Introduction from Dr Markus Reuber, editor-in-chief of Seizure
The discrimination against people on the basis of age is now illegal in many countries and many settings. Nevertheless age clearly has biological and social effects which need to be taken into account when decisions about medical treatments are made. In the field of epilepsy this issue is particularly acute when decisions about epilepsy surgery are made. Like most other treatments for epilepsy, resective brain surgery would be carried out to reduce or stop epileptic seizures whilst minimizing the effects of epilepsy on functioning and independence. Indeed, epilepsy surgery would ideally increase the functional capacity and quality of life of individuals willing to accept the significant risks of this treatment. In the case of surgery for temporal lobe epilepsy, the surgery-related risks are particularly significant with respect to learning and memory.
The interaction between temporal lobe epilepsy (or rather the duration of the disorder) and memory decline has previously been documented in longitudinal studies (1). Verbal learning capacity declines with age in healthy individuals but does so earlier (but not more rapidly) in patients with TLE. Previous research has also highlighted the risk that temporal lobe surgery for epilepsy poses to memory functions which “naturally” decline with advancing age, and the potential for epilepsy surgery to accelerate the effects of “normal” cognitive aging (2).
My editor’s choice paper from this issue of Seizure confirms these findings and provides us with a more detailed understanding of the cognitive risks of carrying out epilepsy surgery in older adults. As recognized previously, Thompson et al. demonstrate that memory impairments were more severe in our older TLE patients prior to surgery. Poorer performance was associated with a longer duration of epilepsy. However, Thompson et al. also demonstrate that post-operative verbal memory decline was also most marked in the oldest cohort (3). This suggests that older patients (or their brains) are not only at greater cognitive risk in relation to epilepsy surgery because their pre-operative memory functioning was least good but also because they are more vulnerable to surgery than younger individuals. The fact that subjective decline of memory function was also greatest in the oldest age group adds ecological validity to this finding.
Of course, these results do not mean that epilepsy surgery is not a suitable treatment for patients over fifty. As Thompson et al. demonstrate, some patient groups (for instance those with right TLE) are at lower risk of acquiring memory deficits through surgery. The benefits of surgery (including the reduction of the risk of SUDEP and seizure-related injuries) may still outweigh the risks of surgical intervention. However, the risk / benefit ratio needs to be carefully considered on a case-by-case basis, and the patient’s biological age cannot be ignored – whatever anti-agesim legislation may say.
(1) C Helmstaedter, M Kurthen M, S Lux, M Reuber, Elger, The effects of chronic epilepsy on cognition: a longitudinal study in surgically- and medically-treated patients with temporal lobe epilepsy. Annals of Neurology 2003,54:425-432.
(2) C Helmstaedter, M Reuber, CE Elger, Interaction of epilepsy surgery and cognitive aging, Annals of Neurology 2002;52:89-94.
(3) P J Thompson, S Baxendale, J Duncan. Cognitive outcomes of temporal lobe epilepsy surgery in older patients. Seizure 2015