Yuzuru Kobayashi

Cervico-Vestibular Interaction in Eye Movements

The cervico-vestibular interaction was investigated in normal subjects and patients with unilateral labyrinthine dysfunction using neck vibratory stimulation and caloric stimulation. There is a functional interaction between sensory inputs from the neck proprioceptors and the peripheral labyrinth in the patients with unilateral labyrinthine dysfunction. However, this interaction was not observed in normal subjects. This result indicates that the role of the cervical sensory inputs in normal subjects and the patients is different. That is, inputs from the neck proprioceptors have little effect on the control of eye movements in normal subjects, whereas the neck inputs are quite important for the control of eye movements in patients with unilateral labyrinthine dysfunction.

Speech Audiometry One Year after Tympanoplasty.

Speech reception thresholds were analyzed in 71 patients with chronic otitis media one month before and after and one year after typmpanoplasty. Bone conduction thresholds of all the subjects were within the normal range.In 19% of the subjects improvement in the reception threshold was observed one month and one year after the operation. The air conduction threshold was also markedly improved after both one month and one year.In 12% of the subjects the speech reception threshold improved after on month, but one year later the threshold had reverted to the pre-operation level. The air conduction threshold was improved after one month, but after one year it was in the low frequency zone.In 17% of the subjects the speech reception threshold remained the same after one month but had improved by one year after surgery. The air conduction threshold also showed no significant change after one month but was improved after one year.In 33% of the subjects no significant change was noted in the speech reception threshold either one month or one year after the operation. The air conduction threshold the same.The results suggest that it is too early to judge the improvement of the speech reception threshold one month after tympanoplasty. Therefore, speech audiometry should be carried out one year after tympanoplasty.In several cases the changes in the air conduction threshold and those in the speech reception threshold were different. Accordingly, pure tone audiometry and speech audiometry are considered necessary to evaluate hearing after tympanoplasty.

Speech audiometry before and after tympanoplasty.

The speech reception threshold and maximum discrimination score were analyzed in 158 patients with chronic otitis media before and after tympanoplasty.The air conduction threshold improved significantly in low and middle frequencies after tympanoplasty. The speech reception threshold also improved significantly, but the maximum discrimination score, did not change significantly.In the patients with improved speech reception threshold after tympanoplasty, the air conduction threshold was improved in the low and middle frequencies. In the same patients, however, there was no improvement in the high frequencies. On the other hand, in patients whose speech reception threshold was worsened after tympanoplasty, the air conduction threshold did not change in the low and middle frequencies and was aggravated in the high frequencies.In 60% of the patients whose air conduction threshold improved after tympanoplasty, the speech reception threshold also improved, while in only 20% of the patients whose air conduction threshold was aggravated after tympanoplasty, the speech reception threshold was also aggravated.These results suggest that both pure tone audiometry and speech audiometry are necessary to evaluate hearing differences before and after tympanoplasty.

Postoperative observations following tympanoplasty.

Postoperative observations were reported after tympanoplasty of 478 patients during last 5 years and 9 months. Changes in hearing level, incidence of re-perforation of the tympanic membrane, presence of ear drainage, and development of cholesteatoma were the main items investigated.Hearing level reached a certain level about one year after tympanoplasty and maintained that level afterwards. The incidence of permanent re-perforation was .5% and that of ear drainage was 2.5%. The development of cholesteatoma was observed 28 patients, 17.2% of all cholesteatoma cases (163 cases). The recurrence of cholesteatoma was usually diagnosed one to three years after tympanoplasty under operation microscope. Therefore, postoperative observation should be carried out for at least three years after surgery. In our clinic, however, more than 10% of the patients who received tympanoplasty did not return for examination three years after surgery. It is important to strive to increase the postoperative observation rate to 100% after tympanoplasty.

Changes of vestibular function after endolymphatic sac surgery.

In order to clarify the direct influence of endolymphatic sac surgery on vestibular function, changes of symptoms and positional nystagmus of 23 patients were analyzed before and after surgery.The incidence of dizziness was highest 7 to 10 days after surgery. During the same period, positional nystagmus was the most prominent. Two months after surgery, the incidence of dizziness had decreased significantly, and positional nystagmus had disappeared in most cases.This analysis revealed that the direct influence of endolymphatic sac surgery on vestibular function was greatest 7 to 10 days after surgery, and that it took about two months to disappear.