OBJECTIVE: To investigate the extent of within-system reliability and 
between-system correlation for the "Sydney" and "Sunnybrook" systems of grading 
facial nerve paralysis, and to examine the interobserver reliability and 
agreement of the "House Brackmann" grading system.
STUDY DESIGN: A fixed-effects reliability study in which 6 otolaryngologists 
viewed videotapes of patients with facial nerve paralysis.
SETTING: University and medical Centers.
PATIENTS: Patients with unilateral lower motor neurone facial nerve dysfunction 
greater than 1 year after onset, none of whom had undergone surgical reanimation 
procedures. Intervention Twenty-one patients with facial nerve paralysis were 
videotaped while they performed a protocol of facial movements. Six 
otolaryngologists viewed the videotapes and scored them with the Sydney and 
Sunnybrook systems, and then gave a House Brackmann grade.
MAIN OUTCOME MEASURE: The 3 systems of grading facial nerve paralysis were 
evaluated and compared with the use of intraclass correlation coefficients, 
Pearson's weighted kappa, and percentage exact agreement values.
RESULTS: The Sydney and the Sunnybrook systems had good intrasystem reliability 
and high intersystem association for the assessment of voluntary movement. 
Grading of synkinesis was found to have low reliability both within and between 
systems. The House Brackmann system had substantial reliability as shown by 
weighted kappa but had a percentage exact agreement of 44%.
CONCLUSIONS: For clinical grading of voluntary movement, there is good 
correlation between ratings given on the Sydney and Sunnybrook systems, and 
within each system there is good reliability. The assessment of synkinesis was 
far less reliable within, and less related between, systems. Although the 
reliability of the House Brackmann system was found to be high, examination of 
individual grades revealed some wide variation between trained observers.