- Email: [email protected]
Rudimentary spike-wave complexes in children during drowsiness
247
Neurophysiol Clin (1990) 20, 247-252 © Elsevier, Paris
Original article
Rudimentary spike-wave complexes in children during drowsiness A Pelliecia*, F Giannotti, G Trasatti I st Chair o f ChiM Neuropsychiatry, University o f Rome La Sapienza, Via dei SabellL 108, 00185 Roma, Italy (Received 13 November 1989; accepted 26 June 1990)
Summary - This study consists of the investigation of the anamnestic and electroclinical features of 37 children who showed paroxysmal activity on EEG during drowsiness. This activity is composed of generalized slow high-voltage waves with intermixed spikes and sharp waves (Rudimentary Spike-Wave complexes). All the children had suffered from febrile convulsions, with none of them developing epileptic syndromes during the 3 years following the onset of the study. We point out the diagnostic value of RSW as well as the necessity of careful monitoring of the waking-drowsy state during EEG in children with febrile convulsions. electroencephalography / drowsiness / rudimentary spike-wave complexes / febrile convulsions
R~sum~ ~,, Pointes-ondes rudimentaires de I'endormissement chez l'enfant. On a ~tudi6 les caract6ristiques anamnestiques et ~lectrocliniques de 37 enfants, qui montraient, ~t I'EEG de l'endormissement, une activit6 paroxystique d'ondes lentes g6n6ralis6es d'amplitude 61ev6e avec l'inscription de pointes (Pointe-Ondes Rudimentaires POR). Tousles enfants ont eu des convulsions f6briles simples et aucun d'entre eux n'a d~velopp6 une 6pilepsie pendant les trois ann6es suivantes. On souligne l'importance diagnostique des POR chez les enfants avec des convulsions f6briles simples et la n~cessit6 de l'enregistrement du trac6 EEG pendant l'endormissement pour rendre cette activit6 6vidente. electroenc~phalographie / endormissement / pointes-ondes rudimentaires / convulsions f~briles
* Correspondence and reprints. Istituto di Neuropsichiatria Infantile dell' l'Universit~ di Roma "La Sapienza", Via dei Sabelli, 108, 00185 Roma, Italy
248
A Pelliecia et al
Introduction
A paroxysmal rhythmic theta activity, also called "hypnagogic hypersyncrony" (Samson-Dollfus et al, 1981), has been observed in normal children up to the age of 2-3 years (Kellaway and Fox, 1950, Brandt and Brandt, 1955). Gibbs and Gibbs (1964) described a similar drowsy pattern in infancy and early childhood consisting o f generalized high voltage 3-4 Hz waves - " with a poorly developed spike in the positive troughs between the slow waves " . This latter activity, however, can be easily distinguished from the former by the occurrence of bursts lasting less than 5 s rather than prolonged stretches containing small spikes that appear as atypical spike-waves and thus justify the term Rudimentary Spike-Waves (RSW) (Niedermeyer and Lopes da Silva (1987) (fig 1). RSW are never associated with clinical manifestations, occur only during drowsiness and disappear with the deepening of sleep passing from stage 1 to stage 2 (appearance of sleep spindles). This phenomenon has frequently been found on EEGs carried out on children and described as atypical spike-and-wave activity,
o
T4-C4
C,-Cz Cz-C C.-T. FP.C4 C,-O FP -C C.-O 50~V l lsec
P.I. 4,2aa
Fig 1. RSW complexes in drowsiness in a child with a history of febrile convulsions.
Spike-Wawe complexes in children during drowsiness
249
N. OF PATIENTS 13 12 11 10
9 8 7
6 5 4 3 2 1 0 0.1-0.6 0.7-1 1.1-1.6 1.7-2 2.1-2.6 2 . 7 - 3 3.1-3.6 3 . 7 - 4 4.1-4.6 4 . 7 - 5 5.1-5.6 5 . 7 - 6
YEARS Age of first F.C.
i
Age of first R S W
Fig 2. Age at the first febrile convulsion and first EEG with RSW. " l a r v a l p e t i t - m a l " ( L e n n o x - B u c t h a l , 1973), h y p n a g o g i c p a r o x y s m a l s p i k e - w a v e activity ( A l v a r e z et al, 1983) or bursts o f large a m p l i t u d e t h e t a with i n t e r m i x e d s p i k e - a n d - s h a r p - w a v e - l i k e activity ( T h a r p , 1986). Since the clinical significance o f R S W has n o t b e e n clarified, t h e a i m o f this i n v e s t i g a t i o n was to s t u d y the clinical c o r r e l a t e s o f this p a r o x y s m a l activity.
Subjects i~and Methods This study is based upon the intake of the EEG laboratory at the Institute of Child Neuropsychiatry, University of Rome La Sapienza, for a period of 6 months, from January to June 1986. During that period 1975 EEGs were carried out. Patients with only waking EEGs had to be eliminated since RSW do not occur in a waking state. A total of 130 out of 462 sleep EEGs were retained because of the availability of a clear sequence of awakedrowsy and NREM sleep states (stage l, 2 and sometimes 3). Rigid adherence to this sequence is necessary for the study of RSW. Drowsiness and sleep were always spontaneous. Among these patients we selected a group of 37 children (18 boys and 19 girls), aged from 16 months to 5 years 4 months (mean age: 4.1 yrs), with RSW. Clinical history including family history of febrile convulsions of epilepsy was carefully studied. General physical and neurological examinations as well as EEGs were carried out on each child at the onset of the study and subsequently at intervals for a period of at least 3 years. In this group it was possible to review the EEGs of 26 children recorded previously. The EEGs were recorded with 8 channel machines. The electrodes were placed following the International 10-20 System, using bipolar montages.
250
A Pelliecia et al
Results
All the children suffered from one or more febrile convulsions. In 15 (41.5%) there was a family history of febrile convulsions and in 6 (16.2%) a family history of epilepsy. In all cases, intellectual development as well as general and neurological examinations were normal. The first febrile convulsions occurred at a mean age of 1 year 6 months (range: 2 months, 4 years 4 months); in all but 1 patient the convulsions occurred after 6 months. There were usually simple febrile convulsions, except in 5 children who experienced longer seizures lasting about 15 min. The mean age of the first appearance was 3.4 years (range : 16 months 9 years). Twenty-two out of 26 previous recorded EEG were judged as normal. The mean interval between the first febrile convulsions and the RSW was 20 months (range: 14-25 months). During the follow-up, all the EEGs showed RSW and no patient developed neither an epileptic syndrome or an epileptiform EEG activity.
Discussion
Kellaway and Fox (1950) and Brandt and Brandt (1955) drew attention to the "paroxysmal hypnagogic hypersyncronous pattern" generally found in normal children during drowsiness and sleep. This hypnagogic rhythmical theta activity of late infancy and early childhood represents a normal feature of that period of life (Niedermeyer, 1987). A similar drowsy pattern, but with intermixed spikes, appearing as bursts of atypical spike-waves at 3-5 Hz is more debatable. Kellaway and Fox (1950) considered this to be abnormal. Gibbs and Gibbs (1964) called this activity pseudo-petit mal pattern and described it as a mild abnormality in infancy and early childhood. In their opinion this pattern is more prominent in parietal areas, disappearing by the age of 8 and often being associated wi~h febrile convulsions. Although the term pseudo-petit mal discharges seems to make it possible to equate spike- waves with petit mal, a transition into a classical or other spike-and-wave pattern has not been observed (Niedermeyer and Lopes da Silva, 1987). Samson-Dollfus et al (1984) noted this type of pattern during drowsiness in children aged from 2-3 years suffer in from "isolated convulsions, very often of febrile origin" and described it as - spike-waves which are not typical. EegOlofsson et al (1971) found a "bilateral paroxysmal activity in drowsiness and light sleep" in 47 out of 599 normal children and considered it similar to the "pseudo-petit mal discharge" of Gibbs and Gibbs (1964). A similar pattern called "Hypnagogic Paroxysmal Spike-and-Wave Activity" (HPSW) was described by Alvarez et al (1983). They were found a high incidence of febrile convulsions in children showing this activity, while no HPSW were found in 92 carefully selected normal children.
Spike-Wawe complexes in children during drowsiness
251
I n o u r findings all the c h i l d r e n showing R S W h a d suffered f r o m 1 or m o r e febrile seizures, with a high incidence o f f a m i l y history o f febrile c o n v u l s i o n s . I n almost all cases, febrile seizures had b e e n simple a n d o u t c o m e s favorable, with n o n e o f the children developing epilepsy in the following 3 years. O n a c c o u n t o f the high incidence o f f a m i l y histories o f febrile c o n v u l s i o n s or epilepsy f o u n d i n o u r g r o u p we are i n a g r e e m e n t with Alvarez et al (1983) that R S W s h o u l d be considered as a genetically t r a n s m i t t e d E E G p a t t e r n . C o n s i s t e n t with previous studies we f o u n d t h a t the a p p e a r a n c e o f R S W is age-dependent. As R S W were n o t f o u n d in children y o u n g e r t h a n 16 m o n t h s , a time lag could be possible b e t w e e n the age at the time o f the first febrile c o n v u l s i o n a n d the time o f the first E E G positive for R S W . I n accordance with Alvarez et al (1983) we t h i n k t h a t a certain degree o f m a t u r a t i o n m u s t be reached before the p a t t e r n o f R S W c a n be p r o d u c e d . M o r e o v e r , with our present investigation we are able to a f f i r m that R S W are associated with febrile c o n v u l s i o n s with a f a v o r a b l e outcome. A clear sequence o f a w a k e - d r o w s y a n d N R E M sleep is necessary to record this activity: therefore it is i m p o r t a n t to stress that for children suffering f r o m febrile c o n v u l s i o n s careful m o n i t o r i n g o f the child's w a k i n g - d r o w s y state d u r i n g E E G is unrenouncable. The c o m m o n error o f m i s t a k i n g this p a t t e r n as e p i l e p t i f o r m activity m a y result i n a misdiagnosis o f febrile c o n v u l s i o n s as epileptic seizures. Therefore we consider it i m p o r t a n t to emphasize the features of this p a r o x y s m a l activity. T h e electroclinical characteristics of R S W synthesized in table I allow us to easily recognize this activity a n d ~ivoid the consequences of incorrect diagnosis o f epilepsy.
Table I. Characteristics of Rudimentary Spike-Wave Complexes [RSW]. - Bursts of generalized slow high-voltage waves with intermixed sharp transients, occurring only in drowsiness, stage 1 of NREM sleep and less frequently on awakening. - The spikes and sharp waves intermixed with slow waves are never present at the onset of the discharges. - The spikes and sharp waves superimposed are bilateral and usually predominant in the central areas, at times being more prominent in one hemisphere, without a tendency for a fixed localization. - The frequency of the slow waves is 4-5 Hz. - The duration of RSW ranges from 1 to 5 s (on average 2 s). - The amplitude of the slow waves ranges from 100 to 200 #V, while the sharp transients are of lower amplitude (50-100 /zV). -The onset and termination of RSW are synchronous in both hemispheres. -RSW are never associated with clinical correlates. - T h e y are never followed by a shift to an arousal EEG pattern or awakening.
252
A Pelliecia et al
References Alvarez N, Lombroso CT, Medina C, Cantlon B (1983) Paroxysmal spikeand-wave activity in drowsiness in young children: its relationship to febrile convulsions. Electroencephalogr Clin Neurophysiol 56, 406-413 Brandt S, Brandt H (1955) The electroencephalographic patterns in y o u n g healthy children from O to 5 years of age. Acta Psychiatr Neurol Scand 30, 77-89 Eeg-Olofsson O, Petersen I, Sellden I (1971) The development of the electroencephalogram on normal children from the age of 1 through 15 years. Paroxysmal activity. Neuropaediatrie 4, 375-404 Gibbs FA, Gibbs EL (1964) Atlas of Electroencephalography, vol 3. Addison-Wesley, Cambridge, Mass Kellaway P, Fox BJ (1950) Electroencephalographic diagnosis of cerebral pathology in infants during sleep. I Rationale, technique, and the characteristics of normal sleep in infants. J Pediat 4, 262-287 Lennox-Buchthal M (1973) Febrile convulsions, a reappraisal. Electroence-
phalogr Clin Neurophysiol (Suppl.) 32, 12-22 Niedermeyer E, Lopes da Silva F (1987) Electroencephalography. Basic Principles, Clinical Applications and Related Fields. Urban & Schwarzenberg, Baltimore, 191 Samson-Dollfus D, Forthomme J, Capron E (1964) EEG of the human infant during sleep and wakefulness during the first year of life; normal patterns and their maturational changes; abnormal patterns and their prognostic significance, ln: Neurological and Electroencephalographic Correlative Studies in Infancy (Kellaway P, Peterson I, eds). Grune and Stratton, Inc, NY, 208-229 Samson-Dollfus D, Nogues B, Delagree E (1981) Aspects 61ectroenc6phalographiques et polygraphiques des transitions veille-sommeil chez des nourrissons normaux ~g6s de 2 12 mois. Rev EEG Neurophysiol Clin 11, 23-27 Tharp BR (1986) Neonatal and pediatric electroencephalography. In: Electrodiagnosis in clinical neurology (Aminoff M, ed). Churchill Livingstone, New York, 77-124
Neurophysiol Clin (1990) 20, 247-252 © Elsevier, Paris
Original article
Rudimentary spike-wave complexes in children during drowsiness A Pelliecia*, F Giannotti, G Trasatti I st Chair o f ChiM Neuropsychiatry, University o f Rome La Sapienza, Via dei SabellL 108, 00185 Roma, Italy (Received 13 November 1989; accepted 26 June 1990)
Summary - This study consists of the investigation of the anamnestic and electroclinical features of 37 children who showed paroxysmal activity on EEG during drowsiness. This activity is composed of generalized slow high-voltage waves with intermixed spikes and sharp waves (Rudimentary Spike-Wave complexes). All the children had suffered from febrile convulsions, with none of them developing epileptic syndromes during the 3 years following the onset of the study. We point out the diagnostic value of RSW as well as the necessity of careful monitoring of the waking-drowsy state during EEG in children with febrile convulsions. electroencephalography / drowsiness / rudimentary spike-wave complexes / febrile convulsions
R~sum~ ~,, Pointes-ondes rudimentaires de I'endormissement chez l'enfant. On a ~tudi6 les caract6ristiques anamnestiques et ~lectrocliniques de 37 enfants, qui montraient, ~t I'EEG de l'endormissement, une activit6 paroxystique d'ondes lentes g6n6ralis6es d'amplitude 61ev6e avec l'inscription de pointes (Pointe-Ondes Rudimentaires POR). Tousles enfants ont eu des convulsions f6briles simples et aucun d'entre eux n'a d~velopp6 une 6pilepsie pendant les trois ann6es suivantes. On souligne l'importance diagnostique des POR chez les enfants avec des convulsions f6briles simples et la n~cessit6 de l'enregistrement du trac6 EEG pendant l'endormissement pour rendre cette activit6 6vidente. electroenc~phalographie / endormissement / pointes-ondes rudimentaires / convulsions f~briles
* Correspondence and reprints. Istituto di Neuropsichiatria Infantile dell' l'Universit~ di Roma "La Sapienza", Via dei Sabelli, 108, 00185 Roma, Italy
248
A Pelliecia et al
Introduction
A paroxysmal rhythmic theta activity, also called "hypnagogic hypersyncrony" (Samson-Dollfus et al, 1981), has been observed in normal children up to the age of 2-3 years (Kellaway and Fox, 1950, Brandt and Brandt, 1955). Gibbs and Gibbs (1964) described a similar drowsy pattern in infancy and early childhood consisting o f generalized high voltage 3-4 Hz waves - " with a poorly developed spike in the positive troughs between the slow waves " . This latter activity, however, can be easily distinguished from the former by the occurrence of bursts lasting less than 5 s rather than prolonged stretches containing small spikes that appear as atypical spike-waves and thus justify the term Rudimentary Spike-Waves (RSW) (Niedermeyer and Lopes da Silva (1987) (fig 1). RSW are never associated with clinical manifestations, occur only during drowsiness and disappear with the deepening of sleep passing from stage 1 to stage 2 (appearance of sleep spindles). This phenomenon has frequently been found on EEGs carried out on children and described as atypical spike-and-wave activity,
o
T4-C4
C,-Cz Cz-C C.-T. FP.C4 C,-O FP -C C.-O 50~V l lsec
P.I. 4,2aa
Fig 1. RSW complexes in drowsiness in a child with a history of febrile convulsions.
Spike-Wawe complexes in children during drowsiness
249
N. OF PATIENTS 13 12 11 10
9 8 7
6 5 4 3 2 1 0 0.1-0.6 0.7-1 1.1-1.6 1.7-2 2.1-2.6 2 . 7 - 3 3.1-3.6 3 . 7 - 4 4.1-4.6 4 . 7 - 5 5.1-5.6 5 . 7 - 6
YEARS Age of first F.C.
i
Age of first R S W
Fig 2. Age at the first febrile convulsion and first EEG with RSW. " l a r v a l p e t i t - m a l " ( L e n n o x - B u c t h a l , 1973), h y p n a g o g i c p a r o x y s m a l s p i k e - w a v e activity ( A l v a r e z et al, 1983) or bursts o f large a m p l i t u d e t h e t a with i n t e r m i x e d s p i k e - a n d - s h a r p - w a v e - l i k e activity ( T h a r p , 1986). Since the clinical significance o f R S W has n o t b e e n clarified, t h e a i m o f this i n v e s t i g a t i o n was to s t u d y the clinical c o r r e l a t e s o f this p a r o x y s m a l activity.
Subjects i~and Methods This study is based upon the intake of the EEG laboratory at the Institute of Child Neuropsychiatry, University of Rome La Sapienza, for a period of 6 months, from January to June 1986. During that period 1975 EEGs were carried out. Patients with only waking EEGs had to be eliminated since RSW do not occur in a waking state. A total of 130 out of 462 sleep EEGs were retained because of the availability of a clear sequence of awakedrowsy and NREM sleep states (stage l, 2 and sometimes 3). Rigid adherence to this sequence is necessary for the study of RSW. Drowsiness and sleep were always spontaneous. Among these patients we selected a group of 37 children (18 boys and 19 girls), aged from 16 months to 5 years 4 months (mean age: 4.1 yrs), with RSW. Clinical history including family history of febrile convulsions of epilepsy was carefully studied. General physical and neurological examinations as well as EEGs were carried out on each child at the onset of the study and subsequently at intervals for a period of at least 3 years. In this group it was possible to review the EEGs of 26 children recorded previously. The EEGs were recorded with 8 channel machines. The electrodes were placed following the International 10-20 System, using bipolar montages.
250
A Pelliecia et al
Results
All the children suffered from one or more febrile convulsions. In 15 (41.5%) there was a family history of febrile convulsions and in 6 (16.2%) a family history of epilepsy. In all cases, intellectual development as well as general and neurological examinations were normal. The first febrile convulsions occurred at a mean age of 1 year 6 months (range: 2 months, 4 years 4 months); in all but 1 patient the convulsions occurred after 6 months. There were usually simple febrile convulsions, except in 5 children who experienced longer seizures lasting about 15 min. The mean age of the first appearance was 3.4 years (range : 16 months 9 years). Twenty-two out of 26 previous recorded EEG were judged as normal. The mean interval between the first febrile convulsions and the RSW was 20 months (range: 14-25 months). During the follow-up, all the EEGs showed RSW and no patient developed neither an epileptic syndrome or an epileptiform EEG activity.
Discussion
Kellaway and Fox (1950) and Brandt and Brandt (1955) drew attention to the "paroxysmal hypnagogic hypersyncronous pattern" generally found in normal children during drowsiness and sleep. This hypnagogic rhythmical theta activity of late infancy and early childhood represents a normal feature of that period of life (Niedermeyer, 1987). A similar drowsy pattern, but with intermixed spikes, appearing as bursts of atypical spike-waves at 3-5 Hz is more debatable. Kellaway and Fox (1950) considered this to be abnormal. Gibbs and Gibbs (1964) called this activity pseudo-petit mal pattern and described it as a mild abnormality in infancy and early childhood. In their opinion this pattern is more prominent in parietal areas, disappearing by the age of 8 and often being associated wi~h febrile convulsions. Although the term pseudo-petit mal discharges seems to make it possible to equate spike- waves with petit mal, a transition into a classical or other spike-and-wave pattern has not been observed (Niedermeyer and Lopes da Silva, 1987). Samson-Dollfus et al (1984) noted this type of pattern during drowsiness in children aged from 2-3 years suffer in from "isolated convulsions, very often of febrile origin" and described it as - spike-waves which are not typical. EegOlofsson et al (1971) found a "bilateral paroxysmal activity in drowsiness and light sleep" in 47 out of 599 normal children and considered it similar to the "pseudo-petit mal discharge" of Gibbs and Gibbs (1964). A similar pattern called "Hypnagogic Paroxysmal Spike-and-Wave Activity" (HPSW) was described by Alvarez et al (1983). They were found a high incidence of febrile convulsions in children showing this activity, while no HPSW were found in 92 carefully selected normal children.
Spike-Wawe complexes in children during drowsiness
251
I n o u r findings all the c h i l d r e n showing R S W h a d suffered f r o m 1 or m o r e febrile seizures, with a high incidence o f f a m i l y history o f febrile c o n v u l s i o n s . I n almost all cases, febrile seizures had b e e n simple a n d o u t c o m e s favorable, with n o n e o f the children developing epilepsy in the following 3 years. O n a c c o u n t o f the high incidence o f f a m i l y histories o f febrile c o n v u l s i o n s or epilepsy f o u n d i n o u r g r o u p we are i n a g r e e m e n t with Alvarez et al (1983) that R S W s h o u l d be considered as a genetically t r a n s m i t t e d E E G p a t t e r n . C o n s i s t e n t with previous studies we f o u n d t h a t the a p p e a r a n c e o f R S W is age-dependent. As R S W were n o t f o u n d in children y o u n g e r t h a n 16 m o n t h s , a time lag could be possible b e t w e e n the age at the time o f the first febrile c o n v u l s i o n a n d the time o f the first E E G positive for R S W . I n accordance with Alvarez et al (1983) we t h i n k t h a t a certain degree o f m a t u r a t i o n m u s t be reached before the p a t t e r n o f R S W c a n be p r o d u c e d . M o r e o v e r , with our present investigation we are able to a f f i r m that R S W are associated with febrile c o n v u l s i o n s with a f a v o r a b l e outcome. A clear sequence o f a w a k e - d r o w s y a n d N R E M sleep is necessary to record this activity: therefore it is i m p o r t a n t to stress that for children suffering f r o m febrile c o n v u l s i o n s careful m o n i t o r i n g o f the child's w a k i n g - d r o w s y state d u r i n g E E G is unrenouncable. The c o m m o n error o f m i s t a k i n g this p a t t e r n as e p i l e p t i f o r m activity m a y result i n a misdiagnosis o f febrile c o n v u l s i o n s as epileptic seizures. Therefore we consider it i m p o r t a n t to emphasize the features of this p a r o x y s m a l activity. T h e electroclinical characteristics of R S W synthesized in table I allow us to easily recognize this activity a n d ~ivoid the consequences of incorrect diagnosis o f epilepsy.
Table I. Characteristics of Rudimentary Spike-Wave Complexes [RSW]. - Bursts of generalized slow high-voltage waves with intermixed sharp transients, occurring only in drowsiness, stage 1 of NREM sleep and less frequently on awakening. - The spikes and sharp waves intermixed with slow waves are never present at the onset of the discharges. - The spikes and sharp waves superimposed are bilateral and usually predominant in the central areas, at times being more prominent in one hemisphere, without a tendency for a fixed localization. - The frequency of the slow waves is 4-5 Hz. - The duration of RSW ranges from 1 to 5 s (on average 2 s). - The amplitude of the slow waves ranges from 100 to 200 #V, while the sharp transients are of lower amplitude (50-100 /zV). -The onset and termination of RSW are synchronous in both hemispheres. -RSW are never associated with clinical correlates. - T h e y are never followed by a shift to an arousal EEG pattern or awakening.
252
A Pelliecia et al
References Alvarez N, Lombroso CT, Medina C, Cantlon B (1983) Paroxysmal spikeand-wave activity in drowsiness in young children: its relationship to febrile convulsions. Electroencephalogr Clin Neurophysiol 56, 406-413 Brandt S, Brandt H (1955) The electroencephalographic patterns in y o u n g healthy children from O to 5 years of age. Acta Psychiatr Neurol Scand 30, 77-89 Eeg-Olofsson O, Petersen I, Sellden I (1971) The development of the electroencephalogram on normal children from the age of 1 through 15 years. Paroxysmal activity. Neuropaediatrie 4, 375-404 Gibbs FA, Gibbs EL (1964) Atlas of Electroencephalography, vol 3. Addison-Wesley, Cambridge, Mass Kellaway P, Fox BJ (1950) Electroencephalographic diagnosis of cerebral pathology in infants during sleep. I Rationale, technique, and the characteristics of normal sleep in infants. J Pediat 4, 262-287 Lennox-Buchthal M (1973) Febrile convulsions, a reappraisal. Electroence-
phalogr Clin Neurophysiol (Suppl.) 32, 12-22 Niedermeyer E, Lopes da Silva F (1987) Electroencephalography. Basic Principles, Clinical Applications and Related Fields. Urban & Schwarzenberg, Baltimore, 191 Samson-Dollfus D, Forthomme J, Capron E (1964) EEG of the human infant during sleep and wakefulness during the first year of life; normal patterns and their maturational changes; abnormal patterns and their prognostic significance, ln: Neurological and Electroencephalographic Correlative Studies in Infancy (Kellaway P, Peterson I, eds). Grune and Stratton, Inc, NY, 208-229 Samson-Dollfus D, Nogues B, Delagree E (1981) Aspects 61ectroenc6phalographiques et polygraphiques des transitions veille-sommeil chez des nourrissons normaux ~g6s de 2 12 mois. Rev EEG Neurophysiol Clin 11, 23-27 Tharp BR (1986) Neonatal and pediatric electroencephalography. In: Electrodiagnosis in clinical neurology (Aminoff M, ed). Churchill Livingstone, New York, 77-124