Book excerpt: A diagnosis of amyotrophic lateral sclerosis (also known as Lou Gehrig's disease or motor neuron disease) is a progressive neurodegenerative disorder that exerts a notorious life-shortening physical toll. Understandably, clinicians are keen to avoid a wrong diagnosis when there are such serious consequences, but any delay in diagnosis can result in unnecessary, and sometimes harmful, interventions, and prevents prompt implementation of much-needed physical and emotional support. Starting from the premise that ALS is not one disease but a syndrome, with a spectrum of upper and lower motor neuron involvement, this highly readable resource examines the causes of diagnostic delay and how to avoid them. With no diagnostic test to confirm the disease, no mandatory investigations and very few plausible 'ALS mimics', the authors take a pragmatic approach to what must always be a clinical diagnosis. With case presentations and teaching points to aid understanding, 'Fast Facts: ALS' will give clinicians the confidence to confirm or exclude a diagnosis of ALS, so that individuals facing this most challenging of conditions can receive rapid multidisciplinary support to maximize the quality of their remaining life. Contents: • Defining the syndrome • Epidemiology and pathophysiology • The first symptoms • Differential diagnosis • Investigations • Emerging diagnostic biomarkers