Frontal lobe dysfunctions in patients with juvenile myoclonic epilepsy

Abstract

Juvenile myoclonic epilepsy (JME) is a common form of idiopathic generalized epilepsy. Behavioral and cognitive problems are frequently observed in JME. Although the underlying mechanisms are still unknown, recent neuropsychological and neuroimaging studies provide strong evidence for frontal lobe dysfunction. Neuropsychological studies have shown JME patients to be impaired in a number of executive functions such as concept formation, abstract reasoning, mental flexibility, and cognitive speed and planning. They scored below average on measures of attention, immediate verbal memory, working memory, and verbal fluency. The patients with JME performed worse than the group with temporal lobe epilepsy on some frontal tasks. Some specific personality features, such as unreliability and emotional instability, poor social adjustment, high rates of anxiety, mood disorders, phobias and somatization disorders seen in patients with JME have also been described in patients with frontal lobe-lesions. Quantitative magnetic resonance imaging studies have shown regional, frontal cortical and thalamic grey matter abnormalities. These findings support the pathophysiological concept of functional abnormalities in the thalamo-cortical circuit in JME. The additional impact of interictal epileptiform electroencephalography activity on cognitive functions was suggested. Poor working memory and impaired executive and motor performance in JME patients may also be attributed to altered dopamine signaling in the striatum and frontal lobes. JME may be a non-uniform condition. Different genetic and pathophysiologic mechanisms could underlie the clinically observed differences in prognosis, cognitive functioning, personality traits, and frontal lobe deficits.