Abstracts

RATIONALE: To examine incidence of partial epilepsies and in particular temporal lobe epilepsy during a time period when magnetic resonance imaging was available in a population-based sample.
METHODS: A population-based retrospective study was performed by the authors utilizing the Rochester Epidemiology Project Records-Linkage System to ascertain patients with a diagnosis of partial epilepsy seen at Mayo Clinic Rochester from 1990 through 1996. 470 patients were identified and partial seizures were confirmed in 180 patients. Of the 180 patients with confirmed partial epilepsy, 98 had onset of their seizure disorder, while living in Olmstead County, between 1990 and 1996. Magnetic resonance imaging was performed in 75 of the 98 patients. Olmstead County population data was obtained from the U.S. Census Bureau.
RESULTS: Of the 98 patients with onset of their seizure disorder while living inside Olmstead County between 1990 and 1996, a temporal lobe seizure disorder was present in 25 patients and an extra-temporal seizure disorder was present 22 in patients. Benign rolandic epilepsy was present in an additional 7 patients. In the remaining 44 patients there was insufficient information to determine location of seizure onset. The incidence of partial epilepsy was 13 per 100,000. Temporal seizure disorders had an incidence per 100,000 of 3.2 and extra-temporal seizure disorders of 2.8. The incidence of benign rolandic epilepsy was 0.9 per 100,000 or 4.5 per 100,000 for children aged 5-17 years. MRI imaging was performed in 20 of the 25 patients with temporal lobe seizures. Hippocampal atrophy was seen with an incidence of 0.3 per 100,000.
CONCLUSIONS: The incidence of hippocampal atrophy was ten percent of the total incidence for temporal lobe epilepsy. The reported incidence of partial epilepsy was comparable to previous studies though lower than a previous epidemiological study performed in Rochester, Minnesota. A difference in the methodologies is suggested as the cause for this discrepancy.