Functional MRI characteristics of a focal region of cortical malformation not associated with seizure onset.
Neuroimaging studies have demonstrated that heterotopic tissue of patients with "double cortex" is activated during motor and somatosensory tasks. Activation in patients with malformations of cortical development (MCD) has been variable, likely due to the heterogeneity of the disorder. We examined clinical, electroencephalography (EEG), neuropsychological, and functional MRI findings in a patient with intractable epilepsy secondary to MCD in the left temporal cortex. Invasive EEG monitoring revealed that the dysplastic tissue was not involved in ictal onset of seizures. Functional MRI tests of motion and object processing, memory encoding, and language demonstrated no activation within dysplastic tissue. Hemispheric asymmetries in activation for motion and object processing were evident, favoring the right hemisphere--a pattern not evident in controls. These weaker activations in the patient were present in tissue proximal to the seizure focus. Thus, nonepileptogenic dysplastic tissue may not support cognitive functions, with abnormal processing evident in epileptogenic tissue.
Danckert
James
J
Department of Psychology, University of Waterloo, 200 University Avenue West, Waterloo, Ont., Canada N2L 3G1. jdancker@uwaterloo.ca
Mirsattari
Seyed M
SM
Bihari
Frank
F
Danckert
Stacey
S
Allman
Ava-Ann
AA
Janzen
Laura
L
D000328:Adult; D002540:Cerebral Cortex / Q000002:abnormalities* / Q000473:pathology*; D003071:Cognition / Q000502:physiology; D004351:Drug Resistance; D004569:Electroencephalography; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D009039:Motion Perception / Q000502:physiology; D009483:Neuropsychological Tests; D021641:Recognition, Psychology / Q000502:physiology; D012640:Seizures / Q000209:etiology*; D013702:Temporal Lobe / Q000473:pathology; D014705:Verbal Behavior / Q000502:physiology