A functional disorder usually occurs suddenly and typically affects one half of the face. This could manifest itself as a full or partial paralysis of the forehead, eye, cheek, and mouth region. Facial expression impaired this way makes smiling, frowning, chewing, and speaking very difficult.
Not all triggers for this symptom have been researched yet. If the cause is unknown, this is called an idiopathic facial paralysis or Bell Parese. Proven causes include inflammations and infections, injuries, tumours of the parotid gland or strokes.
To identify the cause of the paralysis a detailed questioning (anamnesis/medical history), including ultrasound, is performed, as the cause is crucial for the choice of the appropriate therapy.