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Biomedical subjects

Kimitaka Kaga

Publications and source records attributed to Kimitaka Kaga.

At least 55 records · Page 3Linked to original sources
PubMed2005

Facial canal anatomy in patients with mandibulofacial dysostosis: comparison with respect to the severities of microtia and middle ear deformity.

OBJECTIVE: To study the difference in the facial canal anatomy in terms of the severity of microtia and deformity of the middle ear in patients with mandibulofacial dysostosis using high-resolution computed tomography. STUDY DESIGN: Retrospective analyses. SETTING: The study was carried out at the Department of Otorhinolaryngology, University of Tokyo, Tokyo, Japan. PATIENTS: Thirty-six ears of 18 patients with mandibulofacial dysostosis were examined by high-resolution computed tomography. These ears were graded based on the Marx classification and Jahrsdoerfer scoring systems. MAIN OUTCOME MEASURES: The high-resolution computed tomography findings and age distribution of each group were compared with those of other groups by multiple comparison using Tukey's honestly significant difference test. RESULTS: The course of the facial nerve was not significantly different in terms of the severity of microtia and deformity of the middle ear. The bony cochlea in the patients with mandibulofacial dysostosis was displaced by a mean value of 2 mm more anteriorly and a mean value of 0.7 mm shallower than that in the cases with normal auricles. CONCLUSION: The facial nerve of patients with mandibulofacial dysostosis is displaced more anterolaterally than that of the cases with normal auricles; however, the auricle anomaly is not severe.

Adolescent↗
PubMed2005

Are vestibular sensory cells preserved after destruction of Scarpa's ganglion? A study based on metastatic tumors of temporal bone.

OBJECTIVE: The contribution of nerve fibers to the maintenance of vestibular sensory cells is a controversial issue in previous studies using animals and has not yet been studied in humans. The authors investigated this issue by observing vestibular end organs in the temporal bone of three patients in whom the internal auditory canal was infiltrated with tumor cells, and Scarpa's ganglion cells showed complete degeneration. STUDY DESIGN: Retrospective case review. SETTING: University Hospital, Department of Otolaryngology. PATIENTS: Three patients with malignant metastatic temporal bone tumors. INTERVENTION: We investigated the preservative state of vestibular sensory hair cells with the Scalpa's ganglion was destructed. MAIN OUTCOME MEASURES: Maintenances of vestibular sensory hair cells. RESULTS: We found that sensory cells were intact despite the severe destruction of Scarpa's ganglion cells in two of the patients. CONCLUSION: The findings suggest that human vestibular sensory cells can be maintained for an indefinite period after denervation.

Adolescent↗
PubMed2005

Vestibular-evoked myogenic potentials in infancy and early childhood.

OBJECTIVE: Hearing impairment and the often concurrent loss of vestibular function, which is rarely assessed in infants, can both impair sensory integration critical to the development of normal motor coordination. This study demonstrates, for the first time, that vestibular function in infants can be noninvasively assessed using vestibular-evoked myogenic potentials (VEMPs). Our intentions were to demonstrate that VEMPs can be reliably recorded from neonates and to compare neonatal VEMPs with those obtained from normal adults. STUDY DESIGN: Prospective cohort study. METHODS: Myogenic evoked potentials induced by air- and bone-conducted auditory stimuli were recorded from the sternocleidomastoid muscles of 12 normal neonates and 12 neonates with various clinical findings. These included infants with bilateral atresia of the external auditory canals, Treacher-Collins syndrome, and neonates who failed universal neonatal screening. RESULTS: With the exception of one patient with hearing loss, reproducible biphasic VEMPs were recorded from the sternocleidomastoid muscle of all the infants using loud, short tone-burst sounds. CONCLUSIONS: The VEMP has characteristics that differentiate it from the postauricular response and the Jaw reflex. The VEMPs were dominant on the side ipsilateral to the stimulated ear. The overall morphology of the neonatal VEMP is quite similar to that of adults. The major neonatal differences are a shorter latency of the n23 peak and higher amplitude variability. Our results suggest that recording of the VEMP in neonates with various audio-vestibular problems provides useful information about vestibular function in this population and may provide information that leads to better care and rehabilitation for neonates at risk of developmental and motor system delay.

Audiometry, Pure-Tone↗
PubMed2005

Nasal allergic response mediated by histamine H3 receptors in murine allergic rhinitis.

BACKGROUND: Histamine is one of the most important chemical mediators causing nasal allergic symptoms, and H1 receptor antagonist have been used as the treatment first choice in nasal allergy. The presence of H3 receptors has also been determined in the human nasal mucosa, but few studies have investigated the involvement of H3 receptors in nasal allergy. OBJECTIVE: We used a murine allergic model to investigate the presence of nasal mucosa H3 receptor mRNA and any H3 receptor agonist or antagonist influences on clinical nasal allergic symptoms. METHODS: H3 receptor mRNA in nasal mucosa was investigated by reverse-transcription polymerase chain reaction. OVA-sensitized mice were given an intraperitoneal injection of H3 receptor agonist or antagonist, and clinical nasal allergic symptoms were scored over 10 minutes after nasal provocation of OVA. Inhibition of nasal allergic symptoms was also examined using an H1 receptor antagonist alone and using a both an H3 receptor agonist and an H1 receptor antagonist. RESULTS: H3 receptor mRNA was identified in the murine nasal mucosa. The H3 receptor agonist (R)-alpha-metylhistamine significantly inhibited clinical nasal allergic symptoms of OVA-sensitized mice. The H3 receptor agonist and H1 receptor antagonist inhibited clinical nasal allergic symptoms in the murine allergic model more strongly than the single drug. CONCLUSION: The foregoing results indicate that H3 receptors are involved in modulation of nasal allergy. H3 receptor agonists can also be useful as a novel therapeutic approach in nasal allergy. Both H3 receptor agonist and H1 receptor antagonist may be more effective than a single drug.

Allergens↗
PubMed2005

Autologous transplantation of fascia into the vocal fold: long-term result of type-1 transplantation and the future.

OBJECTIVES: Since 1997, we have performed the autologous transplantation of fascia into the vocal fold (ATFV) procedure on cases of sulcus vocalis. In what follows, we report the long-term results of our new surgical approach and discuss the role of these transplantations. We also review and report some complications that can be caused by ATFV. Finally, we discuss the ATFV technique as a contribution to the phonosurgery of the future. STUDY DESIGN: Prospective study. METHODS: We were able to obtain long-term results from 10 volunteer cases (2 female and 8 male, age: 15-71, mean 46.5 years old) who could be followed up for at least 3 years after transplantation. All were cases of pathologic sulcus vocalis.We measured maximum phonation time (MPT) and carried out pre- and postsurgical clinical observation and laryngeal stroboscopy in all cases. These measurements and observations were made before the ATFV and at 6 months, 1 year, 2 years, and 3 years after surgery. RESULTS: In stroboscopic observation 1 year after the ATFV, satisfactory glottal closure and excellent mucosal wave were observed for all cases, and there was no case with hyperadduction of the false vocal folds. MPT measures remained at an improved level 2 years and 3 years after the transplantations. Paired-sample t tests showed that the improvement relative to preATFV levels was significant for all postsurgical measurements up to 3 years. CONCLUSIONS: We conclude that ATFV is a successful surgical procedure for sulcus vocalis and scarred vocal folds. Other phonosurgical clinical applications may also be envisioned.

Adolescent↗
PubMed2005

Easy-to-prepare assembly array of Tungsten microelectrodes.

This paper provides a detailed process flow for fabricating an easy-to-prepare, inexpensive, dense array of tungsten microelectrodes. We designed the process flow to minimize routine tasks by separating an initial preparation of a master mold from a routine preparation of substrate replication, array assembly and tip processing. Sandblast processing first produced a glass mold with a pattern of a series of protruding lines at a requested interval of a few hundred micrometers. Copying the groove pattern onto polystyrene mass-produced a replica substrate. Tungsten probes were then aligned on the substrate, and the tips of probes were finely processed in the block.

Action Potentials↗
PubMed2005

Accessing ampli-tonotopic organization of rat auditory cortex by microstimulation of cochlear nucleus.

Auditory brainstem implants (ABI) that electrically stimulate the surface of cochlear nucleus have been clinically used for the rehabilitation of deaf patients with bilateral vestibular schwannomas. The change of pitch perception with an active electrode location is not as clear in ABIs as in cochlear implants, a factor which might play a role in poorer speech performance in ABIs. The objective of present work was to develop an animal ABI model that could provide physiological data for future ABI development and optimization. The experimental system included a penetrating microelectrode array for microstimulation of the cochlear nucleus and a surface microelectrode array for mapping evoked potentials over the auditory cortex. We first obtained tone-evoked cortical activation patterns, which represented a place code of the frequency and intensity of test tones, i.e., the ampli-tonotopic organization, and compared the patterns with those evoked by cochlear nuclear microstimulation. Our experimental results demonstrated that microstimulation of both the dorsal and ventral cochlear nucleus (DCN and VCN) could access the cortical ampli-tonotopic organization as acoustic stimuli did. We also found that the cortical dynamic range was wider for the DCN than VCN stimulation and for the low-frequency than for the high-frequency pathway. The present results have great implications for improved ABI performance.

Action Potentials↗
PubMed2005

Autologous replacement of the vocal fold: a new surgical approach for adduction-type spasmodic dysphonia.

Many surgical approaches have been developed for the treatment of adduction-type spasmodic dysphonia (SPD). We developed and performed a new type of surgical approach (autologous replacement of the vocal fold). Our new surgical technique increases the advantages and decreases the disadvantages of previous surgical procedures in three ways: (1) It has similar effects to the previous procedures in that it prevents contraction of the thyroarytenoid muscle. (2) It decreases vocal-fold tension, as in framework surgery. (3) It reduces glottal incompetence, as does fibrinogen-glue injection, but it is more suitable because it is autologous. Furthermore, it produces increases in the mass and volume of the vocal-fold body and is also safe because the replacement tissue is autologous. The short-term results appear encouraging in preventing spastic voice while also avoiding vocal-fold atrophy. Long-term follow up will be necessary to determine the actual efficacy. However, this is clearly a possible choice as a surgical approach for treating adduction-type SPD.

Fascia↗
PubMed2004

Distributed representation of sound intensity in the rat auditory cortex.

We epipially mapped tone-burst-evoked potentials over the rat auditory cortex, and investigated the representation of intensity information. The experiments were designed to elucidate how the auditory cortex represents a steady-state plateau sound pressure level (SPL) and dynamic onset temporal structure, i.e., the rate of pressure change (in Pa/s), and how the representations differ across the auditory fields. The anterior and ventral fields have spatial axes of the rate of pressure change. Characteristic frequency (CF) locations mainly handle the dynamic state, while off-CF locations have the potential to code the steady state. Each field represents the intensity information differently, particularly at the off-CF locations. These results suggest that intensity information is distributed in various aspects in the multiple auditory fields.

Acoustic Stimulation↗
PubMed2004

Cortical activation shortly after cochlear implantation.

We evaluated the cortical activations in postlingually deaf cochlear implant (CI) users in the early period (0-2 months) of CI usage. The subjects were 8 early CI users and 8 normal subjects. With tone burst stimuli (1 kHz) delivered to the right side, strong and broad activation of the ipsilateral (right) primary auditory cortex with 2 peaks and weaker activation of the contralateral (left) temporal lobe were observed in early CI users, in a clear contrast with the normal subjects in whom activation was observed in a small area of the contralateral (left) primary cortex. With word stimuli, activation of the superior frontomedian cortex presumably including the supplementary motor area and the neighboring cingulate gyri was observed in early CI users, which was absent in normal subjects. The activation in the immediate association cortices near the primary area was lower in early CI users, while the periphery of the association cortex seemed to be more mobilized.

Acoustic Stimulation↗
PubMed2004

Cortical mapping of auditory-evoked offset responses in rats.

We characterized the auditory-evoked offset responses of the rat auditory cortex by multiple-site surface microelectrode recording. Tone bursts served as test stimuli. Offset responses did not appear tonotopically, but at the fringe of tonotopic onset distributions. Offset amplitude was significantly sensitive to sound intensity, fall time at tone termination, and duration. These results suggest that offset responses are associated with inhibitory responses surrounding excitatory onset responses, and offset responses become large when inhibition becomes strong and long or terminates synchronously. Thus, the rebound after the inhibition in the presence of a stimulus is likely to be a major cause of offset responses in the auditory cortex.

Acoustic Stimulation↗
PubMed2004

The role of the external auditory canal in the development of the malleal manubrium in humans.

OBJECTIVE: To determine if the external auditory canal (EAC) plays a role in the induction and proper positioning of the malleal manubrium in humans. STUDY DESIGN: Retrospective study between 1994 and 2002. SETTING: Academic, tertiary care referral medical center. Patients Fifty-five ears of 50 patients with congenital atresia (n = 47) or stenosis (n = 8) of the EAC, for which meatoplasty was performed at the University hospital between 1994 and 2002. MAIN OUTCOME MEASURES: The presence of the manubrium was examined during surgery, and the corre-lation between the presence of the manubrium and the grade of the microtia was evaluated. RESULTS: The manubrium was identified in all ears with EAC stenosis, whereas it was absent in all ears with EAC atresia. No correlation was observed between manubrium formation and auricular deformity. CONCLUSIONS: Our results demonstrated a close relationship between the formation of the EAC and that of the malleal manubrium in humans. This is consistent with the recent findings in knockout mice. This information is useful for surgical intervention in cases of congenital EAC anomalies.

Adolescent↗
PubMed2004

Temporal bone pathology in hydrocephalus: changes in the inner ear due to increased intracranial pressure.

Changes in the inner ear due to increased intracranial pressure have not yet been clearly defined. We present a postmortem temporal bone study of child with hydrocephalus. The temporal bone was from a 2-year-old female with IVth ventricle ependymoblastoma. In the basal turn of the cochlea, degeneration of the organ of Corti and the nerve ganglion was observed. In the top and middle turn, structures were intact. The utricle and saccule were well preserved. We propose that changes in the inner ear due to increased intracranial pressure begin in the base of the cochlea, and extend to the apex in decreasing degree.

Brain Neoplasms↗
PubMed2004

Hearing evaluation in two sisters with a T8993G point mutation of mitochondrial DNA.

We report on two sisters with a T8993G point mutation of mitochondrial DNA, and their hearing evaluation. Considering auditory function, hearing in the elder sister remains almost normal. However, in the younger sister, the auditory brainstem response (ABR) threshold has fluctuated remarkably during a 3-year follow-up. The threshold changes of ABR in the younger sister suggest that her hearing problems may well be caused by both cochlear nerves and retrocochlear lesions. Our experience is clinically important because there have been only a few reports on hearing evaluation in patients with a T8993G point mutation of mitochondrial DNA.

Audiometry, Pure-Tone↗
PubMed2004

Vestibular-evoked myogenic potentials in three patients with large vestibular aqueduct.

An enlarged vestibular aqueduct (LVA) is a common congenital inner ear anomaly responsible for some unusual vestibular and audiological symptoms. Most of the cases show bilateral early onset and progressive hearing loss in children. The gross appearance on CT scan of the inner ear is generally normal. However, precise measurements of the inner ear components reveal abnormal dimensions, which may account for the accompanying auditory and vestibular dysfunction. Despite extensive studies on hearing and the vestibular apparatus, saccular function is not studied. To our knowledge this is the first report of saccular malfunction in three patients with LVA by means of vestibular evoked myogenic potentials. Conventional audiograms revealed bilateral severe sensorineural hearing loss in two patients and mixed type hearing loss in one patient. Two of the patients complained about vertigo and dizziness but vestibular assessments of the patients showed normal results. The diagnosis had been made by high-resolution CT scans and MR images of the skull that showed LVA in the absence of other anomalies. The VEMP threshold measured from the ear with LVA in two patients with unilateral enlargement of the vestibular aqueduct was 75-80 dB nHL whereas the threshold from normal ears was 95 dB nHL. The third patient with mixed type hearing loss and bilateral LVA had VEMP responses despite a big air-bone gap in the low frequency range. The VEMP in this patient was greater in amplitude and lower in threshold in the operated ear (the patient had a tympanoplasty which did not improve her hearing). These findings and results of other patients with Tullio phenomenon and superior semicircular canal dehiscence, who also showed lower VEMP threshold, confirmed the theory of a 'third window' that allows volume and pressure displacements, and thus larger deflection of the vestibular sensors, which would cause the vestibular organ to be more responsive to sound and pressure changes.

Adult↗
PubMed2004

A case of cortical deafness and anarthria.

Generally, cortical deafness is not complicated by anarthria and cortical anarthria does not affect auditory perception. We report a case of simultaneous progressive cortical deafness and anarthria. At the age of 70 years, the patient, a woman, noticed hearing problems when using the telephone, which worsened rapidly over the next 2 years. She was then referred to our hospital for further examinations of her hearing problems. Auditory tests revealed threshold elevation in the low and middle frequencies on pure-tone audiometry, a maximum speech discrimination of 25% and normal otoacoustic emissions and auditory brainstem, middle- and long-latency responses. An articulation test revealed abnormal pronunciation. Because of these problems only written and not verbal communication was possible; her ability to read and write was unimpaired. She showed no other neurological problems. Brain MRI demonstrated atrophic changes of the auditory cortex and Wernicke's language center and PET suggested low uptake of (18F) 2-fluoro-2-deoxy-d-glucose around the Sylvian fissures in both hemispheres. Neurologically, the patient was suspected of having progressive aphasia or frontotemporal dementia. Her cortical deafness and anarthria are believed to be early signs of this entity.

Aged↗