Biomedical subjects
Jun Kohyama
Publications and source records attributed to Jun Kohyama.
[Rhythmic movement disorder].
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Rapid-eye-movement sleep in jittery infants.
BACKGROUND: The pathogenesis of neonatal jitteriness (JT) remains unknown. Neonatal JT could be one of the symptoms associated with drug withdrawal syndrome due to maternal medication. To study the influence of chemicals and environment on brain development in the fetal period, Swaab and Mirmiran proposed "behavioral teratology". JT could be one of the targets for this concept. Swaab and Mirmiran postulated that rapid-eye-movement sleep (REM sleep) is useful for studying behavioral teratology. AIM: We aimed to determine the neurophysiological alterations in infants with JT by investigating REM sleep. STUDY DESIGN: Sleep records were obtained three times for each of six jittery infants. The mothers of three infants had been on medication (either alpha-methyl dopa, reserpine or haloperidol) during pregnancy, whereas the mothers of the other three infants took no medication during pregnancy. REM sleep parameters (the amount of REM sleep against the total sleep time, newly designated indices-tonic inhibition index (TII) and phasic inhibition index--, and the incidences of gross movements, phasic chin muscle activity (PCMA), and bursts of rapid eye movements) in the six jittery infants were compared with those in age-matched controls. RESULTS: Regardless of maternal medication, TIIs, which represent the shortening of PCMA during REM sleep, were higher in the jittery infants than in the controls. No other REM sleep parameters showed constant differences between the patients and controls. CONCLUSION: Release of the blockade of dopamine D2 receptors in the fetal brain is considered to be critical for the occurrence of neonatal JT with elevation of TII. Since the abnormal elevation of TII continued after 6 months of age when our patients did not show JT anymore, we have to keep monitoring jittery infants from the standpoint of "behavioral teratology".
Rhythmic movement disorder: polysomnographic study and summary of reported cases.
Rhythmic movement disorder (RMD) is classified as a sleep-wake transition disorder. However, some RMD patients show rhythmic movements during rapid-eye-movement (REM) sleep, during which muscle activity is completely absent. In order to determine the sleep stages in which episodes of RMD occur, we investigated two children with RMD by means of polysomnography, and also summarized the polysomnographic reports on patients with RMD. We also quantified the REM sleep atonia in our patients using the tonic and phasic inhibition indices (TII and PII). In addition, to examine the involvement of the basal ganglia in RMD patients, we studied the frequency of gross movements (GMs) during sleep in each sleep stage. Both patients showed rhythmic movements in all sleep stages, i.e. including REM sleep. Few rhythmic movements occurred during sleep-wake transition periods. Both patients showed normal TII and PII scores as well as a normal pattern for the sleep stage-dependent modulation of GMs during sleep. Eighteen of the 33 reported RMD patients, including ours, experienced episodes during REM sleep, while the other 15 patients had no episodes during REM sleep. Among the 18 patients who had episodes during REM sleep, eight experienced the episodes exclusively during REM sleep. It is unlikely that the neuronal mechanisms that underlie RMD episodes were the same in the 15 patients who had no RMD episodes during REM sleep and the eight who had them only during REM sleep. We propose that RMD can be divided into several subgroups according to the differences in the underlying neuronal mechanisms.
Subcortical arousal response in child patients with obstructive sleep apnea.
OBJECTIVE: The objective of this study is to assess subcortical arousal response (SCA) in child patients with obstructive sleep apnea syndrome (OSAS). METHODS: A new index termed SCA was defined as a sigh associated with elevated chin muscle activity. According to the duration, SCAs were divided into three types; SCA short (1s or more and less than 3s), SCA intermediate (3s or more and less than 10s), and SCA long (10s or more). We scored SCAs in six child OSAS patients, aged 2-5 years, before and after adenotonsillectomy. SCAs were also counted in four age-matched controls. RESULTS: In the pretreatment records, 45.5% of SCAs were associated with electroencephalographic arousals. In all patients, SCA short and SCA intermediate decreased after the treatment to the levels in the controls. SCA long exhibited no consistent changes after treatment. The incidence of SCAs was much higher than arousals previously reported in child OSAS patients as well as in normal children. CONCLUSIONS: SCAs, especially SCA short and SCA intermediate, are sensitive and useful indices for assessing subcortical involvement in child OSAS patients.
Potentially harmful sleep habits of 3-year-old children in Japan.
To examine the sleep habits of 3-year-old children, we questioned guardians during a routine health examination for 3-year-old children at a public health center. According to the 1105 questionnaires analyzed, the proportion of children who fell asleep at 10 p.m. or later was 49.6%. The nocturnal sleep onset time was significantly correlated with the wake-up time in the morning and was significantly negatively correlated with the nocturnal sleep duration. The average daily total sleep duration (nocturnal sleep duration + nap duration) of regular nap-takers showed a significant negative correlation with the nocturnal sleep onset time. The average values for height, weight, and body mass index (BMI) were not correlated with the nocturnal sleep onset time. Children who went to sleep later got less sleep than those who went to sleep earlier. Because sleep debt has a harmful impact on older children and adults, late sleep onset may have adverse health consequences in young children.
[A case of childhood onset myoclonus epilepsy with ragged-red fibers--with special reference to various clinical manifestations].
There are few descriptions about the clinical course of children with myoclonus epilepsy with ragged-red fibers (MERRF). We reported a girl who was diagnosed as having MERRF at 10 years of age and developed various clinical manifestations including chronic respiratory failure, paralytic ileus and pancytopenia at 18 years of age. Administration of cytochrome c worsened lactic acidosis and muscle weakness, while intravenous hyperalimentation with copper supplementation gradually improved these findings as well as pancytopenia. Cytochrome c oxidase is a copper dependent enzyme. Its activity is extremely low in MERRF patients. It was suspected that deficiency of serum copper and supplementation of cytochrome c worsened the clinical symptoms of our patient.
Late nocturnal sleep onset impairs a melatonin shower in young children.
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