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Kimitaka Kaga

Publications and source records attributed to Kimitaka Kaga.

At least 37 records · Page 2Linked to original sources
PubMed2005

A case of Mobius syndrome--radiological and electrophysiological findings.

Mobius syndrome is characterized by congenital bilateral facial palsy and abducens nerve paralysis, but reports of radiological and electrophysiological findings are scarce. A 4-year-old boy presented with mask-like facies noted at birth after a 34-week pregnancy. Examination revealed bilateral facial and abducens nerve paralysis with no other neurological abnormalities. Computed tomography revealed bilateral absence of facial nerve canal in the middle ear. Brain magnetic resonance imaging indicated a narrow than expected nerve in the internal auditory canal (IAC). Evoked electromyography and blink reflex testing to evaluate facial nerve function yielded no responses bilaterally. Facial palsy thus appears to be caused by facial nerve dysplasia or aplasia.

Blinking↗
PubMed2005

Audiovisual phonological mismatch produces early negativity in auditory cortex.

During silent reading, visual information provided by letters is converted to auditory information in the mind. The purpose of this study was to identify the primary locus for auditory verbal imagery in the brain. Neuromagnetic recording was obtained from 10 right-handed study participants, who were instructed to identify infrequently occurring phonological mismatches between a random-ordered sequence of syllable sounds and a visually presented syllabogram sequence. The activity difference in early latency, calculated by subtracting the averaged responses to matched syllables from the averaged responses to mismatched syllables, showed a spatiotemporal profile strikingly similar to that of mismatch negativity. Auditory imagery of forthcoming verbal sounds may establish a memory trace as a template for imagery-based mismatch negativity generation in the auditory cortex.

Acoustic Stimulation↗
PubMed2005

A modified parallel paradigm for clinical evaluation of auditory echoic memory.

We established a new parallel paradigm for mismatch negativity by presenting repetitive trains of three consonant-vowel syllables and those of three sinusoidal tones alternately. Magnetoencephalography was performed to test the new method, and mismatch negativities in six study participants with normal hearing were compared with the results of the conventional oddball paradigm. Peak amplitude and latencies of mismatch negativity showed no significant difference between the methods. The maximum amplitude in short memory probe interval of 1.0 s was significantly larger than in long memory probe interval of 3.0 s, demonstrating decay in auditory echoic memory caused by a prolonged memory probe interval. The new method facilitated simultaneous evaluation of mismatch negativity with various stimuli in a shorter period.

Acoustic Stimulation↗
PubMed2005

Perceptual categorization of sound spectral envelopes reflected in auditory-evoked N1m.

Magnetic responses to periodic complex sounds with equivalent acoustic parameters except for two different fundamental frequencies (F0) and 12 different spectral envelopes of vocal, instrumental, and linear shapes were recorded to determine the cortical representation of timbre categorization in humans. Responses at approximately 100 ms (N1m) to vocal and instrumental (nonlinear) sounds were localized significantly anterior to linear sound responses. N1m source strength for nonlinear sounds was significantly larger than that for linear sounds, and this difference was more marked in the left hemisphere than in the right. N1m peak latency only for vocal sounds was not affected by F0. Perceptual categorization was reflected in N1m source strength and location (linear or nonlinear), and in N1m latency (vocal or nonvocal).

Acoustic Stimulation↗
PubMed2005

Alaryngeal speech aid using an intra-oral electrolarynx and a miniature fingertip switch.

We developed and evaluated an intra-oral electrolaryngeal speech aid system for those who could not acquire common alaryngeal speech or for early post-surgery speech rehabilitation. Our system consisted of a denture-base intra-oral vibrator, a wireless miniature fingertip switch and a controller. To produce natural speech, the fingertip switch produced binary commands of voicing and accent and the controller implemented the pitch generation model using the commands. We first estimated the intelligibility of consonant-vowel syllables produced by our system. We then obtained the feedback about the system from the Japanese users on the basis of their daily life use, and evaluated the possibility and acceptability as an alaryngeal speech aid. Although the users were less satisfied at the intra-oral electrolarynx, the intelligibility of the intra-oral electrolarygeal speech was comparable to that of transcervical electrolaryngeal speech, and most of them were willing to employ it if they lost their current electrolaryngeal speech. According to the feedbacks from the users, a completely wire-free system and less eye-catching designs would make the prosthesis more acceptable. These results placed the intra-oral electrolarynx as a useful option of alaryngeal speech aids and encouraged the further development of the intra-oral electrolarynx.

Aged↗
PubMed2005

Alteration of frequency range for binaural beats in acute low-tone hearing loss.

The effect of acute low-tone sensorineural hearing loss (ALHL) on the interaural frequency difference (IFD) required for perception of binaural beats (BBs) was investigated in 12 patients with unilateral ALHL and 7 patients in whom ALHL had lessened. A continuous pure tone of 30 dB sensation level at 250 Hz was presented to the contralateral, normal-hearing ear. The presence of BBs was determined by a subjective yes-no procedure as the frequency of a loudness-balanced test tone was gradually adjusted around 250 Hz in the affected ear. The frequency range in which no BBs were perceived (FRNB) was significantly wider in the patients with ALHL than in the controls, and FRNBs became narrower in the recovered ALHL group. Specifically, detection of slow BBs with a small IFD was impaired in this limited (10 s) observation period. The significant correlation between the hearing level at 250 Hz and FRNBs suggests that FRNBs represent the degree of cochlear damage caused by ALHL.

Acute Disease↗
PubMed2005

Spatial and temporal strategy to analyze steady-state sound intensity in cortex.

Prevailing studies of auditory systems pay most attention to the dynamic temporal changes of sound intensity, but poorly enlighten the encoding of steady-state aspects. Using tone bursts as test stimuli, we epipially map auditory evoked potentials over the rat auditory cortex and investigate how the cortex represents the dynamic and steady states. Our results demonstrate that all of the auditory fields investigated potentially have at least two strategies to represent the two states; a temporal combination of early and late components of the potentials, and a spatial combination of an arbitrary component. In addition, the optimal combination that can distinguish between the two states differs across auditory fields, suggesting robust analyses of sound intensity in the auditory cortex.

Acoustic Stimulation↗
PubMed2005

Correlation between microtia and temporal bone malformation evaluated using grading systems.

OBJECTIVE: To evaluate the relationships between temporal bone abnormalities and the severity of microtia in Japanese patients using objective grading systems. DESIGN: Retrospective case series study conducted between 1992 and 2003. SETTING: Academic, tertiary care, referral medical center. PATIENTS: One hundred forty-two ears of 109 Japanese patients (85 male and 24 female patients; mean age, 12.8 years [range, 2-36 years]) with microtia. MAIN OUTCOME MEASURES: The severity of microtia was classified according to Marx classification. Developmental abnormalities of the temporal bone were evaluated by a computed tomographic (CT) scoring system modified after the system used by Jahrsdoerfer and colleagues, using high-resolution CT scans of the temporal bone. Correlations between the scores obtained from these 2 grading systems were evaluated using a nonparametric statistical method. RESULTS: Male preponderance and incidence of bilateral cases of approximately 30% were observed in our Japanese patients with microtia. There was no significant difference in the severity of microtia between unilateral and bilateral cases. The mean +/- SEM total points in the CT scoring system (full marks, 10) was 7.9 +/- 0.4 for grade I microtia, 6.6 +/- 0.6 for grade II, and 6.4 +/- 0.3 for grade III; the total points correlated inversely with the microtia grade. Development of the auricle correlated significantly with aeration in the middle ear spaces but not with ossicular development or formation of the oval/round windows. Proportion of acceptable surgical candidates according to the CT scoring system (>5 points) was 79% for grade I microtia, 52% for grade II microtia, and 65% for grade III microtia. CONCLUSION: The principle "the better developed the auricle, the better developed middle ear" was confirmed in Japanese patients with microtia; however, even with grade II/III microtia, more than half of the patients were considered suitable for atresia surgery.

Abnormalities, Multiple↗
PubMed2005

Time-intensity trading in bilateral congenital aural atresia patients.

In an effort to examine the rules by which information of bilaterally applied bone-conducted signals arising from interaural time differences (ITD) and interaural intensity differences (IID) is combined, data were measured for continuous 500 Hz narrow band noise at 65-70 dB HL in 11 patients with bilateral congenital aural atresia. Time-intensity trading functions were obtained by shifting the sound image towards one side using ITD, and shifting back to a centered sound image by varying the IID in the same ear (auditory midline task). ITD values were varied from -600 to +600 micros at 200 micros steps, where negative values indicate delays to the right ear. The results indicate that time-intensity trading is present in patients with bilateral aural atresia. The gross response properties of time-intensity trading in response to bone-conducted signals were comparable in patients with bilateral aural atresia and normal-hearing subjects, though there was a larger inter-subject variability and higher discrimination thresholds across IIDs in the atresia group. These results suggest that the mature auditory brainstem has a potential to employ binaural cues later in life, although to a restricted degree. A binaural fitting of a bone-conducted hearing aid might optimize binaural hearing and improve sound lateralization, and we recommend now systematically bilateral fitting in aural atresia patients.

Acoustic Stimulation↗
PubMed2005

Effect of myringotomy on prognosis in pediatric acute otitis media.

OBJECTIVE: In children with acute otitis media (AOM), we compared clinical outcomes between groups with and without myringotomy to elucidate the effect of this procedure on long-term clinical course and prognosis. METHODS: Fifty-nine children (29 male, 30 female) with tympanic membrane bulging or middle ear fluid (MEF) at initial presentation were assigned to one of two treatment groups. Group A received oral antibiotics and also underwent myringotomy at initial enrollment (36 cases), while group B received oral antibiotics without myringotomy (23 cases). Clinical outcomes were evaluated by otolaryngologic specialists using pneumatic otoscopy and tympanometry at 5, 10, 15, 30 days and 12 weeks and then every 2 weeks after the initial treatment. Otitis media with effusion (OME), early recurrence and recurrent AOM were used as the evaluation criteria for the prognosis. RESULTS: In group A, 6 children (16.7%) showed transition to OME, 11 (30.6%) showed early recurrence of AOM, and 9 (25.0%) developed recurrent AOM. In group B 10, 8, and 3 (43.5%, 34.8%, and 13.0%) showed these respective adverse outcomes. While early recurrence rates and recurrent AOM rates did not differ significantly between groups, progression of OME was significantly less frequent in group A than group B (P = 0.036). CONCLUSIONS: Lower rates of progression to OME in the group undergoing myringotomy suggested that myringotomy might be effective in preventing this outcome.

Acoustic Impedance Tests↗
PubMed2005

Sensorineural hearing loss in patients with cerebral palsy after asphyxia and hyperbilirubinemia.

The location of lesions causing hearing loss in patients with cerebral palsy due to asphyxia or neonatal hyperbilirubinemia has remained unclear. We performed behavioral audiometry, distortion product otoacoustic emission (DPOAE) and auditory brainstem evoked response (ABR) in six patients with cerebral palsy due to asphyxia or neonatal hyperbilirubinemia in order to determine the lesion location causing their hearing impairment. In all cases, behavioral audiometry revealed a threshold elevation of 50-75 dB and ABR were no response. DPOAE were totally absent in five patients and normal in one patient. Our study suggests that lesions causing hearing loss potentially include the organ of Corti especially at the outer hair cells and the cochlear nerve.

Adolescent↗
PubMed2005

Cyclooxygenase-2 regulates the degree of apoptosis by modulating bcl-2 protein in pleomorphic adenoma and mucoepidermoid carcinoma of the parotid gland.

CONCLUSION: These results suggest that COX-2 and bcl-2 protein were overexpressed and that apoptosis was reduced in MEC compared to PMA, and that COX-2 may regulate the degree of apoptosis by modulating bcl-2 protein in PMA and MEC. OBJECTIVE: Cyclooxygenase (COX)-2 plays a crucial role in tumorigenesis and overexpression of COX-2 in vitro accompanied by overexpression of bcl-2 protein has been shown to reduce apoptosis. The purpose of this study was to verify that COX-2 regulates the degree of apoptosis by modulating bcl-2 protein in benign and malignant parotid gland tumors. : We examined archival formalin-fixed, paraffin-embedded tissue sections of 10 pleomorphic adenomas (PMAs) and 10 mucoepidermoid carcinomas (MECs) by immunostaining with anti-COX-2, anti-bcl-2 and anti-single-stranded DNA (ssDNA) antibodies. Labeling indices of the three antibodies were calculated using computer-assisted image analysis. RESULTS: Labeling indices (mean+/-SD) of anti-COX-2 antibody in PMA and MEC were 2.05+/-1.30 and 11.2+/-2.95, respectively (p < 0.001), those of anti-bcl-2 antibody were 2.00+/-1.28 and 9.68+/-4.05, respectively (p < 0.001) and those of anti-ssDNA antibody were 8.06+/-2.54 and 2.08+/-1.47; respectively (p <0.001). Correlation coefficients between the labeling indices of anti-COX-2 antibody and anti-bcl-2 antibody, anti-bcl-2 antibody and anti-ssDNA antibody and anti-COX-2 antibody and anti-ssDNA antibody were 0.88, -0.75 and -0.76, respectively (p <0.001).

Adenoma, Pleomorphic↗
PubMed2005

Pathological findings in the temporal bone of newborn infants with neonatal asphyxia.

Hypoxia in adults frequently causes damage to the brain, but not the inner ear. However, hypoxia in neonates with inadequate blood-inner ear barrier function causes damage to the inner ear, leading to hearing loss and equilibration disorder. Clinically, asphyxiated neonates sometimes have the complication of sensorineural hearing impairment at high frequencies. Many reports suggest that this problem is caused by hypoxic encephalopathy. However, it is not clear whether inner ear disorders are present. In this report we examined the inner ear pathology of four asphyxiated neonates using serial sections of temporal bone. The subjects (n=4) were 1-13-day-old neonates with pregnancy periods of 24-36 weeks. Their fetal growth curves were within the normal range. There was one case each of twin pregnancy, placental abruption, placenta previa and meconium aspiration syndrome. For the case of severe neonatal asphyxia, damage to the inner ear included the degeneration and disappearance of outer hair cells of the organ of Corti and edematous changes in the stria vascularis. Degeneration of spiral ganglion and vestibular ganglion cells was observed in two of the other cases.

Asphyxia Neonatorum↗
PubMed2005

Magnetoencephalography and positron emission tomography studies of a patient with auditory agnosia caused by bilateral lesions confined to the auditory radiations.

The aim of this study was to investigate auditory cortex function in the context of auditory stimuli in a patient with auditory agnosia due to bilateral lesions confined to the auditory radiations. A male patient experienced mild left temporal hemiplegia because of right putaminal hemorrhage at the age of 43 years. Thereafter he recovered completely but hypertension persisted. When he was 53 years old, he suffered left putaminal hemorrhage and went into a coma. After recovering from the coma and right hemiplegia he could hear but could not discriminate speech sounds. Brain CT and MRI demonstrated small bilateral lesions confined to the auditory radiations. Magnetoencephalography demonstrated the disappearance of middle latency responses and auditory-evoked potential studies showed a very small Pa peak. In contrast, a positron emission tomography study demonstrated a marked increase in blood flow in the bilateral auditory cortex in response to both click and monosyllable stimuli. It is speculated that the auditory cortex receives functional projections from the cochlea via non-specific pathways in the cerebral hemispheres.

Agnosia↗
PubMed2005

Distal renal tubular acidosis associated with large vestibular aqueduct and sensorineural hearing loss.

CONCLUSIONS: Hearing loss and equilibrium dysfunction have different etiologies in patients with large vestibular aqueduct syndrome. We suggest that all children with distal renal tubular acidosis (dRTA) should be subjected to an equilibrium study and audiological evaluation, as well as to a CT or MRI scan. OBJECTIVE: dRTA has been described in association with sensorineural hearing loss, but there are no reported cases that have been examined in detail using audiological and equilibrium studies. We report here a case of progressive sensorineural hearing loss with a large vestibular aqueduct and dRTA, and the results of audiological and equilibrium studies. MATERIAL AND METHODS: A 31-year-old female presented with hearing loss, tinnitus and vertigo. She had been treated with oral sodium citrate, potassium citrate and potassium chloride supplementation because of dRTA since the age of 1 month. RESULTS: The pure-tone audiogram of the patient was off the scale for the right ear and showed progressive sensorineural hearing loss for the left ear. Ice-water caloric testing showed canal paresis on the left side. Temporal bone CT and inner ear MRI revealed a large vestibular aqueduct and a large endolymphatic sac on both sides.

Acidosis, Renal Tubular↗
PubMed2005

Sacculo-collic pathway dysfunction accompanying auditory neuropathy.

CONCLUSIONS: In a patient with bilateral auditory neuropathy (AN), the vestibular-evoked myogenic potential (VEMP) was probably absent because of a neuropathy involving the inferior vestibular nerve and/or its end organ, the saccule. Our result can therefore be interpreted as a concomitant unilateral sacculo-collic neuropathy. We suggest the use of more precise terms to characterize AN patients with involvement of different parts of the inner ear and its innervations. We encourage detailed vestibular assessment in patients with AN in order to assess the co-existence of any symptomatic or asymptomatic vestibular disorder. Information such as that provided in this report will be valuable for clinicians caring for this group of patients. OBJECTIVE: AN is a disorder characterized by the absence or severe impairment of auditory brainstem responses in the presence of normal cochlear outer hair cell function as revealed by otoacoustic emissions (OAEs) and/or electrocochleography (ECoG). A variety of processes and etiologies are thought to be involved in its pathophysiology. In most literature reports the auditory profile of patients with AN is discussed. However, the extent of vestibular involvement, especially that involving the saccule, is not known. We performed vestibular tests to assess the status of the saccule in a patient with AN. MATERIAL AND METHODS: One patient with AN was studied. The patient was a right-handed 21-year-old female with chief complaints of hearing loss and speech perception difficulty. RESULTS: The auditory test results were consistent with the diagnosis of AN, i.e. absent auditory brainstem responses, moderate hearing loss, an inappropriately profound speech discrimination score and the presence of OAEs and measurable cochlear microphonics on ECoG. On neurological examination, gait and balance tests were normal. Ice-water caloric testing induced a sensation of dizziness in both ears. Short tone-burst VEMPs showed no response on left-ear stimulation and a biphasic response with normal latency and amplitude on right-ear stimulation.

Adult↗
PubMed2005

Three young adult patients with Pelizaeus-Merzbacher disease who showed only waves I and II in auditory brainstem responses but had good auditory perception.

Three young adult males with Pelizaeus-Merzbacher disease have been followed up since childhood. This disease is thought to be a dysmyelinating disorder of the brain during the prenatal period caused by gene mutations. The patients manifested horizontal nystagmus and severe rigidity of the extremities. Although the patients showed only waves I and II in auditory brainstem responses, they had relatively good hearing ability at approximately equal to dB. They could not speak words at all but could hear well and enjoy listening to conversation and music. One of them had a normal hearing threshold in pure-tone audiometry and a normal speech discrimination rate in speech audiometry. This can be explained by a nerve conduction blockade through dysmyelinated axons or the desynchronization of neurons and nerves responsible for the waves following waves I and II. At present, all three patients are living with their families. We report their present hearing, speech and language abilities.

Adult↗