The most commonly used clinical grading scale is the House Brackmann (HB) facial nerve grading system which has proposed a six point scale for reporting the result of surgery for acoustic tumours. This system was modified and called House Brackmann system. The American academy of Otolaryngy0logy – Head and Neck surgery has adopted this system to standardize the reporting of disorder of the facial nerve and treatment result. It differentiates six grades of facial function (I-IV), grade I is normal function and grade VI complete absence of facial motor function and grades II-V are intermediate. It has two domains of assessment:
1) Gross observation
2)Movement of forehead/eye/mouth
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However, the House brackmann scale is not a perfect grading system because of:
- the problems of inter-observer and intra-observer variability
- It is applicable only to disorder of the nerve proximal to the pes-anserinus
- It is not appropriate for single branch injuries such as penetrating injury to the face affecting only the buccal branch.
The House brackmann scale is not useful in assessing transected/ repaired nerves for 3 reasons
- All repair causes mass movement
- Most patients can eventually close their eyes and have good oral sphincter function
- Almost no patients are able to raise the eyebrow or forehead .
The House brackmann system works well as long as there is an intact nerve sheath or incomplete nerve injury (sunderland grades I-IV)
