Electroencephalography in premature and full-term infants. Developmental features and glossary.

Following the pioneering work of C. Dreyfus-Brisac and N. Monod, research into neonatal electroencephalography (EEG) has developed tremendously in France. French neurophysiologists who had been trained in Paris (France) collaborated on a joint project on the introduction, development, and currently available neonatal EEG recording techniques. They assessed the analytical criteria for the different maturational stages and standardized neonatal EEG terminology on the basis of the large amount of data available in the French and the English literature. The results of their work were presented in 1999. Since the first edition, technology has moved towards the widespread use of digitized recordings. Although the data obtained with analog recordings can be applied to digitized EEG tracings, the present edition, including new published data, is illustrated with digitized recordings. Herein, the reader can find a comprehensive description of EEG features and neonatal behavioural states at different gestational ages, and also a definition of the main aspects and patterns of both pathological and normal EEGs, presented in glossary form. In both sections, numerous illustrations have been provided. This precise neonatal EEG terminology should improve homogeneity in the analysis of neonatal EEG recordings, and facilitate the setting up of multicentric studies on certain aspects of normal EEG recordings and various pathological patterns.

[Electroencephalography of the premature and term newborn. Maturational aspects and glossary]. / Electroencéphalographie du nouveau-né prématuré et à terme. Aspects maturatifs et glossaire.

From the first publication of C. Dreyfus-Brisac and N. Monod, a strong tradition combined with tremendous development of neonatal EEG has taken place in France. After 3 years of collaborative work, 12 clinical neurophysiologists trained at the Port-Royal medical school in Paris detail in this paper the currently available neonatal EEG recording techniques. They have synthesized the criteria of maturational state analysis and have defined the normal and pathological neonatal EEG patterns, including descriptions already present in the French as well as the English literature. In this review one may find a complete description of neonatal EEG patterns according to the states of vigilance and to gestational age. Furthermore, definitions of all normal and pathological patterns are provided in a glossary. Both chapters are illustrated by numerous figures. This detailed terminology in neonatal EEG should allow a better homogeneity in EEG reports, and could lead to multicentric studies on normal, unusual or pathological patterns, according to etiology. Although based on analogic EEG data, this work can equally be applied to digitized EEG tracings.

[Severe periventricular leukomalacia: characteristic electroencephalographic features]. / Leucomalacies périventriculaires graves: à propos de quelques aspects électroencéphalographiques particuliers.

Periventricular leukomalacia is an infrequent but severe lesion in the premature neonate. The presence of positive rolandic sharp waves (PRSW) on the electroencephalogram, regardless of their morphology, is a reliable marker of periventricular ischemia, justifying systematic EEG monitoring during the first three weeks of life for infants born at less than 34 weeks of amenorrhea. A retrospective study of 32 premature neonates with extensive cavitary periventricular leukomalacia confirmed the early occurrence of positive rolandic sharp waves in 84% of premature newborns. The mean rate of PRSW was 1.54/min, but showed great variability. In C(Z), these sharp waves which were more frequent or isolated in one case, had the same value as those recorded in C3 or C4. Four neonates had no PRSW, but late periventricular leukomalacia was diagnosed at one month of age. As all these premature infants were born before 29 weeks of amenorrhea, longer EEG monitoring was justified. The prognosis was very poor: 17 newborns died, 11 had motor, sensory and intellectual impairment, and three had motor lesions.

Positive temporal sharp waves in electroencephalograms of the premature newborn.

Positive temporal sharp waves (PTS) were studied in electroencephalograms (EEG) of 92 premature infants born either at 31 and 32 weeks of gestational age, recorded during the first week of life. The infants were assigned either to a reference group (asymptomatic) or to one of three pathologic groups (neonatal asphyxia, hypoglycemia or hypocalcemia, or periventricular leukomalacia with rolandic positive sharp waves). Regardless of the group, no significant differences in PTS criteria (morphology, frequency, amplitude, duration and lateralization) were found between 31- and 32-week infants. The PTS observed in 55% of the asymptomatic infants were characterized by low frequency (0.13 +/- 0.12/min), a mean amplitude of 109.8 +/- 25.8 microV and a mean duration of 148.7 +/- 35.4 ms. For PTS recorded in 72 to 75% of pathologic infants, mean duration and amplitude were significantly greater in all groups than in asymptomatic infants, whereas frequency was significantly greater only in the group presenting with asphyxia. Discriminant analysis based on the three PTS criteria (frequency, amplitude and duration) allowed correct classification for only 30 to 54% of infants in the four groups. The frequency of PTS decreased rapidly during the second week of life in asymptomatic infants, but persisted in a larger number of infants in the pathologic groups. This study shows that PTS have no negative significance when they are few in number, short in duration, moderate in amplitude and rapidly regressive, thus probably reflecting the vulnerability of the temporal lobe during the traumatic period of birth. However, they require attention when they are abundant and/or slow, ample or tend to persist. They may thus constitute a nonspecific response to injury to an immature brain.

Heart rate changes during sleep in normal two-month-old infants.

Thirty-five normal two-month-old infants had nighttime followed by daytime polygraphic recordings. Heart rates were calculated every minute in active and quiet sleep states. A difference in mean heart rates was found between the two states and between the two recordings. Rates were lower at night than during the day (P < 0.0001), regardless of the sleep state. During nighttime or daytime recordings as a function of sleep cycles or during sustained sleep episodes, heart rates were minimal in the middle of recordings, but differences were statistically significant for only a few results (mainly in QS). Intrasleep awakening led to a marked increase in heart rate after sleep was resumed, although differences were only statistically significant when the awakened infant was fed. Infants with episodes of periodic breathing had lower mean heart rates throughout the recordings, but differences were not statistically significant. Respiratory and heart rates showed similar changes during the recordings, and a statistically significant correlation was found between the two measurements.

[Maturation of generalized motility, spontaneous during sleep, from birth at term to the age of 6 months]. / Maturation de la motilité généralisée, spontanée au cours du sommeil, de la naissance à terme à l'âge de 6 mois.

This work analysed the evolution of generalized motility from normal birth (39 to 40 weeks of gestational age) to six months of age, in 73 healthy infants during sleep, according to age. Sleep polygraphic recordings were performed in the morning; body movements were recorded with piezo-electric accelerometers. Our results showed that the number of movements per sleep hour was higher in active sleep (AS) as compared to quiet sleep (QS) whatever the age although the difference was less important in neonates (P < 0.05) than after one month of life (P < 0.001). The number of movements and the percentage of time spent in movements decreased with age; however in QS these parameters decreased sharply from birth to one month and a half but then did not significantly differ; in AS they became progressively lower. There were no statistically significant differences in the duration of body movements between sleep states in each age group; their mean duration became shorter from birth to six months of age (in AS P < 0.0001 and in QS P < 0.05). The distributions of the number of movements throughout the sleep stage were different according to sleep state and age. The movements were equally distributed during AS whatever the age and in the neonate group during QS; in older infants, the number of movements increased at the beginning and at the end of QS stages. During the first six months of life, spontaneous motility during sleep was inhibited, however, this process differed in quiet and active sleep. The relationship between body movements and sleep stages' organisation became closer during maturation.

[Diagnosis of brain death in the newborn and the child]. / Diagnostic de la mort cérébrale chez le nouveau-né et l'enfant.

The purpose of this article was to sum up the problems raised by diagnosis of brain death in the child through a review of the literature. The clinical and paraclinical criteria of the diagnosis are considered in terms of the respective value and complementarity of different examinations. The fact that organ removal has become increasingly frequent in the child requires a rapid and reliable determination of the irreversibility of brain damage. The guidelines set up after conferences in which American authors participated to reach a consensus opinion relate to the child's age, the etiology, of the coma and the results of various paraclinical examinations. The diagnostic value of these examinations is assessed and the limitations of the various approaches are considered, particularly as regards certain etiologies in the newborn. It is suggested that it would be useful to inquire into the different diagnostic means used in France with respect to this difficult problem. Finally, the ethical and moral problems raised by some recent practices such as organ removal in anencephalic patients are discussed.

[The frequency of respiratory variations during daytime and nighttime sleep in 35 normal 2-month-old infants]. / Variations de la fréquence respiratoire au cours du sommeil de jour et de nuit chez 35 nourrissons normaux âgés de 2 mois.

Daytime and nighttime polygraphic recordings were made of 35 normal 2-month-old infants. Respiratory rate was calculated every minute in active (AS) and quiet (QS) sleep states. The study indicates a difference in mean rate between the 2 states and also shows that mean respiratory rate was lower at night than during the day (P less than 0.0001 for both states) and that there was a marked increase in rate during the first cycle. Infants with episodes of periodic breathing had a lower mean respiratory rate throughout the recordings. For each QS phase, both day and night, a marked decrease in mean respiratory rate occurred, especially during the first part of the sleep state, which was not found in AS. Intrasleep spontaneous awakening led to a marked increase in respiratory rate after sleep was resumed both in QS and AS. However, differences were only statistically significant when the awakened infant was fed. There was less difference between respiratory rates after spontaneous awakening without feeding since the pre-awakening rate was more elevated than when the infant was subsequently fed.

[Evolution of gross body movements during sleep in healthy infants aged from 1 to 4 months]. / Evolution des mouvements corporels globaux au cours du sommeil chez des nourrissons témoins, âgés de 1 à 4 mois.

To assess the evolution of body motility according to sleep states and age in young children, we performed day-sleep polygraphic recordings in 45 normal and full-term newborn infants, grouped according to age: 5 to 7 weeks, 9 to 11 weeks, 13 to 15 weeks of age. Generalized gross body movements were only studied. Our results showed that generalized movements varied according to sleep states and also according to age. The number of movements, in each age-group was significantly higher in active (AS) and indeterminate (IS) sleep than in quiet sleep (QS). This work also found that the distribution of the number of movements differed between sleep states. In AS, movements were equally distributed whereas in quiet sleep 40% of movements occurred during the last three minutes of a stage. Our results also showed that the mean number of movements per sleep hour, the mean duration of body movements and the percentage of time spent with movements significantly decreased with age. The distribution of the number of movements as a function of duration, showed that most of them lasted from 5 to 10 sec in each age-group of infants, whatever the sleep state; however, the number of the longest movements, lasting more than 10 sec, significantly decreased with age in IS and AS. These results were difficult to compare with those already published in the literature because of the different techniques for recording body movements; so it seemed impossible to use normal values established by other authors.

[Digital vibration syndrome and carpal tunnel syndrome: possible neurophysiological differences?]. / Syndrome digital des vibrations et syndrome du canal carpien: deux entités electrophysiologiques différentes?

Workers using vibrating tools are exposed to vascular and nervous symptoms called vibration syndrome (VS); moreover, the same subjects show increased prevalence of possible carpal tunnel syndrome (CTS). To determine the diagnostic criteria of both syndromes, we studied clinical and neurophysiological signs and differences in 18 patients with VS and in 18 with CTS; neither group had any other pathologic symptoms. Clinical symptoms clearly distinguished the 2 groups of patients: Raynaud's phenomena were mainly observed in patients with VS (83% of cases), whereas Tinel's sign was found exclusively in patients with CTS (56% of cases). Neurophysiological results were qualitatively similar in both patients groups compared to control group results, showing a significant decrease in median motor and sensory nerve conduction velocities (NCV), a significantly higher motor distal latency and a lower nerve action potential amplitude. These group results and the scattering of interindividual results did not allow us to classify any given patient in one group or the other. Nevertheless, statistical analysis showed differences between the 2 patient groups: median abnormalities were more severe, especially as revealed by the abductor pollicis brevis electromyogram, in patients with CTS, whereas ulnar motor distal latency and motor and sensory NCV were abnormal, exclusively in 50% of patients with VS. These results lend support to the assumption that the mechanical and vascular mechanisms responsible for lesions in both groups of patients may differ in nature or occur in a different sequence.

[Body movements during sleep in the infant: comparison between control infants and siblings of infants dying of sudden infant death syndrome]. / Etude des mouvements corporels au cours du sommeil chez le nourrisson: comparison entre nourrissons témoins et nourrissons issus d'une fratrie de mort subite inexpliquée du nourrisson.

Day-sleep polygraphic recordings were performed in 10 normal infants and 10 siblings of infants who died of sudden infant death syndrome. Body movements were studied in both groups of infants during 3 stages of sleep. In controls and siblings, the mean number of body movements per sleep hour, per infant was respectively 7 or 6 in quiet sleep and 22 and 23 in REM sleep; the mean duration of body movement was longer (11.3 sec) in REM sleep than in non-REM sleep (9.4 sec). In both cases, there was no significant difference between the 2 groups. An analysis of the movement duration showed that most of them lasted between 5 and 10 sec and in siblings were statistically more numerous during indeterminate sleep. In both groups, these movements appeared more often at the beginning and at the end of the quiet sleep, but were more equally distributed in the REM sleep. Respectively 15 and 13.7% of these movements in the normal and sibling group were accompanied by a brief respiratory pause. The relation between body movements and sleep is discussed.

[Digital vibration syndrome: neuro-physiologic study in 17 patients]. / Syndrome digital des vibrations: étude neuro-physiologique chez 17 patients.

Studies were carried out on 17 male workers with clinical vibration disease who had been working with different vibrating tools (compressed-air hammers, chain-saws, rock drills, grinders) for 2 to 39 years. Their neurophysiological results were compared with those of 20 healthy men (control group). Median motor nerve conduction velocity (NCV) between elbow and wrist was significantly reduced and motor distal latency (DL) significantly longer in 43% cases. A distinct decrease of the conduction velocity of distal (finger-wrist) median sensory fibers (in 56% of cases) as well as reduced amplitude of the sensory evoked potential (62% of cases) were found. EMG showed alterations only in patients with NCV abnormalities. These electrophysiological findings point to distal axonal as well as to demyelination damage. The results, which are discussed in relation to previously published work in this field and according to a pathogenetic hypothesis of this syndrome, allowed us to draw practical conclusions for the neurophysiological examination of patients with vibration disease.

[Kidney failure patients undergoing hemodialysis with aluminum poisoning after renal transplantation: electro-clinical aspects]. / Insuffisants rénaux en hémodialyse atteints d'intoxication à l'aluminium et greffe renale: aspects électro-cliniques.

A renal transplantation was performed on 6 dialysis patients using high concentration aluminum water. The post-graft course in 3 patients led to the appearance of worsening or neurological symptoms, with associated deterioration on the EEG. In 3 other patients there was progressive improvement in clinical signs, though with long-term persistance of electrical abnormalities in 1 case. These 6 cases are compared with 10 dialysis patients without aluminum intoxication who underwent renal transplantation in the same conditions. These results are then analyzed with reference to those already published in the literature. Three factors (length of exposure, water aluminum concentration and seizure disorder) seem significant to the prognosis of renal transplantation in patients with aluminum intoxication.

[Motor nerve conduction velocity in children: normal values and application to a few pathologic cases]. / Vitesses de conduction nerveuse motrice chez l'enfant: valeurs normales et applications à quelques cas pathologiques.

Nerve conduction velocity (NCV), according to age, was studied in normal children. Motor distal ulnar NCV (in 63 children, from 1 day to 4 years of age), motor distal tibial NCV (in 93 children, from birth to 15 years of age), proprioceptive tibial NCV (in 59 children, from birth to 5 years of age) and proximal CV (in 133 children from birth to 15 years of age), as well as VIIth superior branch CV (in 67 children) and XIIth CV (in 56 children) from birth to 3 years of age, were measured. These measurements showed that NCV changes were similar; NCV was 45-50% of the adult value during the first month of life. Then NCV increased very quickly, the progression being 90% of the first month's value during the first 18 months of life. The adult value was reached between 2 and 5 years of age. Proprioceptive NCV was 8-13 m/sec higher than motor NCV; proximal NCV was also 10-13 m/sec higher than distal motor tibial NCV. Ulnar NCV remained higher than tibial NCV, although changes in velocity as a function of age remained parallel. These NCV measurements proved significant in some diseases. The were useful for diagnosis of Krabbe's disease or of metachromatic leucodystrophy and to calculate the degree of disturbance in toxic polyneuritis, polyradiculoneuritis and some cranial nerve injuries; they were also useful in following up children undergoing chronic haemodialysis. In each case, NCV was only one aspect of a more complete neurophysiological study.

Maturation of the blink reflex in infants.

The blink reflex was elicited in 50 children from birth to 3 years of age. In the awake state, the R1 response was always obtained; R2 responses, especially contralateral ones, were more difficult to elicit under 9 months of age. R1 latency and VIIth motor nerve conduction variations were a good witness of the peripheral nervous system maturation. The influence of the different states of waking and sleeping on these reflex responses was studied. These results and some of the mechanisms that underlie these changes are discussed.

[Development of the blink reflex during the 1st 3 years of a child's life]. / Evolution du réflexe de clignement pendant les trois premieres années de la vie chez l'enfant.

The blink reflex was elicited in 42 awake and quiet children from birth to 3 years of age. The R1 ipsilateral reflex response was always recorded. Its latency decreased significantly during the first 6 months of life whereas the VIIth nerve motor conduction velocity increased markedly; its threshold stimulus was lower in children after 1 year of age. R2 responses, especially contralateral ones, were sometimes absent in infants under 9 months of age; beyond that age, they were constant and bilateral. The ipsilateral R2 latency response diminished during the first 6 months of life, and the R2 reflex threshold became lower in infants above 1 year of age. When elicited after crying, in 22 children, the reflex components were facilitated; R1 response occasionally appeared bilaterally, its amplitude increased and its threshold was lower. During REM sleep, in 12 children, the reflex responses were similar to those recorded during quiet wakefulness. On the contrary, non-REM sleep recorded in 12 children markedly depressed the reflex responses; this inhibition was more pronounced for R2 responses.

[Localized fast rhythms in EEG tracings following surgery for intracranial meningioma]. / Les rythmes rapides localisés sur les traces EEG après intervention pour méningiome intra-cranien.

Forty-six patients were followed up after removal of an intracranial meningioma. Nine of the 46 patients in their 3rd month postoperative EEG had localised fast rhythms which remained stable. The fast rhythms appeared in small 20-25 Hz and 20-40 microV bursts; they were localised over the craniotomy flap as shown by the control X-ray of the sites of the electrodes; they were unaffected by eye-opening and slightly reduced by fist-clenching. These fast rhythms were sometimes mixed with sharp waves and theta activity and seemed to be equivalent to the 'breach rhythm' described first by Fischgold et al. (1952) and then by Cobb et al. (1979). In our study, these rhythms were more frequently observed in patients with an olfactory or sphenoidal meningioma, in patients with pre-operative seizure and in patients with an extensive post-operative intracranial atrophy (as shown by the scanner). On the other hand, incomplete removal or recurrence of the tumour or post-operative epilepsy did not seem to play a role in the appearance of these rhythms.

[Electroencephalographic changes in patients with cardiopathies, subsequently operated under extracorporeal circulation. Significance and outcome. Evaluation of 679 cases]. / Altérations électroencéphalographiques chez des patients atteints de cardiopathies, opérés ultérieurement sous circulation extracorporelle. Signification et devenir. Bilan de 679 dossiers.

This study analysed the pre-operative electroencephalographic recordings of 679 patients with heart disease, later undergoing surgery under extra-corporeal circulation. The type and the severity of the abnormalities are listed for each heart disease. These results are compared to those already published in the literature on this subject and are discussed in terms of a number of possible aetiological factors: the age of the patients, data provided by the pre-operative cardio-pulmonary assessment. This analysis does not enable us to demonstrate, with any statistical significance, the aetiological factor(s) of these electroencephalographic alterations. Finally, comparison of the pre-, intra- and postoperative EEG in the same patients enables us to evaluate the prognostic value of these electrical abnormalities.

[Electroclinical aspects of intramuscular methohexital anesthesia in children]. / Aspects éléctrocliniques de l'anesthésie au méthohexital intramusculaire chez l'enfant.

Intramuscular methohexital is used in children for short-term anaesthesia. As a seizure was observed in two of our cases after administration of this barbiturate, an EEG study was performed. The EEG pattern was characterized by a particularly slow, sharp, high voltage stage with a decrease of fast rhythms (stage 3a), then fast and sharp rhythms becoming more and more frequent (stage 3b). These stages were particularly pronounced and prolonged in children over 3 years of age, with myoclonic jerks observed in 6 cases, beginning about 3 min after methohexital injection and at the same time as the clinical seizures. These results are discussed in terms of previously reported descriptions of barbiturate anaesthesia, and especially of i.m. or i.v. methohexital anaesthesia. This anaesthetic, although reliable and easy to use, should in our opinion be avoided in epileptic children.