Hironobu Nishijima1, Kenji Kondo2, Ryoji Kagoya2, Hitoshi Iwamura2, Kazuo Yasuhara2, Tatsuya Yamasoba2. 1. Department of Otolaryngology- Head and Neck surgery, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8655, Japan. Electronic address: nishijimahironobu@gmail.com. 2. Department of Otolaryngology- Head and Neck surgery, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8655, Japan.
Abstract
OBJECTIVE: To investigate the clinical and electrophysiological features of facial nerve paralysis (FNP) due to benign temporal bone masses (TBMs) and elucidate its differences as compared with Bell's palsy. METHODS: FNP assessed by the House-Brackmann (HB) grading system and by electroneurography (ENoG) were compared retrospectively. RESULTS: We reviewed 914 patient records and identified 31 patients with FNP due to benign TBMs. Moderate FNP (HB Grades II-IV) was dominant for facial nerve schwannoma (FNS) (n=15), whereas severe FNP (Grades V and VI) was dominant for cholesteatomas (n=8) and hemangiomas (n=3). The average ENoG value was 19.8% for FNS, 15.6% for cholesteatoma, and 0% for hemangioma. Analysis of the correlation between HB grade and ENoG value for FNP due to TBMs and Bell's palsy revealed that given the same ENoG value, the corresponding HB grade was better for FNS, followed by cholesteatoma, and worst in Bell's palsy. CONCLUSIONS: Facial nerve damage caused by benign TBMs could depend on the underlying pathology. Facial movement and ENoG values did not correlate when comparing TBMs and Bell's palsy. When the HB grade is found to be unexpectedly better than the ENoG value, TBMs should be included in the differential diagnosis.
OBJECTIVE: To investigate the clinical and electrophysiological features of facial nerve paralysis (FNP) due to benign temporal bone masses (TBMs) and elucidate its differences as compared with Bell's palsy. METHODS: FNP assessed by the House-Brackmann (HB) grading system and by electroneurography (ENoG) were compared retrospectively. RESULTS: We reviewed 914 patient records and identified 31 patients with FNP due to benign TBMs. Moderate FNP (HB Grades II-IV) was dominant for facial nerve schwannoma (FNS) (n=15), whereas severe FNP (Grades V and VI) was dominant for cholesteatomas (n=8) and hemangiomas (n=3). The average ENoG value was 19.8% for FNS, 15.6% for cholesteatoma, and 0% for hemangioma. Analysis of the correlation between HB grade and ENoG value for FNP due to TBMs and Bell's palsy revealed that given the same ENoG value, the corresponding HB grade was better for FNS, followed by cholesteatoma, and worst in Bell's palsy. CONCLUSIONS:Facial nerve damage caused by benign TBMs could depend on the underlying pathology. Facial movement and ENoG values did not correlate when comparing TBMs and Bell's palsy. When the HB grade is found to be unexpectedly better than the ENoG value, TBMs should be included in the differential diagnosis.