Abstracts

Bilateral perisylvian polymicrogyria (BPP) is a malformation of cortical development in which the cerebral cortex in the border and depth of the sylvian fissures is thickened and abnormally infolded on MRI. Most patients with BPP present with congenital bilateral perisylvian syndrome (CBPS), featuring pseudobulbar palsy, developmental delay, cognitive deficits, pyramidal signs and seizures. Because of severe dysarthria, many patients with CBPS are labelled as severely retarded. In this study, we investigate cognitive functioning in patients with BPP and determine whether BPP is associated with exceptionally low intellect (FS IQ[lt]70). Fourteen patients (6 male, age range 23-60) were selected based on the presence of BPP on MRI and the ability to undergo neuropsychological evaluation. Medical records and EEG reports were reviewed. All MRI data were reviewed by one of the authors, blinded to the clinical features and neuropsychological findings. A ranking was made based on the anatomic extent of the perisylvian involvement according to imaging. Neuropsychological evaluation included assesment of verbal and nonverbal intelligence, verbal and visual memory, receptive and expressive language, frontal lobe function and handedness. The relationship between the extent of the cortical disorganization and the neuropsychological test scores was examined using Spearman[rsquo]s Rank Correlation Analysis. Seizures were present in 85%. Eleven patients had pseudobulbar features. A significant correlation was found between the extent of the cortical disorganization and the performance IQ. Criteria for mental retardation (FS IQ[lt]70) were met in 4 patients. Five had low IQ, 4 had low average IQ and one had normal intelligence. No selective memory impairment was associated with BPP. Frontal lobe function was well preserved. This study demonstrates that cognitive function correlates with the extent of the cortical disorganization and that, despite the clinical picture of severe dysarthria, exceptionally low intellect is only present in a minority of BPP patients. Apart from the extent of BPP and age at testing, seizures can also influence the outcome of cognitive studies, since frequent seizures can aggravate speech dysfuction or cause progressive deterioration in these patients. (Supported by Savoy Foundation for Epilepsy)