Identify abnormalities of esophageal function in patients with Motor Neuron Disease (MND) compared to the asymptomatic population, using esophageal manometry testing. Attention will be given to function of distal (smooth muscle) esophagus and also to the upper esophagus including the upper sphincter and pharynx. A secondary purpose will be to alidate a scoring system for dysphagia in patients with MND, and to compare the presence of dysphagia with observed manometric abnormalities in specific subjects.