Today, an in-depth session at the 10th European Congress on Epileptology discussed the long-term impact of epilepsy surgery. Several high-profile European clinicians called for more research into the lifelong effects of having a surgical resection. They believe that people with epilepsy should be given more information about this before agreeing to have an operation.
Dr Sallie Baxendale (UK) presented an excellent case for a great deal more research in this area. In her session, she outlined several key challenges in assessing how successful surgery really is. She pointed out that people with epilepsy have a right to know certain facts before they can give informed consent to have a surgical procedure.
Dr Baxendale identified key challenges as being the failure rates of epilepsy surgeries and a lack of scientific evidence about its long-term impact. She pointed out that even 30 per cent of people considered 'good' candidates for operations are still not seizure-free afterwards. Given that a majority of people who have brain tissue removed will experience some form of cognitive deficit as a result of the procedure, the patient must be made aware that it may not work.
The majority of studies to explore the impact of surgery have focused on its short-term impact - only following patients for a year after the operation. She pointed out that people who are assessed for surgery are not so much concerned with the short-term effects - but with whether the procedure will have a lifelong impact.
Brain surgery and decline in memory
Dr Baxendale's presentation was followed by a similarly fascinating presentation from Swedish neuropsychologist Lena Andresson-Roswall PhD. Dr Andresson-Roswall confirmed that there is very little evidence about the long-term impact of epilepsy surgery. In fact, there are only nine studies to have explored this, including a total of only 483 patients.
Dr Andresson-Roswall explored what evidence there is relating to the effect of temporal lobe surgery on general cognitive function and memory decline. The available data suggest that cognitive outcomes overall remain stable after temporal lobe surgery. In fact, some studies suggest that there may even be a positive impact. The evidence regarding an effect on memory function is less clear-cut, however.
Existing research studies have offered contradictory evidence on this topic. Some studies have demonstrated a negative long-term impact on verbal memory after left temporal lobe surgery. These people experience progressive memory decline, whereby their memories only continue to worsen in the long term. Meanwhile, some studies have demonstrated that verbal memory remains stable after surgery.
Interestingly, some studies suggest that the brains of people with epilepsy have actually recovered over the long term. Despite experiencing a decline in verbal memory scores in the years immediately after surgery, those scores returned to much nearer pre-surgery levels after several years.
Are the risks worth it?
Dr Andresson-Roswall emphasised the importance of more research in this area to explore the true risks of surgical resection and the long-term impact on memory. She explored two ideas that may categorise people with epilepsy after their surgeries: so-called 'double-winners' and 'double-losers'. Double-winners are described as those people who experience both seizure freedom and the recovery of their verbal memories after surgery.
Double-losers, on the other hand, are the people who stand to lose the most as a result of surgery and must receive thorough and honest counselling about its potential impact. These are the people who not only do not achieve seizure freedom after surgery, but also experience progressive memory decline as a direct result of the procedure. Dr Andresson-Roswall called for work that would help us understand the predictors of which surgical candidates would fall into which category.
During the discussion of the session, Dr Baxendale also brought up the idea of 'pre-hab'. This is a technique she has been employing with surgical candidates, whereby strategies to help them improve their memories are used even before the operation. Reinforcing the patient's memories in this way should hopefully limit the loss of post-surgical memory function.
What predicts post-surgical seizure freedom?
Gail S Bell of University College London continued the session by asking very practical and relevant questions about epilepsy surgery. Namely: does it work? What factors can help us predict whether a person will continue to have seizures after a surgical resection?
Dr Bell's study findings included several interesting pieces of information, including data relating to anti-epileptic drugs (AEDs). She found that the more AEDs a person had tried before they were referred for surgery, the less likely it was that their surgery would achieve seizure freedom. This underscores the importance of referring people with epilepsy for appropriate surgery earlier, instead of trying a large number of different drugs before considering that option. This may only undermine the success of the procedure.
The risks of not going ahead with surgery were also discussed during Dr Bell's presentation. People with epilepsy who understand all the possible risks of having an operation may be unwilling to proceed - knowing that it may not cure their epilepsy and may result in progressive memory decline. There is evidence to suggest, however, that even if a person continues to have seizures after surgery, their risk of sudden unexpected death in epilepsy appears lower.
Research continues in this field - a field that several researchers referred to as 'neglected'. Only if we have a more thorough understanding of the long-term impact of surgery can we inform people with epilepsy about both the risks and the chances of it being successful.