CLINICAL STUDIES ON ACOUSTIC TUMOR (II)

Abstract

The references concerning acoustic tumor are divided into two groups composed of statical and analytical studies.From the latter standpoint, the cases with acoustic tumor experienced in the past five years were investigated and an attempt to establish the basis was made for a more complete clinical study of aco-ustic tumor which are to follow in the succeeding papers.The subjects are 25 cases with unilateral acous-tic tumor which came to the department of otolar yngology, Kyushu University, from 1958 to 1962 and were verified by operation.1. The appearance of initial symptom averaged two years and two months before admission, and the age incidence of 39 years was nearly in accord with the literature. Female subjects were predo-minant for the present series (1: 1.6).2. 80 per cent of initial symptoms and chief complaints were the symptoms of the eighth nerve. Of those, furthermore, complaint of cochlear symp-toms were much more frequent than vestibular symptoms and this tendency increased with the initial symptom.With regard to the character of vestibular symptom, the term vertigo was used to designate hallucination concerning position or movement, either in the individual himself or in external objects, that involves a defect in the equilibrium of the body in a narrow sense. From the patient's complaint of vestibular disturbances, however, it was difficult to differentiate peripheral labyrinthine lesion from acoustic tumor especially in the initial stages.3. In 7 cases the deafness was total and in 8 cases it was moderate. In the remaining 9 cases except in a case unexamined there were islet hear- ing losses.There is no similarity of pattern to be found among these pure-tone audiograms.The discrimination loss for speech was almost parallel to the hearing loss for pure tones except a case of the examined 9 cases.All of the cases with hearing loss for speech on the side opposite the tumor differed from the cases with contralateral pure-tone loss and showed evidence of increased intracranial pressure.It is, therefore, inferred that the auditory disturbance arising from increased intracranial pressure manifested the marked reduction of discrimi-nation when compared with pure-tone audiogram bottleneck principle (Jerger, 1960)-and that this was a diagnostic characteristic.