About 90 percent of cases have no known cause. Clinical Progression of ALS Patients are initially prompted to seek medical attention because of a persistent muscle twitch, muscle fatigue, or even muscle wasting. This usually starts in the hands or lower legs, and is usually accompanied by cramps. As the disease progresses, patients lose the ability to dress and feed themselves, sit up, walk, or even speak. Generally, patients survive three to five years after diagnosis.
Death usually occurs due to respiratory failure.
A biological test does not exist to help establish the diagnosis. ALS is difficult to diagnose because it resembles other diseases, such as primary lateral sclerosis, progressive bulbar palsy, progressive muscular atrophy, and progressive pseudobulbar palsy. Prompt diagnosis and treatment of ALS patients are important in order to optimize care. Typically, neurologists may see only 3-4 ALS patients in their entire career. General practitioners may only see one ALS patient.