What is the role of the House-Brackmann score in evaluating and managing a patient with Bell's palsy?

House-Brackmann Score in Bell's Palsy

The House-Brackmann (HB) grading system is a standardized 6-grade scale used to assess facial nerve function in Bell's palsy, though it was originally designed for post-surgical recovery assessment rather than initial Bell's palsy evaluation. 1

Understanding the Grading System

The HB scale ranges from Grade I (normal) to Grade VI (total paralysis), with specific clinical criteria for each grade 1:

• Grade I (Normal): Normal facial function in all areas 1
• Grade II (Mild Dysfunction): Slight weakness noticeable only on close inspection; normal symmetry at rest; ability to close eye with minimal effort; slight asymmetry with mouth movement; no synkinesis 1
• Grade III (Moderate Dysfunction): Obvious but not disfiguring asymmetry; normal symmetry at rest; slight to no forehead movement; eye closes with maximal effort with obvious asymmetry; obvious mouth asymmetry with maximal effort 1
• Grade IV (Moderately Severe Dysfunction): Obvious weakness and/or disfiguring asymmetry; normal symmetry at rest; no forehead movement; inability to close eye completely with maximal effort 1
• Grade V (Severe Dysfunction): Only barely perceptible motion; possible asymmetry at rest with mouth droop and decreased nasolabial fold; no forehead movement; incomplete eye closure with only slight lid movement 1
• Grade VI (Total Paralysis): Complete loss of tone; asymmetry; no motion; no synkinesis 1

Clinical Applications in Bell's Palsy

Assessment of Recovery and Prognosis

• The HB system is widely used to track recovery in Bell's palsy patients, with HB grades I-II generally considered favorable outcomes 1
• In surgical decompression studies, 91% of patients achieved HB grade I/II with surgery versus 42% with steroids alone, demonstrating the scale's utility in outcome measurement 1
• The system shows good inter-observer reliability at 93%, making it a robust method for clinical assessment 2

Limitations in Bell's Palsy Evaluation

A critical caveat: the HB system was not originally designed to assess initial facial nerve paresis or paralysis in Bell's palsy, though it is commonly used for this purpose. 1, 3

• The HB scale primarily measures facial muscle impairment and asymmetry but neglects other functional aspects of facial disability such as facial comfort, lacrimal control, and social function 4
• The numeric portion of the HB system is not useful for identifying patients at risk of corneal complications—measurements of lagophthalmos and upper lid closure are more valuable for this purpose 5
• Correlation between HB and other grading systems (like Sunnybrook) is weakest at initial presentation (correlation coefficient 0.604-0.626) and improves during follow-up (0.808-0.844) 6, 7

Practical Clinical Use

When to Apply the HB Score

• Use the HB scale to document baseline facial function at presentation and track recovery over time 1
• Assess patients at initial visit, 3 weeks, 6 weeks, and 3 months to monitor progression 6
• Document HB grade when considering surgical decompression for severe cases (typically those with >90% reduction on electroneurography) 1

What the HB Score Does NOT Tell You

• Eye protection needs: The HB grade alone does not adequately predict corneal risk—specifically assess lagophthalmos, upper lid closure, and corneal sensation separately 5
• Patient quality of life: Physician-graded HB scores may show improvement while patients still experience significant functional disability in facial comfort, tearing, and social function 4
• Initial severity stratification: The HB system is less reliable at initial presentation compared to follow-up assessments 6, 7

Integration with Clinical Management

• Immediate eye protection is mandatory regardless of HB grade if incomplete eye closure is present—use lubricating drops, ointment, and eye taping/patching to prevent permanent corneal damage 8, 9
• Reassess or refer to a specialist if HB grade shows incomplete recovery at 3 months, new or worsening neurologic findings develop, or ocular symptoms emerge 8
• Consider combining HB grading with patient-reported outcome measures (like the Facial Clinimetric Evaluation Scale) to capture the full spectrum of facial disability 4