Objective assessment of the reliability of the House-Brackmann and Fisch grading of synkinesis.

The objective of this paper is to assess synkinesis associated with post paretic voluntary facial movements using the objective OSCAR method and to investigate the correlation between synkinesis and paresis to compare the objective results with the subjective scaling systems of Fisch and House-Brackmann. The development of an objective assessment of synkinesis with the OSCAR method is focused on the clinically most relevant eye-mouth and forehead-mouth synkinetic movements. Thirteen patients with unilateral facial paralysis and synkinesis of the University Hospital Zurich were examined. Two types of clinically relevant facial synkinesis were found: a maximal synkinesis and a relative synkinesis. Neither Synkinesis-Index correlates well with the underlying degree of global facial palsy. The relative Synkinesis-Index (rSI) correlates well with the subjective evaluation of synkinesis according to the Fisch Grading, but shows a poor correlation with the traditional House-Brackmann grading. Therefore a single scaling index combining the degree of facial nerve palsy and synkinesis is inappropriate and we propose the use of two independent scaling systems for the evaluation of facial palsy: one for the voluntary facial movements, the other for the involuntary synkinetic movements. The adequate evaluation of the post paretic face should include the results of both scaling systems.