Table 3.

House–Brackmann score (HBS) and Yanagihara grading system (Y-system) to grade severity of facial nerve palsy [21] by assessing motility of forehead, eye, nose, and mouth as 1–6

Grade	HBS	Y-system
Normal, symmetrical function in all areas	I	40
Slight weakness on close inspection, complete eye closure with minimal effort, slight asymmetry of smile with maximal effort, slight synkinesis, absent contracture or spasm	II	32–38
Obvious weakness but not disfiguring, unable to lift eyebrow, complete and strong eye closure, asymmetrical mouth movement with maximal effort, obvious but not disfiguring synkinesis, mass movement or spasm	III	24–30
Obvious disfiguring weakness, inability to lift brow, incomplete eye closure, and asymmetry of mouth with maximal effort, severe synkinesis, mass movement, spasms	IV	16–22
Motion barely perceptible, incomplete eye closure, slight movement corner mouth, synkinesis, contracture, spasm usually absent	V	8–14
No movement, loss of tone, no synkinesis, contracture, spasm	VI	0–6