It’s important to have ALS diagnosed sooner rather than later to help prevent its progression.

There is no one test or procedure that is used to diagnose ALS. Rather, it is diagnosed through a clinical examination and series of diagnostic tests, often ruling out other diseases that mimic ALS. Screening begins with blood and urine laboratory testing. Brain and spine imaging tests (MRIs) are likely, with additional tests to be ordered depending on the patient’s indications.

The diagnosis is made on the basis of history and physical examination. Depending on the clinical findings and test results, the diagnosis of possible, probable and definite ALS would be made. ALS is the most common form of motor neuron disease. There are "relatives" of ALS, including progressive muscular atrophy, primary lateral sclerosis and progressive bulbar palsy.  The prognosis is variable in different motor neuron diseases. Avoiding the delay of ALS diagnosis would reduce patient frustration and uncertainty of the cause of symptoms and would enable earlier use of a disease-modifying therapy. As the disease progresses, patients will experience significant weight loss and muscle deterioration, and require respiratory support as the condition affects the breathing muscles, so early diagnosis is crucial.