Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that carries a high degree of disability and eventually leads to respiratory failure. The incidence of ALS is estimated to be approximately 2 to 3 per 100 000 per year.1 Between October 2010 and December 2011, the US National ALS Registry identified 12 187 definite ALS cases for an overall prevalence in the United States of 3.9 per 100 000.2 There is currently no cure for ALS and the median survival time with ALS is short, ranging from about 20 to 48 months, although a small subset of patients with ALS live much longer.1,3