H. A. C. Kamphuisen

Ambulatory Monitoring of Sleep-Wakefulness Patterns in Healthy Elderly Males and Females (>88 Years): The “Senieur” Protocol

The study was designed to investigate sleep‐wake patterns in healthy elderly men and women (>88 years) using ambulatory recording techniques.

A model-based detector of vertex waves and K complexes in sleep electroencephalogram

A model of sleep phasic events such as vertex waves, K complexes, delta waves and sleep spindles is proposed. It consists of feedback loops that are driven by white noise (simulating tonic delta and sigma activity) and by isolated random impulses, simulating vertex waves or K complexes, depending on the background tonic activity. A model-based method for the detection of sleep phasic events was implemented in a personal computer. Its performance was investigated using simulated and real whole-night EEG signals. The method was able to detect K complexes and vertex waves in a reliable way in spite of their variable shapes and in the presence of a variety of background activities. The detector appears to have superior performance to those so far reported in the literature. The performance of the detector was also compared to that of an electroencephalographer using normal sleep EEG records of 8 h duration from 6 subjects. The performance was satisfactory both in terms of accuracy and reliability. The problem of detecting K complexes in stages 3 and 4 of sleep is discussed.

The prevalence of clinically significant sleep apnoea syndrome in the Netherlands

BACKGROUND Figures for the prevalence of sleep apnoea syndrome range from 0.3% to 8.5%. These widely ranged estimates are probably due to differences in the definitions used, study designs, and study populations. A study was undertaken to determine the lower limit of the prevalence of clinically significant sleep apnoea syndrome. METHODS A cross sectional survey by postal questionnaire was carried out in a general practice of a small town in which three doctors serve 93% of its population of 6747 inhabitants of all ages. All men aged 35 and over and women aged 50 and over were invited to fill in a specially designed questionnaire on snoring and sleep. All men and women whose answers suggested the possible occurrence of sleep apnoea were invited to undergo further investigation. Oronasal thermistry was performed in the subjects’ homes and the results were scored to provide an apnoea index (AI). Those subjects with an AI of ⩾5 were referred to a sleep laboratory for investigation by polysomnography. RESULTS Of the 2466 questionnaires issued, 2182 (88.5%) were completed and returned. The occurrence during the previous three months of regular snoring, together with daytime sleepiness and/or partners’ observation of interruptions in breathing at night, was reported by 194 subjects (169 men, 25 women). In 173 subjects oronasal thermistry applied in their homes provided satisfactory recordings and, of these, 24 men and one woman had an AI of ⩾5. Analysis of the polysomnographic findings showed that 14 men and one woman met the criteria for sleep apnoea syndrome. Scrutiny of their case records disclosed that in seven men this was clinically significant. CONCLUSIONS Our findings suggest that the prevalence of clinically significant sleep apnoea syndrome in men aged 35 and over is at least 0.45%. Extrapolation to the population of the Netherlands suggests that at least 16 000 men suffer from sleep apnoea syndrome that should be relieved by medical care. A large proportion of these subjects remains to be diagnosed.

Syncope or seizure? The diagnostic value of the EEG and hyperventilation test in transient loss of consciousness.

In a prospective study of consecutive patients (age 15 or over) with transient loss of consciousness 45 patients had a history of seizure and 74 patients had a history of syncope. All patients had an EEG, ECG, laboratory tests and a hyperventilation test and were followed for an average of 14.5 months. Epileptiform activity in the interictal EEG had a sensitivity of 0.40 and a specificity of 0.95 for the diagnosis of a seizure. Epileptiform activity nearly doubled the probability of a seizure in doubtful cases. If no epileptiform activity was found, this probability remained substantially the same. The hyperventilation test had a sensitivity of 0.57 and a specificity of 0.84 for the diagnosis of syncope. A positive test increased the probability of syncope half as much in doubtful cases. A negative test did not exclude syncope. Laboratory tests were not helpful except for an ECG which was helpful in elderly patients.

Respiration during sleep in Huntington's chorea

In view of recent reports on lower brainstem dysfunction in Huntingtons chorea, we studied respiration during sleep in 12 patients with Huntingtons chorea (HC) and in controls. There were no statistically significant differences between patients and controls with respect to apnea periods, respiratory frequency and time elapsed between minimal and maximal value of the respiratory curve. No statistically significant differences in respiratory variability were observed between patients and controls. In the present study, no indication was found for dysfunction of lower brainstem structures involved in respiration in HC.

Nocturnal Activity and Immobility across Aging (50–98 Years) in Healthy Persons

Objective: To measure the influence of age on measures of nocturnal activity and immobility in 100 healthy subjects aged 50 to 98 years.

Wrist actigraphic assessment of sleep in 116 community based subjects suspected of obstructive sleep apnoea syndrome.

BACKGROUND--The combined use of wrist actigraphic assessment and self assessment of sleep in the screening of obstructive sleep apnoea syndrome was evaluated in a community based sample. METHODS--One hundred and sixteen community based subjects clinically suspected of having obstructive sleep apnoea (syndrome) were evaluated by means of simultaneous ambulatory recording of respiration (oronasal flow thermistry), motor activity (wrist actigraphy), and subjective sleep (sleep log) during one night of sleep. RESULTS--The subjects were distributed according to their apnoea index (AI); AI < 1 (non-apnoeic snorers) 44%; AI 1- < 5 39%; and AI > or = 5 17%. High apnoea index values were associated with self reported disturbed sleep initiation and more fragmented and increased levels of motor activity and decreased duration of immobility periods, particularly in those with an apnoea index of > or = 5. Across subjects the duration of immobility periods was the only predictor of the apnoea index, explaining 11% of its variance. Use of the multiple regression equation to discriminate retrospectively between those with an apnoea index of < 1 and > or = 5 resulted in sensitivity and specificity values of 75% and 43%, and 5% and 100%, respectively. CONCLUSIONS--The combined use of a sleep log and actigraphic assessment of sleep failed to identify reliably those subjects who suffered from obstructive sleep apnoea (syndrome) in a sample of community based subjects reporting habitual snoring combined with excessive daytime sleepiness and/or nocturnal respiratory arrests.

Multi-centre comparison of five eye movement detection algorithms.

Although various investigators have suggested algorithms for the automatic detection of eye movements during sleep, objective comparisons of the proposed methods have previously been difficult due to different recording arrangements of different investigators. In this study the results of five eye movement detection algorithms applied to the same data were compared to visually scored data. The percentages of true and false detections are given for various threshold levels in rapid and slow eye movement detections. The methods gave best results when they were used with the same electrode montage they were designed for but the performance decreased when other montages were used. Subtracting the cross‐talk of EEG delta activity improved the correctness of eye movement detections.

Pharmacodynamics of temazepam in primary insomnia: Assessment of the value of quantitative electroencephalography and saccadic eye movements in predicting improvement of sleep

quantitative electroencephalographic parameters and saccadic eye movements are frequently used as pharmacodynamic measures of benzodiazepine effect. We investigated the relationship between these measures and the hypnotic effect.

2 Leer van de veroudering: gerontologie

In dit hoofdstuk wordt eerst besproken wat gerontologie is en welke subdisciplines er zijn. Er zijn verschillende manieren om veroudering bij de mens te bestuderen: via transversaal, longitudinaal en time-lag onderzoek (met verstorende invloeden daarop van leeftijd-, cohort- en periode-effecten) en via onderzoek naar mortaliteit en morbiditeit. Een keurkorps van ‘senieurs’ bewijst dat bij sommige ouderen functies tot op zeer hoge leeftijd intact blijven.