Haruo Takahashi

Sensorineural hearing loss in patients with large vestibular aqueduct

In examining 181 patients (327 ears) with sensorineural hearing loss of unknown etiology and 25 people (50 ears) with normal hearing by high‐resolution computed tomography (CT), the image of the large vestibular aqueduct (VA) was defined as being a visible large aperture (≥4 mm), and small distance between vestibule and traceable part of the VA nearest to the vestibule (≥1 mm). The large VA was found in 13 patients (23 ears, 7.0%); it was relatively frequent following hypoplastic cochlea (33 ears, 10.1%) in all the inner ear anomalies detected. In patients with large VA, high‐frequency hearing was affected more than low frequency, and history of sudden hearing loss was observed frequently (61% of ears with large VA), which was found to be triggered by characteristic episodes such as minor head trauma, etc. Those clinical features were observed more in those without cochlear anomaly than in those accompanying cochlear anomaly. Pathogenesis of sensorineural hearing loss and characteristic fluctuation of hearing in those patients are discussed.

Sound-induced activation of auditory cortices in cochlear implant users with post- and prelingual deafness demonstrated by Positron Emission Tomography

Changes of regional cerebral blood flow (rCBF) in the auditory cortices induced by sound stimulation were examined in nine postlingually and five prelingually deaf cochlear implant (CI) users by 15O-labeled water Positron Emission Tomography, and the results were compared with those of eight normal volunteers. Speech stimulation caused significantly greater rCBF increase compared with noise stimulation in the auditory association area in normal and postlingually deaf subjects. In prelingually deaf subjects, however, speech activation of the auditory association area was much less than that found in either of the other two groups. Neuronal networks for speech sound processing in the auditory association area in postlingually deaf individuals are thought be similar to those in normal subjects, while those in prelingually deaf patients who received CI after the speech acquisition period may not develop completely.

Cortical activation with sound stimulation in cochlear implant users demonstrated by positron emission tomography

Six postlingually deaf patients using multi-channel cochlear implants were examined by positron emission tomography (PET) using 15O-labeled water. Changes in regional cerebral blood flow (rCBF) were measured during different sound stimuli. The stimulation paradigms employed consisted of two sets of three different conditions; (1) no sound stimulation with the speech processor of the cochlear implant system switched off, (2) hearing white noise and (3) hearing sequential Japanese sentences. In the primary auditory area, the mean rCBF increase during noise stimulation was significantly greater on the side contralateral to the implant than on the ipsilateral side. Speech stimulation caused significantly greater rCBF increase compared with noise stimulation in the left immediate auditory association area (P < 0.01), the bilateral auditory association areas (P < 0.01), the posterior part of the bilateral inferior frontal gyri; the Brocas area (P < 0.01) and its right hemisphere homologue (P < 0.05). Activation of cortices related to verbal and non-verbal sound recognition was clearly demonstrated in the current subjects probably because complete silence was attained in the control condition.

Gas Exchange Function Through the Mastoid Mucosa in Ears After Surgery

Gas exchange function through the mastoid mucosa was investigated in ears after surgery using nitrous oxide. Increase in the mastoid pressure was assessed by a micropressure sensor placed in the mastoid cavity during the second‐stage revision operation performed under general anesthesia using 67% nitrous oxide, 33% oxygen, and sevoflurane on 14 ears with chronic adhesive otitis media or cholesteatoma as well as on seven ears without inflammation as controls. All seven control ears showed pressure increase in the mastoid in various degrees. In the 14 postoperative ears, nine of the 10 ears on which the mastoid mucosa had previously been able to be preserved in various degrees showed pressure increase in the mastoid, but none of the remaining four ears, which had previously had mastoidectomy, showed any pressure increase. The presence or absence of the mastoid pressure increase of those ears was also found to be correlated well with the presence or absence of mastoid aeration on computed tomography examined just before the second‐stage operation. These results appear to indicate that, in ears after surgery, recovery of both the gas exchange function and aeration in the mastoid is expected only when the mastoid mucosa can be preserved even partially.

Effect of adenoidectomy on otitis media with effusion, tubal function, and sinusitis

Three clinical studies were performed to investigate the effects of adenoidectomy on otitis media with effusion (OME), especially with regard to eustachian tube (ET) disfunction and sinusitis, which often accompanies OME. In the first study, the audiograms, tympanograms, and ET ventilatory functions of 78 adenoidectomized patients (121 ears) and 54 non-adenoidectomized patients (63 ears) were compared over 6 months. The audiograms and tympanograms of the adenoidectomized group showed significant improvement; however, no difference in passive tubal opening pressure was noted despite an improvement in positive pressure equalizing function observed in the adenoidectomized group at 6 months after the operation. In the second study, tubal passive resistance (PR) and the ratio of passive resistance to active resistance (PR/AR) were compared before and 1 month after adenoidectomy using the forced response test (12 subjects, 12 ears). Neither PR nor PR/AR had significantly improved after the operation. In the third study, sinusitis improvement in 45 adenoidectomized patients 6 months after the operation was evaluated in comparison with 33 non-adenoidectomized patients. This condition was found to have improved significantly in the adenoidectomized group. Overall, adenoidectomy appeared effective in reducing the incidence of OME and sinusitis, and in improving the active ventilatory function of the ET without causing changes in the tubal passage. It is conceivable that tubal active ventilatory function was improved due to a reduction of inflammation and pollution around the nasopharynx by adenoidectomy, and that the effect of adenoid mass on the ET is minimal.

Eustachian tube compliance in cleft palate a preliminary study

With the use of the tubal compliance test and the forced response test (FRT), the compliance and ventilatory functions of the eustachian tube (ET) were examined in 19 children with otitis media with effusion (OME) and cleft palate, in 31 children with OME but without cleft palate, and in 19 individuals with traumatic perforation of the eardrum without history of other otological disease (controls). The tubal compliance results in the group with both cleft palate and OME were significantly higher than the results obtained with the controls, but did not differ significantly from the results obtained with the patients with OME but without cleft palate; this indicated that the ETs of those patients with OME and cleft palate, and the ETs of those patients with OME but without cleft palate, appeared to be more collapsible than the ETs of normal subjects. It was speculated that such an aerodynamic property of the ET observed in the group with OME and cleft palate and in the group with OME but without cleft palate may be due mainly to possible inflammatory condition of the tubal mucosa rather than to abnormal anatomy or to an abnormal physical property of the framework (such as cartilage) of the ET.

Efficacy of transmeatal low power laser irradiation on tinnitus: a preliminary report

Thirty-eight patients suffering from tinnitus resistant to several medical therapies for more than 6 months were treated by low power laser irradiation. A 40 mW laser with a wavelength of 830 nm was irradiated via their external auditory meatus toward the cochlea for 9 min once a week, 10 times or more. Patients were asked to score their symptoms on a 5 point scale before and after the treatment for a subjective evaluation of the effect. The results were estimated by the change of the loudness and duration of tinnitus, and the degree of annoyance due to tinnitus. Although only 26% of the patients had improved duration, loudness and degree of annoyance were relieved in up to 58 and 55%, respectively, without major complication. Laser therapy seemed to be worth trying on patients with intractable tinnitus.

Endoscopic findings at the pharyngeal orifice of the eustachian tube in otitis media with effusion

Transnasal endoscopy of the pharyngeal orifice of the eustachian tube was performed on 155 ears with otitis media with effusion (77 ears of children, 78 ears of adults). In children, blockage of the orifice by mucopurulent nasal discharge was the most frequent finding (72.7%), followed by compression of the orifice by the adenoid tissue (52.0%), hypertrophy of the peritubal tonsil (16.9%), and edema around the orifice, especially at its posterior lip (10.4%). In adults, the most frequent abnormal finding was edema of the orifice (26.9%), followed by blockage of the orifice by mucopurulent nasal discharge (23.1 %), and atrophy of the orifice (10.3%). In 39.7% of cases findings were normal. Thus, main pathological findings associated with tubal dysfunction involved inflammation in the nasopharynx.

Influence of the Gas Exchange Function Through the Middle Ear Mucosa on the Development of Sniff‐Induced Middle Ear Diseases

To investigate the influence of gas exchange function through the middle ear mucosa on the development of sniff‐induced middle ear diseases, the authors examined the mastoid pneumatization among patients with sniffing habit using computed tomography, and also examined the change of negative middle ear pressure induced by sniffing using tympanogram. In 20 ears with cholesteatoma or adhesive otitis media, the areas of mastoid cavity measured at the level of the lateral semicircular canal were significantly smaller than those in 26 ears with otitis media with effusion (OME) or attic retraction and in eight normal ears with sniffing habit (P < .01 and P < .0001, respectively). In 26 ears with OME or attic retraction, the areas of mastoid cavity were significantly smaller than those in eight normal ears with sniffing habit (P < .0001). By contrast, in the four ears with sniff‐induced middle ear disease, the recovery of negative middle ear pressure in 5 minutes without swallowing was less than 10 mm H2O, whereas in all seven ears with normal eardrum, negative middle ear pressure recovered by more than 20 mm H2O in 5 minutes. These findings suggested that impairment of gas exchange function through the middle ear mucosa, as well as eustachian tube dysfunction, might be closely related to the development of sniff‐induced middle ear diseases.

Experimental vestibular pharmacology: a minireview with special reference to neuroactive substances and antivertigo drugs.

Neurotransmitters and neuromodulators involved in the function of vestibular nuclei were reviewed with special reference to drugs used for treatment of motion sickness and vertigo. Biochemical, histochemical and electrophysiological studies have demonstrated that acetylcholine is a transmitter candidate from the afferent vestibular nerve to the lateral vestibular nucleus (LVN), because acetylcholine satisfies most criteria for a chemical transmitter in the central nervous system. It is unlikely, however, that monoamines such as noradrenaline, dopamine and serotonin are transmitters in the vestibular neurons, since cell bodies and nerve terminals containing the monoamines have not been detected yet in the vestibular nuclei. Although histamine and H1-receptor blockers inhibit neuron activities in the vestibular nuclei, it is unclear at present whether histaminergic system is directly related to the function of vestibular neurons. It has been established that GABA is an inhibitory transmitter from the cerebellar Purkinje cells to the LVN neurons. Diazepam is considered to enhance the GABA effect on the LVN, thereby modifying the vestibular neuronal firing. Enkephalin-containing cell bodies and nerve terminals are found in the medial vestibular nucleus, and a few substance P-containing neurons have been observed in the vestibular nuclei. However, the functional role of these peptides on the vestibular system remains to be determined. Unlike histamine H1-receptor blockers, vasodilators such as cinnarizine, ifenprodil and adenosine triphosphate, which are effective in treatment of vertigo, produce an enhancement of responsiveness of neuron activities in the vestibular nuclei, probably as a result of an increase in blood flow in the brain.(ABSTRACT TRUNCATED AT 250 WORDS)