Cognitive outcomes in patients with frontal lobe epilepsy.

A typical "cognitive profile" or defining behavioral syndrome for patients with frontal lobe epilepsy (FLE) has not been described. While there have been numerous reports of impaired "executive functions" in this population, the nature and severity of these deficits is highly variable, ranging from impaired attention to difficulty with the more complex behaviors involved in planning, selecting goals, anticipating outcomes, and initiating action. These findings have been more difficult to demonstrate in children, in part due to the later appearance of these abilities in normal development. When a clear focal seizure onset is identified, or in cases of a structural lesion, cognitive impairment may be specific to the side, size, and localization of the abnormal cortex. Children who have undergone surgical resection of the dominant frontal lobe frequently show declines in verbal fluency, and sometimes verbal IQ, visual confrontation naming, and conceptual reasoning. Adult surgical cases have shown the most specific frontal lobe findings, including reduced word fluency with relatively small lesions of the dominant dorsolateral frontal cortex, the analogous finding of impaired nonverbal fluency with nondominant frontal lesions, and other executive deficits following large resections of prefrontal cortex bilaterally. These reports support the likelihood that it may not be possible to identify a specific cognitive syndrome associated with FLE in the absence of a structural lesion.