Article
Interobserver variability of facial nerve function following vestibular schwannoma resection
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Published: | May 13, 2014 |
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Objective: The House-Brackmann (HB) scale was selected as the standard for classification of facial nerve paresis following vestibular schwannoma surgery by the Facial Nerve Disorders Committee in 1985. The interobserver variability of the HB scale is controversially discussed.
Method: 112 patients were included in a prospective, multicenter, clinical phase III trial in order to evaluate the efficacy of prophylactic nimodipine treatment in vestibular schwannoma surgery. Photographs of the main facial movements were independently evaluated by 3 facial nerve specialists (neurologist, neurosurgeon and otolaryngologist) preoperatively, in the early postoperative course and additionally after 3, 6 and 12 months.
Results: Interobserver correlation was 97% for none or mildly impaired facial nerve function (HB I and II). In cases of postoperative facial nerve paresis of HB III-VI the interobserver correlation decreased to 32%. In 44% of the cases a difference of one grade was assessed. Interobserver variability of two (21%) and three grades (3%) were predominantly observed in cases with severe facial nerve paresis.
Conclusions: Interobserver variability in the application of the HB scale increases with the degree of facial nerve paresis. The validity of scientific publications may be influenced by this scale conditioned bias. The development of an objective and computer-assisted measurement of facial nerve function seems to be needed.