Michio Kawano

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.

Regulatory factors of lymphocyte-lymphocyte interaction. I. Con A-induced mitogenic factor acts on the late G1 stage of T-cell proliferation.

DNA synthesis in murine lymphocytes was augmented by a soluble factor in the supernatant of serum‐free cultures of syngeneic spleen cells activated with concanavalin A (Con A). This so‐called mitogenic factor (MF), which is probably identical with interleukin II, partially purified by DEAE‐cellulose and Sephadex G‐75 chromatography, is a fairly homogeneous molecule of 17–25 × 103 daltons. By using partially purified MF, the role of MF in lymphocyte proliferation was investigated.

Cochlear implant in patients with residual hearing

OBJECTIVE The postoperative speech perception abilities of severely hearing-impaired patients with multi-channel cochlear implant were compared with preoperative speech perception performance with conventional hearing aids. METHODS Cochlear implantation was performed in six severely to profoundly hearing-impaired patients. They had unaided pure-tone thresholds of 70-100-dB HL and aided thresholds of 35-90-dB HL in the better ear, but were not able to perceive speech sounds well with hearing aids. RESULTS Postoperatively, all the patients had significantly improved speech perception performance, exceeded the average skills of profoundly deaf cochlear implant users, and were able to communicate without writing. CONCLUSION These results imply that cochlear implant may be indicated for severely to profoundly deaf subjects, if they receive little or no benefit from conventional hearing aids.

Laryngeal fricative in cleft palate speech.

Some of the substitutions for or [integral of] in cleft palate speech, which was earlier regarded as a pharyngeal fricative, on the basis of listeners judgement, was found to be a laryngeal fricative by means of fluorovideoscopy and nasopharyngofiberscopy. The sound was most likely produced at the stricture between the posteriorly inclined epiglottis and the elevated arytenoids. During the production of laryngeal fricatives, the velopharyngeal port remained open just as for nasal sounds.

Recent progress in treating patients with cleft palate.

Over the last 4 decades remarkable progress has been made in the treatment of cleft palate: the rate of attaining normal or nearly normal speech after surgery has risen from about 65% 40 years ago to nearly 90% or more nowadays. One of the main factors is intratracheal intubation anesthesia that has made the surgery much safer and easier. Improved surgical technique and speech therapy also played a great role. This paper deals with two problems: (1) Slight velopharyngeal incompetence: The combined use of fiberscopy and fluorovideoscopy can provide useful information as to: (a) the exact place of the faulty articulation, (b) the detailed pattern of inconsistent velopharyngeal function, (c) changes in articulation induced by speech therapy, and (d) the relation between velopharyngeal function and faulty articulation. All the above information greatly facilitates speech therapy for cleft palate speech. It should be done with utmost care though due to possible adverse effects of radiation. (2) Analysis of faulty articulation. It was revealed that faulty articulations such as laryngeal fricative and affricates, pharyngeal stop, and glottal stop in cleft palate speech, secondary to velopharyngeal incompetence, were produced by articulation in the larynx at various sites such as the epiglottis, arytenoids, aryepiglottic folds and vocal folds. These faulty articulation points were located lower than supposed on the basis of auditory perception.

Evaluation of velopharyngeal closure by CT scan and endoscopy.

Computerized tomography (CT) and endoscopy were used for the objective evaluation of velopharyngeal closure. In 19 patients with cleft palates and 9 normal subjects, CT scans of the velopharynx were made both at rest and during vowel phonation with a scanning time of 3.0 seconds and slicing width of 3 mm. At the same time, endoscopic observations of the velopharynx through the nose were carried out both at rest and during phonation. CT scan during phonation clearly demonstrated the mobility of the velopharynx, i.e., elevation of the soft palate, inward movement of the lateral pharyngeal walls, and protrusion of the posterior pharyngeal wall, in a single picture. Its disadvantage is exposure to x-rays and a rather complicated procedure. However, endoscopy is simple with no exposure to x-rays, but its disadvantage is occasional incomplete visualization because of the dead angle created by the elevated soft palate. Thus the combined use of CT and endoscopy can help to determine a rational choice of treatment for cleft palates.

Eustachian tube function in OME patients with cleft palate. Special reference to the prognosis of otitis media with effusion.

Eustachian tube function was investigated in two groups of cleft palate patients who had otitis media with effusion. One group consisted of 16 ears that healed after one ventilatory tube insertion, the other consisted of 33 ears that needed repeated tube insertion and did not heal in 2 years. The latter group was characterized by low opening pressure and inability to sustain lower middle ear positive pressure. This decrease force in the Eustachian tube was considered to be related to the prognosis of otitis media with effusion in patients with cleft palate.

What Muscle is Responsible for Lateral Pharyngeal Wall Movement

In an attempt to discover what muscle is responsible for medial movement of the lateral pharyngeal wall, the levator muscle was anesthetized with lidocaine under visual control by fiberscope in 3 normal subjects. The results indicate that the medial movement of the lateral pharyngeal wall results from the contraction of the levator. The attendant roll-up of the uvula toward the nasal side induced by the anesthesia was regarded as the action of the uvular muscle without the counterbalance of levator action.

Studies of Currently Used and Experimental Cochlear Implants

Since 1987 we have inserted multichannel cochlear implants in 60 patients with severe hearing impairment. The surgical procedures were not very difficult, and few postoperative complications were encountered. Postoperative speech recognition by every patients was satisfactory. Nevertheless, some patients complained about their hearing in a noisy environment, or while listening to either TV or music. Consequently, cochlear implants needs further improvement. To improve speech recognition ability, a newly developed experimental system was constructed. Judging from the electrode activation pattern, the new system extracted the features of consonants more successfully than the present system. However, when this new system was installed in cochlear implant patients, no significant improvement in consonant recognition was obtained.

Cochlear Implants in 34 Patients; A Clinical Evaluation.

Since 1987 we have performed multichannel cochlear implants in 34 patients with severe hearing impairment. Although we have had little experience with the surgical procedure and postoperative complications, postoperative speech recognition was satisfactory. However, some patients complain about their hearing in a noisy environment or while listening to TV and music. The present cochlear implant system needs further improvement.