Presurgical evaluation in patients with mesial temporal sclerosis

Abstract

Publisher Summary This chapter discusses the pathological and imaging features of mesial temporal sclerosis (MTS). The electroclinical symptoms of mesial temporal lobe epilepsies (mTLE) associated with MTS, the diagnostic procedures and results necessary to identify this syndrome in order to perform epilepsy surgery with an encouraging prognosis is also discussed. If MTS is diagnosed by magnetic resonance imaging (MRI) scans in patients with intractable focal epilepsy, it is a natural conclusion that MTS in this case may be identical to the epileptogenic lesion. However, it has been shown that the positive predictive value of MTS alone is not satisfactory. Apparently, there are patients in whom the mesial temporal cortex is not identical to the epileptogenic zone in spite of MTS. Following the concept of essential cortical zones that have to be identified by complementary diagnostic methods during the presurgical evaluation, one needs to demonstrate in every case that the epileptogenic lesion, the irritative, the symptomatogenic, the seizure onset, and the functional-deficit zones allow the conclusion that the epileptogenic zone is located within the mesial temporal cortex and that therefore, selective surgery, such as selective amygdalahippocampectomy, will lead to postoperative freedom of seizures. Hence, MRI is crucial for the presurgical evaluation in such cases, but requires additional typical findings suggestive for mTLE. Interictal electroencephalography reflecting the irritative zone is another similarly essential method.