Biomedical subjects
Publications and source records attributed to K Michi.
The Kabuki make-up syndrome is characterized by peculiar cranio-facial abnormalities, including cleft lip and palate. A case with velopharyngeal incompetence in a 7-year-old boy is reported. The significance of a possible association of this syndrome with congenital velopharyngeal incompetence is also discussed.
Post-surgical maxillary defects have recently been reconstructed by microvascularized free flaps. However, few reports have evaluated the resulting speech function. This study compared the speech intelligibility of four maxillectomy patients who underwent reconstruction by rectus abdominis myocutaneous flaps (RAMCF) with that of four non-reconstructed patients who were treated with split-skin grafts and prostheses, to explore ways of achieving better speech function. Speech function was assessed by a Japanese language speech intelligibility test. Intelligibility scores ranged from 57.3% to 75.8% (mean, 70.4%) in the non-reconstructed group and from 66.2% to 77.2% (mean, 71.0%) in the reconstructed group. An analysis of articulatory manners and sites revealed that speech disorders resulted mainly from poor oronasal separation in the non-reconstructed group and from incorrect linguopalatal contact in the reconstructed group, especially for linguodentoalveolar and linguovelar sounds. Therefore, for higher speech function in the reconstructed group, dentoalveolar and palatal contours of the maxilla must be restored as closely as possible. This must also be done in patients whose maxillae are reconstructed by other types of microvascularized myocutaneous or cutaneous flaps that have similar postoperative palatal contours.
This study investigated the effect of age and radiation on healing after implantation of hydroxyapatite granule in bone. Two groups of 16 male Wistar rats, aged 4 weeks and 2 years were used for this study. Hydroxyapatite particles were placed into the tibia 28 days after the delivery of 15 Gy of irradiation from a Linac source. The results of the present study suggest that an old rat was more vulnerable to the radiation than a young rat. It seemed that age might also be an important factor in the prognosis of the implanted hydroxyapatite in irradiated bone.
This paper reports on some preliminary aspects of a collaborative cross-linguistic study of normal and disordered Japanese and British English speech. The investigation compares lateralised productions of parallel s which are abnormal in the two languages. EPG and acoustic recordings were made of four Japanese and four British subjects. The EPG patterns were classified according to certain criteria, such as the presence or absence of complete constriction between the tongue and the hard palate, and the area and location of this contact. Findings revealed that lateralised articulations varied between individual speakers, but that Japanese and English productions were broadly similar. Acoustically, misarticulations in both languages were characterised by a lower frequency of peak energy than would be expected in normal productions.
The use of cervical auscultation in the evaluation of the pharyngeal swallow may become a part of the clinical evaluation of dysphagic patients. Though its use is based on subjective evaluation, an acoustic analysis of swallowing sounds might establish more objective criteria in the detection of swallowing disorders. The present study sought to investigate three aspects of the methodology for detecting swallowing sounds: (1) the type of acoustic detector unit suited to an acoustic analysis of the pharyngeal swallow, (2) the type of adhesive suited for the attachment of the detector, and (3) the optimal site for sound detection of the pharyngeal swallow. An accelerometer with double-sided paper tape was selected as the appropriate detector unit because of its wide range of frequency response and small attenuation level. Using this detector unit, swallowing sounds and noise associated with simulated laryngeal elevation and the carotid pulse were acquired at 24 sites on the neck in 14 normal subjects; these signals were acoustically analyzed. The determination of the optimal site for detecting swallowing sounds was based on the signal-to-noise ratio. The site over the lateral border of the trachea immediately inferior to the cricoid cartilage is the optimal site for detection of swallowing sounds because this site showed the greatest signal-to-noise ratio with the smallest variance. The site over the center of the cricoid cartilage and the midpoint between the site over the center of the cricoid cartilage and the site immediately superior to the jugular notch were also considered to be the most appropriate sites.
Cervical auscultation is being used more frequently in the clinical assessment of dysphagic patients. The present study was designed to assess symmetry and the reproducibility of swallowing sounds detected simultaneously from bilateral cervical sites. Symmetry of the swallowing sounds acquired using our method was verified because no significant differences were found for any parameters in both time and frequency domain analyses between swallowing sounds detected bilaterally. This result supports the use of a "unilateral" site for the detection of swallowing sounds. The reproducibility of swallowing sounds was assessed by a coefficient of variation. Results of this analysis suggest that one should evaluate the acoustic characteristics of swallowing sounds from repeated swallows rather than from one swallow.
Reaction of bone tissue was investigated after placement of two different types of implants in vascularized iliac bone grafting. After the mandibles of six Göttingen minipigs were reconstructed with vascularized bone of the iliac crest, hydroxyapatite-coated implants and titanium screw implants were placed in the graft. The animals were killed at 14, 28, and 56 days after the implantation, and the healing processes were examined histologically. In the vascularized bone graft, new bone formed well around the implants, but some of the implant surfaces were covered with soft tissue by advancing bone resorption. The results suggest that a hydroxyapatite-coated implant as well as a titanium screw-type implant might be applied with a vascularized bone graft for jaw reconstruction. However, implants placed simultaneously with the vascularized bone graft had less osteointegration than implants placed in nongrafted control sites.
The purpose of this study was to histomorphometrically evaluate the use of hydroxylapatite (HA) implants in 60Co-irradiated bone. HA implants were installed in rabbit mandibles 3 months, 6 months, and 12 months after 15-Gy irradiation. Nonirradiated rabbits served as controls. The rabbits were killed 7, 14, 30, 60, and 90 days after the HA implantation. The histologic features of the healing process were examined and histomorphometric measurements were made to quantify the percentage of HA-bone contact and trabecular bone in the medullary cavity. In the irradiated groups, although HA-bone contact was observed later than that in the controls, recovery increased with time after irradiation and the rate of HA-bone contact bone-contacting implant surface ratio; BCSR exceeded 90% in all groups examined before 90 days. In the radiated groups, the average trabecular bone-specific volume was lower than that in the controls and began to decrease before BCSR exceeded 90%. Based on the present data, as well as data from the literature, it is suggested that the success rate of HA implants in irradiated bone increases with the interval after radiotherapy. It is also recommended that HA implants in irradiated bone be installed so that bearing by the cortical bone is increased.
This study compares the bone responses of old rats when implanted with hydroxyapatite ceramic (HAC)-coated titanium, high-density HAC, and uncoated titanium. Twelve two-year-old Wistar rats were used in this study. Cylindrical implants were placed into each tibia, and the animals were killed seven, 14, 28, or 56 days after implantation. Undecalcified sections were prepared and were then stained with toluidine blue. The healing process was examined histologically, and histomorphometric measurements were made with a computer-based image analyzer to quantify the percentage of implant-bone contact. The results indicated that the HAC-coated implants were superior to the uncoated titanium implants in relation to bone contact. In the cases where the bone-free surface of HAC coating was dissolved, macrophages were often seen on the surface of the implant. Although further longitudinal data are needed to evaluate the decrease of HAC coating, in this animal model, HAC-coated implants may be useful for osseous response in bones of poor quality.
This study established a method of detecting temporomandibular joint sounds based on signal-to-noise ratios. After comparing the temporomandibular joint signals obtained from three different sites over the skin, the articular eminence was found to be the best site for detecting temporomandibular joint sounds; this site provided the highest mean amplitude in the time domain waveform. However, using an electret condenser microphone at the intra-auditory meatus provided a broader, 20-decibel signal-to-noise bandwidth, which resulted in minimized artifacts. This method may be useful for recording temporomandibular joint sounds in the differential diagnosis of various temporomandibular joint conditions using spectral analysis.
The effects of calcium phosphate ceramic implants on tooth eruption were investigated radiographically and histologically in 20 3-month-old dogs. Four kinds of ceramic particles were used: dense and porous hydroxyapatite particles, and dense and porous tricalcium phosphate particles. These particles were implanted in the sockets after deciduous tooth extraction. The four types of calcium phosphate ceramic particles produced similar radiographic and histologic findings. There was no delay of tooth eruption, no dysplasia, and no resorption of dental hard tissue.
Surgical and prosthetic treatments for speech disorders attributable to surgically acquired soft palate defects were investigated. Ten patients who had undergone soft palate resection for extensive cancer served as the subjects. In four patients, the resected portion of the soft palate was confined to the anterior or middle segments, with an intact posterior band, whereas in the remaining six patients the resected portion extended into the posterior edge. An obturator with or without a speech appliance was adapted to all patients in the former group and to one patient in the latter group. The remaining five patients in the latter group underwent surgical reconstruction using a free radial forearm flap immediately after resection of the soft palate. The speech of each patient was evaluated either before and after surgery in those treated only surgically or with and without the obturator in the other patients using a standard intelligibility test of 100 Japanese syllables. These tests showed that two of the four patients with a posterior band of soft palate remaining postsurgically achieved excellent restoration of speech and improvement of velopharyngeal function following placement of a special prosthesis. The patients who had resection extending into the posterior edge of the soft palate obtained better restoration of speech and function from surgical reconstruction rather than prosthetic management. All three patients who had surgical reconstruction, in whom the special obturator was applied achieved a slight increase in speech intelligibility scores resulting from the improvement of velopharyngeal function. These results suggest that surgical reconstruction and prosthetic management may best be applied selectively based on the extent of resection of the soft palate.
An unusual case of patent nasopalatine duct appearing in the central region of the hard palate in a young adult is reported. The origin and clinical symptoms of this anomaly are discussed.
Postoperative articulatory function was assessed in 5 patients who had had radical operations for cancers of the oropharyngeal region with surgical reconstruction using free jejunum flaps. A patient with total resection of the soft palate had the lowest scores of 39.9%. 4 patients with less resection than total removal of the soft palate had good scores (86.0%), and the articulatory dysfunction was limited only in plosive sounds produced in the velar region. A comparative study with glossectomized patients revealed that those who had had resection of the oropharynx achieved excellent articulation except for sounds produced in the velar region. The importance of operative function was stressed, to evaluate indications for the surgical technique for reconstruction of large tissue defects after ablation of head and neck cancers, and to improve the quality of life of those patients.
The role of visual feedback in the treatment of defective /s/ sounds in patients with cleft palate is described. Six patients with cleft palate who were similar in age, velopharyngeal function, and type of misarticulation were selected for this study. Treatment was provided using either visual feedback or no visual feedback. Visual feedback for tongue placement was provided by the Rion Electropalatograph (EPG). Visual feedback for frication was provided by a multi-function speech training aid (MFSTA). Improvement in /s/ sound production was assessed objectively using a method described previously (Michi et al., 1986). The results indicated that visual feedback for tongue placement and frication was especially useful in the treatment of defective /s/ sounds in patients with cleft palate who exhibited abnormal posterior tongue posturing during the production of dental or alveolar sounds.
A palatal lift prosthesis (PLP) is a prosthetic speech aid used to compensate for palatopharyngeal incompetence. However, it requires dental abutments to facilitate its function. In two edentulous patients with cleft palate, hydroxyapatite-coated dental implants were used to increase PLP retention. In both cases, palatopharyngeal closure was obtained and PLP function was deemed effective, as determined by speech evaluation and nasal air flow measurements, for more than 3 years. This treatment is useful for enhancing the retention of a PLP in patients who have few or no remaining natural tooth abutments.
The purpose of this study was to investigate the effect of aging on the healing process after insertion of a hydroxylapatite (HA) implant into bone. Three groups of eight male Wistar rats, aged 6 weeks (young group), 12 weeks (adult group), and approximately 2 years (old group) were used in this experiment. Two implants were placed into the tibia of each rat. The animals were killed 7, 14, 28, and 56 days after implantation, and 15-microns, hematoxylin-eosin-stained, undecalcified sections were prepared. The healing process was examined histologically, and histomorphometric measurements were made by a computer-based image analyzer to quantify the percentage of HA-bone contact and trabecular bone in the medullary cavity. In the young group, new trabecular bone formed actively around the HA implant and good HA-bone contact was achieved more rapidly than in the adult group. In the old group, both the quantity of newly formed trabecular bone around the implant and the extent of HA-bone contact were less than in the other groups. The results suggest that the rate and volume of new bone formation around implants decrease with increasing age.
Postoperative articulation in 18 glossectomized patients was investigated. The subjects were: 5 cases of tongue tumour, 7 cases of tumour of the anterior part of the floor of the mouth and 6 cases of tumour of the lateral part. A new modification of the Freiburger test for speech audiometry was used as test material. Then the articulatory function was assessed according to an overall score based on 180 monosyllables, the manner of production of 171 initial consonants and the place of production of 85 glossal sounds. The cases of tumour of the tongue and the lateral part of the floor of the mouth had excellent scores in all classes of sounds, which were compatible with the normative data. The subjects of tumour of the anterior part of the floor of the mouth had low overall scores, low scores for plosive and affricative sounds, and very low scores for sounds produced with the rear of the tongue. The relation between the site or amount of resection and subsequent articulation was significantly poor in all categories of sounds for the cases of anterior tumour, particularly in the movement of the posterior portion of the tongue even though it was not involved in the operation. In all groups there was a weak negative relation between the amount of resection and postoperative articulation. In reviewing the literature, reconstruction with a free jejunum flap was considered to lead to better articulation than reconstruction by other techniques. The need to assess postoperative function objectively was stressed, to compare the postoperative functions and to determine the indications for the reconstructive technique.