Factors predicting the outcome following medical treatment of mesial temporal epilepsy with hippocampal sclerosis
Introduction from Dr Markus Reuber, editor-in-chief of Seizure
There is increasing evidence for significant change in the incidence and prevalence of hippocampal sclerosis – the most common of lesions identified as the cause of medically refractory epilepsy in epilepsy surgery centres around the world in the nineties and noughties. In Western countries, patients with hippocampal sclerosis are ever harder to find. Those patients who can be found are older and have had epilepsy for longer (1). The reasons for these changes remain even more obscure than the cause(s) of hippocampal sclerosis – even if recent research is homing in on genetic and immune-related or inflammatory factors (and a paper on the susceptibility to childhood febrile seizures in this issue of Seizure makes an indirect contribution to this debate) (2).
However, temporal change and causes are not the only things we don’t know about hippocampal sclerosis. There are also many clinical questions. Obviously, we benefit from the outcome of a randomized controlled trial of epilepsy surgery versus medical treatment demonstrating the superiority of surgical intervention in terms of seizure control and health-related quality of live over the short term (3). In Samuel Wiebe’s study 8% of patients in the medical group and 58% in the surgically treated group were seizure-free at the one-year follow-up point.
One very important thing we need to know more about is the longer-term outcome of medical and surgical treatment for hippocampal sclerosis. Studies of surgical outcome suggest that just under 50% of patients remain seizure free ten years after surgery (excluding simple partial seizures). Whilst the proportion of seizure-free patients is likely to decline in the surgical group over time, it may well increase in the medically-treated group.
My editor’s choice from this issue of seizure, the paper by Javier Sànchez, suggests that complete seizure control can be achieved in over 30% of individuals with hippocampal sclerosis after two years of follow-up (even if their cases may have had less refractory epilepsy than those presenting to tertiary epilepsy surgery centres in more developed countries) (4). What is more, the study suggests a number of factors which patients and doctors may consider when the balance the relative risks and benefits of surgical and medical treatment for hippocampal sclerosis.
(1) Helmstaedter C, May TW, von Lehe M, Pfaefflin M, Ebner A, Pannek HW, Elger CE, Stefan H, Schramm J. Temporal lobe surgery in Germany from 1988 to 2008: diverse trends in etiological subgroups. Eur J Neurol 2014;21:827-834.
(2) Emsley HC, Appleton R, Whitmore C, Jury F, Lamb J, Martin J, Ollier W, Potier de la Morandiere K, Southern K, Allan S. Variations in inflammation-related genes may be associated with childhood febrile seizure susceptibility, Seizure 2014, please complete
(3) Wiebe S, Blume WT, Girvin JP, Eliasziw M. A randomized, controlled trial of surgery for temporal lobe epilepsy. N Eng J Med 2001; 345: 311–318.
(4) Sànchez J, Centanaro M, Solìs J, Delgado F, Yèpez L. Factors Predicting the Outcome Following Medical Treatment of Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis. Seizure 2014, please complete.