How long does it take to diagnose als?

Depends: There are cases in which the physical signs and symptoms are so characteristic that the diagnosis can be made on the first office visit, or at least strongly suspected. In other cases if the situation is less clear, other entities may need to be ruled out, such as spinal cord diseases etc. This may require tests like mri, or electromyogram. The time to get these tests can vary.

Not long: Once the weakness becomes apparent, the muscular atrophy and fasciculations start to appear, and within a period of a few weeks the diagnostic studies can be completed. Best to start a drug such as Riluzole as early as possible to provide best outcomes.