Takashi Futaki

Fluctuating Hearing Loss in Lipoma of the Cerebellopontine Angle

Two cases of lipoma of the cerebellopontine angle are presented. Both of them showed fluctuating hearing loss, and one case exhibited Menière-like symptoms. In one of the cases, continued clinical surveillance is considered in view of a high chance of postoperative morbidity.

Immunological analysis of IgG and other protein fractions in endolymph obtained from endolymphatic sac of Meniere patients and a control.

During endolymphatic sac surgery on patients with Menieres disease, very small amounts (1 microliter) of the intra-sac endolymph were obtained with micro-glass pipets. An immunological assay of microanalysis of the protein by the single radial immunodiffusion (SRID) method was applied to 2 patients, one with bilateral involvement and the other unilateral. Among the protein fractions Alb, IgG, IgM, IgA, C3, C4, transferrin and alpha 2M, the concentrations of IgG were relatively higher, especially in the Meniere patient in the active stage. From 2 other patients and a control deaf patient with temporal bone fracture, the same amounts of endolymph were obtained, accompanied by a tiny specimen of the outer wall of the sac. When a radio-immunological procedure was applied to the endolymph and the homogenized sac, the specific concentration of IgG was higher in the Meniere patients than in the control.

Detection of Delayed Endolymphatic Hydrops by the Furosemide Test

Delayed endolymphatic hydrops, an entity which can be differentiated from Menieres disease, was first reported simultaneously by Nadol et al. (1975) and Wolfson & Leiberman (1975) and specified by Schuknecht (1978). They diagnosed it from the anamnesis of patients and confirmed the hydropic condition of the labyrinth solely by evidence obtained from surgical procedures such as labyrinthectomy. The aim of the present study was to emphasize the usefulness of the furosemide test for distinguishing this entity before surgery by detecting the hydropic condition in the labyrinth. In these 3 years, we encountered 11 cases of endolymphatic hydrops, 9 ipsilateral and 2 contralateral, in our clinic (Univ. of Tokyo Hospital). Among the ipsilateral cases, the estimated genesis of pre-existing hearing loss was most frequent in mumps (44%). The result of the furosemide test in this group was 89% positive. On the basis of this result, we have been able to choose the method of treatment, i.e. 4 cases treated by epidural shunt operation on the endolymphatic sac, 2 by labyrinthectomy, one by cochleosacculotomy and 2 by medication with steroids and diuretics. In the 2 contralateral cases, one was treated by epidural shunt and the other by medication. The authors are therefore able to confirm the usefulness of the furosemide test for detecting delayed endolymphatic hydrops.

Development of Pressure Monitoring and Controlling System for Quantitative Analysis of Experimentally Induced Perilymph Fistula

The cause of perilymph fistula, a subgroup of sudden deafness, has not been clearly understood. To study its etiology quantitatively, the inner ear pressure monitoring system with a computer controlled pressurizing device and three types of low-pressure monitoring sensors was constructed and utilized in ex vivo experiments using white guinea pigs. Hypothesizing that cerebrospinal pressure increases cause rupture of the round window membrane, direct and indirect pressurization to cerebrospinal region and simultaneous measurement of inner ear and cerebrospinal pressures were carried out. Ruptures of the round window membranes were seen in the experiments with direct saline infusion into the cochlea when the increment of inner ear pressure exceeded 500 mmH2O. There was no sign of rupture when squeezing abdomen was employed as an indirect pressurization, although cerebrospinal pressure increased.