As shown above, patients with FLE have behavioural disorders which appear very mild when compared with those reported in patients with frontal mass lesions. With respect to mood disorders, they appear less affected than patients with TLE, and they also showbetter academic achievement. The finding that hyperactivity, addiction and obsession might be a behavioural feature of FLE is of great interest, and can be discussed as reflecting frontal dysfunction in general and to be in line with the behaviour observed in neuropsychological examination and during seizures. The question which remains open, is how consistent the behaviour in focal epilepsies is over time.
We can not yet give a conclusive answer to this question on the basis of long-term follow-up observations. The impact of epilepsy and seizures on behaviour, however, can be estimated by comparisons of patients who after surgery still have seizures with those who became completely seizure-free. We therefore analysed data from surgically and nonsurgically treated patients who participated in a long-term follow-up study, which was originally designed to show the cognitive development of these patients over time (Helmstaedter et al., 2000b). However, at the time of the long-term follow-up visit we also assessed depression by use of the BDI and quality of life by use of a German modified QOLIE-10. For the present purpose we extracted from the total database only the data of the patients with temporo-mesial epilepsy and hippocampal sclerosis as compared with those with FLE. Fifty-seven patients had mTLE with hippocampal sclerosis (27 had surgery, 20 were treated conservatively) and 30 patients had FLE (16 had surgery and 14 were treated conservatively). Taking depression and quality of life measures as the dependent variables in a multivariate analysis with consideration of surgery, localization and lateralization of epilepsy as independent variables, and age and the follow-up interval (mean 56 months; 2-10 years) as covariates, seizure outcome turned out to be the only significant predictor. Only 14% of the seizure-free patients in contrast to 51% of those who still had seizures showed elevated depression scores greater than the cut-off score of 12 points. It should be noted that 14% is much less than the normally reported 30% of patients with focal epilepsy and depressive mood, and that 51% clearly exceed this number. Comparably, 45% of the seizure-free patients reported good quality of life with QOLIE-10, as compared to only 11% of the patients who continued to have seizures. Although these data are not follow-up data and although depression and quality of life represent only two facets of the whole range of behaviour, these data show quite impressively what a difference the presence or absence of seizures can make. The finding parallels recent findings in children who after successful epilepsy surgery show marked improvement in behaviour disorders (Lendt et al., 2000). Long-term follow-up studies on personality and behaviour disorders are thus badly needed to complete our understanding of the interaction between brain damage, epilepsy and behaviour.
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