The early diagnosis of acoustic tumor and the choice of surgical approach (author's transl)

Abstract

From our experience of more than 200 cases of verified acoustic tumors, the diagnostic problems of acoustic tumor and the choice of the surgical approach were discussed. Hearing loss, tinnitus and dizziness are known as early signs of acoustic tumor. However, as far as tinnitus was concerned, only 57 % of our cases experienced this sympton. Hearing loss of sudden onset is sometimes the earliest presenting symptom of acoustic tumor as MIeyer (1941)12, Hallberg et al (1959)2, Straud et al (1969)17 and Higgs (1973)3 have already pointed out. Six such cases were found in our series. This indicates, in cases of so called sudden deafness, careful examination to rule out acoustic tumor must be carried out. Audiometric study was important in small acoustic tumor, when hearing loss was not so marked. However, sophisticated audiometry did not always demonstrate typical retrocochlear lesion. Hearing loss is said to progress gradually. However, some of our cases showed almost no progression over 6 years. In bilateral acoustic tumor mainly due to von Recklinghausen's disease, even though tumor was large hearing was less impaired compared with unilateral tumor. Small tumors did not show any lateral gaze nystagmus, saccardic pursuit eye movement nor abnormal optokinetic nystagmus response, whereas these signs of the oculomotor dysfunction was demonstrated in large tumors. The authors proposed a system to diagnose early acoustic tumor as is shown in the figure 9. The relationship between the choice of surgical approach and the results of the functional tests such as hearing loss, other cranial nerve involvements, gaze nystagmus, disturbance of induced optokinetic nystagmus and cerebellar symptoms were mentioned, which is shown in the table 1.