Grade I: normal function, normal facial muscle movement in all regions; Grade II: mild functional abnormality, gross: mild facial muscle weakness on close examination, very light joint band movement may be present. Resting state: symmetrical face with normal muscle tone. Movement: normal forehead, complete eye closure with slight force, mild asymmetry of the corners of the mouth; Bin Grade III: moderate functional abnormality, gross: marked facial muscle weakness but no facial deformation, marked joint band movement or hemifacial spasm. Resting state: facial symmetry, normal muscle tone. Motor: frontal diminished, complete eye closure after force, mild asymmetry at the corners of the mouth with maximum force; Grade IV: moderate to severe functional abnormalities, gross: marked facial muscle weakness and/or facial deformation. Resting state: facial symmetry with normal muscle tone. Movement: absent in the frontal region, incomplete eye closure, asymmetry in the corners of the mouth after using maximum force; Grade V: severe functional abnormality, gross: only barely perceptible facial movement. Resting state: facial asymmetry. Movement: no frontal, incomplete eye closure, slight movement of the corners of the mouth; Grade VI: complete paralysis, no movement.