| Abstrakt: |
Within the battery of functional tests used in patients considered to have an acoustic neuroma, the use of vestibular examination has been reduced by the widespread use of magnetic resonance imaging. Especially small tumors often show normal or atypical results in electronystagmographic examinations (ENG). The purpose of the present study was to determine the diagnostic value of preoperative vestibular diagnosis in predicting the origin of an acoustic neuroma, as well as the duration of postoperative vestibular compensation and facial nerve function. Sixty-seven patients with intraoperatively confirmed tumor origins were examined preoperatively by ENG and electroneurography in addition to careful clinical examination. Group 1 (n = 45) consisted of patients with tumor originating from the inferior vestibular nerve and group 2 (n = 22) had tumor involving the superior vestibular nerve. Postoperatively, facial nerve function was determined by using the House grading system and vestibular function was defined by ENG 3, 6 and 12 months after surgery. Forty-seven percent of the patients in group 1 showed a pathologic caloric response compared to 64% in group 2. When patients had only a small tumor (< 1 cm), 27% of the patients in group 1 and 71% in group 2 had abnormal caloric results. Vestibular recovery was prolonged in group 1, but a statistically significant difference in postoperative facial nerve function could not be found. These findings confirm that especially small tumors arising from the inferior vestibular nerve can remain undetected by using ENG for diagnosis. |
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