Mitsutaka Taniguchi

Responsiveness of jaw motor activation to arousals during sleep in patients with obstructive sleep apnea syndrome.

OBJECTIVES We aimed to characterize the association between jaw muscle contractions and respiratory events in patients with obstructive sleep apnea syndrome (OSAS) and to investigate the responsiveness of the contractions to respiratory events in comparison with that of leg muscles in terms of arousal types and sleep states. METHODS Polysomnographic (PSG) recordings were performed in 19 OSAS patients (F/M: 2/17; 53.1 ± 13.7 years; AHI: 31.8 ± 19.9/h) with no concomitant sleep bruxism or other sleep-related movement disorders. Muscle contractions of unilateral masseter (MAS) and anterior tibialis (AT) muscles were scored during sleep in association with graded arousals (microarousals and awakenings) related or unrelated to apneahypopnea events. RESULTS Arousals were scored for 68.2% and 52.3% of respiratory events during light NREM and REM sleep, respectively. Respiratory events with arousals were associated with longer event duration and/or larger transient oxygen desaturation than those without (ANOVAs: p < 0.05). Median response rates of MAS events to respiratory events were 32.1% and 18.9% during NREM and REM sleep. During two sleep states, MAS muscle was rarely activated after respiratory events without arousals, while its response rate increased significantly in association with the duration of arousals (Friedman tests: p < 0.001). A similar response pattern was found for AT muscle. Motor responsiveness of the two muscles to arousals after respiratory events did not differ from responsiveness to spontaneous arousals in two sleep stages. CONCLUSION In patients with OSAS, the contractions of MAS and AT muscles after respiratory events can be nonspecific motor phenomena, dependent on the duration of arousals rather than the occurrence of respiratory events.

Efficacy and tolerability of ramelteon in a double-blind, placebo-controlled, crossover study in Japanese patients with chronic primary insomnia

The aim of this study was to evaluate the efficacy and safety of ramelteon 4, 8, 16 or 32 mg and placebo in Japanese patients with chronic insomnia using a randomized, double-blind, five-period crossover design. A total of 65 Japanese patients with chronic primary insomnia received ramelteon or placebo for two nights each in sleep laboratories. Changes in sleep parameters were assessed objectively by polysomnography and subjectively by postsleep questionnaires. Safety and tolerability was evaluated by assessment of the occurrence of adverse events, next-day residual effects and laboratory and ECG investigations. Ramelteon 8 and 32 mg significantly shortened the mean latency to persistent sleep in comparison with placebo, and there was a statistically significant trend for linear dose–response for this sleep parameter. Overall changes in sleep architecture were modest (<3% changes vs placebo), with increases in stage 1 and decreases in stage 3/4. Ramelteon was well tolerated, the most common adverse effect being somnolence, which was similar to placebo at doses up to 8 mg, but increased with higher doses. Next-day residual effects occurred no more frequently with ramelteon at any dose than with placebo. When compared with sleep latency data from a similarly-designed US study, there was no evidence of any ethnic differences in the efficacy of ramelteon between Japanese and US patients. Overall, ramelteon 8 mg showed the most favorable balance between sleep-promoting effects and tolerability. The unique efficacy profile of ramelteon, promoting sleep initiation without affecting other sleep parameters, may be due to its circadian shifting effect.

Development of REM sleep atonia.

Objectives – To study the functional development of neuronal systems that suppress muscle activity, we quantified the chronological change of atonia in rapid‐eye‐movement sleep (REMS). Methods – REMS atonia was quantified by the tonic and phasic inhibition indices (TII and P1I). TII indicates the shortness of chin muscle activity, whereas PII standardizes the simultaneous occurrence of chin muscle activity and bursts of rapid eye movements. TII and PII were calculated in REMS of 135 polysomnographical recordings obtained in healthy humans from premature babies to a 77‐year‐old man. Results – TII increased significantly with age, while PII decreased significantly. TII reached an adult level at preadolescence, while PII at early infancy. Conclusion – Human nervous systems involved in both tonic and phasic inhibition in REMS raise their activities with age. Since TII and PII reach adult levels at different ages, suppression of muscle activity is hypothesized to be mediated through at least 2 independent systems in humans.

Tonic and phasic inhibition indices are constant among nights: new indices for evaluating the degree of the two types of motor inhibition during REM sleep

BACKGROUND Tonic inhibition index (TII) and phasic inhibition index (PII) were proposed as indices for evaluating the degree of two types of motor inhibition activity during rapid eye movement (REM) sleep. METHODS In the present study, therefore, six healthy men underwent two consecutive all-night polysomnography, and reproducibility of TII and PII was evaluated. RESULTS TII was 0.85+/-0.07 (mean+/-SD) on the first night and 0.88+/-0.08 on the second; and PII was 3.4+/-2.1 on the first night and 4.9+/-1.8 on the second. Neither TII nor PII was significantly different between the two nights. CONCLUSION One night sleep study is considered sufficient for using TII and PII as a tool for evaluating motor inhibition activity during REM sleep in adults.

The impact of obstructive sleep apnea syndrome on nocturnal urine production in older men with nocturia.

OBJECTIVE To investigate the impact of obstructive sleep apnea syndrome (OSAS) on night-time secretion of brain natriuretic peptide (BNP) and antidiuretic hormone (ADH) in older men with nocturia accompanied by nocturnal polyuria. MATERIALS AND METHODS One hundred six men with nocturia aged ≥ 60 years underwent full-night polysomnography to determine whether they had OSAS. Blood count, standard chemistry panel, BNP, urinary ADH, urinary creatinine (u-Cre), and urinary osmolarity were measured at 6:00 AM, and a frequency volume chart was recorded on the same day that polysomnography was performed. RESULTS We evaluated 83 patients after excluding 18 with mild OSAS and 5 with nocturnal polyuria index <0.35. Participants with OSAS had higher apnea-hypopnea index (P < .0001) than those without OSAS. Body mass index and systolic blood pressure were higher in OSAS patients than those in the control group. BNP was higher in the OSAS patients than in the control patients (48.6 ± 41.4 vs 30.7 ± 31.5; P = .0006). On urinalysis, OSAS patients showed higher urinary sodium and u-Cre secretion than controls (24.7 ± 11.3 vs 16.2 ± 5.1; P <.0001). Urine osmolarity was also higher in OSAS patients than in the control patients (616 ± 172 vs 516 ± 174; P = .0285). There was no significant difference in urinary ADH and u-Cre (6.7 ± 10.4 vs 6.8 ± 7.8; P = .3617) between the 2 groups. CONCLUSION Our results indicated that older men with nocturnal polyuria and OSAS did not compensate their fluid imbalance presented with decreased secretion of ADH but increased BNP level.

Clinical characteristics of upper airway resistance syndrome

Polysomnographic findings and clinical symptoms were investigated in 14 cases of upper airway resistance syndrome. The mean scores of the Epworth sleepiness scale and self‐rating depression scale in eight cases were 13.5 and 38.6, respectively. The mean sleep latency of the multiple sleep latency test in four cases was 10.2 min. Seven cases were treated with continuous positive airway pressure (CPAP), and one with hormone replacement therapy. The most common symptom was daytime sleepiness. Five cases had hypertension. CPAP reduced increasing negative esophageal pressure (Pes) and frequency of EEG arousals, and improved hypertension in one case. Hormone replacement therapy ameliorated increasing negative Pes and clinical symptoms.

Obstructive sleep apnea syndrome aggravated propriospinal myoclonus at sleep onset

Article history: Received 11 February 2011 Received in revised form 22 June 2011 Accepted 29 June 2011 Available online 26 October 2011 2011 Elsevier B.V. All rights reserved.

Idiopathic REM Sleep Behavior Disorder in the Aged

As showing in Table 1, rapid eye movement (REM) sleep behavior disorder (RBD), is characterized by the intermittent loss of electromyogram (EMG) atonia and by the appearance of the elaborate motor activity associated with dream. Therefore, it is considered that diagnosing typical RBD patients according to these minimal criteria is not difficult, but that polysomnographic (PSG) examination is required to differentiate accurately between this and other sleep disorders.

A case of severe obstructive sleep apnea mimicking REM sleep behavior disorder

The rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by dream-enacting behaviors related to the loss of the normal generalized skeletal muscle atonia during REM sleep, and shows REM sleep without atonia (RWA) during polysomnography (PSG). Patients with idiopathic RBD have been known to have a siginificantly increased risk of developing one of the α-synucleiopathies later in life, therefore the diagnosis of RBD is very important and must be dealt with carefully. A 51-year-old man was identified presenting dream-enacting behaviors and unpleasant dreams suggesting the diagnosis of RBD, in addition to snoring and excessive daytime sleepiness. Attended video-PSG excluded RBD showing REM sleep with atonia and without increased phasic EMG activity, and diagnosed with severe obstructive sleep apnea (OSA) with an apnea-hypopnea index of 30.1 demonstrating that the reported abnormal sleep behaviors occurred only during respiratory event-induced arousals. Continuous positive airway pressure therapy eliminated the abnormal behaviors, unpleasant dreams, snoring and daytime hypersomnolence. This case shows that severe OSA mimic the symptoms of RBD and that attended video-PSG is necessary to establish the diagnosis of RBD, and identify or exclude other causes of dream-enacting behaviors.

Subjective oropharyngeal symptoms for abnormal swallowing in Japanese patients with obstructive sleep apnea syndrome: a descriptive questionnaire study.

Objectives: This study aimed to investigate the prevalence of clinical symptoms related to abnormal swallowing in a large sample of obstructive sleep apnea syndrome (OSAS) patients. Methods:Oropharyngeal symptoms for abnormal swallowing were assessed by a self-administered questionnaire in 507 consecutive patients (females: 65, males: 442; mean age: 49.6 ± 12.6 years old) with clinical symptoms of OSAS, enrolled for cardiorespiratory evaluation. Results:Overall, 16.2% of patients (82/507) had at least one symptom for abnormal swallowing and 6.3% (32/507) had two or more symptoms. The most frequent symptom was difficulty with coughing up phlegm during or after a meal (8.3%). Demographic, sleep, and clinical variables did not differ between the patients with and without abnormal symptoms. Conclusions:The results of the current study showed that 16% of middle-aged OSAS patients reported pharyngeal symptoms related to abnormal swallowing, regardless of the severity of OSAS.