Abstracts Al39 of the transcallosal fibres and of the intracortical synpatic circuitry. This study investigated the maturational changes of MT and IhI seen in children, adolescents and adults. Methods: Normal healthy children (mean age 8.4 years, n=30), adolescents (mean age 13.1 years, n= 13), and adults (mean age 25.1 years, n=ll) were investigated: EMG traces were recorded from the 1st dorsal inter- osseus muscle; MT was measured in the relaxed muscle as a P ercentage of maximum stimulator output (MagStim 200”‘); IhI was determined from ten averaged trace recordings in the active muscle with stimulus intensities of 1.2 times MT. To quantify the IhI, a quotient of inhibition (Qi) was calculated by dividing the mean EMG activity of the inhibitory period by the mean activity of a time period before application of the magnetic pulse. Thus, Qi represents the reduced motor activity per cent. Results: MT was shown to decrease continuously with significant group differences (mean values 68.6 &-9.9 SD ?is 58.7% k 11.5 SD us 40.9% + 9.1 SD; p < 0.01-0.001). IhI was detectable in children above the age of 6 years only. Qi was significantly reduced in adolescents in compar- ison with children (mean value 39.5%$11.3SD US 56.8% + 13.9 SD, respectively; p < 0.05). Adults had lower Qi than children, but displayed less inhibition than adolescents with a mean Qi of 52.7% f 15.6 SD. Conclusions: The MT matured until adulthood. The IhI matured until adolescence. The stimulus intensities should be considered highly influential on the latter parameter. The different maturation of MT and IhI provides further evidence that these two parameters are generated by different neuronal substrates, as was suggested by other studies making use of pharmacolo- gical agents. It shows that MT and IhI in combination can serve as parameters for brain maturation. This refers to intracortical excitability as well as to the development of inhibitory interhemispheric transfer. Section XV: Prognosis and long-term studies 138 Long-term cognitive impairment after cerebellar tumour surgery in children F AARSEN,’ C E CATSMAN-BERREVOETS,’ H R VAN DONGEN,’ P F PAQUIER’ ‘Department of Child Neurology, University Hospital RotterdamLSophia Children’s Hospital, Rotterdam, The Nether/an@; ‘Department of Neurology, University Hospital Erasme, Brussels and Department of ENT Surgery, University ofAntwerp (U/A), School of Medicine, Antwerp, Belgium Purpose: Anatomical, physiological and functional neuro- imaging studies, as well as clinical studies in adults and children suggest that the cerebellum participates in the organization of higher order function. In our study we investigated the late effects of cerebellar tumour on surgery on neuropsychological functioning in children. Material and methods: We included eight children (five boys, three girls), who had been exclusively surgically treated for a cerebellar pilocytic astrocytoma, at least 1 year prior to neuropsychological assessment. They all were in excellent physical and neurological condition. Tests for verbal and non-verbal intelligence, verbal and non-verbal memory, distractibility, language, verbal fluency, set shifting and visuospatial abilities were administered. Results: Both behavioural abnormalities (disinhibited or flattened affect) and neuropsychological disturbances were observed. The following neuropsychological dis- turbances were found: executive functions (verbal fluency, working memory, distractibility or inattention, mental slowness), visual skills (visual scanning, visuo- spatial, visual memory, visuomotor), language (poor spontaneous language production) and speech (high- pitched voice and a dysarthria). Conclusion: Our results support long-term neuropsycho- logical and behavioural disturbances in cases of surgical traumatic lesions of the cerebellum. 024 Neurological and neuropsychological outcome of non-accidental head injury K M BARLOW, E THOMSON,’ R A MINNS Department of Paediatric Neurosciences, Royal Hospital for Sick Children; ‘Department of Clinical Psychology, Astley Ainslie Hospital, Edinburgh, Scotland, UK Despite its importance and increasing recognition, there are only a few publications which detail the sequelae of ‘shaken baby syndrome’. Aims: The aim of this study was to examine both the neurological and neuropsychological outcome in non- accidental head injury (NAHI) in children. Methods: All children diagnosed with NAHI admitted to the Royal Hospital for Sick Children since 1981 and who consented to follow-up were entered into the study. A second group of children diagnosed with NAHI through- out Scotland since 1997 were identified and followed prospectively. A neurological examination together with neuropsychometric testing was performed in the cross- sectional group and 6- to 12-monthly in the prospective group. A proforma detailing the neuromotor, sensory, cerebellar, brainstem, higher cortical and developmental function was completed at each examination. The neuropsychometric tests performed were Bayley Scales of Infant Development, British Ability Scales II, Reynell- Zinkin (for children with visual impairment) and Vine- land Adaptive Behaviour. Results: 50 cases were identified. The average age at presentation was 5.8 months (range: 3 weeks-2.8 years). There was a mortality rate of 14%. Follow-up was obtained in 30 patients (14 were followed prospectively). The average length of follow-up was 4.4 years (9 months-21 years). For a global outcome score, we used a modified Glasgow Outcome Score. At follow-up 18% were classified as severe, 22% - moderate, 18% - mild and 32% were normal. Motor abnormalities/delay were found in 13 patients (ten had predominantly cortico-