Cognitive Side-effects of Antiepileptic Drugs. In: Jambaqué I, Lassonde M, Dulac O, editors. Neuropsychology of Childhood Epilepsy. Boston: Springer US; 2001. pp. 257-67. [DOI: 10.1007/0-306-47612-6_27]

Adjunctive lamotrigine for refractory epilepsy in adolescents with mental retardation

Epilepsy is a major comorbid condition in adolescents with mental retardation and is often characterized by multiple seizure types that are refractory to treatment. This study (n = 22) describes a subanalysis of data from a larger multicenter study of adjunctive lamotrigine therapy in patients with mental retardation and refractory epilepsy and focuses on the outcome measures of seizure reduction, safety and tolerability, and impact on behaviors in adolescents with mental retardation and refractory epilepsy. The study kept baseline antiepileptic drugs constant and titrated lamotrigine over 8 weeks to the target dose, followed by an 8-week maintenance phase and then a 12-week optimization phase during which all antiepileptic drugs and lamotrigine could be altered as clinically indicated. Sixty percent of subjects had a 50% decrease in seizures by the end of the maintenance phase and a mean 39% reduction in seizure frequency by the end of the maintenance phase (25% by end of study) compared with baseline. Global improvements were observed in most patients, with statistically significant improvements in the Aberrant Behavior Checklist and the Habilitative Improvement Scale, which is predictive of less need for supportive care in activities of daily living and thus enhanced potential for greater independence. Lamotrigine-associated improvements in behavior can be attributed to improved control of seizures, a reduction in concomitant antiepileptic drugs, and/or direct mood-stabilizing and behavior-enhancing properties independent of the antiseizure effects of the drug. The results of this study suggest that lamotrigine is an important treatment option in adolescents with mental retardation and comorbid epilepsy.

Atypical language representation in patients with chronic seizure disorder and achievement deficits with magnetoencephalography

PURPOSE

To characterize the relation between hemispheric asymmetries in language-specific brain activity and reading/spelling achievement by using magnetoencephalography (MEG).

METHODS

Patients (n = 83) with medically intractable complex partial seizures of either left- or right-hemisphere origin were classified as having reading and/or spelling deficits (RS) or as not impaired (NI) by using standard achievement tests. All patients had undergone noninvasive functional mapping of receptive language cortex by using MEG as part of a preoperative seizure surgery evaluation.

RESULTS

RS patients with left-hemisphere seizure onset exhibited relatively greater activation and earlier onset of late, language-specific MEG activity in posterior temporal and inferior parietal areas of the right as compared with the left hemisphere than did NI patients. These findings also were evident on an individual basis and were independent of global intellectual abilities.

CONCLUSIONS

Reading and spelling achievement deficits in patients with complex partial seizures of left-hemisphere origin are associated with atypical language organization, possibly secondary to reorganization of language function to right-hemisphere areas that are not as efficient as homotopic areas in the left hemisphere in supporting reading and spelling functions.

Relative influence of epileptic seizures and of epilepsy syndrome on cognitive function

Cognitive impairment is frequently observed in children with epilepsy. We aimed at addressing to what extent cognitive function is affected by paroxysmal epileptiform activity with or without clinical seizures or by clinical features characteristic of the epilepsy syndrome. To this purpose, combined electroencephalographic (EEG) recording and cognitive testing (IQ and reaction times) were performed in 28 children. Frequent epileptiform EEG discharges significantly reduced reaction time, as did the occurrence of seizures during cognitive testing. Syndrome-related factors tended to affect cognitive functions as well: children with generalized epilepsy and high average seizure frequency obtained lower scores. Linear regression analysis showed that stable aspects of cognitive function, as reflected in intelligence level, are most closely related to the severity of the epilepsy syndrome (average seizure frequency), whereas transient aspects of cognitive function, such as reaction times, are related to the occurrence of epileptiform EEG discharges. This suggests that seizures have a direct effect on transient cognitive aspects, which can accumulate and result in effects on intelligence level.