Relationships Between Morphologic and Functional Patterns in the Polymicrogyric Cortex.
Polymicrogyria is a malformation of cortical folding and layering underlying different cognitive and neurological manifestations. The polymicrogyric cortex has heterogeneous morphofunctional patterns, qualitatively described at magnetic resonance imaging (MRI) by variable severity gradients and functional activations. We investigated the link between abnormal cortical folding and cortical function in order to improve surgical planning for patients with polymicrogyria and intractable epilepsy. We performed structural and functional MRI on 14 patients with perisylvian polymicrogyria and adopted surface-based methods to detect alterations of cortical thickness (CT) and local gyrification index (LGI) compared with normal cortex (30 age-matched subjects). We quantitatively assessed the grade of anatomic disruption of the polymicrogyric cortex and defined its relationship with decreased cortical function. We observed a good matching between visual analysis and morphometric measurements. CT maps revealed sparse clusters of thickening, while LGI maps disclosed circumscribed regions of maximal alteration with a uniformly decreasing centrifugal gradient. In polymicrogyric areas in which gyral and sulcal patterns were preserved, functional activation maintained the expected location, but was reduced in extent. Morphofunctional correlations, evaluated along cortico-cortical paths between maximum morphologic alterations and significant activations, identified an interindividual threshold for LGI (z-value = -1.09) beyond which functional activations were no longer identifiable.
Neuroscience Department, Children's Hospital A. Meyer-University of Florence, 50139 Florence, Italy.
Matteo
M
Lenge
Neuroscience Department, Children's Hospital A. Meyer-University of Florence, 50139 Florence, Italy.
Carmen
C
Barba
Unit of Neuroradiology.
Domenico
D
Montanaro
Unit of Neuroradiology.
Gayane
G
Aghakhanyan
Unit of Neuroradiology.|U.O.C. Bioingegneria e Ingegneria Clinica, Fondazione G. Monasterio CNR-Regione Toscana, 56124 Pisa, Italy.
Francesca
F
Frijia
Neuroscience Department, Children's Hospital A. Meyer-University of Florence, 50139 Florence, Italy.|IRCCS Stella Maris Foundation, 56018 Calambrone, Pisa, Italy.
Renzo
R
Guerrini
D001931:Brain Mapping; D016022:Case-Control Studies; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D065706:Polymicrogyria / Q000000981:diagnostic imaging* / Q000503:physiopathology*
D010100:Oxygen
cortical development; cortical thickness; fMRI; gyrification index; polymicrogyria