Progression in Temporal Lobe Epilepsy: An Interview with Dr. Bruce Hermann
In a prospective study, Bruce Hermann, M.D., Professor and Director, Charles Matthews Neuropsychology Section, Department of Neurology, University of Wisconsin, and colleagues are investigating changes in brain structure, cognitive function and psychiatric status that take place over a 4-year period in patients with chronic temporal lobe epilepsy compared to healthy patients. Below is an interview with Dr. Hermann regarding his findings from this study as presented at the 58th annual American Epilepsy Society (AES) conference in New Orleans.
Q. "What prompted you to study chronic temporal lobe epilepsy? What percentage of the population has chronic temporal lobe epilepsy?"
A. "Temporal lobe epilepsy (TLE) is a very common type of focal (localization-related) epilepsy that can be difficult to control with medications. My colleagues and I spent many years evaluating people with TLE who were candidates for epilepsy surgery. Not uncommonly, persons with TLE suffered from poorly controlled epilepsy for many (20 ) years before they were finally seen at a surgical center and many exhibited considerable cognitive and psychosocial difficulties. One concern we had was whether the problems we saw at the time of surgery evaluation were progressive, that is, whether they worsened over time."
Q. "Why is there so much interest in whether TLE is associated with progressive adverse changes in brain structure, cognitive function or psychiatric status?"
A. "One reason there is so much interest in the issue of progression is that epilepsy surgery may be curative for some people with TLE whose seizures are very poorly controlled by medications. If poorly controlled TLE has progressive adverse effects on brain structure, cognition, or psychosocial function this would be another reason to be especially careful in identifying individuals with intractable TLE who are surgical candidates earlier rather than later in the course of their disorder. Everyone hopes that early identification and effective treatment will prevent or avoid any progressive effects."
Q. "In your methodology you mention a “group by time interactions” can you explain this in simplistic terms? What is the test-retest interval?"
A. "The study participants were seen 4 years after their baseline assessment and underwent a second cognitive evaluation, MRI, and psychiatric interview. We were especially interested in any adverse changes in cognition over time, increased rates of emotional-behavioral distress, or greater than age-expected changes in brain structure. The most striking finding was that over the 4-year interval persons with TLE experienced many more episodes of significant depression and anxiety than the controls—the differences were really quite striking, and in fact the most striking finding of the study. Regarding cognition, the most straightforward finding is that a subset of persons with TLE (about 20-25%) exhibited poorer cognitive performance at their retesting. Most persons with TLE (75-80%) had largely stable mental status over time, but this subset of about 20-25% of persons with TLE is having greater difficulty in regard to cognition. We are conducting analyses right now to identify what features (e.g., seizure control, medications) may be associated with this increased risk of cognitive decline."
Q. "What are the implications of your study?"
A. "First, there needs to be much greater attention to the psychological/psychiatric complications of chronic epilepsy. Depression and anxiety are very common in patients with intractable epilepsy. These problems only get worse over time, and they contribute significantly to the burden of living and dealing with epilepsy. Depression and anxiety are very treatable, but these problems need to be discussed, identified, and treated effectively. Second, there is a subgroup of persons with TLE that appear to have a difficult “course”. We will obtain a better picture of exactly who these people are and the characteristics of their epilepsy. It is this group that needs to be monitored very carefully as they are at an increased risk of adverse cognitive outcomes. The same is true for the MRI results, adverse changes are seen in only a minority of persons, and again, our efforts will be devoted to identifying the characteristics of this subgroup."
Q. "What is the next step in researching this particular subject? How can health care professionals apply this information?"
A. "Treatment and prevention are key. There is, of course, tremendous interest in new and more effective ways to treat and prevent seizures, which is extremely important. There needs to be equally serious attention and effort devoted to the early recognition of important comorbidities (e.g., anxiety, depression, other behavioral problems, memory impairment, and learning difficulties), provision of effective treatments, and prevention of these problems. Healthcare professionals can be especially helpful in addressing the issues related to these comorbidities."
The abstract of this study is published in Epilepsia, 2004;45,Suppl 7: p.183