Biomedical subjects

K Gyo

Publications and source records attributed to K Gyo.

At least 73 records · Page 4Linked to original sources

PubMed1991

Inflammatory pseudotumor of the facial nerve as a cause of recurrent facial palsy: case report.

This is a report of a case presenting recurrent facial palsy due to inflammatory pseudotumor of the facial nerve. The patient was a 41-year-old man suffering from facial palsy on the right side once in 1983, which recurred in 1988. The initial facial palsy was cured after conservative treatments including steroid administration. Three months after the recurrence, the same treatments were attempted without noticeable effect. He was referred to our clinic two and half months later. Electromyographic examination indicated pronounced denervation of the facial nerve. Imaging study including high resolution CT and MRI revealed a mass lesion around the geniculate ganglion. Facial neuroma was initially suspected. Surgical exploration revealed a tumor involving the geniculate ganglion and the horizontal portion of the facial nerve. The tumor was resected through a combined transmastoid and middle cranial fossa approach, followed by nerve grafting. Histologically, the tumor proved to be an inflammatory pseudotumor originating from the nerve sheath, although the etiologic factor causing the inflammation was not verified.

Adult↗

PubMed1990

Chronic otitis media and tympanoplasty in aged patients.

Results of tympanoplasty in patients over 60 years old were analyzed mainly in terms of hearing and postoperative course. Tympanoplasty was carried out in 78 ears of 67 patients during the last ten years. The following types of tympanoplasty were employed: type I in 34 ears, type III-Columella in 23 ears, type IV-Columella in 13 ears, and other types in 8 ears. The results were compared to those of 145 ears from 119 patients ranging from 20 to 59 years of age who had undergone tympanoplasty during the last 3 years. In tympanoplasty type I, closure of the air-bone gap within 20 dB was attained in 70% of the patients over 60 years old, 90% in the 50-59 year age group, and 100% in the 20-49 year age group. In type III-Columella, these values were 60, 78, and 94%, respectively. During the postoperative follow-up, perforation of the eardrum recurred in 5 of 78 ears (6.4%) in the patients over 60, in 5 of 52 ears (9.6%) in the 50-59 year group, and in 7 of 93 ears (7.5%) in the 20-49 year group. These results suggested that hearing results were worse in patients over 60 than in the other age groups, even though the incidence of graft failure did not greatly differ by age.

Adult↗

PubMed1990

[Recurrence of perilymphatic fistula].

Recurrence of the perilymphatic fistula is not rare and may be a tough problem for surgical treatment. This is because a graft is usually applied on the ruptured window(s) from the middle ear and therefore the perilymphatic pressure directly acts on the graft. The recurrence may be caused by a technical failure, use of an unsuitable graft material, poor postoperative bedrest, trauma, increased inner ear pressure, etc. In our clinic, the recurrence occurred in 7 of 48 cases surgically treated. Vertigo accompanied with spontaneous or positional nystagmus was seen in all 7 recurrent cases, while only 2 of them complained of worsening of the existing hearing loss. Re-operation was carried out in two patients. In the first case, closure of the round window by the previous operation was found incomplete, and the perilymph leaked through the gap around the graft. In the second case, closure of the round window was complete, but perilymph leaked from the oval window. In order to prevent the recurrence, the operation should be carefully performed by using strong and adhesive tissue as a graft material, applying a glue between the graft and the inner ear window(s), and keeping strict postoperative bedrest.

Adolescent↗

PubMed1990

[Audiological evaluation of the middle ear implant--temporal auditory acuity].

Temporal auditory acuities provided by the middle ear implant (MEI) and by the hearing aid (HA) were compared in ten patients implanted with the MEI. Test sounds used in the experiment were tone bursts [rise and fall time: 25 msec, duration (t): 982-1000 msec, interval (T): 1000 msec] of 500 Hz or 2000 Hz at 70 dBSPL. A speaker was placed in front of a subject one meter apart. At first, the subject adjusted the gain control of outer unit at the most comfortable loudness level. He heard totally fifty times of the test sounds, which varied in duration each 2 msec difference between 982 and 1000 msec and were provided in random manner. Therefore, sound of each duration was given 5 times. The notch [= (T-t) x 2] of the test sounds recognized by the patients was regarded as time gap. Fifty percent discrimination thresholds, which were indicated by the gap times of the test sounds half identified, were obtained as the index of the temporal auditory acuity. Following the above test, performance of the HA was investigated by use of the same procedure. The results indicated that the temporal auditory acuities of the MEI were superior to those of the HA at 500 Hz (P less than 0.01) and 2000 Hz (P less than 0.001). When the intensity of the test sound at 2000 Hz decreased from 70 dBSPL to 60 or 50 dBSPL, the temporal auditory acuities of the MEI and the HA were almost depreciated together with consistent difference in the test of 6 patients (P less than 0.01, 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

[Audiological evaluation of the middle ear implant--speech discrimination under noise circumstances].

Speech discrimination scores under noise circumstances were studied by use of the middle ear implant (MEI) and the conventional hearing aid (HA, HA-33, RION, Co, Ltd). The studies were performed in 10 patients implanted with the MEI and in 12 adult volunteers with normal hearing as a control. The tests were carried out using Japanese monosyllabic lists from 57S-speech discrimination test list as a test sound and multi-talker noise as a noise source. A speaker was placed in front of a subject in one meter apart. Sound characteristics of HA were adjusted as far as possible to those of the MEI by use of a sound equalizer. The intensity of speech sound pressure was adjusted at 65dB SPL, while that of the noise was changed to 65, 70 and 75dB SPL in the position of patients. Audiological evaluation of the MEI, the HA and control obtained by percentages of correct answers to 50 words in speech discrimination test with and without noise (65, 70, 75dB SPL). When the test was performed without noise, speech discrimination scores by the MEI and the HA were either 96.8 +/- 3.6% and 94.8 +/- 4.1%. However, under noise circumstances (65dB SPL) that by both devices were either 81.6 +/- 9.1% and 66.8 +/- 10.6% (P less than 0.001). When the intensity of the noise increased to 70 and 75dB SPL, speech discrimination scores by both devices deprecated together with consistent difference (P less than 0.01). Moreover speech discrimination scores by the MEI were almost same as control.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Present status and outlook of the implantable hearing aid.

An implantable hearing aid (IHA), in which the direct driving of the stapes by a ceramic vibrator is a fundamental mechanism, was applied to 24 patients with mixed hearing loss of varying degree due to chronic otitis media. The instrument used in the present study was a partial IHA, in which only the vibrator and secondary coil were implanted and the remaining components were packed in a unit to be located behind the auricle. All the patients reported that quality of sound provided by the IHA was natural, clear, and intelligible without causing fatigue with long use. Speech discrimination tests conducted under conditions with background noise demonstrated that speech perception with the partial IHA was superior to that with a conventional hearing aid. These advantages may be ascribed to the direct oscillation of the stapes by the piezoelectric element.

Adult↗

PubMed1989

Comments on "Acoustic Transfer Characteristics in Human Middle Ears Studied by a SQUID Magnetometer Method" [J. Acoust. Soc. Am. 82, 1646-1654 (1987)].

The study by Brenkman et al. [J. Acoust. Soc. Am. 82, 1646-1654 (1987)] of malleus umbo and anterior crus of stapes displacement in 14 human temporal bones shows a mean -7.3-dB/oct slope above 1.0 kHz for stapes displacement in response to a 80-dB SPL input at the eardrum. The slope they obtained for midfrequency (1.0-4.0 kHz) stapes displacement is significantly flatter than what was found previously [Gyo et al., Acta Otolaryngol. 103, 87-95 (1987); Gundersen, Prostheses in the Ossicular Chain (University Park, Baltimore, MD, 1971); Kringlebotn and Gundersen, J. Acoust. Soc. Am. 77, 159-164 (1985); Vlaming and Feenstra, Clin. Otolaryngol. 11, 353-363 (1986a)]; in these studies, stapes displacement rolled off at -12.0 to -14.9 dB/oct above 1.0 kHz. It appears that their mean midfrequency stapes displacement slope has been flattened by some unusual results in a small number of ears. Possible reasons for these results are discussed.

Acoustic Stimulation↗

PubMed1989

Intentionally induced abnormalities in optokinetic pattern tests.

Abnormalities of optokinetic nystagmus are easily detected by administering an optokinetic pattern test, in which optokinetic nystagmus responses to acceleration and deceleration of a series of optokinetic stimuli are recorded at slow paper speed, and the results are visually assessed based on the response pattern. Although optokinetic pattern tests are regarded as valuable in diagnosing lesions of the nervous system that directly or indirectly relate to the reflex route of optokinetic nystagmus, these tests can be significantly influenced by the intention of the person being tested. The present study revealed that the majority of abnormal optokinetic patterns can be induced intentionally. This indicates that optokinetic pattern tests are of limited diagnostic value, and a definite diagnosis should not be made based solely on the optokinetic pattern test result.

Brain Diseases↗

PubMed1989

[Single channel cochlear implant: application to three patients].

Single channel cochlear implant of 3M/House design was implanted to the three patients with profound hearing loss. Before the implantation, use of hearing aid had not afforded serviceable hearing enough for speech recognition in these patients. Postoperative courses were uneventful. Speech rehabilitation was started at 3 weeks after the surgery. The speech tracking scores with the cochlear implant plus lipreading achieved 20-25 bunsetues (the minimum meaningful unit of the Japanese sentence) per minute at three or four months after the operation. All the patients could recognize speech of daily life with help of lipreading. However, speech recognition by the cochlear implant alone was not satisfactory.

Adult↗

PubMed1989

[Modification of speech encoding process of single channel cochlear implant utilizing digital delay circuit].

Speech perception by single channel cochlear implant can be improved to some extent by modifying the encoding process of the speech signals. The principle of our encoding strategy is to present speech signals with appropriate delay time for lower frequency components of the speech sound, while without delay for higher frequency components. This is based on a cochlear physiology that higher frequency sounds are perceived earlier than lower frequency sounds, since the former is perceived at the basal turn and the latter at the apical turn. The following tests were performed without the aid of lip reading in the two patients implanted with a single channel cochlear implant of 3M-House design. Lower frequency components of the speech signals were digitally delayed with a Sony SDP-777 ES surround processor. The results indicated that the optimal delay time for identification of /i/, /e/ and /u/ needed longer delay time, while that of /a/ and /o/ need shorter delay time, corresponding to the difference between the first and second formant of each vowel. Comparison of vowel perception with and without delay coding showed that vowel identification with delay coding was superior to that without it; 30% vs. 16% in case 1, and 48% vs. 30% in case 2.

Adult↗

PubMed1989

[The effect of intravenous administration of xylocaine for the treatment of tinnitus].

One hundreds and forty-nine patients (221 ears) suffering from tinnitus were treated by an intravenous administration of Xylocaine. Xylocaine, 1mg per kg, was administered once a week. The immediate effect of Xylocaine on tinnitus was evaluated subjectively for all the patients. The long term effect in 57 patients who received Xylocaine administration more than 12 times was also analyzed. The results can be summarized as follows. 1. Short and long term relief of tinnitus was obtained in 165 of 221 ears (74.7%) and in 35 of 57 cases (61.4%), respectively. 2. This therapy was more effective in old patients and in the patients with low pitch tinnitus, or with positive residual inhibition. 3. The numbers of the effective cases increased after the 8th time administration of Xylocaine. Thus we recommend the Xylocaine administration at least 8 times. 4. The results of the loudness balance test were not correlated with the change of the subjective improvements. 5. The suppressive effect of tinnitus by injecting saline solution intravenously was recognized in 24 of 73 cases. At present, repeated administration of Xylocaine would be one of the most significant therapies of tinnitus.

Adolescent↗

PubMed1988

Benign paroxysmal positional vertigo as a complication of postoperative bedrest.

Seven cases of benign paroxysmal positional vertigo (BPPV) after operation were reported, occurring between the fourth and 14th postoperative day. In three of the seven cases, the condition occurred when the patients first arose from bed after 5 to 6 days of postoperative bedrest. In two cases, BPPV occurred when patients moved their head while maintaining strict bedrest. In the other two cases, it occurred 1 to 4 days after patients had been released from bedrest. The cause of BPPV was considered to be postoperative bedrest which might have facilitated the deposition of precipitate on the cupula of the posterior semicircular canal. The prognosis was good, and all the patients recovered within 20 days.

Bed Rest↗

PubMed1988

Experimental study on autograft material for repair of round window rupture.

The healing process following experimentally produced rupture of the round window (RW) and subsequent closure with autograft materials were investigated in guinea pigs. The covering materials studied were fascia and perichondrium, both of which were placed over the RW after extensive rupturing of the RW membrane. The grafts were observed 1, 2, and 3 months after the operation. No substantial difference in the results for the two materials could be discerned. They adhered to the surrounding bone and were incorporated into the RW membrane within 3 months.

Animals↗

PubMed1988

Pressure transmission properties from the externa ear canal to the inner ear. An experimental study using guinea pigs.

The inner ear pressure (PIE) in response to pressure changes in the external ear canal was measured in guinea pigs while alternatively opening and closing the perforation of the otic bulla. When the bulla was opened, only a transient degree of applied pressure was transmitted to the inner ear and the amplitude of the PIE was smaller than that of the corresponding PIE when the bulla was closed. This was because the applied pressure was exclusively transmitted to the inner ear via the ossicular chain. When the otic bulla was closed, the pressure was transmitted not only via the ossicular chain but also via the round window (RW) through the middle ear cavity. When the bulla was closed, the amplitude of PIE was larger by a positive pressure load than by the corresponding negative one. The amplitude of PIE showed a linear relationship to ear canal pressure of at least within the +/- 200 mmH2O range, as long as pressure was slowly applied to the ear canal. When the loading pressure was abruptly changed, a bouncing response, possibly reflecting elasticity of the RW, was evoked, which diminished or disappeared when the round window was artificially ruptured.

Acoustic Impedance Tests↗

PubMed1988

Implantable hearing aid in fourteen patients with mixed deafness.

An implantable hearing aid (IHA) in which the stapes was directly driven by a ceramic vibrator of bimorph design was applied to fourteen patients with mixed deafness of varying degree due to chronic otitis media. In the partial IHA system, only the output transducer and secondary coil are implanted, the remainder of the components such as microphone, amplifier, battery and primary induction coil remain in the location behind the auricle. The vibrator was activated by an electric signal transmitted electromagnetically through the induction system from the outer unit. All the patients admitted that sound quality provided by the IHA was natural, clear and easy to hear without causing fatigue in long-term use. Speech discrimination test under noise circumstance showed that acoustic perception by the IHA was superior to that by a conventional hearing aid. In four patients, however, the implanted unit was replaced with a new one due to recurrence of cholesteatoma, head trauma, and accidental disruption of wire by manipulating the ear canal. They regained good hearing after re-implantation.

Adult↗

PubMed1987

Implantable hearing aid. Report of the first human applications.

To our knowledge, this is the first report of human application of the partial implantable hearing aid. Direct driving of the stapes by an ossicular vibrator of piezoelectric ceramic bimorph is the fundamental mechanism of this device. Acoustic signals received by a microphone were transmitted to the external link coil after amplification. By means of electromagnetic induction, the internal coil placed under the retroauricular skin excited electroacoustic energy, which is transmitted to the vibrator directly coupled with the stapes. The device used in this first patient has been functioning for longer than one year. Excellent frequency response of the vibrator and highly efficient direct transmission of electroacoustic signals to the inner ear gave rise to acoustic perception of superior quality that could not be obtained by other surgical or rehabilitative measures.

Deafness↗

PubMed1987

Stapes vibration produced by the output transducer of an implantable hearing aid. Experimental study.

The function of the output transducer of an implantable hearing aid was assessed by applying it to the stapes head in seven fresh human cadaver temporal bones while observing vibration of the stapes under a microscope with the use of a stroboscope and a video measuring system. The transducer was a 5 X 1.2 X 0.6-mm piezoelectric ceramic bimorph with attached metal holder. Transmission changed with the amount of force holding the transducer tip on the head of the stapes. An optimal connection between the vibrator and stapes produced better transmission than a tight or loose connection. Gluing the connection with cyanoacrylate cement decreased transmission in the optimal connection, produced no change in the tight connection, and improved transmission in the loose connection. Comparison of stapes displacement produced by the vibrator at 1 kHz with that produced by normal middle-ear sound transmission revealed that the vibrator-induced stapes displacement for a 1 V peak-to-peak input was equivalent to that produced by a sound stimulus of 90-dB sound pressure level at the tympanic membrane.

Ear Ossicles↗

PubMed1987

Effects of middle ear pressure changes on umbo vibration.

Effects of middle ear pressure changes on umbo vibration were studied in 5 fresh human temporal bones taken from cadavers. Umbo vibration to a constant sound pressure of 120 dB SPL at the tympanic membrane was measured with an MTI 1000 Fotonic Sensor. The results showed that there was a loss of umbo vibration at lower frequencies below 2 kHz; 5.0 +/- 1.0 dB loss at -100 mmH2O, 9.2 +/- 1.3 dB loss at -200 mmH2O, and 13.1 +/- 1.8 dB loss at -300 mmH2O. In contrast, there was a slight increase in umbo vibration at around 2-3 kHz. The effect was considered to be mainly due to increased stiffness of the tympanic membrane and decreased air volume in the middle ear cavity.

Cadaver↗