A new grading system for assessing orbicularis muscle function

Abstract

Purpose To establish an objective parameter (orbicularis function) to measure the efficacy of botulinum toxin treatment in weakening the orbicularis of blepharospasm and hemifacial spasm sufferers.

Methods The following scale has been used by one of the authors (VTT) in his botulinum clinic for several years:

• Grade 0: Incomplete eyelid closure.

• Grade 1: Lids just closing, minimal resistance to overcome.

• Grade 2: Closing well, some resistance, easily overcome.

• Grade 3: Strong closure, can be overcome with difficulty.

• Grade 4: Very strong closure, cannot be overcome or overcome with extreme difficulty.

In order to establish the interobserver agreement, one consultant ophthalmologist, three ophthalmologists in training, and one nurse practitioner evaluated the same 65 patients, undergoing treatment with botulinum toxin for essential blepharospasm and hemifacial spasm. Observers assessed orbicularis function by asking each patient to close both eyes forcefully, while the observer tried to open them manually. The measure of agreement across the observers was estimated by κ statistics.

Results Overall interobserver agreement (κ=0.54) was satisfactory. We used Kruskal–Wallis nonparametric test to determine agreement between the observers. The P-values for both right and left eyes were well above 0.05, indicating good consistency between the observers when using this grading system.

Conclusions A simple, new, five-point, clinical grading system for orbicularis muscle function is presented. Medical staff with different levels of experience can use it reliably.

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