Abstracts

There is growing evidence that hippocampal epilepsy is progressive but few studies regarding neocortical epilepsy. Liu et al (2003) reported focal or generalized volume losses in 54% of chronic epilepsy patients vs 24% of controls over 3.5 years. We have reviewed our quantitative PET data (Swartz et al, 1996) and neurospycological tests on frontal lobe epilepsy patients to look for progression in this group.
The diagnosis of FLE (n = 15) was based on the neuro exam, EEG, video-EEG, neuropsyhological tests, MRI and 18-FDG-PET. To analyze the PET, 87 ROI[apos]s were drawn on the entire brain of 15 individuals with FLE as previously reported. The correlation between the dorsal prefrontal cortex (DPFC) regional glucose uptake (rCMRGlc) and duration of epilepsy was evaluated. Six of the subjects had pre-operative neuropsychological testing done several times over periods of 3 - 6 years. Changes in frontal lobe tests were compared over time in these individuals, who refused surgery or were not considered candidates.
There was a trend for the DPFC rmRGlc to decrease with time on the hemisphere ipsilateral to the epileptogenic zone (p = 0.07, 4 = 0.46). This was not found in the contralateral hemisphere (p = 0.43). SImilarly, the rCMRGlc in DPFC tended to increase as age of onet increased, ipsilateral to the focus (p = .08, r = .40). Not all subjects had every test each time they were tested as some were not presurgical. Scores on the Purdue pegboard (both hand) decreased over time in 4/4 tested. Digit span decreased over time in 4/5 tested with no change in 1/5. TIme to complete the Pin test increased in 5/6 over time with a small decrease in 1 (p=.09 for year 0 vs 3-6, t-test). On the Wisconsin Card Sort, total errors decreased in 1, increased in 1, showed no change in 2, but perseverations increased in 4/4 (p = .04, year 0 vs 6, t-test).
The small sample size and retrospective nature of this data do not lend themselves to firm conclusions. Changes in antiepileptic drugs need to also be taken into account, although these patients were generally changed from older AED[apos]s (phenobarbital, phenytoin) to newer ones believed to be less sedating. Given the trends towards decline in prefrontal function and glucose uptake over time, further study is warranted and a prospective study of the question of progression in frontal lobe epilepsy is underway.
1. Liu RS, et al. Annals Neurol.2003;53(3):312-324. 2. Swartz, et al. Neurology 1996;46:737-747
[Supported by: Veteran[apos]s Adminstration Research Service, Merit Review Grant.]