RecruitingDevice studyInvestigating the Impact of Electrical Stimulation on Facial Pain, Jaw Movement and Oral Health in People With Motor Neuron Disease.The goal of this clinical trial is to evaluate the impact of non-invasive electrical stimulation, when placed on the facial muscles can reduce facial pain and improve jaw mobility, and chewing in individuals with Amyotrophic Lateral Sclerosis (ALS) and Primary Lateral Sclerosis (PLS). The secondary goal is to evaluate the impact of non-invasive electrical stimulation on patient reported difficulty performing oral hygiene tasks in individuals with ALS and PLS. Participants will attend one in-person clinic visit and participate in one telephone interview 24 hours after the treatment. The clinic visit will include pre-intervention assessments, a single 30-minute treatment of electrical stimulation followed by post-intervention assessments. The assessments will include a self-rating of jaw and facial pain, a range of motion test where participants will be asked to open their jaw as wide and as far to the side as possible, and a chewing efficiency test using a saltine cracker. Twenty-four hours later, participants will receive a follow-up phone call to self-rate their facial pain and report any difficulty performing oral hygiene tasks. The treatment consists of a single 30-minute electrical stimulation session. Electrode pads will be placed on the participant's facial region, specifically over the masseter muscle belly and the TMJ area, while the participant is seated comfortably. The pads will be connected to an FDA-approved electrical stimulator, and the current will be adjusted to the participant's comfort level. Once set, the participant will remain seated for 30 minutes. At the end of the session, the stimulator will be turned off and the electrode pads removed.