Search

The purpose of the present study was to clarify the developmental changes of electroencephalogram (EEG) background activity in term and preterm infants that take place with increasing conceptional age (CA) through an autoregressive (AR) model. Polygraphical EEG recordings were obtained from 76 healthy term and preterm infants with a CA ranging between 31 and 40 weeks. Decreases in total power and component power of delta were noted with CA during burst activity (BA) in quiet sleep (QS) and during active sleep (AS). Increases in total power and component power of delta were noted with CA during interburst interval activity (IBIA) of QS. Regression analysis (RA) of the information amount (IA) indicated a negative correlation with increasing CA in AS and in the monopolar EEG tracings Fp1, C3, O1 and O2 in BA, and a positive correlation in O1 in IBIA. Regression analysis of the IA of delta indicated a negative correlation with increasing CA in AS and in Fp1, C3, O1 and O2 in BA, and a positive correlation in O1 in IBIA. Regression analysis of the IA of delta indicated a negative correlation with increasing CA in BA and AS. These results showed that the high voltage slow wave component changed to a low voltage slow one with development in AS and that BA was longer in duration and lower in power with increasing CA, while IBIA was shorter in duration and higher in power. In conclusion, significant developmental changes occur in all derivatives of AS. Even though the EEG of BA and IBIA change separately, they are followed by EEG of QS in a continuous pattern.

A number of lines of evidence indicate that the human cochlea is fully functional as a mature sound transducer by 6 months of age. However, information about the development of the active cochlear mechanisms and notably the development of outer hair cell (OHC) activity is yet incomplete. Recording and analysis of otoacoustic emissions (OAEs), probably generated by the OHCs of the organ of Corti, have led to a better understanding, in humans, of how sounds are analysed in the cochlea by means of active mechanisms. Evoked OAEs (EOAEs) and spontaneous OAEs (SOAEs), when they can be recorded in full-term and preterm neonates, show different characteristics from those in adults, suggesting that maturation of the peripheral auditory system is incomplete at birth. To learn more about this maturation, using the best-established facts concerning SOAEs in adults, such as their greater prevalence in females and also in right ears, SOAEs were studied in more detail in 81 preterm neonates, from 30 to 40 weeks of conceptional age, all presenting bilateral EOAEs according to objective criteria. The first finding of this study was that SOAEs existed and could be recorded as of 30 weeks of conceptional age in humans. Some SOAE characteristics in preterm neonates, such as prevalence, peak number and acoustic frequencies, showed similarity with full-term neonates. Comparison of other criteria between the two populations, such as greater SOAE prevalence in right ears and higher SOAE peak number in females, suggested that these developmental factors emerge around term in humans. Comparison of SOAE characteristics between male and female preterms suggested that male preterms were less advanced in peripheral auditory development than were female preterms.

Birth rapidly changes the demands placed on the kidneys with respect to infant homeostasis. Conceptional age (gestational plus postnatal), general health, and medical management may independently, or, in concert, give rise to important metabolic abnormalities marked by apparent renal functional inadequacies. The chronology of the renal functional changes occurring with maturation in infants born before or at term is now well described. The confounding effects of treatment on the development of renal function in very low birth weight infants are also becoming more apparent. However, the mechanisms responsible for these changes are just becoming to be understood with the use of molecular biologic techniques.

The development of the corpus callosum was documented by magnetic resonance imaging in low-risk preterm infants and results were compared with those of term infants. Thirty-three magnetic resonance imaging studies were performed on 21 preterm infants whose corrected ages were 1–13 months. Twenty-one magnetic resonance imaging studies were performed on 17 term infants. All infants exhibited normal development. The thickness of the corpus callosum was measured at a point one-third of the length of the entire corpus callosum from the most anterior aspect of the genu. The thickening of the corpus callosum was related to age in the preterm group. The development of the corpus callosum in preterm infants was suggested to be the same as that of term infants matched by conceptional age.

Brainstem auditory evoked potentials (BAEPs) were recorded from 39 preterm infants, divided into 3 groups: small-for-gestational-age, with a birthweight less than or equal to 1500 g (SGA); appropriate-for-gestational-age, with a birthweight less than or equal to 1500 g (AGA1); and appropriate-for-gestational-age, with a birthweight higher than 1500 g (AGA2). A significant shortening of the I-V interval due to an increase in wave I latency was found in the SGA group. The lower-weight AGA group (AGA1) was never significantly different from the SGA group. Although there was no correlation between conceptional age and weight at the time of the examination for the studied population, negative correlations were found between wave I latency and weight at the time of the examination. These findings confirm previous research and suggest the existence of a link between weight and basal cochlear maturation.

Long-term cassette EEG monitoring in the neonatal intensive care unit has established prognostic criteria regarding the developmental outcome by quantifying seizure activity. The clinical significance of the organization of continuous and discontinuous EEG patterns in the early premature is still an open question. This report presents quantified EEG data from repeated 24 h records during the first week of life in premature infants (conceptional age less than 32 weeks) with and without ultrasound evidence of intracerebral hemorrhage. The repartition and evolution of EEG background activity is not a reliable parameter regarding pathology. The continuity index is rather a maturational variable and its ultradian fluctuation is an early expression of the "basic rest activity cycle" (BRAC) rhythm.

The maturation of the traveling-wave delay in the human cochlea was investigated in 227 subjects ranging in age from 29 weeks conceptional age to 49 years by using frequency specific auditory brain-stem responses (ABRs). The derived response technique was applied to ABRs obtained with click stimuli (presented at a fixed level equal to 60-dB sensation level in normal hearing adults) in the presence of high-pass noise masking (slope 96 dB/oct) to obtain frequency specific responses from octave-wide bands. The estimate of traveling-wave delay was obtained by taking the difference between wave I latencies from adjacent derived bands. It was found that the traveling-wave delay between the octave band with center frequency (CF) of 11.3 kHz and that with CF of 5.7 kHz decreased (about 0.4 ms on average) in exponential fashion with age to reach adult values at 3-6 months of age. This decrease was in agreement with reported data in kitten auditory-nerve fibers. The traveling-wave delays between adjacent octave bands with successive lower CF did not change with age.

The technique of ABR testing was applied to 25 infants with neonatal hyperbilirubinemia at levels exceeding that for exchange transfusion, in an attempt to study potential influence of bilirubin toxicity on the auditory brainstem pathway. The test was performed at a mean conceptional age of 40.4 +/- 0.6 weeks just after discharge. Twenty normal term neonates of comparable birth weights and conceptional ages, who had no hyperbilirubinemia, were also examined for comparison. Fifty six percent (n = 14) of the hyperbilirubinemic neonates had some abnormality in the ABR pattern, the major one being a transient increase in the threshold of wave V (7, fail-30; 5, fail-45). Wave V, however, was consistently present at 30 dBnHL click stimulus in all the normal neonates (pass-30; normal threshold). Further, mean ABR latencies (wave III, V) and 1-V interpeak latency (brainstem conduction time) were significantly prolonged in jaundiced neonates as compared with controls (P less than 0.01). ABR changes were strongly correlated with the serum bilirubin levels (P less than 0.001). On follow up retesting at 3 months, however, all infants were found to have normal ABR latencies and threshold. Neonatal jaundice was associated with significant transient aberrations of ABR, suggestive of a transient toxic brainstem encephalopathy.

We examined brainstem auditory evoked potentials in 2 neurodevelopmentally different groups of high-risk premature infants during the first year of life. Our 77 patients were considered at birth to be at risk for neurologic disabilities, but were found to have normal development in the second year of life. The patients were divided into 2 groups on the basis of their neurologic findings during the first year of life; 24 of the 77 patients demonstrated transient neurologic abnormalities (group I) and the remaining 53 demonstrated normal neurologic findings through the first year of life (group II). Normative data of brainstem auditory evoked potentials were obtained from 60 low-risk and neurologically normal infants. Group I patients had prolonged III–V and I–V intervals at 2 months of age or younger and poorly detectable waves VI and VII at 5 months of age or younger, compared with control subjects. Wave VI was poorly detected in group II patients only at 35–39 weeks of conceptional age. Brainstem auditory evoked potentials suggested that the patients with transient neurologic abnormalities had transient dysfunction or maturational delay in the brainstem and upper auditory pathway early in the first year of life.

Seventy-three premature infants were born at conceptional age 25–37.5 weeks (birth weight 728–2620 g) and examined ophthalmologically, including ultrasound oculometry, at conceptional age 36–54 weeks (mean 41.9 weeks). Axial length averaged 17.08 in girls (n = 33) and 17.38 mm in boys (n = 40).

In order to evaluate the influence of extrauterine life on auditory brainstem response in neonates, we performed serial ABR recordings twice a week in 10 preterm infants. A marked decrease of I–III interpeak latency was observed in 7 infants during the first 2 or 3 weeks after birth. Wave I latency also remarkably reduced during this period in 5. These findings were related not to the conceptional age but to the extrauterine age. In 2 infants III–V interpeak latency increased during the first 1 or 2 weeks after birth, and the rate of latency increase seemed to be inversely proportional to that of decrease of I–III interpeak latency.

A method has been developed for long-term continuous recordings of several physiological variables in humans, including body movements, core temperature, heart rate and respiratory rate. This method enabled us to study circadian rhythms of body temperature and rest-activity in preterm infants. In 5 out of 9 infants (recorded at 28–34 weeks conceptional age) circadian rhythms were found in body temperature. We conclude that circadian rhythmicity is present during the early neonatal period in certain physiological variables (body temperature) but not in others (rest-activity).

We examined ABRs and MLRs for click and/or 500-Hz tone pip stimuli in infants (36–44 weeks conceptional age) admitted to the NJBU and measured the threshold and detectability of those responses. We took the threshold indicators of those responses as Jewett V for ABR measurement and wave Po Nal Na2 for MLR measurement. Thresholds of MLRs for click stimuli were almost equal to those of ABRs for click stimuli. On the other hand, thresholds of MLRs for 500-Hz tone pip stimuli were slightly worse than ABRs for click stimuli, the average differences being less than 10 dB. Wave Po Nal Na2 are the best threshold indicators of MLRs in infants, but the diagnostic significance of wave Pa was questionable in our measurements.

We have conducted two studies to evaluate the maturational changes of SEP in 206 subjects from neonatal period through adulthood. The first study was done with a cephalic reference electrode and included 137 subjects from 41 weeks (conceptional age) to 9 years of age, divided in 5 different age groups. In the second study, we used an extracephalic reference electrode and recorded SEPs in 69 normal subjects aged from 4 to 34 years, divided in 3 age groups. Our results show that there is a highly significant correlation between age and height in all the age groups studied. Peripheral and central components of SEP mature at different rates with adult values being reached for central conduction times (N9–P14, N9–N20, N13–N20 and P14–N20) between 4 and 9 years of age. Male and female subjects were compared in both studies and no significant differences were found in any of the age groups for any of the wave latencies or interpeak latencies analyzed.

Towards elucidation of mechanisms in initiation and termination of apnea and occurance of bradycardia polygraphic recordings were performed to 10 preterm infants (mean gestational age 28.0 / range 26.1 to 32.1 weeks) at 36, 40, 44 and 52 weeks conceptional age including EEG, submental and diaphragmatic EMG, ECG, thoracal respiratory movements, nasal airflow, tcpO2 and tcpCO2. A total of 148 apneas (>10 sec.) were recorded. 33 of them were mixed/obstructive events in N-REM-sleep and 66 in REM-sleep. Apneas followed a sigh in 16 of 106 REM apneas and 29 of 43 N-REM apneas (20 of the N-REM apneas were mixed with the inactive part proceeding the obstructive part). A significant suppression of EEG-activity (Wilcoxon Rank, p

Brainstem (ABR), Middle Latency (MLR) and Cortical (ACR) Auditory Responses were studied in 65 healthy preterm and 25 healthy term infants at 40 weeks conceptional age (CA) and al 52 weeks CA in order to establish the differences between intrauterine and extrauterine maturation of BMC ARs. The latencies of the ipsilateral ABR components I, II, V and ihe contralateral ABR components He and Ve at 40 and 52 weeks CA showed no significant differences between preterm infants and term infants, although in preterm infants a consistent tendency towards longer latencies was found. The latency of MLR component P0 was significantly longer in preterm infants compared to term infants, whereas MLR component Na showed no significant latency differences. The most interesting findings are related to the latency differences of the ACR components between term infants and preterm infants. At 40 weeks CA the latencies of components Na, Nl and P2 were significantly shorter in preterm infants, whereas at 52 weeks CA these latencies were significantly longer in preterm infants. Further, it was notable that at 40 and 52 weeks CA there was a striking difference in ACR wave form between preterm infants and lerm infants. At 40 and 52 weeks CA in preterm infants ACR wave form showed a less mature than in term infants, whereas term infants show a more mature wave form.

This was a clinical trials study of self-regulation of rhythmic stimulation in preterm infants. Infants were enrolled in three regional hospitals and followed in four outlying hospitals. Forty-five premature infants, 22 males and 23 females, enrolled at 29–33 weeks conceptional age (CA) received in

Summary The electroencephalograms of 82 infants (between 27 and 37 weeks of conceptional age) recorded during the neonatal period were analyzed and compared with the ultimate clinical evolution. Three groups of infants were identified according to their neurological state at 3 years of age or older : group A : normal (34 infants), group B : minor neurological sequellae (13 infants) and group C : major neurological sequellae (17 infants). A fourth group (group D : 18 infants) died during the neonatal period. The E.E.Gs were classified as : normal, questionably abnormal, moderately abnormal or grossly abnormal. The analysis revealed that E.E.Gs classified as grossly abnormal, were found only in groups B, C and D. Serial E.E.Gs were of more value in distinguishing these groups. Only infants in groups C and D (with I exceptional case in group B) had E.E.Gs which remained abnormal for several weeks or which deteriorated during the neonatal period. This study shows the prognostic value of the E.E.G. recorded during the neonatal period, particularly serial recordings obtained during and after a period of clinical deterioration. A detailed statistical analysis of the E.E.Gs is in progress.

Composite group averages were constructed from cortical auditory evoked responses (ACRs), which are recorded sequentially at maximally 8 conceptional age levels in 5 groups of 49 preterm infants, with additional inclusion of the records of 16 prematures obtained at different conceptional age levels. The group averages for the 5 gestational age groups showed replicable waveforms at all conceptional age (CA) levels reflecting the intragroup stability of the ACR complex. From the earliest age levels, from 25 weeks CA on, ACR group averages can be obtained, containing relative low voltage fast waves and high voltage slow waves. The most outstanding developmental changes in the ACR complex are the waveform changes. Until about 36 weeks CA a premature waveform is found, followed by a transitional phase with low voltage noisy records. Finally the adult waveform is found in the measurements at three months after term date. The latency values of the group averages are determined by the waveform changes. Persistent amplitude differences are found for the slow late waves between the vertex and the central temporal derivations.

The extra- vs intrauterine development of both visual and auditory cortical evoked response patterns was compared at 33, 37 and 40 weeks conceptional age. The maturation of visual cortical evoked responses is retarded in infants at 37 and 40 weeks conceptional age when born with a gestational age of less than 32 weeks, which thus implies a long extrauterine life span. The maturation of the auditory cortical evoked responses is not influenced by premature exposure to the extrauterine environment. The results are explained on the basis of the particular central nervous system growth spurt periods and a thus defined vulnerable period of different brain structures.

The authors have studied auditory brainstem responses (ABR) in 49 preterm (Group A) and in 54 fullterm (Group B) newborns, classified according to the birthweight related to conceptional age, in order to verify the influences of this latter parameter upon ABR. In Group A newborns, 4 recording sessions were performed, while only 3 in Group B, to evaluate data obtained at the same extra-uterine age. The obtained data show that birthweight related to conceptional age seems to play a major role on the development of ABR, since no significant differences were detected between preterm and fullterm newborns, provided the birthweight was appropriate for conceptional age (ACA). On the contrary, small for conceptional age (SCA) newborns showed an abnormal ABR pattern at birth, which tended to normalize at the following recording sessions. The authors conclude that birthweight related to conceptional age represents an important factor in the development of auditory brainstem responses and that the audiological diagnosis has to be very cautious in SCA newborns, regardless if they are pre- or fullterm.

A retrospective analysis of 184 EEGs performed during the neonatal period was accomplished on 81 premature infants (gestational age less than or equal to 36 weeks). The neurological outcome of the 64 surviving infants, considered as normal or abnormal with minor or major sequelae, was compared with the neonatal EEGs which were graded as normal, moderately or markedly abnormal. Infants whose serial EEGs were normal during the neonatal period were usually normal at follow up or suffered minor sequelae. All the children who had at least one markedly abnormal EEG suffered some type of neurological sequela or died. EEGs were classified as markedly abnormal if they contained at least one of the following patterns: isoelectric or paroxysmal backgrounds, positive rolandic sharp waves, electrographic seizures, marked interhemispheric voltage asymmetry or asynchrony or excessively slow background with a reduction or absence of the patterns expected at the particular conceptional age. A moderately abnormal EEG was of no significant prognostic value. This study also revealed the value of recording serial EEGs in the neonatal period. In many cases, markedly abnormal EEG patterns were transient and normal records were often obtained prior to the child's release from the nursery.

Auditory brainstem response (ABR) audiometry was performed on 76 non-selected premature infants from 32 to 40 weeks conceptional age. Follow-up ABR was completed on 45 infants at 4 months of age. The results were compared to data from selected, relatively low risk infants of comparable age. No significant differences were seen between the two groups, which indicates that normative data from non-selected premature infants can be obtained to identify ABR abnormality.

In the early premature, the EEG is mostly discontinuous. Discontinuity becomes limited to quiet sleep periods by the 36th week of conceptional age (CA). Temporal theta bursts, or the "sawtooth" pattern, come and go between 27 and 32 weeks' CA. Delta brushes attain their maximum about 32 to 34 weeks' CA and disappear about 40 to 44 weeks' CA. Frontal sharp transients have their peak occurrence at 35 or 36 weeks' CA and are still present at 44 to 48 weeks' CA. The background activity is essentially symmetric but transient patterns are less symmetric and frequently asynchronous. Lack of variability in the record is abnormal after 34 weeks' CA. Responses to isolated light flashes are prominent from very early prematurity through full-term. On the other hand, photic driving is frequent in early prematures (29-32 weeks' CA), but it then declines and is difficult to detect in the full-term neonate. Nonspecific responses to stimulation occur from early prematurity. Sleep--waking cycles are clearly discernible about 37 weeks' CA. Active sleep (rapid eye movement) goes from 60% at 34 weeks' CA to the 25% of adulthood at about 8 months of age. The EEG of the full-term newborn has four patterns, corresponding to three states: the low voltage irregular for wakefulness, high voltage slow and tracé alternant for quiet sleep, and the mixed for either wakefulness or active sleep.

Summary Polygraphic recordings including EEG, eye movements (REMs) and limb movements (recorded by piezo-electric crystals), chin EMG and respiratory rate, were performed in 23 normal neonates of 31 to 38 weeks conceptional age (CA). The concordance between various parameters characteristic for sleep states was analysed. For all infants, it was possible to define periods (> 7 min) of active (AS) and quiet sleep (QS) according to EEG and REM criteria. Mean duration of the 1st sleep cycle (including both AS and QS) lasted 57 to 65 min; no significant difference regarding CA was observed. According to EEG and REM criteria, AS accounted for 47 to 52 % of each sleep cycle ; QS rose from 27 % at 31–34 wCA to 33 % at 35–36 wCA (P At all ages studied, the observed duration of AS was not modified when other criteria were considered in addition to EEG and REMs. On the contrary, the observed duration of QS was frequently shortened and scattered with interruptions (indeterminate sleep) when respiration and body motility were considered; but the tonic EMG remained for 80 % of QS. The concordance betweenn different criteria characteristic for QS was not better at 37 – 38 wCA compared to 31–34 wCA.

In 384 healthy prematurely born infants, full-term newborns and older infants (conceptional age: 26 to 60 weeks; weight at investigation: 720 g to 5800 g) the flow in the anterior cerebral arteries was measured by pulsed doppler-sonography. All infants were investigated with a 5 MHz probe (ATL Mark 600 and Acuson 128). The following parameters were measured from the flow profile: The maximal systolic velocity, the end-systolic and end-diastolic velocity as well as the mean flow velocity, the pulsatility-index and the resistance-index. For all parameters the relationship to the conceptional age and weight were analysed. All flow velocities increased with increasing conceptional age: There was an exponential increase of the flow velocities with the conceptional age, whereas the relationship between the weight and the flow velocities was linear. In contrast to this neither the pulsatility-index nor the resistance-index changed with increasing conceptional age and weight. As flow velocities in the anterior cerebral arteries increase with increasing conceptional age and weight both parameters must be taken into consideration when pathologic flow velocities are measured.

By means of polygraphic sleep recording, the sleep apnea profile with respect to the number and duration of inactive, obstructive and mixed apneic episodes as well as periodic breathing has been investigated in infants born preterm at 40, 52 and 64 weeks conceptional age and compared to that of term infants. At 40 weeks preterm infants showed significantly more apnea and periodic breathing compared to term infants. The difference was essentially due to obstructive and mixed apnea in non-REM sleep. There was a sharp decrease in all apneic variables--inactive, obstructive and mixed apnea as well as of periodic breathing--at 52 weeks conceptional age in infants that were previously preterm. Both groups exhibited a rather identical sleep apnea profile at 64 weeks. Two prospectively studied infants in the preterm group later became SIDS victims. One of them might have been identified as being at risk on the basis of his apnea profile compared to the normative data now available.

Reevaluation of neonatal EEGs and polygraphic tracings of 40 infants with infantile spasms and/or hypsarrhythmia resulted in the constitution of a compound score for the identification of infants at risk for infantile spasms by neonatal EEG. The score comprises 8 distinct items: 2 concern behavioral characteristics, 6 abnormality of EEG background activity and paroxysmal events. A tracing registered at conceptional age 36 to 44 weeks (eventually up to 50 weeks) presenting at least 4 of these 8 items is scored positive for the risk of evolving hypsarrhythmia. In a prospective study the polygraphic tracings of 941 newborn infants were evaluated for risk: 18 infants suffering from perinatal distress and 7 newborns with malformations of the brain were scored positive and all 25 developed infantile spasms and/or hypsarrhythmia. One infant with later infantile spasms was missed by the scoring system. None of the remaining infants scored negative manifested infantile spasms. Thus, correct positive prognostication was 100% and false negative 0.1%. By conventional EEG 5 out of 8 patients with infantile spasms were correctly predicted. The high validity of the risk-score based on polygraphic tracing between conceptional age 36 to 44 weeks may allow pre-onset treatment preventing secondary mental deterioration due to hypsarrhythmia and infantile spasms.

Summary Normal EEG rhythms depend on conceptional age (CA), i.e., gestational age plus legal age. To assess whether pathological rhythms are also related to the level of maturation, EEG seizures have been compared in 26 premature neonates (PN) — 16 from 26 to 32 weeks of CA, 10 from 33 to 36 weeks of CA — and in 20 full-term neonates (FTN). The amplitude, the frequency, the polarity, the duration of paroxysmal discharges, the presence of variations in localization and the presence of clinical seizures are not related to CA. In FTN, the discharges during seizures, display a more complex pattern; the foci of spike discharges are more often on the rolandic area; spikes or delta waves are more often asynchronous than in PN. In PN

A study was conducted in very-low-birth-weight (VLBW) neonates to correlate structural damage to the central nervous system due to intracranial hemorrhage (ICH) with electrophysiological function of the lower auditory system as measured by brainstem auditory evoked potentials (BAEP). BAEP testing of 61 VLBW neonates was completed at 36 weeks conceptional age. BAEP Wave III and V latencies significantly increased with increasing severity of ICH. Although significant at conventional levels (P less than 0.05), these correlations were of modest size. Furthermore, after adjusting for the effects of birthweight, hypoxia, lowest pH and associated pCO2 the correlation between ICH and BAEP was reduced in magnitude and no longer significant. Thus, there is little evidence that ICH shortly after birth affected functioning of the auditory brainstem pathways in VLBW neonates at 36 weeks conceptional age.

Physical growth of 212 randomly selected Swedish urban children has been investigated from birth to sixteen years as part of a prospective longitudinal study of growth and development. Twenty body measurements have been taken at specified ages. In all, about 66,000 values of measurement have been recorded. At sixteen years 179 (84.4%) ofthe original children were still regularly being followed. Thirty-three (15.6%) of the 212 children left the study at various ages. A comparison between the children who left the study and those remaining did not show any significant differences in physical growth. All recorded data have been scrutinized in order to detect errors of measurement or administrative errors. Such values have been corrected or excluded. The editorial procedures also included the adjustment of each measurement to exact target age, interpolation of missing examinations and exclusion of children with an aberrant growth pattern. When comparing the present study with older Swedish investigations a secular trend was established, while there was good agreement with other contemporary Swedish investigations. Growth charts of distance values of various body measurements are presented. In the charts standard deviation lines (+/- 1, 2, 3 SD) and mean values are plotted. A logarithmic time scale (logarithmic conceptional age) has been used for both practical and theoretical reasons. When evaluating individual values in comparison with reference values standard deviations should be used rather than centiles. With this approach even grossly deviating values can be evaluated. Longitudinal follow-up of individual children and comparison of children of different ages will also be facilitated by this approach.

Head position preference in 15 low-risk pre-term infants studied in relation to conceptional age and nursing routines. A head position preference to the right is evident with respect to the head position imposed by the nurse. The observed spontaneous head position preference might be ascribed to the influence of the foregoing imposed head position, the influence of which diminishes with increasing observation time. After several spontaneous head turnings the low-risk pre-term infants show no head position preference anymore.

EEGs were taken of 33 premature babies of 27-32 weeks of conceptional age who were considered normal for their conceptional age by clinical criteria. The EEGs were divided into epochs of 1 min each and their characteristics of temporal and spatial organization as well as amount and distribution of special patterns were coded and analyzed. The records were mostly discontinuous, with synchronous and symmetric bursts. There was much rhythmic activity in all frequencies and some patterns were consistently asymmetric. At least one pattern, the sawtooth, seems to be characteristic of this early conceptional age. Follow-up EEGs and clinical examinations were done on 17 children at 6-8 months of age post term. Three more died before 6 months and on one a telephone report was obtained from the mother. The characteristics of the neonatal EEGs were compared with those published on smaller groups of early prematures and those on later premature babies.

Renal handling of beta-2-microglobulin in the human neonate. Glomerulotubular balance for beta-2-microglobulin (β2M) in the human kidney has been reported to occur after 34 weeks conceptional age (CA), and fractional tubular reabsorption of β2M (Tβ2M) has been suggested as a useful index of renal tubular maturation. To confirm and extend these observations to include still less mature infants, renal handling of β2M was investigated during timed-urine collections with corresponding blood samples obtained from 57 infants with CA of 26 to 43 weeks and postnatal ages (PNA) 0.2 to 12 days (study 1); 18 infants were studied a second time 5 to 17 days later (study 2). GFR was measured by endogenous creatinine clearance (CCr). Tβ2M and fractional reabsorption of sodium (TNa) were calculated. Results indicated that while both increased with CA, Tβ2M (r = -0.69, P < 0.0001) and TNa (r = -0.79, P < 0.0001) varied inversely with fractional urine flow rate (V/CCr). Moreover, an inverse relationship between changes in Tβ2M and V/Ccr was observed in the same infant between study 1 and study 2 (r = -0.47, P < 0.05). These data suggest that the renal handling of β2M in the human neonate is influenced by physiologic variables that are independent of CA, and thus Tβ2M may not be a reliable predictor of renal tubular maturation in the human neonate.Elimination rénale de la béta-2-microglobuline chez le nouveau-né humain. Il a été rapporté que la balance glomérulo-tubulaire pour la béta-2-microglobuline (β2M) dans le rein humain apparait au bout de 34 semaines d'âge conceptionnel (CA), et il a été suggéré que la réabsorption tubulaire fractionnelle de la β2M (Tβ2M) est un index utile de maturation tubulaire rénale. Afin de confirmer et d'étendre ces observations en incluant des nouveau-nés encore moins matures, l'élimination rénale de β2M a été étudiée pendant des recueils d'urines minutés, avec les échantillons sanguins correspondants chez 57 nouveau-nés avec un CA de 26 à 43 semaines et des âges postnataux (PNA) de 0.2 à 12 jours (étude 1); 18 nouveau-nés ont été étudiés dans un second temps, 5 à 17 jours plus tard (étude 2). Le débit de filtration glomérulaire a été mesuré par la clearance de la créatinine endogène (CCr). Tβ2M et la réabsorption fractionnelle du sodium (TNa) ont été calculées. Les résultats ont montré que tout en augmentant avec CA, Tβ2M (r = -0.69, P < 0.0001) et TNa (r = -0.79, P < 0.0001) variaient inversement avec le débit fractionnel urinaire (V/CCr). En outre, une relation inverse entre les modifications de Tβ2M et les modifications de V/CCr a été observée chez le même nouveau-né entre l'étude 1 et l'étude 2 (r = -0.47, P < 0.05). Ces données suggèrent que l'élimination rénale de la β2M chez le nouveau-né humain est influencée par des variables physiologiques qui sont indépendantes de CA, et donc Tβ2M pourrait ne pas être un index prédictif fiable de la maturation tubulaire rénale chez le nouveau-né humain.

Auditory brain stem responses were recorded in 114 ears of 63 high risk infants in NICU. The responses were evoked by 4kHz logon in 90dB.The mean values and standard deviations of wave 1 latencies were calculated in every con-ceptional age. The mean values of the latencies and the conceptional age showed a linear relationship, which was roughly indicated by the following formula; "the latency of 1 wave"="conceptional age" X (-0.07)+4.13.Delay of wave 1 peak were found in the cases of acute otitis media and Treacher Collins syndrome.Absence of wave 1 peak were found in the cases of congenital rubella syndrome and kernicterus.The measurement wave 1 latency, which was elicited by intense tone such as used in the present study, seemed to be useful to distinguish cochlear deafness from conductive deafness.

To assess the distribution of body motility according to sleep states and age, we performed polygraphic tracings in 39 normal premature and full-term infants during the neonatal period, grouped according to conceptional age in weeks (wCA): 31-34, 35-36, 37-38, and 39-41 wCA. Movements of the upper and lower limbs (UL, LL) were recorded using piezo-electric crystals. Time passed with movements (TWM) was automatically measured at an accuracy of 0.01 seconds. Sleep states were defined according to EEG and REMs criteria. We did not find any significant difference when TWM was compared between age-groups before the 38 wCA, on both UL and LL. TWM decreases significantly after 39 wCA (p less than 0.01). In all infants studied TWM was significantly higher in active sleep (AS) than in quiet sleep (QS). TWM in indeterminate sleep (IS) was usually similar to that in AS. The prevalence of body motility during AS compared to QS further confirms the observation of differences in the control of physiological variables according to sleep states as early as 31 wCA (the lower limit of our study).

Sixty-one mothers rated 12 infant cries. There were four cries (30 sec each) of healthy full-term neonates, four cires of very low-risk preterm infants, and four cires of medium-risk preterm infants. The cries were each rated on five 7-point scales with the conceptually “negative” polarity representing the urgent, grating, sick, arousing, and immature qualities of cries. Preterm cires were not uniformly rated as more urgent, grating, sick, arousing or immature than cries of full-term infants of the same conceptional age and of similar racial and socioeconomic background. Some preterm cries were rated as significantly more urgent, grating, sick, arousing or immature than full-term cries; other preterm cires were rated as significantly less urgent, etc., than full-term cries. Even though all the preterm infants were ostensibly healthy when their cries were recorded at expected date of birth, the ratings of the cries were related to the medical risk associated with the cryers' neonatal medical condition. The findings have implications for future research regarding cry features as adaptive and maladaptive communications that influence infants' development.

This review describes the characteristics of the normal electroencephalogram (EEG) of the newborn and the important role of the technologist in obtaining an accurate recording. The designation of conceptional age (CA), history-taking, clinical features of the sick neonate, developmental features of the immature brain, and technical aspects of neonatal EEG recording are discussed. The characteristics and selected samples of the normal EEG of newborns from 27 weeks through 44 weeks CA are presented. A checklist for recording the neonatal EEG is proposed, which may be used as a reference by EEG technologists.

It has been argued that human infants (with their relatively large foreheads and eyes) evoke nurturant behaviors from adults. This study empirically tests whether or not conceptional age affects these facial features and adult perceptions of the infants. Pictures (full frontal views of the face) were taken of 29 newborns: 10 born at term, 10 born 1 month early, and 9 born 2 months before term. All facial features were measured proportionally, and three composite drawings (one for each gestational age) were made. Using a 7-point Likert-style scale, college-aged subjects rated the composite drawings on the basis of overall impressions, perceived functional evaluations, and judged behavioral inclinations. Results indicated that full-term infants possessed proportionally wider eyes and rounder heads than did preterm infants. Composite drawings depicting the fullterm characteristics evoked much more favorable responses for all items than did the two composite drawings depicting preterm infants' characteristics. Moreover, the composite drawing depicting an infant born 1 month early elicited more favorable responses than did the composite drawing depicting an infant born 2 months prematurely.

A mobile conjugate reinforcement paradigm was used to assess differences in the acquisition and long-term retention of an operant response in young preterm and full-term infants of equivalent conceptional age. Infants received training on two days separated by 24 hours and a long-term retention session one week later. Full-terms successfully acquired the task in the first session but preterms did not show any significant increase in response rate from baseline until the second day of training. Both groups showed equivalent levels of immediate retention; however, only the full-terms demonstrated reliable long-term retention. Correlational analyses indicated that, regardless of term, long-term forgetting was related to neonatal measures of developmental risk. The data were discussed in terms of the similarities with previously reported ontogenetic changes in learning and memory of full-term infants with the implication being that preterms were more immature than the full-terms.

SUMMARY The prognostic significance of the auditory brainstem evoked response (ABR) was examined in this prospective study of neonates at risk for neurodevelopmental sequelae. ABR testing was performed in the neonatal period (37 to 45 weeks conceptional age) and at two and/or six months corrected age. 34 high-risk newborns and 14 controls were followed to one year of age, when they received neurological and developmental assessments. Increased I to III and I to V interwave latencies predicted gross motor delay at one year, with a positive predictive power of 83 per cent and a specificity of 94.7 per cent. Increased brainstem conduction, dispersal of waves III to V and V/I amplitude ratio abnormalities predicted abnormal neurological findings at one year, with positive predictive values of 100, 100 and 80 per cent, respectively. A standard clinical examination of the newborn, performed on the at-risk and control infants at 40 weeks conceptional age, was not found to be strongly predictive of neurodevelopmental deficits at one year. RESUME Signification pronostique des reponses auditives evoquees du tronc cerebral chez les nouveaux-nes a haut risque La signification pronostique des reponses auditives evoquees du tronc cerebral (ABR) est analysee dans cette etude prospective chez les nouveaux-nes a risques de sequelles neuro-developpementales. L'examen ABR a ete realise dans la periode neo-natale (37 a 45 semaines d'âge conceptionnel) ainsi qu'a deux et six mois d'age corrige. 34 nouveaux-nes a haut-risque et 14 controles ont ete suivis jusqu'a I'age d'un an, beneficiant alors d'une evaluation neurologique et developpementale. Des latences inter-ondes I-III et I-V accrues etaient predictives d'un retard de la motricite generale a un an, avec une valeur predictive positive de 83 pour cent et une specificite de 94.7 pour cent. Une conduction du tronc cerebral accrue, une dispersion des ondes III a V, et des anomalies du rapport d'amplitude V/I etaient predictives d'anomalies neurologiques a un an, avec des valeurs predictives positives respectivement de 100, 100 et 80 pour cent. Un examen clinique standard du nouveau-ne, realisea 40 semaines d'âge conceptionnel chez les nouveaux-nes a haut risque et les contreales, n'est pas apparu fortement predictif des defauts neuro-developpementaux, a un an.

The purposes of this study were to quantify certain aspects of the neuromuscular development of preterm infants, and to ascertain if differences exist which may be attributable to the degree of prematurity at birth. Two groups of ten infants were compared at 35 weeks of conceptional age. One group of infants was born at 28, the other at 35 weeks of gestational age (GA). Resting posture, upper extremity recoil, dorsiflexion angle of the foot, scarf sign, palmar grasp and response to traction, rooting response and head control were objectively assessed using devised rating scales. Scarf sign revealed significantly greater motion, implying lower tone, in the 28 week GA group. This group also exhibited a significantly less extensive rooting response to a corner lip stimulus than the infants born at 35 weeks GA, which may have been because of differences in feeding schedules. The remaining eleven items tested and the total mean scores of all criteria showed no significant differences between these groups of in...

It has been suggested that the cry may reflect the neurophysiologic integrity of the infant and relate to later developmental outcome. In this study, the cry was recorded at term conceptional age in 18 preterm and 13 term infants using a standardized procedure and analyzed by high-speed computer. At 18 months of age, a significant number of infants were correctly classified as scoring high or low on the Bayley Scales of Infant Development based on the mean and variability in the fundamental frequency, variability in the first formant, and the amplitude of the cry. At 5 years of age, a significant number of infants were correctly classified on the McCarthy General Cognitive Index and on the verbal, perceptual-performance, and quantitative subscales based on the variability of the fundamental frequency, variability of the first formant, and amplitude and duration of the cry. Although preliminary, this study supports the potential use of the cry as a noninvasive measure to detect developmental outcome in the infant at risk.

Generally, studies which have compared full term infants shortly after birth with prematurely born infants tested at the date of their expected birth (i.e., 40 weeks conceptional age) have stressed the similarities rather than any differences which have appeared in the data. Nonetheless, numerous differences have been noted, and the present study documented an additional discrepancy in function between full term and premature infants at 40 weeks conceptional age as well as maturational changes in state responsivity during the premature period. Premature infants were given repeated neurological examinations at 31-33, 34-36, and 38-42 weeks conceptional age. Full term infants were tested at 38-42 weeks conceptional age. Included in the scoring of the examination were 37 measures of state, designed to assess the infant's responsivity to the increasingly stressful items of the neurological examination. The younger prematures were more often judged to be asleep and had lower scores throughout the examination when compared to the 38-42 week infants. Crying occurred significantly more often with increasing age. In addition, the full term infants had significantly more crying scores than the prematures of the same conceptional age.

1. A method of plotting growth curves is presented which is considered more useful than the usual method in bringing out a number of important phenomena such as the equivalence of age in different animals, difference in the shape and duration of corresponding growth cycles in different animals, and also in determinating the age of maxima without resorting to complicated mathematical computations. 2. It is suggested that after the third cycle is past the conceptional age of the maximum of the third cycle may be taken as the age of reference for estimating the equivalent physiological ages in different animals. Before the age of the third cycle, the maxima of the second and first cycles are most conveniently used as points of reference. 3. It is shown that the product of the conceptional age of the maximum of the third cycle by 13, gives a value which is, with the possible exception of man, very near to the normal duration of life of animals under the most favorable conditions of life. In other words, the equivalent physiological ages in different animals bear an approximately constant linear relation to the duration of their growth periods. 4. Attention is called to certain differences in the shape and duration of the corresponding growth cycles in different animals and of the effect of sex on these cycles.

The Moro reflex motor response was studied by electromyographic analysis of extensor and flexor activity in normal fullterm, preterm, and small-for-dates fullterm infants. Flexor motoneuron activity increased significantly with maturation, whereas duration and amount of extensor motoneuron activity remained constant. The triceps/biceps Moro response activity quotient decreased with conceptional age. Rhythmic Moro response activity occurred in normal fullterm, small-for-dates, and preterm newborn infants above 34 weeks conceptional age. A special type of Moro response with delayed flexor activity was found more often in preterm than in fullterm newborn infants. The Moro response was not found suitable for an exact estimation of conceptional age. Particularly in small-for-dates infants, the Moro response pattern was influenced more by pathophysiological factors than by age differences.

The ontogenesis of sleep was studied in prematures from 32 to 41 weeks of gestational age The characteristics of the EEG, the patterns and rate of respiration, the cardiac rate, body motility comprised of localized and diffuse movements, localized and diffuse jerks, clonic movements and electromyo-graphic activity of the chin, as well as periods of total quietness were observed and correlated with the progressive organization of behavior in these infants. The data obtained at each gestational age, i.e., at 32–34 weeks, 35–37 weeks, and 38–41 weeks, were compared to those obtained in full-term newborns. The relationships between the different events and the features of the EEG and of the respiratory patterns were ascertained and compared to similar data obtained in the full-term newborn. This comparison shows that the premature at 40 weeks of gestational age has not attained a level of organization as high as that of the full-term newborn. An hypothesis suggesting a possible mechanism of this discrepancy is presented.