes it difficult to speak and swallow. These muscles are known as the “bulbar muscles,” which is why this type of ALS is referred to as “bulbar-onset” ALS.
The most rare type of ALS onset is “respiratory-onset,” meaning that the muscles that control breathing are first affected.
As the weakening and paralysis spreads to the muscles of the trunk of the body, it will become harder for the patient to speak, swallow, chew and breathe. When the breathing muscles become affected, the patient will ultimately need permanent ventilatory support in order to survive.
Because ALS attacks only motor neurons, the sense of sight, touch, hearing, taste and smell are not affected at any stage of the disease. For many people, muscles of the eyes and bladder will also generally not be affected.