It is estimated that 2–4% of the population will have a seizure during their lifetime and 1–2% will develop epilepsy. Of these patients, 40% have medically refractory epilepsy and therefore should be considered for surgery. Mesial temporal sclerosis (MTS) is the most common cause of medically refractory epilepsy. Patients with uncontrolled epilepsy have approximately five-times the incidence of death compared with the normal population Citation[1].
Epilepsy has a bimodal distribution, with peaks occurring in early childhood and after the age of 60. The type of seizure and underlying pathology differ between the two groups, with the former usually being generalized and idiopathic, and the latter partial with structural pathology. This editorial focuses on MTS, and not other structural lesions, which are usually treated based on the underlying pathology, for example, tumors and arteriovenous malformations.
Age should not, in the opinion of the authors, be regarded as a contraindication to epilepsy surgery in patients with medically refractory epilepsy, in particular a temporal lobectomy, if the semiology, localizing data from appropriate imaging modalities, video-EEG and, if indicated, intracranial monitoring, are concordant. Unfortunately this group of individuals has received little attention, despite the well-recognized increasing incidence of epilepsy in the elderly Citation[2]. In 2001, Wiebe et al. published a randomized controlled study of patients with temporal lobe epilepsy, which demonstrated that 8% of patients treated with medication alone were seizure-free at 12 months, compared with 58% of patients who had surgery Citation[3].
There is little conclusive evidence that supports age as having a negative or positive outcome after epilepsy surgery. Many studies in the past have focused on younger patients, denying older patients surgery, because of concerns with respect to duration of seizures and cognitive impairment, in particular verbal memory loss, as well as postoperative complications. In 2006, Acosta et al. compared patients over the age of 60 with younger patients and found comparable safety and efficacy with respect to epilepsy surgery Citation[4].
Those studies that have looked at surgery in patients over the age of 50 have unfortunately included a patient population with heterogeneous pathology and preoperative seizure types, as well as a variety of surgical procedures, which are often tailored depending on the pathology. The pathologies have included MTS, tumors and dysplasias Citation[5–7], and it is well known that differing pathologies often have different outcomes with respect to seizure control. In 2009, Murphy et al. published a study that examined patients over 50 years of age who had isolated hippocampal sclerosis, and had been operated on by a single surgeon and a mean follow-up of 9.57 years Citation[8]. There were 21 patients in the over 50 group, with 95.2% having a satisfactory seizure outcome (Engel classes 1 and 11) compared with 90.3% in the under 50 group. There was no statistically significant difference in outcome between the two groups.
In this study, no relationship was found between the duration of surgery, the neuropsychological sequelae of the procedure were no more evident than with the under 50-year group and the permanent postoperative complications were not increased in the older patients. Previous studies in the literature had shown increased postoperative complications in older patients Citation[9], which were supported by our article, but these were temporary and not permanent. This is not unexpected in the elderly, who have increased comorbidities.
Dominant hemisphere resections are associated with an increased risk of verbal memory loss postoperatively. This is despite the surgical approach for conditions such as MTS, but obviously will be directly related to the involvement of the mesial temporal structures pathologically, as well as the extent of resection of these structures. Concerns have been raised in relation to cognitive changes as a result of the surgery in older patients, and in our study we found that preoperative neuropsychological testing is likely to be poorer at the baseline level in older patients. Therefore, it is fair to assume that elderly patients have less ‘at risk’ memory and in the case of MTS should have minimal postoperative change.
Medical treatment has for many years been the mainstay treatment for many elderly people who are significantly disabled by refractory partial seizures. Unfortunately, these seizures complicate activities of daily living, often necessitating large doses of potentially sedating medications, and providing a range of practical management issues in relation to care and safety. Complications of medical therapies are also higher in this group, with problems related to acute and long-term complications of medication. Therefore, with appropriate assessment and counseling regarding the risks, surgery should be more widely available to this growing population.
It is the authors’ opinion that patients, irrespective of their age, who have medically refractory epilepsy, should be referred to a tertiary epilepsy center for assessment of their current treatment and suitability for surgery. To not do this is to deny a patient the best medical management. To base it on age has no supporting evidence, and in fact, the evidence is to the contrary. Although the study by Murphy et al. only looked at patients with hippocampal sclerosis, there is no reason why neocortical temporal lobe epilepsy or extratemporal epilepsy should not be assessed in elderly patients with refractory epilepsy. Obviously this will involve more extensive tests, including possibly invasive monitoring, but again age should be part of the exclusion criteria.
Key issues
• Medically refractory epilepsy affects a significant number of people in the community.
• Previous studies looking at elderly patients who have had epilepsy surgery have looked at patients with heterogeneous pathology and seizure types.
• Previous studies have demonstrated that patients with medically refractory epilepsy arising from the temporal lobe are more likely to become seizure free with surgery than medication.
• Murphy et al. demonstrated that with homogeneous pathology (mesial temporal sclerosis) and seizure type, there is no difference in seizure outcome postsurgery in patients over the age of 50 years compared with those aged less than 50 years.
• Seizure duration, neuropsychological and postoperative complications are not increased in the elderly.
• Medical treatment for epilepsy in older patients is often associated with significant complications.
• There is no evidence to support denying elderly patients surgery for medically refractory epilepsy if they meet the criteria for surgery.
Financial & competing interests disclosure
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
No writing assistance was utilized in the production of this manuscript.
References
- Sperling MR, Feldman H, Kinman J, Liporace JD, O’Conner MJ. Seizure control and mortality in epilepsy. Ann. Neurol.46, 45–50 (1999).
- Cloyd J, Hauser W, Towne A et al. Epidemiological and medical aspects of epilepsy in the elderly. Epilepsy Res.68(Suppl. 1), S39–S48 (2006).
- Wiebe S, Warren T, Blume WT, Girvin JP, Eliasziw M. A randomized controlled trial of surgery for temporal-lobe epilepsy. N. Engl. J. Med.345(5), 311–318 (2001).
- Acosta I, Vale F, Tatrum WO 4th, Benbadis SR. Epilepsy surgery after 60. Epilepsy Behav.12, 324–325 (2008).
- Beran RG, Hall L, Michelazzi J. An accurate assessment of the prevalence ration of epilepsy adequately adjusted by influencing factors. Neuroepidemiology4(2), 71–81 (1985).
- Hauser WA, Annegers JF, Kurland LT. Prevalence of epilepsy in Rochester, Minnesota: 1940–1980. Epilepsia32(4), 429–445 (1991).
- Leuders H. Epilepsy Surgery. Raven Press, NY, USA, 85 (1992).
- Murphy M, Smith PD, Wood M et al. Surgery for temporal lobe epilepsy associated with mesial temporal sclerosis in the older patient: a long-term follow-up. Epilepsia51(6), 1024–1029 (2010).
- Rydenhag B, Silander HC. Complications of epilepsy surgery after 654 procedures in Sweden. September 1990–1995: a multicenter study based on the Swedish National Epilepsy Surgery Registrar. Neurosurgery49, 51–56 (2001).