Biomedical subjects

Y Koike

Publications and source records attributed to Y Koike.

At least 163 records · Page 9Linked to original sources

PubMed1994

Effects of aging on amplitude-modulation following response.

Phase spectral analysis as developed by Fridman (1982) was used to detect amplitude-modulation following response (AMFR). The threshold of AMFR was determined with greater sensitivity and accuracy by phase spectral analysis than by visual analysis. Using this method, a modulation frequency (MF) of 80 Hz was found optimal for detecting AMFR in young children (ranging in age from 2 to 4 years) during sleep, for whom there is no advantage in recording 40-Hz steady-state responses. To determine the optimal MF for detecting AMFR during sleep in children less than 2 years of age and age limitation for using 80-Hz MAFR in objective audiometry, AMFR as a function of MF was investigated during sleep in 25 children with normal hearing ranging from 4 months to 15 years of age, and 10 normal hearing adults. The stimulus was a 1000 Hz, 50 dBnHL sinusoidally amplitude modulated tone with a modulation depth of 95%. MF was varied from 20 to 200 Hz in 20 Hz steps. Response was determined by phase spectral analysis and the S/N ratio calculated by spectral amplitude at the modulation frequency and noise level around the modulation frequency using fast Fourier transform. Phase spectral analysis showed AMFR at MF of 80 Hz to be the most stable and reliable in all children during sleep among MFs from 20 to 200 Hz. Spectral amplitude analysis demonstrated 80-Hz AMFR to have a high S/N ratio in all children.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗

PubMed1994

Detectability of amplitude-modulation following response at different carrier frequencies.

To assess the detectability of amplitude-modulation following response (AMFR) elicited at different carrier (CFs) and modulation frequencies (MFs) during sleep, as well as the usefulness of AMFR in evoked response audiometry, AMFR was examined in 10 adults with normal hearing while sleeping. The stimulus was a 50 dBnHL sinusoidally amplitude-modulated (SAM) tone with a modulation depth of 95%. The MF of the stimulus tone was varied from 20 to 120 Hz in 20 Hz steps and CFs were 500, 1000, 2000 and 4000 Hz. An SAM tone with a CF of 20,000 Hz was used for stimulation in 5 subjects to confirm that the response did not contain any artifact. Response was determined by phase spectral analysis. The component synchrony measure of AMFRs at MF of 40 Hz (40-Hz AMFR) was high at lower CFs, but 40-Hz AMFRs at higher CFs were unreliable. The detectability of 80-Hz AMFR was high for all CFs. It was confirmed that the response waveform was not contaminated by any electromagnetic artifact. Eighty-Hz AMFR detected by phase spectral analysis should thus be useful for predicting frequency-specific hearing thresholds during sleep.

Acoustic Stimulation↗

PubMed1994

A study on the phase spectral analysis of middle latency response and 40-Hz event-related potential in central nervous system disorders.

The synchrony measure method, or SM method, a phase spectral analysis described by Fridman in 1984 for ABR, was applied to 40-Hz event-related potential (40-Hz ERP), and was found to be a useful method for automatic detection in predicting hearing thresholds across the audiometric frequencies. Although 40-Hz ERP was claimed by Galambos to be the summation of middle latency responses (MLR), its origin is still controversial. Moreover, only a few articles have reported on the clinical use of 40-Hz ERP in patients with neurological disorders. We recorded ABRs, MLRs, and 40-Hz ERPs in 59 patients with central nervous system (CNS) disorders, and analyzed the relationship between central lesions and MLR or 40-Hz ERP using phase spectral analysis. Abnormal findings in 40-Hz ERP were observed in 43 (72.9%) out of 59 cases with CNS disorders, and most of the abnormal cases had disorders involving the midbrain or thalamic lesions, especially on the side contralateral to stimuli. The results suggest that phase spectral analysis of 40-Hz ERP is useful in the detection of CNS disorders.

Acoustic Stimulation↗

PubMed1994

Hearing preservation and improvement of auditory brainstem response findings after acoustic neuroma surgery.

Among 9 patients with acoustic neuroma who underwent tumor removal by the middle cranial fossa approach during the past 5 years, 6 were selected for hearing preservation surgery which was successful in 5 cases (83.3%). For the prediction of success in hearing-preservation, factors related to hearing preservation, including preoperative findings of neurotological examination, were analyzed. Postoperative hearing threshold correlated significantly with wave V latency and I-V interpeak latency of preoperative auditory brainstem response (ABR) and the SP/AP ratio of preoperative electrocochleogram and postoperative facial palsy. The size of tumors and preoperative results of speech audiometry did not correlate with hearing results. Postoperative ABR findings were normalized within the observation period from 5 days to 10 months in 3 hearing-preserved patients. Possible mechanisms for improvement of ABR findings after the removal of acoustic neuroma are discussed.

Adult↗

PubMed1994

Postoperative changes in the contralateral auditory brainstem response after microvascular decompression in cases of trigeminal neuralgia.

Postoperative changes in auditory brainstem response (ABR) in 40 patients with trigeminal neuralgia (TN) who underwent microvascular decompression (MVD) were analyzed. A high proportion (60%) were found to have a decrease in the latency of wave V in the contralateral (unaffected) ABR in the postoperative period. In some cases, a decrease in the latency of wave V was found on the unaffected side postoperatively while an increase was found on the affected side. Furthermore, in one case it was found that an improvement of the shortened latency of wave V on the unaffected side occurred in parallel with a recovery of prolonged latency on the affected side. This indicates that the decrease in the latency of wave V on the unaffected side corresponds to some retrocochlear lesion produced by MVD on the affected side, and shortened latency is considered to be a result of damage to the efferent system of the auditory pathway.

Adult↗

PubMed1994

Three frequency component waveforms of auditory evoked brainstem response in spinocerebellar degeneration.

Under adequate stimulus intensities, the power spectra of normal auditory evoked brainstem responses (ABRs) are composed of three major components: 0-350 Hz, 350-700 Hz and 700-1200 Hz. By means of a digital filter using fast Fourier transform, three ABR waveforms consisting of each frequency component of the power spectrum were obtained. The significance of these three component waveforms in the analysis of ABR abnormality was estimated in 30 patients with spinocerebellar degeneration (SCD). In conventional wave latency analysis, 9 out of 30 patients (30%) had abnormal ABRs, the main abnormality being prolonged interpeak latencies of waves I-III, I-V and the disappearance of wave V. On the other hand, component waveforms were abnormal in 82.5% of the cases. These results suggest that analysis of ABRs by the use of component waveforms is useful for detecting abnormality in the brainstem auditory pathway in SCD patients.

Audiometry, Evoked Response↗

PubMed1994

Phase spectral analysis of auditory brainstem response in cats.

In order to apply the phase spectral analysis of auditory brainstem response (ABR) to the clinical diagnostic test, the phase spectra of ABRs were investigated under adequate stimulus intensity in normal cats and after the destruction of acoustic nerve and brainstem auditory pathways in cats. The results were as follows; i) In normal ABRs, the phase spectra were mainly composed of three frequency components at 0-300 Hz (component A), 300-900 Hz (component B) and 900-1500 Hz (component C). ii) A greater decrease of the component synchrony measure (CSM) occurred if ipsilateral destruction was performed in a peripheral lesion. Lesions of the auditory pathway were followed by a decrease of the CSM of component C in response to contralateral stimulation. These results suggest that the phase spectral analysis of ABRs has significant clinical value in the detection of brainstem lesions.

Acoustic Stimulation↗

PubMed1994

ABR topographic mapping with digital filtering using fast Fourier transform.

The power spectrum of normal ABR consists of three major parts: low (0-350 Hz: component A), middle (350-700 Hz: component B) and high (700-1200 Hz: component C) frequency components. With digital filtering using fast Fourier transform (FFT), three component waveforms of ABR were obtained and designated as component A, B and C. Component A has a positive peak which corresponds to wave V or the slow component of the original ABR. Component B has three positive peaks (B1-B3) which correspond to wave I, III and V, and component C has five positive peaks (C1-C5) which correspond to wave I-V. These three component waveforms of ABR were analyzed topographically in normal hearing adults and cats. In addition, changes in the topography of three component waveforms of ABR were studied in a series of experimentally induced lesions in the brainstem auditory pathway in cats. The following results were obtained: i) The highest voltage (HV) area of component B1 was detected on the ipsilateral side in normal adults and cats. The HV areas of component C1, C2 and C3 in normal adults and C1, C2 in normal cats were detected on the ipsilateral side. ii) There was a correlation between changes in component C and the lesion site of the auditory pathway. Component C appears to be the most sensitive indicator of the lesion site of the brainstem.

Acoustic Stimulation↗

PubMed1994

Measurement of cochlear basilar membrane traveling wave velocity by derived ABR.

Auditory brainstem response (ABR) can be used to measure the basilar membrane traveling wave velocity (TWV). Traveling wave velocity was calculated from the latency difference between wave V of different derived ABR and the cochlear location distance between the appropriate derived band center frequency. The latency of wave V of derived ABR produced by 6 noise-masked ABR using high pass filtered noise and the location of the corresponding cochlear partition (distance from the stapes foot-plate) were measured, and five traveling wave velocities were estimated based on this parameter. Ten subjects with normal hearing, 7 patients with Meniere's disease, and 8 patients with sensorineural hearing loss were used in this study. The traveling wave velocity in the sensorineural hearing loss group was within normal limits at all frequencies, whereas the traveling wave velocity at 8 kHz in the Meniere group greatly exceeded that of the normal and sensorineural hearing loss group.

Acoustic Stimulation↗

PubMed1994

Acoustic neuroma presented as repeated hearing loss.

Up to 15% of patients with acoustic neuroma may have a history of sudden hearing loss. Recovery from sudden hearing loss with acoustic neuroma is rare. In this paper, a case of bilateral acoustic neuromas presented as repeated sudden hearing loss with recovery on the left side after removal of right-sided tumor were reported. She experienced three episodes of sudden hearing loss, showing various types of audiograms and ABR on the left side. There was no relationship between the type of audiograms and ABR findings. Factor influencing ABR might be different from the cause of hearing impairment. Acoustic neuromas can be reliably identified by performing MRI properly. However, MRI showed negative scan and ABR finding was abnormal in the first episode of our case. ABR continues to be a sensitive diagnostic back-up test to MRI for the detection of acoustic neuromas. Even if the patient, who showed abnormal ABR findings suggesting retrocochlear pathology, showed normal MRI, acoustic neurinoma should not be ruled out and both ABR and MRI must be re-examined at regular intervals.

Adult↗

PubMed1994

Effects of aging on hearing results in tympanoplasty.

The effects of aging on the preoperative and postoperative hearing results of tympanoplasty were assessed in 642 patients with chronic suppurative otitis media (COM) or cholesteatoma (CHL). Analysis focused on the correlation between hearing results and age for each disease and type of tympanoplasty. Data were evaluated by calculating the regression line, mainly using second order polynomial regression analysis. Averaged air and bone conduction thresholds (PTA) in patients were appreciably poorer in younger patients and increased with age, compared with physiological hearing impairment in old age (presbyacusis). Regression lines for PTA of air and bone conduction in patients and for normal data (air conduction) separated from each other after the age of 30 and hearing impairment gradually accelerated with age. Means of air-borne gap, however, were almost the same in each age group, though hearing thresholds in individual patients were distributed widely. This was more dominant in patients who had undergone type III or IV tympanoplasty than those with type I tympanoplasty, and in patients with COM than with CHL. Labyrinthine function thus appears to be gradually aggravated with age in patients with chronic inflammatory ear disease. Patients with chronic otitis media should be thus recommended to undergo tympanoplasty at an early age.

Adolescent↗

PubMed1994

Frequency analysis of transiently evoked otoacoustic emissions in sensorineural hearing disturbance.

Transiently evoked otoacoustic emissions (TEOAE) are present in nearly all normal hearing ears and recognized as useful for objective auditory screening. In the spectral analysis of TEOAE with click stimuli, the normal power spectrum of TEOAE has yet to be obtained. In this study, the normal range of the power spectrum was determined for 42 adults with normal hearing and compared with sensorineural hearing disturbance data. The power spectrum of TEOAE in normal hearing adults sloped down at high frequencies and was the same for right and left ears in both males and females. For comparison with sensorineural hearing disturbance, a significant correlation between the audiogram and power spectrum of TEOAE was sought. Frequency specificity was noted in the power spectrum of TEOAE with click stimulation.

Adult↗

PubMed1994

Quantitative assessment of influence of aging on optokinetic nystagmus.

A quantitative assessment of the influence of aging on optokinetic nystagmus (OKN) was investigated using 50 normal adults in ages ranging from 30 to 70 years. In linear stimulus-induced OKN, a statistically significant difference was demonstrated in slow-phase OKN velocity only between the 30-59 year old age group and the 70-79-year-old age group, when OKN stimulus was more than 60 degrees/s. Step stimulus-induced OKN was investigated in the same age groups in order to compare aging effects upon slow-phase OKN velocity. No statistically significant difference was found in slow-phase OKN velocity between younger age groups and the oldest age group. There was no significant difference in fast-phase velocity among the age groups. Thus, step-induced OKN has a wider clinical application than linear stimulus-induced OKN.

Adaptation, Physiological↗

PubMed1994

Computer analysis for routine electronystagmography tests.

A computer program has been developed for on-line analysis of routine electronystagmography (ENG) tests. With this system, data acquisition of eye movements and stimulus signals obtained from ENG are accomplished at a rate of 200 Hz through a 12-bit analog-digital converter. A small spotlight for eye tracking tests is sinusoidally driven by a computer-generated analog signal. Six optokinetic stripes projected onto a screen are also controlled by the computer. Seven spots for saccade tests can be turned on or off based on digital signals produced through a digital output device. There are three types of eye movements in this series: nystagmus, pursuit eye movement and saccadic eye movement. An algorithm for the analysis of different eye movements is described in this paper. Recent significant advances in computer technology make it possible to perform such complicated tasks and to accomplish quantitative assessment of any type of eye movements in routine ENG tests. Consequently, computer analysis provides clues to the location of a disease and is very useful as a diagnostic tool in routine ENG testing.

Artifacts↗

PubMed1994

Rebound positional nystagmus as a peripheral origin.

Three cases of rebound positional nystagmus (RPN) are discussed in the present study. In all cases, spontaneous nystagmus was absent in the primary position, but positional nystagmus appeared in the side down position, and then nystagmus in the reversed direction appeared when the patient was returned to the primary position. The characteristics of RPN in the cases we studied were very similar to those of benign positional nystagmus. Tinnitus was accompanied with vertigo in Cases 2 and 3, and the glycerol tests were positive in Cases 1 and 3. There were no other abnormalities of ocular movements, neurological and neuroradiological examinations suggestive of central nervous system disorders indicating that RPN can be ascribed to peripheral lesions. A selective review of the literature is presented.

Electrooculography↗

PubMed1994

Role of the prepositus hypoglossi nucleus on primary position upbeat nystagmus.

Electrolytical destruction of the floor of the fourth ventricle was performed on 10 cats in order to produce primary position upbeat nystagmus (PPUN). In 5 cats who had unilateral lesions of the floor of the fourth ventricle, PPUN was never seen. Two of the remaining 5 cats, who had bilateral lesions, showed PPUN. In 2 cats with PPUN, the oculomotor level of the caudal fourth ventricle, in order that PPUN may be developed, it is necessary that the prepositus hypoglossi nucleus (PH) be destroyed bilaterally. The present experiment suggests that bilateral PH lesions could result in a tonic imbalance for eye positions and eye movements of the vertical axis, resulting in a downward drift with a corrective saccade; PPUN.

Animals↗

PubMed1994

The effect of uvulonodular lesions on horizontal optokinetic nystagmus and optokinetic after-nystagmus in cats.

The effect of uvulonodular lesions on horizontal optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN) was investigated in alert cats. A lesion in each of 6 cats was made by suction-ablation under anesthesia. In the 3 cats with only a uvular lesion, both the initial slow phase velocity and the time constant of OKAN were unchanged. In the remaining 3 cats whose lesions included the nodulus as well as the uvula, the time constant of OKAN was markedly prolonged, but the initial slow phase velocity of OKAN was not affected. The postoperative average time constant of OKAN increased from the normal value of 9 s to about 40 s. In contrast, OKN parameters (the steady-state velocity and the rising time constant) were not affected by uvular or uvulonodular lesions. These results strongly suggest that the nodulus is involved in the velocity storage mechanism and might control the discharge characteristics of the velocity storage integrator.

Animals↗

PubMed1994

Effect of aging on smooth pursuit eye movement.

Examination of smooth pursuit eye movement is useful for detecting central nervous system disorders. It is important to take patient's age into consideration when evaluating smooth pursuit eye movement. The purpose of the present study was to clarify the effect of aging on smooth pursuit eye movement. Thirty healthy volunteers (three groups of 10 volunteers, in their fifties, sixties, and seventies and over, respectively) served as subjects, and 10 healthy young volunteers (23 to 33 years old: mean age 26) served as controls. The pursuit target was driven by sinusoidal waveform with various amplitudes and frequencies. Target peak velocities ranged from 12.6 to 94.2 degrees/s. Eye movement signals were recorded d.c. EOG and pursuit gain (ratio of eye peak velocity to target peak velocity) was measured by a computer. Pursuit gain decreased with increasing target frequency and velocity in all age groups. This tendency was more remarkable in the older groups than in the young controls; in particular, it was more frequently seen at a frequency of 0.5 Hz. On the other hand, there was no significant relationship between pursuit gain and the target amplitude. In the group in their seventies and over, pursuit gain was saturated at about 60 degrees/s.

Adult↗