Abstracts

Evaluating cognitive and psychosocial function prior to surgery serves an important function in identifying the impact of the lesion/epileptogenic zone and aids consideration of the potential impact of surgery. Identifying neuropsychological outcomes of surgery is important for children and families and an aid to planning of education and other services required. It also serves a key function in evaluating the overall outcomes of the programme and success relative to other centres. Nevertheless, undertaking meaningful analysis of change data in a small surgical programme is challenging. This study reviews surgery at Birmingham Chidlren[apos]s Hospital in the UK since the early 1990s and looks at the neuropsychological data for 27 cases where both pre-operative and post-operative data were available., Pre- and post-surgical neuropsychological data were considered for 27 children. The mean age at surgery was 9 years and the range was 1.0 to 14.7 years. Paired t-tests, two-tailed, were used for the analysis., Data are reported to show that overall there were few signficant changes in function following surgery. For example, Global Standard Scores (mean 100, sd 15) were compared , with a mean of 70.52 at pre-operative testing and 70.48 at post-operative testing, showing no significant difference at the p[lt]0.05 level. Comparison of scores for other aspects of function (eg some language and global memory measures) before and after surgery also showed no signficant differences. This was at one level a positive finding, confirming the value of the surgery in alleviating epilepsy and preserving cognitive function. However, there were some trends in the data which were masked in the global analysis. For example, there was a significant difference between the difference between the Verbal Scale IQ (VIQ) and the Performance Scale IQ (PIQ) before surgery (Mean of VIQ-PIQ= +2.83) and the difference between these scores after surgery (Mean of VIQ-PIQ= -2.61) (p+0.018), suggestive of some meaningful changes arising from surgery. In addition, the sample of cases having surgery was mixed, with 10 involving left hemisphere surgery and 15 right, with a mix of procedures including hemispherectomies and temporal lobe procedures. Detailed analysis revealed that for left side surgery patients, there was an almost signficant decline in VIQ (p=0.054). Variability within the data made it difficult to demonstrate statistically significant change. In addition, it is not clear that statistically significant change is necessarily clinical meaning., The paper considers the test protocol used, the role of evaluation within a small programme with limited resources, proposes alternative ways of classifying scores (Impaired, Same, Improved) that might be more meaningful, along with consideration of the most helpful timing of post-operative assessment both clinically and with respect to outcome evaluation., (Supported by National Health Service, UK.)