ALS, also known as Lou Gehrig's disease, is a rapidly progressive, degenerative disease of motor neurons in the brain and spinal cord that leads to muscle atrophy and spasticity in limb and bulbar muscles. Clinical presentations of this fatal disease include weakness, loss of ambulation, oropharyngeal dysfunction, weight loss, and ultimately respiratory failure. Average survival is approximately 3 years after symptom onset. The initial symptoms are similar to other neuropathies (e.g., motor neuropathy, progressive muscle atrophy, etc.) and include limb weakness leading to partial or total paralysis, and increasing difficulties in speech and breathing. ALS clinical diagnosis typically takes 12 months from symptom onset and relies on exclusion of other potential causes of the clinical symptoms. To date there are no FDA-approved diagnostic tests for ALS. Diagnostic tools for accurate and early diagnosis are under investigation. These tools would not only permit early intervention, but also would improve clinical trial design for new drug therapies.