A 52-year-old female patient complains of dry mouth, taste impairment, burning and pricking sensations in the tongue that disappear during eating but intensify at the end of the day. For the first time such problems arose 2 years ago after a psychic trauma. She has a history of anacid gastritis. Objectively: the general condition is satisfactory, the patient is restless, tearful. Oral mucosa is pale pink, dry; filiform papillae on the dorsum of tongue are reduced. Pharyngeal reflex is dramatically reduced. There is segmetal disturbance of facial skin sensation. What is the most likely diagnosis?