Focal cortical dysplasia: Improvements of SHE scores and cognitve parameters in patients with epilepsy after surgery

Background: In the first instance the aim of epilepsy surgery is the control of seizures, but the improvement of quality of life and cognitive functions is also of big importance. In order to quantitatively analyze post-surgical outcomes of quality of life, attention and memory functions in patients with epilepsy caused by focal cortical dysplasia (FCD), we compared pre- and post-surgical scores using standardized methods. The more precise analyses for special patient groups are, the better the surgery outcome prediction for individual cases may be.

Method: The sample of 17 patients with a FCD (pre-surgical age range: 15 and 57 years, M=33.58, SD=13.66) were recruited with a pre-post surgery interval between 12 and 35 months (M=16.35, SD=6.11). The mean age at epilepsy onset was 9.88 years (SD=12.84) and mean disease duration was 23.71 years (SD=15.45). In 12 patients the FCD was located right hemispherically (5 frontal, 7 temporal) and in 5 patients left hemispherically (1 frontal, 4 temporal). Histologically (classification according to Palmini) 13 patients had a FCD type 1 and 4 patients a FCD type 2. An additional hippocampal sclerosis was diagnosed in 7 patients (3 left hemispherical). Eleven of the 17 patients (65%) were postoperatively completely seizure free (Engel class 1a). On the one hand we analyzed data of the self-rating questionnaire of subjective handicap of epilepsy (SHE) by Donoghue et al. (Brain, 1998) and on the other hand we compared objectively measured cognitive parameters like selective attention (d2 Test of Attention), verbal and nonverbal declarative memory (German version of CVLT and DCS – a visual learning and memory Test for Neuropsychological Assessment). Statistical analyses were made using the nonparametric Wilcoxon test or Mann-Whitney-U-test. Tests with p<0.05 were regarded as significant.

Results: Patients post-surgically scored higher in domains like working and activity, social and personal life, feelings about oneself, physical scale and change during the last year. The only post-surgical score of SHE which did not show significant improvement was life-satisfaction, even in the 11 post-surgical seizure free patients. Contrary to our expectations improvements in SHE scores of seizure free patients were not higher than improvements of the not seizure free patients. Neuropsychological assessment showed that selective attention as a basic cognitive function also improved after surgery. The patients' post-surgical processing speed was significantly higher, while they were not more prone to mistakes than pre-surgically. Neither patients with left hemispherical FCD, nor patients with right hemispherical FCD improved in declarative memory functions; post-surgical memory results were unchanged in both groups.

Conclusion: Summarizing, nonparametric analyses showed, that a surgical treatment of FCD in patients with epilepsy leads to improvements in most domains of quality of life even though the life-satisfaction did not improve. Further analyses of socioeconomic factors may help to understand the missing life-satisfaction improvement. Further, the surgical treatment of FCD elicits an improvement of selective attention and did not contribute to deterioration in declarative memory.