RECURRENT SEIZURES MAY CAUSE HIPPOCAMPAL DAMAGE IN TEMPORAL-LOBE EPILEPSY

Objective: To investigate whether recurrent seizures cause hippocampal damage in temporal lobe epilepsy (TLE). Patients: Eighteen patients w ith newly diagnosed cryptogenic TLE, 14 patients with chronic well-con trolled cryptogenic TLE, 32 patients with chronic drug-resistant crypt ogenic TLE, and 25 healthy subjects were studied. Measurements: Hippoc ampal MRI volumetry and T2 relaxometry were used. Results: Chronic dru g-resistant patients with seizure focus in the left temporal lobe had an 18% smaller left hippocampus and chronic drug-resistant patients wi th seizure focus in the right temporal lobe had a 14% smaller right hi ppocampus than did the control group (p < 0.05). Chronic drug-resistan t patients with seizure focus on the left side had longer T2 relaxatio n times in the body of the left hippocampus than did the control group (p < 0.001) and chronic drug-resistant patients with seizure focus on the right side had longer T2 relaxation times in the body of the righ t-hippocampus than did the control subjects (p < 0.01). In all patient s with a left seizure focus, the left hippocampal volume correlated in versely with the estimated total number of partial (r = -0.391, p < 0. 01) or generalized (r = -0.312, p < 0.05) seizures the patient had exp erienced. The prolongation of the left T2 relaxation time in the body of the hippocampus correlated with the total number of both partial (r = 0.670, p < 0.001) and generalized (r = 0.481, p < 0.001) seizures a nd with the duration of TLE symptoms (r = 0.580, p < 0.001). Conclusio ns: In patients with cryptogenic epilepsy, recurrent seizures may caus e damage to the hippocampus throughout the lifetime of the patient.