What are the grades of facial nerve palsy and their corresponding treatments?

Facial Nerve Palsy Grading: The House-Brackmann System

The House-Brackmann grading system is the universally accepted standard for assessing facial nerve function, consisting of six grades from normal function (Grade I) to complete paralysis (Grade VI). 1

The Six-Grade Classification System

The American Academy of Otolaryngology-Head and Neck Surgery defines the House-Brackmann grading system as follows: 1, 2

Grade I: Normal

• Normal facial function in all areas 1, 2
• Complete symmetry at rest and with movement 1

Grade II: Mild Dysfunction

• Slight weakness noticeable only on close inspection 1, 2
• At rest: Normal symmetry of forehead 1
• Motion: Ability to close eye with minimal effort and slight asymmetry; ability to move corners of mouth with maximal effort and slight asymmetry 1
• No synkinesis, contracture, or hemifacial spasm 1, 2

Grade III: Moderate Dysfunction

• Obvious but not disfiguring difference between the two sides 1, 2
• No functional impairment 1
• At rest: Normal symmetry and tone 1
• Motion: Slight to no movement of forehead; ability to close eye with maximal effort and obvious asymmetry; ability to move corners of mouth with maximal effort and obvious asymmetry 1, 2
• Patients with obvious but not disfiguring synkinesis, contracture, and/or hemifacial spasm are Grade III regardless of degree of motor activity 1

Grade IV: Moderately Severe Dysfunction

• Obvious weakness and/or disfiguring asymmetry 1, 2
• At rest: Normal symmetry and tone 1
• Motion: No movement of forehead; inability to close eye completely with maximal effort 1, 2
• Patients with synkinesis, mass action, and/or hemifacial spasm severe enough to interfere with function are Grade IV regardless of motor activity 1

Grade V: Severe Dysfunction

• Only barely perceptible motion 1, 2
• At rest: Possible asymmetry with droop of corner of mouth and decreased or absent nasolabial fold 1, 2
• Motion: No movement of forehead; incomplete closure of eye with only slight movement of lid with maximal effort; slight movement of corner of mouth 1
• Synkinesis, contracture, and hemifacial spasm usually absent 1, 2

Grade VI: Total Paralysis

• Loss of tone; asymmetry; no motion 1, 2
• No synkinesis, contracture, or hemifacial spasm 1, 2

Clinical Application and Treatment Implications

Eye Protection (Critical for Grades IV-VI)

• Inability to close the eye completely (Grades IV-VI) requires immediate eye protection measures to prevent corneal exposure and damage 1, 3
• This includes artificial tears, lubricating ointments, and potentially eyelid taping or moisture chambers 3

Medical Management for Bell's Palsy

• Oral steroids should be initiated within 72 hours of symptom onset for all grades of Bell's palsy 3
• Antiviral therapy alone is not recommended but may be offered in combination with oral steroids 3

Surgical Considerations

• Middle fossa decompression may be considered for severe cases (typically Grade VI or high-grade V) with electroneurography showing >90% reduction in amplitude on the affected side, performed between 3-14 days after onset 1
• Rehabilitative procedures (eyelid weights/springs, muscle transfers, nerve substitutions, facial slings, botulinum toxin for synkinesis) are options for long-term sequelae 1

Important Clinical Pearls

Original Design vs. Current Use

• The House-Brackmann system was originally designed to quantify facial nerve functional recovery after surgery that puts the facial nerve at risk, not to assess initial facial nerve paresis or paralysis of Bell's palsy 1, 2
• Despite this, it has become the standard for assessing all facial nerve dysfunction 1, 2

Reliability

• The system demonstrates 93% inter-observer reliability, making it a robust method for clinical assessment 4
• The scale shows adequate agreement among examiners, with most disagreements differing by only one grade 5, 4

Prognosis by Grade

• Most Bell's palsy patients begin showing recovery within 2-3 weeks, with complete recovery typically occurring within 3-4 months 3
• Without treatment, approximately 70% of patients with complete paralysis (Grade VI) achieve full recovery within 6 months, while up to 94% of patients with incomplete paralysis recover 3

Red Flags Requiring Further Investigation

• Advanced age, bilateral facial weakness, and new or worsening neurologic findings require evaluation for alternative diagnoses beyond Bell's palsy 3
• Consider stroke, brain tumors, parotid gland tumors, Herpes zoster, and Lyme disease in the differential diagnosis 3