C o m m u n i c a t i o n s ora l e s /Ora l c o m m t m i c a t i o n s 11 s

029 POINTES T~MPORALES SUR LES E L E C ' I ~ O E N C E P H A I , O G ~ DE

NOUVEAUX- NES pRRMATURES . M.F. VECCHIERINI-BLINEAU, B. NOGUES, J.C. ROZE et A. MOU~ZARD, Laboratoire de Physiologie appliqu~e aux Explo- rations Fonctionnelles et Service de Pediatrie - C.H.R. NANTES - FRANCE.

La valeur pronostique de l'41ectroenc4phalogramme (E.E.G.) chez les nouveaux-n4s normaux et pathologiques a d~j~ fait l'objet de nombreux travaux. Une attention particu- li~re a ~t~ port4e aux pointes positives rolandiques (p.P.R.) chez les nouveaux-n~s pr4maturls porteurs d'une h4morragie intra-ventriculaire ou d'une isch~mie plri- ventriculaire. Pour notre part, nous avons 4t~ frapp4s par la survenue de pointes temporales sur certains E.E.G. de nouveaux-n4s pr4matur4s.

Cette ~tude a pour but d'analyser les caract~ristiques de ces pointes : polarit4, amplitude, dur4e et fr4quence de r4p4tition chez des pr4matur4s, n4s au terme de 31

33 semaines, enregistr~s dans la premiere semaine de vie et r~partis en 2 groupes. Le premier groupe de 12 nouveaux-n~s a des trac~s E.E.G. avec d'autres anoma- lies : alt4rations de l'activit4 de fond avec ou sans P.P.R., alors que le deuxi~me groupe (n = 12) a des E.E.G. subnormaux ~ l'exclusion de pointes temporales. Les E.E.G. sont contrSl4s au 14e et 21e jour de vie.

Les auteurs montrent que certaines caract4ristiques ~lectrophysiologiques des pointes different entre les 2 groupes. Ils analysent la valeur pronostique de ces pointes temporales : d'une part en comparant la valeur respective des anomalies de l'activit~ de fond, des P.P.R. et des pointes temporales dans le let groupe de nouveaux-n4s et d'autre part en comparant l'incidence, l'4volution de ces pointes, les r~sultats des autres examens compl~mentaires et le devenir neurologique des enfants ~ court terme, dans les 2 groupes de nouveaux- n~s.

03O

INTRAUTERINE VERSUS EXTRAUTERINE MATURATION OF AUDITORY EVOKED RESPONSES (BMC ARs).

J.W. Pasrnan* , J.J. Rotteveel ~. Dept. of Neurophysiology*, Interdisciplinary Child Neurology Center ~, University Hospital, Nijmegen, The Netherlands.

Brainstem, Middle Latency and Cortical Auditory Responses (BMC ARs) were studied in 65 healthy premature born and 25 healthy mature born infants at 40 weeks conceptional age (CA) and at 52 weeks CA in order to establish the differences between intrauterine and extrauterine matura- tion of BMC ARs. The latencies of the ipsilateral Auditory Brainstem Response (ABR) components I, II, V and the contralateral ABR compo- nents IIc and Vc at 40 and 52 weeks CA showed no significant differ- ences in comparing the premature born group with the mature born group. The latency of Middle Latency Response (MLR) component P0 was significantly longer in the group premature born infants than in the group mature born infants, whereas MLR component Na showed no significant latency differences. The most interesting findings in this study are related to the latency differences of the Auditory Cortical Response (ACR) components between the mature and premature group. At 40 weeks CA the latencies of components Na, N1 and P2 were significantly shorter in the premature born group, whereas at 52 weeks CA these latencies were significantly longer in this premature born group. Further, it was notable that at 40 and 52 weeks CA there was a striking differ- ence in ACR wave form obtained from the premature born group compared to the ACR wave form obtained from the mature born group. The ACR wave form of premature born infants at 40 and 52 weeks CA was less well developed, whereas the ACR wave form of mature born infants at the same CA levels showed a more advanced form. From our study it can be concluded that the intrauterine maturation of BMC ARs differs from the extrauterine maturation with respect to some MLR and ACR components. It seems that earlier exposure to the extrauterine environment has a negative influence on the auditory propagation, the higher one advances in the auditory central nervous system.

O31 NEUROLOGICAL PROGNOSIS EVALUATION IN NEWBORN

A.Lea__f,C.Green,A.Esack,N.Sharief,K.Costeloe,P.Prior St. Bartholomew's Hospital Medical College, London.

PURPOSE: Prediction of neurodevelopmental outcome is important to parents of babies with perinatal problems. We used flash ERGs and VEPs in the neonatal intensive care unit (NICU) on infants with any condition predisposing to adverse neuro- logical and/or visual outcome, to assess the prog- nostic value of a single early investigation. METHOD: 13 infants aged 2-17 weeks have been studied (gestational ages 27-42 weeks, post-con- ceptual ages 32-47 weeks). Ten were preterm: 5 with cerebral ultrasound abnormalities and 5 with severe intrauterine growth retardation (IUGR). Three were fullterm: 2 with birth asphyxia and 1 with unexplained convulsions and hydrocephalus. VEP and ERG were made when the infant was stable with DTL silver thread, or surface electrodes if the mother preferred. Neurodevelopmental assess- ment was timed at discharge and regular intervals until 24 months corrected age and also at expected date of delivery (EDD) in preterms. RESULTS: No infant had abnormal ERGs. VEPs were normal in 5 preterm and 3 term infants in spite of IUGR or significant ultrasound abnormalities; all but 2 (i with persistent primitive reflexes at 4 months, 1 floppy at 3 weeks but normal at 5 weeks) had normal development at EDD to 9 month assess- ments. VEPs were immature in 2 preterm infants at post-conceptual ages 3~ and 33 weeks, 1 with periventricular leukomalacia; both later developed asymmetries, in 1 the reverse of that on scan, but both have normal development on limited follow-up. VEPs were abnormal in 3, with asymmetries not always congruent with scan abnormality but devel- Opment was normal at up to 6 months. CONCLUSION: VEP and ERG are easy to investigate on the NICU and when normal may give useful informa- tion in predicting favourable neurodevelopmental outcome following adverse perinatal events.

032 ELECI2q)PHYSIOIDGICAL ~ OF NEONATAL VISUAL HJNC'TICIN P. ADkarian, M. Mirmiran, R.O. TiJssen, Tne Netherlands Ophthalmic Researc/% Institute, P.O.12141, ii00 AC Amsterdam

Visual function within the first week of life was assessed with itallinance evoked potentials (EPs). The transient iLmlin- arx:~ flash EP and respoilses to sine-wave modulated lum/nance flicker (i to 62 Hz) were recorded under state defined con- ditions in 58 healthy full term neonates. Infant state (quiet/active wakefulness and quiet/active sleep) was deter- m/ned by behavioral ob~-/mration and polygraphic recordings of respiration, eye movem~_nte, heart rate, n~uscle activity and EEG. The results indicate that state dramatically affects both the luminance flash response as well as the higher frequency luminance flicker responses. For the lumin- ance flash response, latency, waveform, a~plitude and corti- cal topography show significant differences between sleep states and between sleep and wakefulness.While the neonatal luminance flash EP has been described in literature, failure to appropriately account for state has introduced consider- able intra and intersubject variability resulting in the restricted use of this visual measure for clinical applica- tion. In th/s study, revised normative EP standards of the neonatal lumi/lance flash EP as a function of state are proposed and examined in 8 high risk premature infants tested between 40 and 44 weeks ge~tational age. The results suggest that with proper state definitions,the luminance flash EP is a viable clinical test of functional integrity along the visual pathway. As with the luminance flash response a normative standard for the luminance flicker response within the first week of life is also proposed. The mature EP responses to luminance flicker show three distinct temporal frequency regions, low, medium and high, each reflecting different visual processes. This study shows that within the first week of life, the temporal tuning functions consist of only two distinct temporal frequency regions both of which are present only during wakefulness. As predicted from an Jam~ture visual system, the peak frequencies of these functions are lower than cc~parable (low and medium) peak frequencies of the adult flicker profile. Clinical application of ~ral flicker seu%s~civity is under investigation.