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Electrocochleography by the tympanic electrode technique was performed on 37 ears of positive recruitment phenomenon and 10 ears of negative recuitment, totalling 47 ears, and the following results were obtained. The positive recruitment phenomenon was understood to be observed in cases wherein the auditory nerve action potential (AP) shows a steep increment, and where the AP output potnetial at intensive sound stimulation is equal to or higher than normal level. The recruitment phenomenon was positive in cases of dominant negative summating potential (dominant — SP) even if the AP output potential was low. The negative recruitment phenomenon was observed mostly in cases wherein the AP output potential was much lower than normal level even at stimulation of intensive sound pressure, and where the —SP was lower than normal level. Even though clinical EcoG is recorded from the promontory, the —SP seems to play an important role in increasing the AP output potential, in other words, causing recruitment phenomena.

In the study on regional difference in susceptibility to damage of vestibulosemicircular canals upon causing labyrinthine lesion by four different procedures, namely, by intracranial approach, through the middle ear, through the facial nerve and by means of experimental endolymphatic hydrops, the following results were obtained. 1. The crista of posterior semicircular canal among the semicircular canals and the macula of the saccule within the vestibule were most susceptible to impairment. In other words, the most susceptible region was the so-called pars inferior. In regard to the impairment of the cupulas, the posterior semicircular canal was the most susceptible region. 2. 2. Recovery from markedly reduced caloric nystagmus within a short period so as to see provocation of caloric nystagmus may result from the reconstruction of the cupulas and the normalization of vacuole-like findings of the sensory epithelium.

Cerebrospinal fluid was examined in 20 patients experiencing sudden deafness. Pressure, protein, glucose and cell counts were measured, virus culture was done, and IgG, IgA, IgM in concentrated cerebrospinal fluid were measured by means of the single radial immunodiffusion method and IgE also by means of the radio-immunosorbent test. Pressures ranged from 110 mm H2O to 330 mm H2O and the mean being 178 mm H2O. Protein and glucose were almost normal, IgG and IgE were normal. In five cases, IgM were demonstrated. IgA ranged from 0.08 mg/dl to 1.7 mg/dl. In two cases, the viruses were cultured and were determined to be Herpes according to morphological features. In the group showing complete recovery and/or improvement, the initial pressure and glucose value were rather low; in the group showing no change, the value of IgA was low. In the two cases where virus was isolated, there was no alteration of pure tone audiometry nor was there any improvement of hearing acuity. The virus isolated from the two cases presented was of low virulence since the number of cells in the CSF was small and the virus grew poorly even after serial cultivation. Accordingly, virus such as these may act one of the causative agents in sudden deafness.

The purpose of this paper is to demonstrate the variation of the direction of nystagmus which is elicited from the peripheral labyrinth. The direction of nystagmus depends, among other things, on the nature of the stimulus. Depending on the degree of pathophysiological conditions in the labyrinth, atypical nystagmus which does not comply with the rule is occasionally elicited even though the same stimulus is given. Hyperfunctional stimulation to the labyrinth, such as allergy, causes nystagmus which beats to the affected side and also shows hyperactivity of the whole nerve action potential and cochlear microphonics.