Interictal Problems

A long-standing bias suggests that temporal lobe epilepsy (TLE) is the epilepsy syndrome most often complicated by interictal (the time between seizures) cognitive and behavioral problems. This may be true, but the available evidence does not clearly support this view.

• Few studies have controlled for seizure frequency and severity, medication burden, family history, and other relevant factors.
• There is a lack of well-defined incidence and prevalence rates for cognitive and behavioral problems in community epilepsy samples.
• Patients with all forms of epilepsy—including benign rolandic, childhood absence, juvenile myoclonic, and frontal lobe epilepsies—have increased rates of cognitive and behavioral problems (1–3).

The interictal period comprises more than 99% of most patients’ lives. Interictal cognitive and behavioral disorders profoundly impair the quality of life. These problems are continuous, unlike the seizures, which are intermittent. Encompassing a wide spectrum, these disorders often fit awkwardly into neuropsychiatric categories. Even when patients fit into Diagnostic and Statistical Manual of Mental Disorders (4) categories, they often remain untreated because some physicians believe that using medications to treat other problems might lower the seizure threshold.

Some of the most devastating neurobehavioral disorders that complicate epilepsy have neither a defined symptom- nor a syndrome-level diagnosis. For example, the ability to read social cues and respond appropriately in social settings is essential for successful social function. These skills are often lacking in patients with right hemisphere or frontal lobe seizure foci. Hence, there is a need for the development of systematic approaches to define these disorders and therapeutic interventions to reduce symptom severity.

References

1. Devinsky O, Najjar S. Evidence against the existence of a temporal lobe epilepsy personality syndrome. Neurology. 1999;53(suppl 2):S13–25.
2. Wirrell EC, Camfield CS, Camfield PR, Gordon KE, Dooley JM. Long-term prognosis of typical childhood absence epilepsy: remission or progression to juvenile myoclonic epilepsy. Neurology 1996;47:912–8.
3. Yung AW, Park YD, Cohen MJ, Garrison TN. Cognitive and behavioral problems in children with centrotemporal spikes. Pediatr Neurol 2000;23:391–5.
4. American Psychiatric Association. Diagnostic and statistical manual of mental disorders. Fourth edition. Text revision. Washington, DC: American Psychiatric Press, 2000.

Reproduced and adapted with permission from Orrin Devinsky, M.D. and Epilepsia.