House-Brackmann Facial Grading Scale

TheFacial Nerve Grading Scale (FNGS), often referred asHouse-Brackmann grading scale (HBGS), was initially introduced by House in 1983 [2], and modified to its final form by House and Brackmann in 1985 [3]. To put the adjustment briefly, a method for measurement was added to the descriptive grading scale. [3]

The House-Brackmann scale was endorsed by Facial Nerve Disorders Committee (FND Committee) of the American Academy of Otolaryngology - Head and Neck Surgery Foundation, in 1985 to be used as the standard grading scale for reporting facial nerve function [3]. In 2009 Vrabec et al. [20] reported that the House-Brackmann scale has indeed become the standard scale. This statement was supported by a survey conducted in 2014 which revealed that by then the House-Brackmann scale was the most commonly used grading scale [5].

The House-Brackmann scale is a six-point gross scale. The scale ranges from Grade 1 (normal) to Grade 6 (total paralysis) and includes the secondary features within. [2]

Table 2.2 illustrates the measurement system of the House-Brackmann scale whereas Table 2.3 details the grade descriptions.

The method for measurement is represented in Table 2.2. The observer measures the movement of the patient’s paralyzed side. The upwards (superior) movement of the midpoint of the eyebrow, and the outwards (lateral) movement of the oral commissure are measured. One point is assigned for each 0.25 cm movement, 1.0 cm being the maximum displacement for both the eyebrow and oral commissure.

Thus, both structures may gain four points in total producing the maximum score of eight. The Measurement-column shows the score, or scores, corresponding the grade in question in the nominator. The denominator represents the maximum score. In the Function-column, the range for the amount of function is given in percentages, and the Estimated function-column displays the percentage of facial nerve function that the paralyzed side should have in theory for the specific grade. [3]

Table 2.2 The measurement method of the House-Brackmann grading scale. Table is recreated from [3]. The Measurement-column shows the amount of points available (denominator) and how many points are required for a certain grade (nominator).

The Function-column displays the facial performance in percentages.

Grade Description Measurement Function % Estimated function %

I Normal 8/8 100 100

II Mild dysfunction 7/8 76-99 80

III Moderate dysfunction 5/8 - 6/8 51-75 60

IV Moderately severe dys-function

3/8 - 4/8 26-50 40

V Severe dysfunction 1/8 - 2/8 1-25 20

VI Total paralysis 0/8 0 0

The description of the House-Brackmann scale is given in Table 2.3. The two left-hand columns contain the grades from one to six, and the function level’s descriptive name. The right-hand column holds the explanation for the grade in question. The definition of each grade begins with a general description of the grade; for example, for Grade V that is "Only barely perceptile motion." [3]. The finer elucidation of the grades then contains information for the observer about rest, motion, and secondary symptoms of the grade, respectively. The motion characteristics are given separately for forehead, eye, and mouth.

The House-Brackmann scale is widely used due to its position as the standard reporting scale, and its simple usage [20]. However, the House-Brackmann scale is also widely criticized on several matters.

Firstly, there are issues related to the measurement method of the House-Brackmann scale: it seems to be completely ignored in practice. Thus the grading in clinics is done simply based on the descriptions of the different grades, in other words based on Table 2.3. [20] Additionally the measuring method has not been verified adequately [20] and an analysis done by Lewis and Adour concluded that the measurements could not be generalized to the descriptive scale [21]. In the same analysis, problematic situations were reported to be arisen, if the healthy side’s movement was above the maximum displacement of 1cm. Hence, the paralyzed side could move less than the healthy side, but still gain the maximum score. There is no procedure given by House and Brackmann for such patients [3].

Table 2.3 The description of the House-Brackmann grading scale. Table is recreated from [2]. Each grade is given a description and definition. In the Defined by-column, there is at first a general specification, and explanations for appearance at rest and motion behavior follow. Finally, the secondary symptoms related to the specific grade in question are explained.

Grade Description Defined by

I Normal Normal facial function in all areas II Mild

dysfunc-tion

Slight weakness noticeable only on close inspection.

At rest: normal symmetry and tone.

Motion: some to normal movement of forehead; ability to close eye with minimal effort and slight asymmetry;

ability to move corners of mouth with maximal effort and slight asymmetry.

No synkinesis, contracture, or hemifacial spasm.

III Moderate dys-function

Obvious but not disfiguring difference between two sides;

no functional impairment; noticeable but not severe synk-inesis, contracture, and/or hemifacial spasm.

At rest: normal symmetry and tone.

Motion: slight to no movement of forehead; ability to close eye with maximum effort and obvious asymmetry.

Patients with obvious but not disfiguring synkinesis, con-tracture, and/or hemifacial spasm are Grade III regard-less of degree of motor activity.

IV Moderately severe dys-function

Obvious weakness and/or disfiguring asymmetry.

At rest: normal symmetry and tone.

Motion: no movement of forehead; inability to close eye completely with maximal effort; asymmetrical movement of corners of mouth with maximal effort.

Patients with synkinesis, mass action, and/or hemifacial spasm severe enough to interfere with function are Grade 4 regardless of degree of motor activity.

V Severe

dys-function

Only barely perceptile motion.

At rest: possible asymmetry with droop of corner of mouth and decreased or absence of nasal labial fold.

Motion: no movement of forehead, incomplete closure of eye and only slight movement of lid with maximal effort;

slight movement of corner of mouth.

Synkinesis, contracture, and hemifacial spasm usually absent.

VI Total paraly-sis

Loss of tone; asymmetry; no motion; no synkinesis, con-tracture, or hemifacial spasm.

Secondly, Coulson et al. [22] and Murty et al. [23] have reported notable interobserver variability in House-Brackmann grading between trained observers. Further, Murty et al. [23] suggested that the reasons behind the interobserver variability would inter alia include inadequate recording of secondary defects. That brings up the third issue: the House-Brackmann scale admits of several interpretations for secondary movement grading [20].

Finally, the House-Brackmann scale has been criticized due to its gross scale nature.

A single global score has been found to be inadequate to describe differential facial function [24–26]. The reason for insufficiency has been explained further: other than grades I or VI (normal and total paralysis) may be difficult to assess if the patients have different levels of function in the upper and lower facial parts [24]. However, it is controversial that which part of the face the global score primarily correlates in unclear cases; in [25] the score was found to mostly reflect the function of the eye whereas in [26] the function of the midface.

Another element of the gross scale criticism is the deficient sensitivity of the House-Brackmann scale. Ross et al. [4] argued that the House-House-Brackmann scale is too coarse to detect clinically important change. An example of such situation is reported by Gidley et al. [27] who stated that the House-Brackmann scale is inappropriate to be used as a measure of the change after surgical repair of nerves.

This criticism has led to an updated version of the original House-Brackmann scale.

The Facial Nerve Grading Scale 2.0 is considered in Subsection 2.3.2.