Hippocampal malrotation in pediatric patients with epilepsy associated with complex prefrontal dysfunction.

PURPOSE: 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. DISCUSSION: 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.

Specific memory impairment in a multiple disabled male with fragile X syndrome and temporal lobe epilepsy.

Evaluation of the cognitive repercussions of an epileptic disorder and its treatment are important issues in clinical follow-up. This especially holds true for temporal lobe epilepsy (TLE) where resective surgery can be a valid treatment option. However, in patients where TLE coexists with another neurocognitive disorder, questions can arise about the precise nature of the neuropsychological deficits. The aim of the present study was to evaluate memory impairments, found in a male aged 12 years who had the dual pathology of fragile X syndrome and refractory TLE. Memory functions of this child were compared with those of a male aged 11 years 7 months with fragile X syndrome matched for intellectual functioning as indicated by highly comparable verbal (5 y 5 mo vs 5 y 9 mo) and non-verbal (7 y 2 mo vs 6 y 1 mo) cognitive age equivalents. Performance on each neuropsychological measure was evaluated twice, separately with normative data based on chronological age and on verbal or non-verbal cognitive level. A specific, distinguishable profile of task performance could be found only when controlling for general level of cognitive functioning. This made it possible to accurately evaluate neuropsychological abilities before and 6 months after anterior temporal lobe resection even in this male with a complex neurological pathology.