[14C] deoxyglucose was injected into the peritoneal cavity of rats with destructed brainstem, and the auditory stimulation was sustained for 45 minutes. At the end of the stimulation, the brain as a whole was immediately removed and frozen sections of 8μm were made. Autoradiographs were then prepared by exposing the sections to x-ray films. The results of autoradiograms were compared with the changes of ABR induced by the destruction. These results lead to the following conclusions in summary: (1) Waves of P2, P3, P4 and P5 might have their corresponding generators respectively in several parts of the brainstem auditory pathway. (2) The inferior colliculus is not essential for the generation of fast waves. (3) The wave of P5 has its main generator in the afferent nerve fibers which project to the contralateral inferior colliculus. (4) The generators of P4 are distributed between the contralateral superior olivary complex and the vicinity of ventral nucleus of the contralateral lateral lemniscus. (5) The wave of P3 is generated by bilateral auditory pathways in the vicinity of the superior olivary complex. (6) Main generator of P2 is in the ipsilateral cochlear nucleus, however, the medial portion of the 8th nerve and the ipsilateral superior olivary complex might participate to some extent.
Since it is generally thought that ketamine hydrochloride has no depressive effect on the reticular formation, we expected that the acoustical stapedial reflex has not been affected by this medicine. On the contrary, ketamine hydrochloride supressed the acoustical stapedial reflex in the guinea pig, that is, mainly changed the slope of the stimulus-response curve without appreciablly raising its threshold. Since ketamine hydrochloride has a depressant effect on thalamic and cortical activity, we thought that ketamine hydrochloride did not supress the direct route which was located in the lower brain stem but supressed the indirect route which would facilitate the acoustical stapedial reflex. As a conclusion, there seems to be neuro-anatomical links to the final common pathway of the acoustical stapedial reflex which would have to descent from at least the mid-brain level.
In 368 subjects with relatively advanced noise-induced deafness, the relationship between speech audiometry and pure tone audiometry and the relationship with age and the number of years worked under noise were studied. 1) There was a correlation between speech audiometry and pure tone audiometry; that is, the results of speech audiometry became worse as hearing level for pure tone audiometry became lower. 2) As for the age and the number of years worked, the results were not obtained because of unevenness among the subjects. 3) The horizontal type gave slightly better results of speech audiometry as compared with the abrupt type. There was not much difference from other kinds of sensorineural deafness so far as the results above are concerned.
In this paper we report the cases in which the ears were injured during an ear mold was being made, and a nationwide questionnairing was conducted at 395 medical institutes to find how the injuries are happened. There were injury of the external ear, bleeding and inflammation of the external ear after making of an ear mold, and foreign bodies in the ear, such as an impression material. According to the results of the questionnaire “injuries” were found in 12.4 percent. Bleeding of the external ear was reported from 11 hospitals. Particularly, the difficulty in removing the ear mold was occurred in the patients received radical mastoidectomy in many cases. Some patients received surgical treatment for removal of the foreign body. These findings indicate that various injuries of the ear could occur during, before and after making of an ear mold and this fact is suggesting the danger involved in making the ear mold.