Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. It should be determined whether the tremor he manifests about the mouth is the consequence of what we call an essential, action or rubral type of tremor or is it related to Parkinsonism? Depending upon the type of tremor, certain medications or interventions may be better suited to treating him such as oral medication vs. botox injection, or depending on the severity of the situation or even something on the order of Deep Brain Stimulation (DBS). Hope I have answered your query. Let me know if I can assist you further.