What is the proper bedside assessment of the facial nerve (cranial nerve VII) using the House‑Brackmann scale?

Bedside Assessment of Cranial Nerve VII Using the House-Brackmann Scale

The House-Brackmann facial nerve grading system provides a standardized 6-grade scale for assessing facial nerve function by evaluating facial symmetry at rest and during specific movements, though it was originally designed for post-surgical recovery assessment rather than initial Bell's palsy evaluation. 1

The House-Brackmann Grading System

The assessment involves evaluating both resting facial appearance and active facial movements across six grades 1:

Grade 1: Normal

• Normal facial function in all areas 1

Grade 2: Mild Dysfunction

• At rest: Normal symmetry of forehead, minimal effort to close eye with slight asymmetry, slight asymmetry of mouth 1
• On movement: Slight weakness noticeable only on close inspection 1
• No synkinesis, contracture, or hemifacial spasm 1

Grade 3: Moderate Dysfunction

• At rest: Normal symmetry and tone 1
• On movement: Slight to no forehead movement, ability to close eye with maximal effort and obvious asymmetry, ability to move mouth corners with maximal effort and obvious asymmetry 1
• Obvious but not disfiguring difference between sides 1
• No functional impairment 1
• Noticeable but not severe synkinesis, contracture, and/or hemifacial spasm may be present 1

Grade 4: Moderately Severe Dysfunction

• At rest: Normal symmetry and tone 1
• On movement: No forehead movement, inability to close eye completely with maximal effort 1
• Obvious weakness and/or disfiguring asymmetry 1
• Synkinesis, mass action, and/or hemifacial spasm severe enough to interfere with function classify as Grade IV regardless of motor activity 1

Grade 5: Severe Dysfunction

• At rest: Possible asymmetry with droop of corner of mouth and decreased or absent nasolabial fold 1
• On movement: No forehead movement, incomplete eye closure with only slight lid movement with maximal effort, slight movement of mouth corner 1
• Only barely perceptible motion 1
• Synkinesis, contracture, and hemifacial spasm usually absent 1

Grade 6: Total Paralysis

• Loss of tone, asymmetry, no motion 1
• No synkinesis, contracture, or hemifacial spasm 1

Key Examination Components

When performing the bedside assessment, systematically evaluate 1:

• Forehead movement: Ask patient to raise eyebrows and wrinkle forehead
• Eye closure: Assess ability to close eyes gently and with maximal effort
• Mouth movement: Ask patient to smile and show teeth, observing corner of mouth symmetry
• Resting facial symmetry: Observe nasolabial folds, mouth position, and overall facial tone

Important Clinical Caveats

The House-Brackmann scale was not originally designed to assess initial facial nerve paresis or paralysis in Bell's palsy but rather to quantify facial nerve functional recovery after surgery. 1 Despite this limitation, it remains the most commonly used scale in clinical practice and literature. 1

In patients with differential facial function across nerve branches, a single global House-Brackmann score may inadequately communicate the full clinical picture. 2, 3 The global score most strongly correlates with eye function (61%), followed by nose/midface (40-59%), mouth (32-51%), and forehead (18-35%). 2, 3 Regional assessment using the format F(w) E(x) N(y) M(z)—where w, x, y, and z represent House-Brackmann grades for forehead, eye, nose, and mouth respectively—provides more comprehensive documentation. 2, 3

Inter-rater reliability improves significantly with clinical experience, particularly for midface and global scores. 3 An updated version (FNGS 2.0) incorporates regional scoring while maintaining comparable agreement to the original scale. 4