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Biomedical subjects

K Gyo

Publications and source records attributed to K Gyo.

At least 37 records · Page 2Linked to original sources
PubMed1998

Varicella-zoster virus distribution in Ramsay Hunt syndrome revealed by polymerase chain reaction.

The pathogenesis of facial nerve paralysis and vestibulo-cochlear dysfunction of Ramsay Hunt syndrome remains unclear as varicella-zoster virus (VZV) has not been demonstrated in the lesions. Using the polymerase chain reaction, we detected VZV genomes not only in the vesicles on the auricles or oral cavity but also in the facial nerve sheath, middle ear mucosa and cerebrospinal fluid from patients with Ramsay Hunt syndrome. The VZV genome was undetectable in the same kinds of clinical samples obtained from control patients with facial nerve paralysis of other etiologies. The results indicated that VZV spreads widely in the neural components, mucocutaneous tissue and cerebrospinal fluid. The present study will facilitate better understanding of the pathogenesis of facial nerve paralysis, vertigo, hearing impairment and other cranial nerve dysfunction of Ramsay Hunt syndrome.

Adolescent↗
PubMed1998

Effects of mastoid cavity obliteration on the growth of experimentally produced residual cholesteatoma.

The effects of obliteration of the mastoid cavity on the growth of residual cholesteatoma were histologically studied in an animal model. A dermal cyst was produced by grafting a piece of autologous auricular skin in the otic bulla of 11 guinea-pigs. Three weeks after grafting, part of the cyst wall facing the cavity was removed and the debris accumulated inside was inserted into the surrounding granulation using a micropick. This procedure simulates the growth mechanism of cholesteatoma residue which sometimes occurs after middle ear surgery in human subjects. In six animals, the bulla was then obliterated with plaster of Paris. The remaining five animals were used as controls. Animals were killed for histological study at 2, 4 or 8 weeks postoperatively. Microscopic examinations revealed that in the obliteration group, severe inflammatory reactions were induced in the otic bulla, although the graft epithelium survived there; dermal cyst reformed in only one of six animals. In the controls, cyst reformation was recognized in all animals. This indicated that severe inflammation induced by plaster prevented growth of the graft epithelium in the otic bulla.

Animals↗
PubMed1998

Effect of increased inner ear pressure on middle ear mechanics.

Velocity of malleus, umbo, and stapes footplate in response to stepwise increases up to +400 mm H2O in hydrostatic pressure of the inner ear was investigated in 10 fresh human temporal bones by using a laser Doppler interferometer. The sound-pressure input was 114 dB SPL, and the frequency range was 0.4 to 5.0 kHz. Static displacement of these sites was also measured by a video measuring system. When the inner ear pressure was increased, the malleus and stapes moved outward. Amplitude of umbo velocity decreased below 1.0 kHz with a slight increase around 2.0 kHz, whereas stapes velocity decreased at all frequencies with the major effect below 1.0 kHz. The phase angle of malleus umbo velocity advanced markedly in response to the increased inner ear pressure between 1.0 and 1.4 kHz. Change in the vibration of the umbo was thought to be primarily caused by an increased stiffness of the middle ear conduction system, and that of the stapes was caused by distention of the annular ligament and increased cochlear impedance produced by the increased inner ear pressure. These changes in TM vibration and its phase angle may help detect indirectly an elevation of inner ear pressure.

Aged↗
PubMed1998

Rapid diagnosis of varicella zoster virus infection in acute facial palsy.

Patients with zoster sine herpete and Ramsay Hunt syndrome without pathognomonic vesicles at the initial visit are often misdiagnosed with Bell's palsy and treated without antiviral agents. With PCR, we found that varicella zoster virus genomes were frequently detectable in auricular skin exudate from patients with zoster sine herpete or Ramsay Hunt syndrome before the appearance of vesicles.

Acute Disease↗
PubMed1998

Staged intact canal wall tympanoplasty for treatment of middle ear cholesteatoma.

Results of surgery for middle ear cholesteatoma were investigated in 202 ears of 197 patients who had undergone surgery by the staged intact canal wall technique. Surgical procedures used in the second stage for prevention of a retraction pocket were classified into three types: Type S1, no scutumplasty; Type S2, scutumplasty; Type S3, scutumplasty plus mastoid obliteration. Recurrent cholesteatoma was found in 9 ears (4%) and retraction pocket in 47 ears (23%). They occurred between 2 and 120 months (average: 26 months) after the second stage, most frequently at 1 to 3 years. The incidence was higher after Type S3 surgery than after the other types, probably because the middle ear was severely involved in patients who were indicated Type S3 surgery. For prevention of a retraction pocket, bone putty and cartilage were proved to be appropriate materials for scutumplasty, and hydroxyapatite for mastoid obliteration. As the retraction pocket tended to recur in patients with the pocket at the second stage, these patients needed obliteration of the mastoid cavity to prevent a retraction pocket. Postoperative hearing was evaluated according to the criteria proposed by the Japan Society of Clinical Otology. Of 145 ears of the 142 patients who were followed for more than 1 year, 118 ears (81%) the surgery was judged successful. The success rate in hearing was in good accordance with the condition of the tympanic membrane.

Adolescent↗
PubMed1997

Efflux of glutamate into the perilymph of the cochlea following transient ischemia in the gerbil.

Using a microdialysis technique followed by an enzyme cycling analysis, we measured changes in the glutamate levels in the perilymph of gerbil cochleae before, during and after transient ischemic insult. The basal glutamate level in perilymph was 0.35 +/- 0.22 pmol/microl. An almost immediate and continuous rise in the level of glutamate occurred after the ischemic insult, which advanced even further after recirculation; the average concentration was higher than 40 pmol/microl 55 min after recirculation. The compound action potentials (CAP) monitoring the auditory function totally disappeared after ischemic insult. However, CAP reappeared after recirculation; the threshold for acoustic stimulation was higher than that observed at the pre-ischemic state.

Acoustic Stimulation↗
PubMed1997

Treatment of Ramsay Hunt syndrome with acyclovir-prednisone: significance of early diagnosis and treatment.

Although the antiviral agent acyclovir is currently used for the treatment of Ramsay Hunt syndrome, its effects on facial nerve and hearing recovery remain controversial. We retrospectively analyzed the effects of acyclovir-prednisone treatment in 80 Ramsay Hunt patients. Of 28 patients for whom treatment was begun within 3 days of the onset of facial paralysis, the recovery from paralysis was complete in 21 (75%). By comparison, of 23 patients for whom treatment was begun more than 7 days after onset, recovery from facial paralysis was complete in only 7 (30%). A significant difference in facial nerve recovery was found between these groups. Early administration of acyclovir-prednisone was proved to reduce nerve degeneration by nerve excitability testing. Hearing recovery also tended to be better in patients with early treatment. There was no significant difference in facial nerve outcome between intravenous and oral acyclovir treatment.

Acyclovir↗
PubMed1997

Surgical rehabilitation of deafness with partially implantable hearing aid using piezoelectric ceramic bimorpli ossicular vibrator.

We developed two types of implantable hearing aids, a totally implantable hearing aid (TIHA) and a partially implantable hearing aid (PIHA) in 1983. In both types a piezoelectric ceramic bimorph was used as an ossicular vibrator which was coupled to the stapes to transmit sound signals to the inner ear efficiently. Due to technological immaturities, clinical application of the TIHA has not yet been realized. But the PIHA is available for clinical use at present. In the PIHA only the ossicular vibrator is implanted with inner link coil. The rest of components such as microphone, amplifier, battery, and outer link coil remain in their usual location behind the auricle. Since 1984, we have applied the PIHA to 37 patients with mixed deafness. Careful follow-up studies have been conducted on all of them to assess clinical and audiological results. We have confirmed that the device could function safely for more than 10 years affording natural quality of hearing without howling and wearing discomforts. Our studies suggest that the PIHA can be a choice of rehabilitation for mixed deafness due to middle ear diseases which cannot be rehabilitated satisfactorily by either surgical means or a conventional hearing aid. Functional principle of device, indications and surgical methods of implantation were described. Failures and delayed problems we experienced were also presented together with the preventive measures. We believe that an implantable hearing aid of this type will be an otologic breakthrough if substantial technological difficulties are cleared.

Adult↗
PubMed1997

Effect of middle ear pressure change on middle ear mechanics.

The effect of graded variations in middle ear pressure on ossicular vibration was measured in 15 normal human temporal bone specimens. The displacement amplitude of the umbo and stapes head was measured at 16 frequencies between 0.2 kHz and 3.5 kHz at a constant sound pressure of 134 dB SPL at the tympanic membrane (TM) using a non-contacting video measuring system. Both negative and positive pressures decreased umbo and stapes vibration at low frequencies and slightly increased the vibration at higher frequencies. The effects were greater for negative pressure than for positive pressure. The change in stapes vibration was less than that of the umbo at low frequencies, but increased at higher frequencies. In some temporal bones, a small positive pressure produced improvement in stapes vibration at all frequencies. These effects were thought to be primarily due to an increased stiffness of the TM and a damping of ossicular vibration, due to stretching of the ossicular suspensory ligaments and the annular ligament of the footplate.

Aged↗
PubMed1997

Replacement of a single-channel with a multichannel cochlear implant as an upgrade.

The removal of a functioning cochlear implant in order to upgrade to a more advanced device is a critical issue to many otologists, since we currently have no means to predict the results preoperatively. This paper reports on two patients who successfully upgraded from a single-channel to a multichannel implant. The new implants outperformed the original devices in both the live-voice test and the videotaped test. The patients stated that the hearing quality afforded by the multichannel implant was much better than that provided by the original implant.

Adult↗
PubMed1997

Masking the protrusion of the receiver-stimulator of electronic implants in otology.

Protrusion of the receiver-stimulator of a cochlear implant or a piezoelectric implantable hearing aid (IHA) was masked using bone dust applied in the gap between the receiver and the surrounding bone, making a smooth transitional border. The bone dust was then fixed with fibrin glue. Bone pâté (a mixture of bone dust and fibrin glue) was also used to fix the lead wire of a cochlear implant at the region of the posterior tympanotomy and to fasten an IHA vibrator holder to the temporal bone. Over the past two years, the use of these techniques in six patients with cochlear implants and two patients with IHAs has resulted in gratifying results; the edge of the receiver remained flush in all cases. They have been free from problems such as infection of the wound, necrosis of the overlying skin, and protrusion or migration of the receiver.

Cochlear Implants↗
PubMed1996

Residual bacterial infection in the tympanic cavity following surgery for ears with chronic discharge.

In surgical treatment of ears with chronic discharge, pathogenic microorganisms may remain in the middle ear even after meticulous tympanomastoidectomy, and cause recurrent infection unless an appropriate antimicrobial agent is administered. The present study was conducted to determine the incidence of residual bacterial infection in the tympanic cavity by examining secretions from a drainage tube placed there via the mastoid cavity during surgery. Comparison of the bacterial flora before and after surgery demonstrated that some of the microorganisms continued to be present in the tympanic cavity for up to 2 weeks despite medication, and that the incidence of Pseudomonas aeruginosa and Staphylococcus epidermidis remained fairly high.

Adolescent↗
PubMed1996

Configuration of experimentally produced cholesteatoma by transplantation of a free skin graft.

Residual cholesteatoma was experimentally produced in guinea pigs by transplanting a free skin graft into the middle ear bulla. In group A, the graft was placed on the mucosa after scratching the surface with a pick, while in group B, it was placed on the bone surface following removal of the mucosa and drilling with a diamond burr. The group A procedure was conducted on the left ear and the group B procedure on the right ear in 12 guinea pigs. The animals were sacrificed at two, four and eight weeks after transplantation. In all 12 ears of group A, the graft kept its original flat shape, resembling an open type residue. In eight of 12 ears of group B, the graft grew forming a squamous pearl, while in the remaining four ears it retained a flat shape. The difference in configuration is thought to be due to the amount of granulation around the graft.

Animals↗
PubMed1996

Residue of middle ear cholesteatoma after intact canal wall tympanoplasty: surgical findings at one year.

The rate of residual disease after surgery for acquired middle ear cholesteatoma was investigated in 167 ears of 164 patients who had undergone planned second-look tympanoplasty by the intact canal wall technique. Overall, operative findings at the second stage revealed 65 cases of residual disease in 48 ears (29%). These consisted of 50 squamous pearls, 11 cases of the flat, open type, and 4 cases of the extensive type. The configuration of residual disease is closely related to the technical difficulty of eradication, since en bloc removal is much easier in the squamous pearl than in the open or extensive type, mainly because of the unclear margin with the surrounding tissues. The proportion of cases of the open type was greater in children than in adults, in pars tensa cholesteatoma than in pars flaccida cholesteatoma, and in severe primary middle ear disease than in moderate or mild disease, although these differences were not statistically significant. The extensive type occurred in 4 ears with severe primary disease, 3 of which were in children. These results support the value and importance of the staged procedure for middle ear cholesteatoma, particularly when operated on by the intact canal wall technique.

Adolescent↗
PubMed1996

[Blood patch therapy of the perilymphatic fistulas--an experimental study].

Blood patch is a therapeutic procedure that uses a perilymphatic fistula to repair an inner ear window rupture by filling the tympanic cavity with autologous blood. The experimental study was conducted in 13 guinea pigs. Autologous blood or commercially available fibrin glue was poured into the otic bulla after artificial rupture of the round window. The animals were sacrificed immediately, or 1 to 7 days after the operation. The results showed that the blood or the fibrin glue successfully closed the window rupture by closing directly and by facilitating the formation of granulation at the margin of the rupture. Fibrin glue seemed to be preferable to autologous blood due to its non-toxic nature in the inner ear.

Animals↗
PubMed1996

[Fates of bone defects in the mastoid cavity studied from the findings of two-stage tympanoplasty].

The incidence and prognosis of bone defects occurring in the mastoid cavity were investigated in 205 ears of 197 patients who underwent planned two-stage tympanoplasty by the intact canal wall technique. Bone defects found at the first stage had spontaneously closed by the second stage in 43 of 62 ears at the mastoid tegmen, in 13 of 15 ears at the posterior wall of the mastoid cavity and in 2 of 17 ears at the posterior wall of the external ear canal. Twenty two ears developed bone defects at the ear canal between the first and second operations, despite the canal wall having been primarily preserved. Of the 6 ears with closure of the labyrinthine fistula using temporalis fascia at the first stage, the defects were obliterated with regenerated bone in 5 ears at the second stage. Bone defects at the facial canal were recognized in 67 ears at the first stage, 21 of which were no longer seen at the second stage.

Adolescent↗