Amyotrophic lateral sclerosis, or ALS, is a disease that attacks the nervous system, and it is incurable as of 2015, according to Mayo Clinic. Eventually, it leads to death. No one knows what causes ALS, though some cases are hereditary.
The symptoms of ALS come on gradually and can last for years, according to Mayo Clinic. The patient first feels weakness in his hands, legs or feet. He may slur his speech or have difficulty swallowing, and he may have trouble raising his head and maintaining good posture. As the disease progresses, muscles all over the body begin to weaken. Interestingly, ALS does not cause the patient to become incontinent, nor does it normally affect a person's ability to think.
Most people with ALS die within three to five years of diagnosis when the muscles that control respiration no longer work, according to the National Institute of Neurological Disorders and Stroke. There is no one test for ALS; a physician only tests a patient to rule out other diseases. Physicians give ALS patients neurological exams at regular intervals to see if symptoms are worsening.
ALS is also called Lou Gehrig's disease, after a baseball player who contracted the disease, says Mayo Clinic.