Shigeru Higami

Mechanism of action and therapeutic indication of prosthetic mandibular advancement in obstructive sleep apnea syndrome.

Abstract Prosthetic mandibular advancement (PMA) was applied to nine patients with obstructive sleep apnea syndrome (OSAS) and its therapeutic usefulness, mechanism of action, and clinical indication were discussed based on polysomnographic findings and serial examination of upper airway before and during PMA treatment. Apnea hypopnea index significantly decreased during PMA treatment compared with the value before treatment (P < 0.01) and the rate of the treatment responder counted 78.1%. Cephalometric variables indicated forward and inferior advancement of mandible in our subjects. Magnetic resonance imaging of the upper airway during sleep revealed a marked improvement of velopharyngeal obstruction in most subjects. In addition, intraesophageal negative pressure during sleep decreased significantly. Our results confirmed the high therapeutic efficacy of PMA for OSAS and indicated forward advancement of the mandible and decrease of negative pressure loading on upper airway with PMA might suppress velopharyngeal collapse. Thus, PMA was regarded as one of the treatments of choice for OSAS occurring based on with velopharyngeal narrowing.

Age-related changes in cerebral lactate metabolism in sleep-disordered breathing

Thirty-one patients, aged 22-71 years, with nocturnal apneic episodes and/or habitual snoring were studied with magnetic resonance spectroscopy (MRS) and diagnostic polysomnography separately to determine whether accumulation of lactate caused by cerebral hypoxia during sleep is associated with sleep-disordered breathing (SDB), aging and co-morbidities related to SDB. Eight proton magnetic resonance spectra for sleep and two for periods of arousal were obtained from the right centrum semiovale. All patients were evaluated for the presence or absence of co-morbidities including hypertension, cardiac disease, diabetes mellitus, and hyperlipidemia. Significant lactate signals were found in seven patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) during sleep periods, and none during periods of arousal. Aging was significantly related to the presence or absence of significant lactate signals during sleep periods as determined by logistic regression analysis (beta=0.2480; 95% confidence interval, 0.0905-0.5094; P=0.0001). Apnea index (AI), apnea-hypopnea index (AHI), and minimum value of peripheral oxyhemoglobin saturation each significantly interacted with age (P=0.0081, 0.0284, and 0.0302, respectively). Our findings suggest that SDB combined with aging is related to accumulation of lactate during sleep.

Non-linear behaviour of respiratory movement in obstructive sleep apnoea syndrome

In this study we investigated the non‐linear properties of respiratory movement in patients with obstructive sleep apnoea syndrome (OSAS) during sleep without and with nasal continuous positive airway pressure (nCPAP). To calculate the correlation dimension (D2) in respiratory movement we applied an algorithm proposed by Grassberger and Procaccia. Non‐linearity in respiratory movement was tested by comparing D2 for the original data with that for surrogate data. Respiratory movement was recorded from 10 patients with OSAS. D2 during both wakefulness with eyes closed and during sleep with nCPAP at 8 cm H2O could be computed in all subjects (2·50 ± 0·69 and 1·68 ± 0·17, respectively). On the other hand, D2 during sleep with apnoea could not be computed in patients with severe OSAS. These results indicate the abnormal properties of respiratory movement during apnoeic sleep in severe OSAS. Moreover, respiratory movement with nCPAP was shown to be non‐linear deterministic behaviour in respiratory movement during sleep. Analysis of D2 for respiratory movement may be useful in adjusting (titrating) nCPAP and classifying severity in OSAS.

Relationship between hypersomnia and respiratory disorder during sleep in Prader–Willi syndrome

Abstract To assess whether hypersomnia in Prader–Willi syndrome (PWS) patients is related to the respiratory disorder during sleep (RDDS), we made a systematic evaluation regarding the relationship between the two disorders in three patients. All patients showed hypersomnia manifested as the long duration of night sleep and shortened sleep latencies of multiple sleep latency test. Although magnetic resonance imaging and laboratory studies revealed obstruction of the upper airway and mild increase of esophageal pressure during sleep, the number of other apneic episodes or awakenings was not as frequent. From the above results, we speculate that the mechanism of excessive daytime sleepiness in PWS is not caused by RDDS and quite resembles that of essential hypersomnia.

Endoscopic classification of pharyngeal stenosis pattern in obstructive sleep apnea hypopnea syndrome

Abstract Twenty‐one patients with obstructive sleep apnea–hypopnea syndrome (OSAHS) were classified into three categories according to their pharyngeal stenosis patterns during sleep, as determined from endoscopic findings: (i) a falling type (n = 6); (ii) an all‐round type (n = 11); and (iii) a bilateral type (n = 4). In all patients with the bilateral type, the palatine tonsils were hypertrophied, and the apnea–hypopnea indexes (AHI) were improved markedly by surgery. Conversely, the AHI of patients with the falling and all‐round types were reduced by a smaller percentage. Surgical therapy is only to be recommended to patients with OSAHS whose pharynx is bilaterally stenotic.

Clinical significance of sleep‐related breathing disorder in narcolepsy

Abstract Both the influence of comorbid obstructive sleep apnea–hypopnea syndrome (OSAHS) on daytime sleepiness and its pathological mechanism in 10 narcoleptic patients was studied. Mild elevation of esophageal negative pressure and obstruction in the velopharyngeal area, as observed by upper airway magnetic resonance imaging, during apneic episodes was observed in the subjects. Severity of the disorder was correlated positively with body mass index, and the latencies of the multiple sleep latency tests were not improved with nasal continuous positive airway pressure treatment in subjects. Pathogenesis of OSAHS in narcolepsy was thought to be almost similar to typical OSAHS, and that the disorder seemed to lack a pathological influence on daytime sleepiness.

Clinical efficacy of prosthetic mandibular advancement on obstructive sleep apnea syndrome

In order to clarify the efficacy and indication of prosthetic mandibular advancement (PMA) on obstructive sleep apnea syndrome (OSAS), we made a comparison of both the polysomnographic findings and the upper airway configuration between before and during PMA on 19 OSAS patients. During PMA, there was a significant decreased apnea hypopnea index compared to before treatment. The changes in magnetic resonance imaging of the upper airway during sleep with PMA indicated that the treatment is regarded to be the first choice for OSAS patients with glossopharyngeal obstruction. In addition to that, the treatment might be considered for use in velopharyngeal obstruction.

Clinical significance of negative esophageal pressure in sleep apnea syndrome

The authors investigated the relationship between esophageal pressure fluctuation (DPes) during sleep and the following parameters: respiratory disorder variables and daytime sleepiness manifested as the Epworth sleepiness scale (ESS). In the younger patient group under 60 years of age (n = 33), DPes was correlative to both the apnea‐hypopnea index and ESS. However, in the elderly group of 60 years and over (n = 16), the variables showed smaller values than did those in the younger group. These results suggest that DPes may be associated with the aggravating process of sleep apnea syndrome (SAS) in the younger patient.

Evaluation of cervical lymph node tuberculosis

From January 1990 to December 1999, we treated twelve patients with cervical lymph node tuberculosis. The diagnosis was confirmed by histopathological findings of biopsy, 10 cases by resection of lymph node, 1 case by fine needle aspiration biopsy and 1 case was diagnosed following resection of lymph node at another hospital. After diagnosis, all patients received antituberculous chemotherapy and one patient with pocket formation underwent total resection of neck masses with infectious skin. Four cases were lost to follow-up, but the others showed good response and had no recurrence.Tuberculosis is an important infectious disease demanding constant attention because of the possibility of herd infection. We should consider tuberculosis when cervical lymph node swelling is seen, and early diagnosis and treatment are needed to prevent the spread of infection to others. Antituberculous chemotherapy is effective, however, when pocket and abscess formation occur, combination therapy of chemotherapy and operation such as neck dissection are needed in early course.