NOVELTY EVENT RELATED POTENTIAL ABNORMALITIES IN CHILDREN WITH INFANTILE SPASMS
Abstract number :
1.161
Submission category :
Year :
2003
Submission ID :
3887
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
Klaus G. Werner, Torsten Baldeweg, Stewart G. Boyd, Rod C. Scott, Brian G. Neville Neurosciences Unit, Institute of Child Health, London, United Kingdom; Developmental Cognitive Neuroscience Unit, Institute of Child Health, London, United Kingdom; Radiolo
Infantile spasms (IS) are associated with acute cognitive regression, long-term learning disability and autistic spectrum disorder. Although there may be a structural basis to the epilepsy, seizure activity itself is implicated in the pathogenesis of these disabilities. There are strong indications of temporal lobe dysfunction in children with this and related epileptic regressions; from the site of lesions in tuberous sclerosis and early onset developmental tumours, and from the EEG localisation in the Landau-Kleffner syndrome. We therefore tested if the temporal lobe is functionally abnormal in children with infantile spasms by recording event related potentials (ERPs) to novel environmental sounds known to be generated in temporal lobe regions.
26 full term infants (age range 2-10 months) and 24 infants with IS (range 2-10 months) were recruited. EEG was recorded continuously from 19 electrodes (10-20 system). An oddball paradigm was used with frequent sounds (p=80%, 1kHz), deviants (p=10%, 1.5kHz) and brief novel sounds (p=10%), delivered binaurally (interstimulus interval 700 ms) via speakers at a distance of 30 cm. Infants were either asleep (stage II) or awake/drowsy. 3 blocks were recorded, with 240 deviants and 240 novels.
Robust and reproducible ERPs to novel sounds were detected in sleep in all normal infants showing a negativity (N2) at 250 ms and positivity (P3) at 500-900ms over inferior temporal electrodes. Polarity inversion at central electrodes is consistent with a generator site within the temporal lobe. Control infants showed decreasing P3 latencies with age (F(2,17)=22.3, p[lt]0.0001). Despite the presence of severe EEG abnormalities ERPs to novel sounds could be recorded in 75 % of patients with IS. Patients with IS had significantly prolonged P3 (F(1,40)=13.6 p=0.001), but normal N2 latencies compared to controls with age as a covariate.
1. Novelty ERPs can be recorded reliably from 2 months of age in control infants and infants with IS. Their topography suggests a bilateral generator in the posterior superior temporal lobe.
2. ERPs show markedly decreasing latencies of the P3 in the first year of life.
3. Patients with IS show increased P3 latencies during the first year of life, consistent with the hypothesis of abnormal temporal lobe development.
[Supported by: Hospital Savings Association, The Wellcome Trust]