Abstracts

Material specific memory deficits are commonly identified in patients with intractable temporal lobe epilepsy (TLE), but the extent and time course of cognitive deterioration over time has not been well established. We studied cognitive changes in patients with intractable TLE with serial neuropsychological testing available prior to anterior temporal lobectomy (ATL). The objectives of this study were to 1) describe the proportion of patients who experience [gt] 1 stdev decline in memory, and 2) to identify independent variables associated with memory decline in patients with intractable TLE prior to surgery.
Forty consecutive patients (20 left TLE, 20 right TLE) were identified who met the following inclusion criteria: 1) Age [gt] 16 years at the time of the initial test; 2) two neuropsychological tests [gt] 1 y apart available prior to ATL (Test 1 and Test 2); and 3) all patients underwent ATL after Test 2. Data from Test 1 and 2 were analyzed. Average length of time between Test 1 and 2 was 4.4 y (range 1.1-12.5 y). Informed consent for the use of clinical information was obtained from each patient.
Fifteen of 40 patients (38%) experienced [gt] 1 stdev decline on at least 1 memory test (8 left TLE, 7 right TLE). Multiple regression analyses identified several significant models. LEFT TLE PATIENTS: Higher frequency of complex partial seizures (CPS) (p=.003), higher initial test score (p[lt].0005), and older age at initial test (p[lt].0005) were associated with greater decline in verbal memory. Higher frequency of CPS (p=.039), and higher initial test score (p=.023) were associated with greater decline in nonverbal memory. RIGHT TLE PATIENTS: Higher initial test score (p[lt].0005), older age of onset of epilepsy (p=.024) and greater anticonvulsant toxicity (p=.015) were associated with greater decline in verbal memory. Higher initial test score (p=.047) was associated with greater decline in nonverbal memory. These models explained between 25.3-88.0% of the variance.
This study demonstrated that more than one-third of patients with intractable TLE experienced significant memory decline over a few years. The independent variables associated with memory decline included higher frequency of seizures, higher initial test score and older age at initial test. Our study differs from previous longitudinal studies by demonstrating a highly significant correlation between frequent CPS and memory deterioration in patients with TLE. Early and effective control of seizures in patients with TLE is likely to be important in preventing cognitive deterioration.
[Supported by: MINCEP[reg] Epilepsy Care]