Cognitive sequencing impairment in patients with focal or atrophic cerebellar damage.

Although cognitive impairment after cerebellar damage has been widely reported, the mechanisms of cerebro-cerebellar interactions are still a matter of debate. The cerebellum is involved in sequence detection and production in both motor and sensory domains, and sequencing has been proposed as the basic mechanism of cerebellar functioning. Furthermore, it has been suggested that knowledge of sequencing mechanisms may help to define cerebellar predictive control processes. In spite of its recognized importance, cerebellar sequencing has seldom been investigated in cognitive domains. Cognitive sequencing functions are often analysed by means of action/script elaboration. Lesion and activation studies have localized this function in frontal cortex and basal ganglia circuits. The present study is the first to report deficits in script sequencing after cerebellar damage. We employed a card-sequencing test, developed ad hoc, to evaluate the influence of the content to be sequenced. Stimuli consisted of sets of sentences that described actions with a precise logical and temporal sequence (Verbal Factor), sets of cartoon-like drawings that reproduced behavioural sequences (Behavioural Factor) or abstract figures (Spatial Factor). The influence of the lesion characteristics was analysed by grouping patients according to lesion-type (focal or atrophic) and lesion-side (right or left). The results indicated that patients with cerebellar damage present a cognitive sequencing impairment independently of lesion type or localization. A correlation was also shown between lesion side and characteristics of the material to be sequenced. Namely, patients with left lesions perform defectively only on script sequences based on pictorial material and patients with right lesions only on script sequences requiring verbal elaboration. The present data support the hypothesis that sequence processing is the cerebellar mode of operation also in the cognitive domain. In addition, the presence of right/left and pictorial/verbal differences is in agreement with the idea that cerebro-cerebellar interactions are organized in segregated cortico-cerebellar loops in which specificity is not related to the mode of functioning, but to the characteristics of the information processed.

Early hemispherectomy in catastrophic epilepsy: a neuro-cognitive and epileptic long-term follow-up.

The authors report their experience about a neuro-cognitive and epileptic long-term follow-up of children with catastrophic epilepsy treated with hemispherectomy in the first 5 years of life. Nineteen children with resistant epilepsy that significantly interfered with their neuro-cognitive development underwent hemispherectomy within 5 years of life (mean: 2 years, 3 months; range: 5 months to 5 years). All patients were assessed before surgery and after, at least at the end of the follow-up (mean: 6 years and 6 months; range: 2-11 years and 2 months) with a full clinical examination including motor ability and functional status evaluation as well as behaviour observation, neuroimaging and an ictal/interictal prolonged scalp video-EEG. A seizure-free outcome was obtained in 73.7% of patients. Gross motility generally improved and cognitive competence did not worsen, with an evident progress in two cases. Consistently with previous reports, evolution was worse in cortical dysplasia than in progressive or acquired vascular cerebropathies. The excellent epileptic outcome and the lack of developmental deterioration in comparison with other more aged series seem to suggest a possible better evolution in earlier surgery treatment. To confirm this suggestion, however, further experience with larger series is needed.

Developmental plasticity after right hemispherectomy in an epileptic adolescent with early brain injury.

OBJECTIVES: The authors present the case of an adolescent affected with refractory epilepsy due to a neonatal ischemic infarction of the right medial cerebral artery. Hemiplegic since the first months of life, she began presenting motor partial seizures associated with drop attacks at 4.5 years; these were initially well controlled by antiepileptic drugs, but at 10 years seizures appeared again and became refractory. Thus, at 14 years and 10 months, she was submitted to a right hemispherectomy that made her rapidly seizure free. In the post-surgical follow-up lasting 5 years, neuropsychological serial assessments showed an impressive progressive improvement of cognitive skills, namely, visuospatial abilities. This case seems to challenge the widely spread feeling that functional catch-up in brain-injured children could only occur early in life. In effect, the astonishing recovery especially of visuospatial skills in our case occurred in adolescence after a late surgical intervention of right hemispherectomy. METHODS: Different neuropsychological aspects are discussed. The reorganisation process recovered the spatial and linguistic abilities as well as the verbal and visuospatial memory; however, there was a persistent impairment of complex spatial and perceptual skills as well as recall abilities. Despite the deficit of complex visual stimuli processing, the patient showed a good performance in the recognition of unknown faces. CONCLUSIONS: Probably, the absence of seizures in the first 4 years of life could have allowed a generally adequate compensatory reorganisation, successively masked by the persistent and diffuse epileptic disorder. The seizure control produced by surgery eventually made evident the effectiveness of the brain reorganisation.

Reversible aphasic disorder induced by lamotrigine in atypical benign childhood epilepsy.

PURPOSE: We studied an eleven year-old girl with atypical, benign partial epilepsy who acutely presented a severe aphasia associated with marked EEG deterioration after lamotrigine administration. A parallel monitoring of language disorders and EEG changes during the gradual withdrawal of lamotrigine was performed in order to evaluate their possible correlation with lamotrigine administration. METHODS: Detailed neuropsychological and linguistic examinations in association with awake and sleep EEG were periodically performed. RESULTS: The evolution of the aphasic disorder was closely related to the EEG abnormalities, and disappeared after the withdrawal of lamotrigine. CONCLUSIONS: We considered the hypothesis that our case could be an expression of a paradoxical reaction to lamotrigine, in which the transitory aphasic disorder was sustained by an epileptiform electric activation.