Grading Severity
As facial muscle weakness can vary from mild to complete, grading it can help in the prognosis and follow-up. The modified House-Brackmann classification is the most commonly used scale as in the table below.
Table 1: The modified House-Brackmann classification
| Grade | Description | Characteristics |
| I | Normal | Normal facial function |
| II | Mild dysfunction | Slight weakness noticeable on close inspection. May have slight synkinesis |
| III | Moderate dysfunction | Obvious, but not disfiguring, difference between two sides. Compete eye closure with effort. Noticeable but not severe synkinesis, contracture or hemifacial spasm |
| IV | Moderately severe dysfunction | Obvious weakness or disfiguring asymmetry. Normal symmetry or tone at rest. Incomplete eye closure |
| V | Severe dysfunction | Only barely perceptible motion. Asymmetry at rest |
| VI | Total paralysis | No movement |