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Biomedical subjects

J Matsushima

Publications and source records attributed to J Matsushima.

36 records · Page 2Linked to original sources
PubMed1994

[Electroconduction system for implantable tinnitus suppressor].

The purpose of this study was to introduce the electroconduction system for an implantable tinnitus suppressor. This system is a modification of the extracochlear implant system, which was developed at Hokkaido University. This system consists of a stimulator and two coils. One of the coils is implanted inside the temporal bone and its size, including the current limiter, is 9 mm long, 6.4 mm wide and 6 mm thick. Another is contained in the plastic case which is used for hearing aids. The efficacy of conduction depends on the wave frequency. The most effective frequency was about 30 kHz. The maximum current required to relieve tinnitus is 100 microA when using this system. The heat emitted from the coil inside the case is so minimal at an intensity of 100 microA as to be negligible systemically. The electromagnetic coupling system works well for more than 4 months in saline.

Cochlear Implants↗
PubMed1994

[A tinnitus case with an implanted electrical tinnitus suppressor].

An electrical tinnitus suppressor, which was developed at Hokkaido University, was implanted in a female tinnitus patient. She had suffered from bilateral chronic otitis media and her bilateral hearing was seriously impaired. The electrical tinnitus suppressor consists of a stimulator, a coil inside the plastic hearing aid case and an implanted coil in the mastoid. The auditory nerve is stimulated at home twice. Using the system, her hearing ability and emotion improved in addition to tinnitus suppression. Her hearing level and tinnitus also improved in the ear contralateral to the stimulated side.

Cochlear Implants↗
PubMed1993

Thyroplasty type I with ceramic shim.

To improve hoarseness or misswallowing caused by unilateral recurrent laryngeal nerve paralysis, medialization of paralyzed vocal cord has frequently been performed. This method includes such techniques as injection method, insertion method, and arytenoid adduction, each presenting its merits and demerits. The insertion method which can be done while monitoring the patient's voice seems advantageous in that the technique is easy to perform and generally guarantees the voice improvement. Among insertion methods, Isshiki thyroplasty type I is the one most representative as well as popularized. However, since a silicone shim is inserted in this operation, it may be accompanied by the risks of carcinogenicity, foreign body reaction, and induction of collagen disease of silicone. Therefore we planned to use a ceramic as a safe substitute instead of silicone. There has been no article reporting the use of ceramic in this type of surgery. We used a fibrin glue to fix the ceramic shim and for hemostasis, which was found very useful. Hitherto, 2 cases of unilateral recurrent laryngeal nerve paralysis underwent Isshiki thyroplasty type I using ceramic shim with satisfactory results.

Aged↗
PubMed1992

Recording eye movement during stepping in place with a CCD (charge-coupled device) imagesensor.

A new system for recording eye movements using a charge-coupled device (CCD) imagesensor in a video camera, in which less than 0.5 degree of horizontal and vertical eye movements can be recorded, was applied in 7 subjects. Eye movements were recorded while they stepped in place. We observed 5 normal subjects, a patient with horizontal and vertical oscillopsia during walking, and one with a chronic limp. In the normal adults, the amplitude of vertical eye movement was less than 0.5 degree, and the horizontal eye movement was less than 2 degrees. The mean amplitude of horizontal and vertical eye movements in the subject who limped was larger than that of normal subjects. The patient who complained of vertical oscillopsia during walking showed the largest amplitude of vertical eye movement among any subject tested. The vertical oscillopsia in the patient was due to the largest amplitude of vertical eye movement. This system for recording eye movements will be useful in analyzing the mechanism of gaze fixation during walking.

Adult↗
PubMed1992

[A comparison of time resolution among auditory, tactile and promontory electrical stimulation--superiority of cochlear implants as human communication aids].

Our previous reports showed that second formant information, using a speech coding method, could be transmitted through an electrode on the promontory. However, second formant information can also be transmitted by tactile stimulation. Therefore, to find out whether electrical stimulation of the auditory nerve would be superior to tactile stimulation for our speech coding method, the time resolutions of the two modes of stimulation were compared. The results showed that the time resolution of electrical promontory stimulation was three times better than the time resolution of tactile stimulation of the finger. This indicates that electrical stimulation of the auditory nerve is much better for our speech coding method than tactile stimulation of the finger.

Cochlea↗
PubMed1992

[Intracochlear electrical stimulation of the auditory nerve in deaf kittens--brainstem response audiometric and histopathologic studies].

The effects of long-term electrical stimulation of the auditory nerve on the morphology of the cochlear nucleus were investigated in young pharmacologically deafened kittens. Comparing the amplitude of EABR with the soma area, there was a strong positive correlation between the amplitude of EABR and the soma area of neurons within the anterior ventral cochlear nucleus on the stimulated side. However, there was no correlation between the amplitude of EABR and the soma area of neurons within the unstimulated anterior ventral cochlear nucleus. In addition, there was no correlation between the amplitude of EABR and the survival rate of spiral ganglion cells. This showed that EABR may be affected not only by the survival rate of the spiral ganglion cell, but also by the development of the central auditory nervous system in kittens, which were deafened under the development of the central auditory nervous system.

Animals↗
PubMed1991

Glycolipids in rat cochlea.

In recent years, the functions of glycolipids have been intensively studied. Before the research of the roles of glycolipids in the inner ear, it seemed to be necessary to demonstrate the composition of glycolipids at first. Therefore, rat cochlea has been examined for glycolipid composition in the present study. Glycolipids extracted from 200 cochlea samples were separated into neutral and acidic glycolipid fractions. Each fraction was analyzed by thin-layer chromatography. The neutral glycolipid was almost exclusively galactosylceramide (cerebroside) with trace amounts of globoside and unidentified glycolipids. In acidic glycolipids, sulfated galactosylceramide (cerebroside sulfate) was most abundant. Of the gangliosides (sialic acid-containing glycolipids), ganglioside GM3 (51.8%) was the predominant component, and GM2 (6.0%), GM1 (8.8%), GD3 (10.7%), GD1a (8.7%), GD1b (5.9%), and GT1b (3.6%) were also detected. In addition to these, rat cochlea also contained several, minor, unidentified gangliosides. This pattern of the cochlear acidic glycolipids is very similar to that of the renal acidic glycolipids. This finding seems to be very interesting when considering that the toxic side effects of aminoglycosides occur only in the kidney and the inner ear.

Animals↗
PubMed1991

Cochlear pathology following chronic electrical stimulation using non charge balanced stimuli.

During the course of a chronic intracochlear electrical stimulation study using charge balanced biphasic current pulses, one animal inadvertently received a short period of direct current (DC) stimulation at a level of approximately 1 microA. Subsequent, the animal was chronically stimulated using a poorly charge balanced waveform that produced a DC level of approximately 2 microA. Extensive pathological changes were observed within the cochlea. These changes included widespread spiral ganglion cell loss and new bone growth that extended throughout all turns of the cochlea. Significant changes in the morphology of the electrically evoked auditory brainstem response (EABR) were associated with these pathological changes. EABRs recorded prior to the DC stimulation exhibited a normal waveform morphology. However, responses recorded during the course of the DC stimulation were dominated by a short latency response believed to be vestibular in origin. The response thresholds were also significantly higher than levels recorded before the DC stimulation. In contrast, the contralateral cochlea, stimulated using charge balanced stimuli, showed no evidence of adverse pathological changes. Furthermore, EABRs evoked from this cochlea remained stable throughout the chronic stimulation period. Although preliminary, the present results illustrate the adverse nature of poorly charge balanced electrical stimuli. These results have important implications for both the design of neural prostheses and the use of DC stimuli to suppress tinnitus in patients.

Animals↗
PubMed1991

[Effects of intravenous injection of salicylate on the spontaneous discharge rate of the cochlear nerve].

This study was aimed to elucidate the effects of salicylate on the cochlear nerve by recording the spontaneous activity in guinea pigs. After guinea pigs were given salicylate (200 mg/kg) intravenously, the transient reduction in cochlear spontaneous activity and the elevation over the subsequent 10-20 minutes were observed in three of four fibers recorded for more than 30 minutes. The mean spontaneous discharge rate of 102 fibers after administration of salicylate (200 mg/kg) was not significantly higher than the control values from 30 to 120 minutes after salicylate administration, while that rate of 112 fibers after administration of salicylate (400 mg/kg) was significantly higher. The observed changes in spontaneous activity due to salicylate administration may represent the evidence of a tinnituslike phenomenon in guinea pigs.

Animals↗
PubMed1988

Rapidly progressive sensorineural hearing loss (rapid deafness).

28 ears of 28 patients, aged 15 to 60 years, whose sensorineural hearing loss had developed over a period of a few hours to 3 days, were defined as having rapidly progressing sensorineural hearing loss (rapid deafness), in comparison with so-called sudden deafness with instantaneous onset. For other criteria, their hearing loss was idiopathic and the rate of hearing loss was confirmed by reliable means. The rate was greatest within the first 1-3 days. Of the 28 patients, 12 (43%) recovered completely, while another 12 improved markedly. The prognosis in rapid deafness was relatively good, but the recovery time was longer than in spontaneously healing sudden deafness. Sensorineural hearing loss in contralateral ears more often preceded rapid deafness (9 cases, 32%). No clear-cut difference could be found between rapid deafness and sudden deafness.

Adolescent↗
PubMed1982

[Origin of N1 wave of the cochlear nerve action potential recorded at the bony wall of the cochlea].

As an objective audiometry, the cochlear nerve action potential (AP) evoked by tone stimulation has been clinically utilized. But the origin of AP wave is still obscure. In order to know the origin of the N1 wave of AP, the author intended to compare the AP waves (AP(W)) recorded at the bony wall of the cochlea with action potentials of the individual spiral ganglion cell (spikes) and group of the spiral ganglion cells (AP(R)) in the Rosenthal canal of the guinea pig. Spikes and AP(R) were recorded by glass pipettes filled with 2M NaCl. The results showed that waves of AP(R) demonstrated a wide monophasic negative wave in contrast to diphasic AP(W) wave. The Input-Output Curves (I.O.C.) of the AP(W) and AP(R) were compared in order to ascertain whether both APs were derived from the cochlear nerve or not. The I.O.C. of latency, onset, amplitude, offset and width of both AP(R) and AP(W) N1 waves showed a same pattern with high correlation coefficient. So it was confirmed that both AP(R) and AP(W) N1 waves were the direct and indirect cochlear nerve action potential respectively. The thresholds of both AP(W) and AP(R) at the characteristic frequency of a single ganglion cell showed a high correlation. The time of onset and latency of AP(R) were longer than those of AP(W). Based on anatomy and electrophysiology, it is concluded that AP(W) N1 wave originates from the action potential generated at the habenula perforata, where spikes are first produced. The curves of the AP(R) were flat in respect of frequency-threshold relationship. The threshold was the lowest in the spiral ganglion cell followed by AP(R) and AP(W).

Acoustic Stimulation↗
PubMed1980

Vestibular responses and branching of interstitiospinal neurons.

1. Interstitiospinal neurons were activated by antidromic stimulation of the ventromedial funiculus of the spinal cord at C1 and C4 in cerebellectomized cats under chloralose anesthesia. 46% of these neurons responded only at C1 (N cells) and the remaining 54% responded at C4 also (D cells). There is no topographical difference in the location of N and D cells. Conduction velocities of N cells were significantly slower than those of D cells. 2. Stimulation of the contralateral whole vestibular nerve evoked firing of 31% of both N and D cells; some responded early enough to suggest disynaptic connections, many responded late. Stimulation of the ipsilateral whole vestibular nerve evoked firing of several cells, one spontaneously discharging D cell was inhibited. 3. Stimulation of the contralateral individual semicircular canal nerves evoked firing of 33% of N cells and 13% of D cells. Most of these responses were late. N cells responded not only to the vertical canals but also to the horizontal canal, whereas D cells responded to the horizontal canal, but seldom to the vertical ones. Most canal responding neurons received specific input, only two N cells received convergent input from both the anterior and horizontal canals. Stimulation of the ipsilateral canals did not evoke excitation of any cells tested; one D cell was inhibited by stimulation of the horizontal canal nerve. 4. Stimulation of the rostral medial vestibular nucleus evoked characteristic negative field potentials centered in the contralateral interstitial nucleus of Cajal (INC). Approximately 60% of both N and D cells received excitation from the contralateral vestibular nuclei. About 17% of these responding neurons received monosynaptic excitation, most frequently from the rostral medial nucleus. Stimulation of the ipsilateral vestibular nuclei evoked firing of 12% of both N and D cells. 5. Twenty-nine neurons were fired antidromically by weak stimuli applied to the ipsilateral vestibular nuclei. Twenty-seven of the 29 were activated only from C1 and were found in the INC (10 cells) and in the reticular formation dorsal to the INC (19 cells). Measurement of the spread of the effect of stimulus current and comparison of latencies to stimulation of the vestibular nuclei and C1 indicated that these neurons have axon collaterals going to the ipsilateral vestibular nuclei. Only one of them received excitation from the contralateral posterior canal, others did not respond to the labyrinth. Some were activated by stimulation of the vestibular nuclei.

Animals↗
PubMed1979

Trunk-ocular reflex in the rabbit.

The trunk-ocular reflex of the rabbit was investigated by recording EMGs of right lateral rectus and splenius muscles. The skull and the chest of the rabbit were restrained and the lower part of the trunk was flexed laterally around the axis at the TH10--11 intervertebral joint. Two kinds of eye movements, small with short latencies and large with longer latencies, were induced counter to the direction of the lateral flexion. The latency of the former was 158 msec (range: 64--200 msec) and that of the latter was 255 msec (range: 180--380 msec).

Abdomen↗