Psychopathological outcome of extratemporal lobe surgery: the need for international collaboration on data collection

Abstract

Antiepileptic treatment involves a careful balance between benefits and adverse effects. Key factors affecting quality of life are psychiatric and cognitive adverse effects.1 Against this background, it is surprising that there is relatively little information on the psychiatric outcome of extratemporal lobe neurosurgery, especially in children.2 Colonnelli et al.3 are to be congratulated on collecting this important data on 71 children. However, the paper also raises a number of questions. In particular, the largest group, those who had frontal lobe surgery was only 52 children; stratification into side of focus, brain pathology, pre-operative seizure type/frequency, family or personal history of psychiatric history, and other parameters would result in very small numbers in any one group, implying that it is difficult to draw firm conclusions in terms of specific outcomes for various types of extratemporal lobe surgery. This is an open, retrospective case-note study with all the shortcomings of this methodology. The risk is to make the assumption that the results from small numbers (when stratified) can be generalized to other patients. There are aspects of the methodology that could be addressed in future studies, at least in principle, and some that would be difficult to address. For example, on one hand there would appear to be a very strong argument for collating international data on these patients to provide adequate numbers. On the other hand, carrying out a controlled trial of surgery versus no surgery in matched participants would be fraught with major ethical and other issues. With the standard surgical procedures, it would also be impossible to carry out a double-blind controlled trial, although with the advent of gamma-knife surgery this might become a possibility. Of great interest is whether the surgery results in improvement or exacerbation of psychiatric disorders or cognitive problems. Frontal lobe epilepsy is associated with a high rate of psychiatric disorder.4 Because the large majority of the group had frontal lobe epilepsy, the finding that all the children who developed new psychiatric conditions and that all six of the children who needed psychotropic medication post-operatively (compared with only one pre-operatively) had frontal lobe surgery is, perhaps, not surprising. This was an open study with, as already discussed, no control group; the finding that more children required psychotropic medication after surgery might simply reflect intensive scrutiny in the post-operative period. A factor that is frequently omitted from these studies is whether pre-surgical frequent epileptiform discharges are abolished by the surgery. Surgical removal of a frontal lobe focus causing frequent epileptiform discharges can result in a marked improvement in behaviour, whereas removal of functional frontal lobe tissue could result in disinhibition and other problems leading to psychiatric disorders. What are we to conclude? First, the rate of psychopathology in children with epilepsy is high, as has been shown by various epidemiological studies.5 Second, the rate of psychiatric disorder in children referred for extratemporal lobe epilepsy neurosurgery to a specialist centre is, as might have been expected, very high. Third, the small numbers of patients (when stratified) imply that no general conclusions can be drawn about whether extratemporal lobe surgery is likely to improve or worsen psychiatric disorders, although anecdotally it is clear that improvement or deterioration can occur. Finally, and perhaps most important, this study highlights the need to gather data prospectively on large numbers of patients so that, when stratified, meaningful analysis of the results can be performed. International collaboration, with agreement on not only careful clinical assessment, including electroencephalogram and neuroimaging data, but also the use of standardized psychometric/psychiatric instruments before and after surgery might be the best way of achieving this. Perhaps in the future, when adequate data are available, both in terms of numbers and in terms of the quality/extent of preoperative and post-operative assessments, we shall be able to provide patients and their families with good prognostic information that will enable them to make informed decisions about whether to proceed with surgery.