Biomedical subjects

K Gyo

Publications and source records attributed to K Gyo.

At least 55 records · Page 3Linked to original sources

PubMed1995

A case of acquired petrous cholesteatoma associated with insidious middle ear infection treated by staging the surgical procedures.

Surgical treatment of petrous cholesteatoma is difficult, especially in infected cases, since it often involves vital structures. We report the case of a patient successfully treated for an infected petrous cholesteatoma by staging the surgical procedures to reduce the risk of intracranial complications. The patient, a 53-year-old man, was referred to our hospital because of vertigo during coughing or strenuous effort. The left side mastoid cavity was open to the external ear canal and wholly covered with cholesteatoma epithelium with purulent discharge. The superior basal turn of the cochlea, superior and posterior semicircular canals, and roof of the internal auditory canal were eroded. Conservative treatment was not effective in eradicating the otorrhea. Four weeks after the first operation (radical mastoidectomy), the second operation was conducted following a combined middle cranial fossa and transmastoid approach. The postoperative course was uneventful. Normal facial nerve function was preserved and unsteadiness disappeared, but hearing could not be preserved. The MRI examination, performed one year after surgery, did not reveal any evidence of residual cholesteatoma.

Cholesteatoma↗

PubMed1995

Herpetic vestibular neuritis: an experimental study.

An animal model of vestibular neuritis was developed by inoculating herpes simplex virus type 1 (HSV-1) into the auricle of mice. Postural deviation was observed in 5 of 99 mice at 6 to 8 days after inoculation. Following evaluation of the vestibular function, the animals were sacrificed and the vestibular nerves examined for histopathology and immunohistochemically. All mice developed postural deviation, presented as abnormal behaviour; they could not perform various vestibular tasks, such as gait, traversing a narrow path, climbing a rope, negative geotaxis, grasping a rod, and swimming. Degeneration of Scarpa's ganglion was observed in 4 of 5 mice that developed postural deviation, while HSV-1 antigens were found in 2 of them. No such histological findings were seen in animals with normal vestibular function.

Animals↗

PubMed1995

[Dilemma in surgical treatment of petrous cholesteatoma].

Surgical treatment of petrous cholesteatoma that involves the petrous pyramid and extends beyond the internal auditory canal is often difficult because of the site and extent of the cholesteatoma. Various problems pertaining to the operation are discussed from our experience with fourteen patients who underwent surgery in our hospital. When accompanied with otorrhea, the middle ear was eradicated by radical mastoidectomy before total removal of the cholesteatoma in order to avoid intracranial infection. Staging operation was conducted in 6 patients in which otorrhea could not be stopped by conservative treatment. The surgical approach was translabyrinthine in 10 patients, middle cranial fossa plus transmastoid in 2, and a combination of these methods in 2. The postoperative large cavity was totally exteriorized in 5 cases in which eradication of the cholesteatoma was deemed too risky, although the exposed internal auditory canal and the denuded dura were supplemented locally. In the other 9 cases, the cavity was obliterated with abdominal fat and/or muscle flap. Facial nerve palsy was present preoperatively in 11 patients. They were treated by decompression in 7 cases, nerve-anastomosis in 2 and nerve grafting in one. In one patient, atrophy of the nerve was too severe to perform nerve grafting. Plastic surgery, such as suspension of the eyelid and masseter muscle transfer, was additionally carried out in 6 of the above patients. Postoperative follow-up study with CT and MRI is very important. In 3 of our cases, the cholesteatoma recurred and the reoperation was needed.

Adult↗

PubMed1995

[Middle fossa acoustic neuroma surgery--indications and predictive factors for hearing restoration].

Between June 1990 and May 1993, 17 acoustic tumors were removed by the middle cranial fossa approach with attempted hearing preservation. Measurable hearing was restored in 13 patients (76.5%) and useful hearing (PTA < 50 dB, SDS > 50%) in 10 patients (58.8%). In addition, significant hearing improvement, greater than 10 dB in pure-tone average, was noted in 6 patients (35.3%). In the hearing improvement group, useful hearing was restored after tumor resection in two patients with poor preoperative hearing. These six patients with hearing improvement exhibited several findings in common: smaller tumors, sudden deterioration of hearing, trough type of audiogram, inferior vestubular nerve origin and short duration of hearing loss before surgery. Such signs suggested favorable preoperative prognostic factors for potential postoperative hearing improvement. Because there was no significant difference between postoperative facial nerve outcome in the middle cranial fossa approach and the translabyrinithine approach in our series of small tumors, we recommend the use of the middle cranial fossa approach for hearing preservation in patients with small tumors, even when their hearing is poor preoperatively.

Adult↗

PubMed1995

Partially implantable hearing aid using piezoelectric ceramic ossicular vibrator. Results of the implant operation and assessment of the hearing afforded by the device.

The aim of designing an implantable hearing aid (IHA) is to compensate for some of the disadvantages of conventional hearing aids. The IHA described in this article is a direct oscillation type in which the piezoelectric ceramic ossicular vibrator coupled directly to the stapes transmits sound signals to the perilymph effectively. This type of IHA can give a better fidelity of sound perception than a conventional hearing aid.

Adult↗

PubMed1994

Solubilization of keratin debris in conservative treatment of middle ear cholesteatoma: an in vitro study.

A variety of solutions were tested in vitro to find a suitable solvent which could be used in clinical practice for cholesteatoma debris. Though a little weak as a solvent, a liquid soap composed mainly of plant oil did not cause irritation of the middle ear mucosa, and was thought to be a promising solvent with which to rinse away tenacious debris, especially when used in combination with hydrogen peroxide.

Cholesteatoma↗

PubMed1994

Resection of persistent nasopharyngeal carcinoma.

Although radiotherapy has been generally accepted as the treatment of choice for nasopharyngeal carcinoma (NPC), NPC at the primary site is not always controlled by this therapy. We performed surgical treatment to eradicate such residual tumor through a transmandibular, transpterygoid approach, on four patients with local residual NPC after curative radiotherapy. Two patients survived with no evidence of disease for more than 6 years. The other two patients died of multiple metastases to the liver or bone at 4 years and at 6 months after treatment. However, the nasopharynx remained free of disease in these two patients. Although the number of patients in the present series is small, surgical treatment of local persistent tumor after radiotherapy was beneficial. The indication for this technique is tumor in the nasopharynx extending to the parapharyngeal space, not invading intracranially. The transmandibular, transpterygoid approach offers a wide operative field with minimal postoperative morbidity, making it possible to manage the internal carotid artery easily.

Journal Article↗

PubMed1994

Experimental cholesteatomas arising from autologous free skin grafting in the middle ear cavity.

An autologous free skin graft taken from the upper or the lower external ear canal or the auricle was implanted in the otic bulla of 28 guinea pigs. An epidermal cyst simulating middle ear cholesteatoma was successfully produced in 25 (89.3%) animals 8 weeks after grafting. Using this model, the histological reaction of middle ear granulation tissue to the debris was studied. Cysts originated from the auricular skin showed the strongest activity with regard to growth rate, amount of debris produced, and inflammatory reaction to the exposed debris. We conclude that the exposed debris plays an important role in chronic granulomatous inflammation in association with cholesteatoma.

Animals↗

PubMed1994

Effects of combined rupture of Reissner's membrane and the round window on hearing in the guinea pig.

Hearing impairment caused by sequential rupture of Reissner's membrane and the round window was investigated in guinea pigs to determine if the double-membrane break can cause acute profound sensorineural hearing loss. Reissner's membrane was lacerated through the stria vascularis at one of the turns of the cochlea, followed by rupture of the round window to create leakage of the perilymph. Action potentials (APs) to tone pip stimuli were recorded from the Fallopian canal electrode before and 90 min after these procedures. The results showed that the ears with the double-membrane break at the second turn showed a larger increase in AP threshold than did the control ears with only round window rupture. However, this was not seen when Reissner's membrane had been ruptured at the other turns.

Acoustic Stimulation↗

PubMed1994

Postoperative recurrence of perilymphatic fistulas.

Postoperative follow-up study of perilymphatic fistulas (PLFs) showed that recurrence of PLF was not rare and revision was sometimes needed to relieve the symptoms associated with leakage of perilymph. Of the 54 PLF patients surgically treated in our clinic, some sign or symptom of recurrence was found in 9 cases (17%). Vertigo accompanied by spontaneous or positional nystagmus was noted in all 9 cases, while only 3 complained of exacerbation of the existing hearing loss. Revision was indicated in 3 patients since they had no predisposition to spontaneous healing. Various etiological and underlying factors contributed to the incidence of recurrence. Careful operative procedures together with strict postoperative management are required for surgical treatment of PLF.

Adolescent↗

PubMed1994

[A case of revision of a cochlear implant].

The patient was a 41-year-old man who lost his hearing on the left at 7 years of age and on the right at 34 years of age due to meningitis. At 35 years of age a single-channel cochlear implant, 3M/House design, was implanted. Five years after the initial operation, the single-channel prosthesis was replaced by a multichannel device (Cochlear Corp.) because of the patients earnest wish to obtain better hearing. Explanation of the short electrode of the single-channel device was easy, but reimplantation of the longer electrode of multichannel device was somewhat difficult, probably because of the presence of the peri-implant fibro-osseous cuff in the Scala tympani. Single-channel and those of the multichannel speech data were compared in relation to performance in the same individual. The reimplanted multichannel device was equivalent to or outperformed the original 3M prosthesis. The patient preferred the hearing afforded by the multichannel device.

Adult↗

PubMed1993

Experimental vestibular neuritis induced by herpes simplex virus.

An animal model of vestibular neuritis was developed by inoculating herpes simplex virus type 1 (HSV-1) in the auricle of a mouse. Deviation of the body was observed in 4 of 30 mice 6 days after inoculation. These animals were sacrificed 6 to 10 days after inoculation and the vestibular nerve was examined histopathologically and immunohistochemically. The HSV-1 antigens were recognized exclusively in Scarpa's ganglion of the vestibular nerve in 2 of 4 mice in which signs of vestibular involvement were manifested.

Animals↗

PubMed1993

[Development of a cochlear input-impedance measuring device and its application in the temporal bones of dogs].

Cochlear input impedance was measured in 6 temporal bones taken from 3 dogs by use of a newly developed ceramic device. The device was composed of two ceramic bimorph elements, one for activation of the stapes and the other to pick-up vibration of the former element in the form of an electric output, which varies in accordance with the magnitude of cochlear impedance. Average impedance in the dogs was 2.3 Mohm at 2 kHz, 6.3 Mohm at 4 kHz and 17.8 Mohm at 6 kHz. Effect of closure of the round window was also investigated by placing dental cement on the window. In 3 ears, the impedance increased mainly below 4 kHz, while in the remaining 3 ears no such change occurred. This was probably because the closure was complete in the former but not in the latter.

Acoustic Impedance Tests↗

PubMed1993

Prevention of recurrence of cholesteatoma in intact canal wall tympanoplasty.

In the treatment of cholesteatoma employing intact canal wall tympanoplasty, staging the operation and re-establishment of aeration of the tympanic cavity are required to eradicate possible causes of recurrence, cholesteatoma residue, and retraction pocket. The planned staged tympanoplasty with preventive measures for recurrence has evolved. At the second-stage operation, one of the following three types of operations was performed according to the grade of aeration and healing of tympanic cavity: type S1, only ossiculoplasty; type S2, ossiculoplasty and scutumplasty; and type S3, ossiculoplasty, scutumplasty, and mastoid obliteration. The surgical concept, indication, and technique are described in detail. The recurrence rate in the 134 patients without previous surgery, 95 adults and 39 children, operated on between 1987 and 1991 was 2.2 percent (7.6% in the children and 0% in the adult). Although the rate of the recidivism was significantly reduced, deep retraction pocket developed in 15 percent of adults and in 23 percent of children. The incidence of deep retraction pocket formation was lowest in the adults with type S1 operation and highest in the children with type S3 operation.

Adolescent↗

PubMed1992

Incidence of attic retraction after staged intact canal wall tympanoplasty for middle ear cholesteatoma.

Incidence of retraction pocket and recurrent cholesteatoma in the attic after surgery for middle ear cholesteatoma using the staged intact canal wall technique were investigated in 95 ears of 91 patients, all of which had various degrees of bone defect in the tympanic scutum. Surgical procedures employed in the second stage for prevention of attic retraction were classified into three types: Type I, no scutumplasty; Type II, scutumplasty; Type III, scutumplasty plus mastoid obliteration. In 83 ears followed up for more than 1 year after the second stage, such retraction troubles occurred in 2 of 13 ears (15%) in Type I, 8 of 20 ears (40%) in Type II, and 24 of 50 ears (48%) in Type III. Incidence of retraction troubles was higher in Types II and III, probably because these procedures were indicated in ears with large scutum defects. Dislocation and atrophy of the graft materials, together with bone resorption around the bone defect were the main reasons for failure in scutumplasty. Dysfunction of the eustachian tube and traction of the eardrum by the scar tissue behind it may have also contributed to attic retraction. Mastoid obliteration with small blocks of hydroxyapatite was more effective in prevention of retraction troubles than that with pedicled temporalis muscle flap.

Adolescent↗

PubMed1992

Transmission of change in the atmospheric pressure of the external ear to the perilymph.

In experiments using guinea pigs, the middle ear and perilymphatic pressures were simultaneously registered in response to pressure change in the external ear canal. In the first experiment, pressure was slowly loaded in the ear canal in the range of 200 mm H2O to -200 mm H2O. Pressure transmission to the perilymph was smaller when the bulla was open to the outside than when it was closed. It was significantly impaired by disruption of the ossicular chain and especially by closure of the round window. The data indicate that air volume in the middle ear cavity plays an important role in transmission of slowly changing atmospheric pressures. In the second experiment, the eustachian tube was closed and the pressure was changed in the range of 1000 mm H2O to -1000 mm H2O. The middle ear and perilymphatic pressures increased or decreased corresponding to the loading pressure in the range of 400 mm H2O and -200 mm H2O. Beyond these levels, response rate of the middle ear pressure decreased and perilymphatic pressure declined in spite of further increase in loading pressure. The increase in pressure difference between the middle ear and the inner ear might cause disruption of the round and/or oval windows.

Animals↗

PubMed1991

[Experiment study on solubilization of cholesteatoma debris].

A variety of solutions were tested in vitro to find a suitable solvent of cholesteatoma debris for use in clinical practice. The specimens were taken during surgery from the patients of otitis media with cholesteatoma. They were divided in pieces and put in test tubes. Each tube was then admixed with one of the test solutions and incubated at 37 degrees C for 48 hours. Hydrochloric acid (1N) and sodium hydroxide (1N) had no substantial effect to solve the debris. Urea (10N), acetylcysteine (20%) and chymotrypsin (1%) had a weak such effect. Proteolytic agents such as diiodosalitylic acid (0.1N), sodium dodecyl sulfate (0.1N) and cholic acid (0.1N) showed a stronger effect but not enough for clinical use. In contrast, a detergent which contains interfacial active agents and a proteolytic enzyme (alkaline cellulase), such as Attack and Hi-Top, proved to be more effective to solve the debris. However, biological effect of such detergent on the ear is not clear. Further study will be necessary before actual application in the patients.

Cholesteatoma↗

PubMed1991

Defects in the bony wall of the mastoid bowl: a study based on staged intact canal-wall tympanoplasty.

The incidence and outcome of bony wall defects in the mastoid bowl were studied in 175 ears of 167 patients who underwent staged tympanoplasty by the intact canal-wall technique. In the first stage, the middle fossa dura was exposed iatrogenically in 38 ears and pathologically in eight ears through a defect at the tegmen. In the second stage, the bone defect was cured in 27 ears of the former group and in 3 ears of the latter group. The overall cure rate of the defect in the tegmen during these stages was 65.2 percent (30/46). Exposure of the sigmoid sinus or posterior fossa dura, which had occurred iatrogenically in 12 ears in the first stage, was cured in 11 ears (91.7%) in the second stage. Defects of the anterior wall of the mastoid bowl, i.e., the posterior wall of the external auditory canal, were recognized in 105 ears in the first stage, 91 of which involved pathologic defects of the tympanic scutum caused by cholesteatoma. In the second stage, these defects remained unhealed with cures occurring in only two ears (1.9%), in which a small hole had been created iatrogenically in the middle of the canal wall. Defects in the canal wall due to bone resorption following the first stage operation were noted in the second stage in 26 of 175 ears (14.9%).

Adolescent↗