Hippocampal malrotation in pediatric patients with epilepsy associated with complex prefrontal dysfunction.
OBJECTIVE
The cognitive consequences of hippocampal malrotation (HIMAL) were investigated in a matched control study of children with epilepsy.


METHODS
Seven children with HIMAL were compared on a range of memory and attention tasks with 21 control children with epilepsy without temporal role pathology and 7 children with epilepsy and magnetic resonance imaging (MRI)-documented hippocampal sclerosis. In addition, in a statistical morphometric analysis, MRI studies from four children with HIMAL were compared to similar images of 20 age-matched typically developing control children.


RESULTS
Although the task battery was sensitive to the memory deficit of the children with hippocampal sclerosis, it did not reveal memory impairment in the patients with HIMAL. In contrast, the patients with HIMAL were impaired on the attentionally more demanding dual tasks, compared to both the control and the hippocampal sclerosis group. The structural MRI analysis revealed morphometric abnormalities in the tail of the affected hippocampus, the adjacent neocortex, and the ipsilateral medial thalamus. The basal forebrain was bilaterally affected. Abnormalities in remote cortex were found in the ipsilateral temporal lobe, the contralateral anterior cingulate gyrus, and bilateral in the dorsolateral and lateral-orbitofrontal prefrontal cortex.


CONCLUSIONS
Because the prefrontal cortical regions have been shown to be active during dual-task performance, the MRI results converge with the neuropsychological findings of impairment on these tasks. We conclude that HIMAL had no direct memory repercussions, but was secondary to subtle but widespread neurologic abnormalities that also affected morphology and functioning of the prefrontal cortex.
Stiers
Peter
P
Department of Paediatric Neurology, University Hospitals K.U. Leuven, Herestraat 49, Leuven, Belgium.
Fonteyne
Annick
A
Wouters
Heidi
H
D'Agostino
Emiliano
E
Sunaert
Stefan
S
Lagae
Lieven
L
D000293:Adolescent; D001288:Attention / Q000502:physiology; D002540:Cerebral Cortex / Q000002:abnormalities / Q000473:pathology / Q000503:physiopathology; D002648:Child; D003072:Cognition Disorders / Q000175:diagnosis* / Q000503:physiopathology; D004292:Dominance, Cerebral / Q000502:physiology; D004833:Epilepsy, Temporal Lobe / Q000151:congenital*; D005260:Female; D006624:Hippocampus / Q000002:abnormalities* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007360:Intelligence / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000503:physiopathology; D008570:Memory, Short-Term / Q000502:physiology; D019579:Neocortex / Q000002:abnormalities / Q000473:pathology / Q000503:physiopathology; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D017397:Prefrontal Cortex / Q000002:abnormalities* / Q000473:pathology / Q000503:physiopathology; D012153:Retention, Psychology / Q000502:physiology; D012598:Sclerosis; D013788:Thalamus / Q000002:abnormalities / Q000473:pathology / Q000503:physiopathology; D014706:Verbal Learning / Q000502:physiology