Surgical treatment for mesial temporal lobe epilepsy associated with hippocampal sclerosis

Introduction: Hippocampal sclerosis is the most common cause of pharmacoresistant epilepsy amenable for surgical treatment and seizure control. The aim of this article is to review and evaluate the published literature related to the outcome of the surgical treatment of mesial temporal lobe epilepsy (MTLE) associated with hippocampal sclerosis (HS) and to describe the future prospects in this field.

State of art: Surgery of MTLE associated with HS achieves long-term seizure freedom in about 70% (62-83%) of cases. Seizure outcome is similar in the pediatric population. Mortality following temporal resection is very rare (<1%) and the rate of definitive neurological complication is low (1%). Gamma knife stereotactic radiosurgery used as a treatment for MTLE would have a slightly worse outcome to that of surgical resection, but would provide neuropsychological advantage. However, the average latency before reducing or stopping seizures is at least 9 months with radiosurgery. Regarding palliative surgery, amygdalohippocampal stimulation has been demonstrated to improve the control of epilepsy in carefully selected patients with intractable MTLE who are not candidates for resective surgery.

Perspectives: Recent progress in the field of imaging and image-guidance should allow to elaborate tailored surgical strategies for each patient in order to achieve seizure freedom. Concerning therapeutics, closed-loop stimulation strategies allow early seizure detection and responsive stimulation. It may be less toxic and more effective than intermittent and continuous neurostimulation. Moreover, stereotactic radiofrequency amygdalohippocampectomy is a recent approach leading to hopeful results. Closed-loop stimulation and stereotactic radiofrequency amygdalohippocampectomy may provide a new treatment option for patients with pharmacoresistant MTLE.

Conclusions: Mesial temporal lobe surgery has been widely evaluated and has become the standard treatment for MTLE associated with HS. Alternative surgical procedures like gamma knife stereotactic radiosurgery and amygdalohippocampal stimulation are currently under assessment, with promising results.