Abstracts

RATIONALE: Mesial temporal sclerosis (MTS) is frequently associated with intractable temporal lobe epilepsy (TLE). The literature documents a strong relationship between MTS and memory impairment. In contrast, relatively little is known regarding the memory performance in patients with intractable TLE related to other kinds of pathology. The goal of the current study was to compare pre-operative and post-operative performance on memory tests in patients who underwent a standard anterior temporal lobectomy (ATL) with different underlying pathologies.
METHODS: The current study employed a retrospective analysis of 99 patients with TLE(Left TLE = 49, Right TLE = 50) who underwent standard ATL from January 1998 to December 2001. The study relied on an IRB approved archival database consisting of relevant demographic, medical and neuropsychological data collected as part of the patients[ssquote] routine medical care. The patients were divided into different pathology groups based on the surgical pathology report. The vast majority of patients were diagnosed with MTS (Left = 34, Right = 31). The other patients were divided among those with Other pathology (e.g., Tumor/DNET, vascular, cortical dysplasia; Left = 6; Right = 8), MTS + Other pathology (Left = 7, Right = 8) and Normal or nonspecific changes such as mild gliosis (Left = 3, Right = 4). The primary variables of interest included the patients[ssquote] index and individual subtest scale scores on the Wechsler Memory Scale -III. The data were analyzed at the group level and at the individual patient.
RESULTS: The patient groups did not differ with respect to age, education, or Full Scale IQ. The analyses for the left ATL patients indicated that patients with Other pathology (e.g., tumor, DNET, cortical dysplasia, vascular) generally performed better on most memory measures than those with MTS prior to surgery. Following surgery, the left ATL patient groups without histopathological evidence of MTS tended to show greater declines on memory tests using standardized regression based change scores.
The data for the right ATL pathology groups revealed better performance on the Family Pictures visual memory subtest in patients with Other pathology versus those with MTS prior to surgery. Following surgery, right ATL patients with evidence of Other pathology (either Other or Other + MTS) were more likely to show declines on both the immediate and delayed Family Pictures subtests than those with only MTS or Normal/mild gliosis.
CONCLUSIONS: The results of these preliminary data suggest that the underlying neuropathological substrate is related to memory performance prior to and following ATL in patients with TLE. It is important to note that many patients in the Other pathology group had lesions involving mesial structures as well as neocortical regions. Thus, our findings do not appear to simply reflect the extent of mesial temporal involvement. These preliminary data suggest that the underlying neuropathological status, to the extent that it is known prior to surgery, might assist in improving predictions of post-operative memory decline following ATL.