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Excessive daytime sleepiness (EDS) is multifactorial. It combines, among other things, an excessive propensity to fall asleep ("physiological sleepiness") and a continuous non-imperative sleepiness (or drowsiness/hypo-arousal) leading to difficulties remaining awake and maintaining sustained attention and vigilance over the long term ("manifest sleepiness"). There is no stand-alone biological measure of EDS. EDS measures can either capture the severity of physiological sleepiness, which corresponds to the propensity to fall asleep, or the severity of manifest sleepiness, which corresponds to behavioral consequences of sleepiness and reduced vigilance. Neuropsychological tests (The psychomotor vigilance task (PVT), Oxford Sleep Resistance Test (OSLeR), Sustained Attention to Response Task (SART)) explore manifest sleepiness through several sustained attention tests but the lack of normative values and standardized protocols make the results difficult to interpret and use in clinical practice. Neurophysiological tests explore the two main aspects of EDS, i.e. the propensity to fall asleep (Multiple sleep latency test, MSLT) and the capacity to remain awake (Maintenance of wakefulness test, MWT). The MSLT and the MWT are widely used in clinical practice. The MSLT is recognized as the "gold standard" test for measuring the severity of the propensity to fall asleep and it is a diagnostic criterion for narcolepsy. The MWT measures the ability to stay awake. The MWT is not a diagnostic test as it is recommended only to evaluate the evolution of EDS and efficacy of EDS treatment. Even if some efforts to standardize the protocols for administration of these tests have been ongoing, MSLT and MWT have numerous limitations: age effect, floor or ceiling effects, binding protocol, no normal or cutoff value (or determined in small samples), and no or low test-retest values in some pathologies. Moreover, the recommended electrophysiological set-up and the determination of sleep onset using the 30‑sec epochs scoring rule show some limitations. New, more precise neurophysiological techniques should aim to detect very brief periods of physiological sleepiness and, in the future, the brain local phenomenon of sleepiness likely to underpin drowsiness, which could be called "physiological drowsiness"., Competing Interests: Declaration of Competing Interest No conflicts of interest were reported for this study., (Copyright © 2023 Elsevier Masson SAS. All rights reserved.)

The French Society of Research and Sleep Medicine (SFRMS) organized a meeting on obstructive sleep apnea syndrome (OSAS) in children. A multidisciplinary group of specialists (pulmonologist, ENT surgeons, pediatricians, orofacial myofunctional therapists, neurophysiologists, and sleep specialists) reached a consensus on the value of isolated or clustered clinical symptoms and of questionnaires completed by parents in the clinical diagnosis and in assessing the severity of OSAS. Are clinical history with validated questionnaires and a rigorous physical examination sufficient to suspect OSAS, to appreciate its severity, and finally to confirm the diagnosis? Usually, a sleep recording of respiratory parameters remains mandatory for the diagnosis of OSAS to be made. However, clinical symptoms are very useful for estimating the probability of the diagnosis and the severity of the disease, and therefore for classifying which children will benefit form polysomnography and for proposing an adapted follow-up after OSAS therapy. Even if they are not able to ascertain the diagnosis of OSAS in children, clinical history, questionnaires, and physical examination are very important. Finally, we propose a classification of the indications for polysomnography in children suspected of having OSAS., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

This article presents normal EEG characteristics and their maturational pattern in premature infants of 24-30 weeks gestational age. Although the very premature infants with a normal outcome are not that numerous, their normal EEG pattern should be known, as EEG constitutes a basis for neurological prognosis. Background activity is first discontinuous but the discontinuity gradually decreases and the activity is completely continuous at 30 weeks of age, during active sleep. At the same time, interburst intervals become shorter so that the proportion of time without EEG activity decreases. Based on EEG activity and eyes movements, a rough sleep state differentiation appears as early as 25 weeks of gestational age and is complete at 30 weeks. The main EEG figures are high-voltage delta waves, whose frequency is slower and amplitude higher in younger infants. Temporal delta waves occur in sequences and are characteristic of the very premature infant; they progressively become smaller and less numerous and disappear around 27-28 weeks. In contrast, occipital delta waves remain numerous; they are of high voltage and usually bilaterally superimposed with fast rhythms. Both types of frontal delta waves that are seen in 24-27 weeks premature babies disappear with maturation. Bursts of synchronized delta waves, which are less numerous than localized delta waves, also disappear before 28 weeks of gestational age. Finally, diffuse theta bursts which are mainly recorded at 26-27 weeks, progressively focus on temporal areas with maturation. At 30 weeks, they are observed on temporal areas, mainly during slow-wave sleep.

Electroencephalography (EEG) recording techniques in early premature babies are not very different from those used for full-term neonates. Here, we emphasise the most important points: asepsis precautions, full knowledge of the clinical data and drug therapies, fundamental role of a well-trained technician in supervising the EEG recording and monitoring the baby. We discuss the best electrode positions, the most informative montages, and their standardisation between neurophysiological laboratories. Artefact detection constitutes an important aspect of EEG signal analysis in preterm babies of less than 30 weeks. It is obviously necessary to discriminate between meaningful information and artefacts. The complexity of the signal in neonates makes artefact detection difficult. We present some characteristic features and describe some methods for eliminating them. We underline the positive aspect of some artefacts and their clinical use. We emphasise the crucial role of the technicians.

This article aims at summarizing normal EEG criteria and their maturational pattern in premature infants of 24 to 30 weeks gestational age. Although very premature infants with a normal outcome are not numerous, their normal EEG patterns must be known, as EEG constitutes a basis for neurological prognosis. Background activity is first discontinuous. Discontinuity decreases thereafter with increasing age, so that some long periods of continuous activity may be observed in active sleep, around 30 weeks of age. Conversely, interburst intervals become shorter and the proportion of time without EEG activity is decreasing. Based on EEG activity and eye movements, a rough sleep-state differentiation was described as soon as 25 weeks of gestational age and is completely achieved at 30 weeks. The main EEG figures are high-voltage delta waves of higher amplitude and slower frequency in younger infants. Temporal delta waves occur in sequences, these are very characteristic of the very premature infant; thereafter, they become smaller, less numerous and eventually disappear around 27-28 weeks. In contrast, occipital delta waves remain numerous and of high voltage, are usually bilateral and superimposed with fast rhythms. The two types of frontal delta waves that are observed in 24-27 weeks prematures disappear with maturation. Bursts of synchronized delta waves are less numerous than localized delta waves and also disappear before 28 weeks of age. Finally, diffuse theta bursts are mainly recorded at 26-27 weeks GA and become more localized in temporal areas with maturation. At 30 weeks, they are observed on temporal areas, mainly during slow-wave sleep.

EEG recording techniques in early premature babies are not very different from those used for full-term neonates. Here, we emphasise the most important points: asepsis precautions, full knowledge of the clinical data and drug therapies, the fundamental role of a well-trained technician in supervising the EEG recording and monitoring the baby. The best electrode positions, the most informative montages and their standardisation between neurophysiological laboratories, are suggested. Artifact detection constitutes an important aspect of EEG signal analysis in preterm babies of less than 30 weeks. It is obviously necessary to discriminate between meaningful information and artefacts. The complexity of the signal in neonates makes artifact detection difficult. We present some characteristic features and describe some methods for eliminating them. We underline the positive aspect of some artifacts and their clinical use. We emphasise the crucial role of the technicians.

This review deals with F responses, which are late responses obtained by supramaximal stimulation of virtually all the motor and mixed peripheral nerves. They are recorded over a muscle innervated by the stimulated nerve. The first description of F-waves was published in the fifties. Their neurophysiological mechanisms have been abundantly discussed in the literature leading to a current consensus, whereby F-waves are considered as antidromic responses produced by a pool of motoneurons activated by peripheral nerve stimulation. In the first part of this review, the neurophysiological mechanisms of F-waves as well as the distinction between these and H reflexes are described from a historical point of view. Other late responses are intentionally not reported; nevertheless A-waves are discussed since they are frequently ill-described in a number of conditions. Stimulation and recording procedures as well as F-wave parameters analysis are detailed, with emphasis on measures most useful for clinical purposes. A rigorous F-wave recording method is mandatory for reliable and meaningful analyses. Physiological factors, which influence F-waves such as ageing, drugs and sleep, must be known and their effects discussed. Also, as maturation is an important factor in clinical neurophysiology, data on F-wave ontogenesis are reviewed and discussed. Finally, the different F-wave alterations described so far in the literature, in either peripheral or central disorders, are listed and commented. It is emphasised that F-waves are particularly useful for the diagnosis of polyneuropathies at a very early stage and for the diagnosis of proximal nerve lesions. F-wave recording is indeed one of the rare methods in routine examination allowing at the same time the functional assessment of motor fibres on their proximal segment, and contributing to the evaluation of motoneuronal excitability.

The electroencephalogram (EEG), an easy-to-use and non invasive cerebral investigation, is a useful tool for diagnosis and early prognosis in newborn babies. In newborn full term babies manifesting abnormal clinical signs, EEG can point focal lesions or specific aetiology. EEG background activity and sleep organization have a high prognostic value. Tracings recorded over long period can detect seizures, with or without clinical manifestations, and differentiate them from paroxysmal non epileptic movements. The EEG should therefore be recorded at the beginning of the first symptoms, and if possible before any seizure treatment. When used as a neonatal prognostic tool, EEG background activity is classified as normal, abnormal (type A and type B discontinuous and hyperactive rapid tracing) or highly abnormal (inactive, paroxysmal, low voltage plus theta tracing). In such cases, the initial recording must be made between 12 and 48 h after birth, and then between 4 and 8 days of life. Severe EEG abnormalities before 12 h of life have no reliable prognostic value but may help in the choice of early neuroprotective treatment of acute cerebral hypoxia-ischemia. During presumed hypoxic-ischemic encephalopathy, unusual EEG patterns may indicate another diagnosis. In premature newborn babies (29-32 w GA) with neurological abnormalities, EEG use is the same as in term newborns. Without any neurological abnormal sign, EEG requirements depend on GA and the mother's or child's risk factors. Before 28 w GA, when looking for positive rolandic sharp waves (PRSW), EEG records are to be acquired systematically at D2-D3, D7-D8, 31-32 and 36 w GA. It is well known that numerous and persistent PRSW are related to periventricular leukomalacia (PVL) and indicate a bad prognosis. In babies born after 32 GA with clinically severe symptoms, an EEG should be performed before D7. Background activity, organization and maturation of the tracing are valuable diagnosis and prognosis indicators. These recommendations are designed (1) to get a maximum of precise informations from a limited number of tracings and (2) to standardize practices and thus facilitate comparisons and multicenter studies.

The aim of this prospective study was to describe and quantify EEG patterns in 10 very premature infants (24 weeks 2 days- 26 weeks 4 days GA) without neonatal neurological pathology and with a normal outcome at 3 years of age for nine of them. EEG and eye movements were recorded in the first 5 days of life. All tracings were discontinuous; EEG inactivity (<15 microV) never exceeded 1 min, representing 45.3% of total recording time. The EEG bursts, mainly synchronous, could last up to 83 s when >50 microV and to 197 s when >15 microV. High voltage delta waves (0.5 Hz; up to 330 microV), either smooth or superimposed with 7-12 Hz rhythms, were the most typical and frequent figures, mainly in temporal (mean number 257.2 +/- 73.3) and occipital (237.7 +/- 65.8 per hour recording) areas. In temporal areas, they appeared mainly in clusters; more often unilateral than bilateral (P < 0.05). Occipital delta waves were as often bilateral and synchronous as unilateral. The two distinct frontal delta waves were significantly less numerous than other delta waves (P < 0.05). Bursts of hypersynchronous high voltage delta waves and of diffuse sharp theta waves were less numerous than other waves (P < 0.01). Considering periods with or without eye movements, the mean percentage and the mean longest period of EEG activity (< or =50 microV) were significantly greater (P < 0.01) when eye movements were present, indicating a rough sleep state differentiation as early as 25 weeks CA. These EEG patterns are qualitatively and quantitatively reproducible. They constitute standards of normality and a basis for the determination of neurological prognosis.

Intramuscular methohexital was used in pediatric anesthesia to carry out special investigations. There seemed to be few side effects but twitches or seizures have been reported. An electroencephalographic study was performed in normal children. The electroencephalogram showed periods of increased amplitude. The authors discussed the problem of side effects following the intramuscular administration of methohexital in the normal child, and prescribed its use in the epileptic.