Fifty patients with sleep-related breathing disorders were tested with nocturnal polysomnography and with nasendoscopic diurnal polysomnography after diazepam administration, and various indices of breathing disorders were examined, and the results obtained in the two sleep studies compared. There were no significant differences between the two sleep studies in either the type of apnoea or the indices of breathing disorder except for the longest duration of apnoea. There was a significant difference in the duration of REM sleep between the two sleep studies, but no significant difference in the duration of each stage of non-REM sleep. We speculate that nasendoscopic diurnal polysomnography with diazepam can be used as a substitute for nocturnal polysomnography in the clinical study of non-REM sleep stage but it is not sufficient in evaluating REM sleep stage, in patients with sleep-related breathing disorders without pathological obesity or abnormal respiratory function.

We performed sleep studies in eight patients with multiple system atrophy (MSA) and three patients with peripheral bilateral vocal fold palsy (PBVFP) and investigated stenosis of the upper airway tract during sleep in MSA patients with vocal fold palsy. Among the eight MSA patients in this study, five had definite glottic snoring and two others were suspected of having glottic snoring. Of the PBVFP patients, two had glottic snoring. Three of 11 patients died, and two of the three deaths occurred during sleep. Glottic snoring indicated a high degree of negative esophageal pressure. High negative esophageal pressure demonstrates severe narrowing of the upper airway tract. Therefore, glottic snoring should be considered a risk factor for sudden death in sleep. Repeated laryngoscopic examination is useful in evaluating the progressive process of vocal fold palsy while awake, but this examination performed only while awake is not enough to evaluate narrowing of the upper airway during sleep. Sleep studies that include the measurement of esophageal pressure can be very useful in evaluating the severity of narrowing in the upper airway tract. It is suspected that sudden nocturnal death in MSA patients is caused not only by abnormal respiration resulting from impairment of the respiratory center, but also by glottic obstruction caused by sputum or by edema of the vocal folds. We recommend treatment of respiratory disorders when loud laryngeal snoring occurs in patients with MSA, even if they do not complain of dyspnea while awake.

We performed perceptual and acoustic studies to demonstrate articulation after uvulopalatopharyngoplasty (UPPP) in Japanese patients at 28.6 days (mean) after surgery (range 21-50 days). The results of listening tests showed that there were no significant changes between pre- and postoperative articulation scores for any of 25 monosyllables tested, and there were no significant changes in the timbres of 5 Japanese vowels after UPPP. In the acoustic study of the first and second formant frequencies of the vowels, some formant frequencies had significant changes after UPPP. However, these changes in formants fell within the range of intraindividual variation. In the acoustic study of /ka/ with a palatal plosive /k/, there was no significant change in the voice onset time or F2 transition after UPPP.

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