Temporal Lobe Epilepsy (TLE) and Neuroimaging

Abstract

Temporal Lobe Epilepsy (TLE) comprises 30% of all epilepsies and is the most common cause of focal seizures in both adults and children, accounting for 60% of all cases of focal epilepsy evaluated in specialized centers. Nearly 30% of these patients will develop drug resistance and, of these, 30% will have negative MRIs with the routine epilepsy protocol. Detection of epileptogenic lesions is crucial in both the initial diagnosis and the presurgical assessment, and Clinical Neuroradiology plays a fundamental role in managing these patients.

The most common cause of TLE is mesial temporal sclerosis (MTS), a syndrome which displays signs of hippocampal sclerosis (HS) on MRI, accompanied by a characteristic electroclinical profile. Alternative causes of TLE include other focal lesions located in the temporal lobes, some of them undetectable with current technology (cryptogenic TLEs); there are also familiar forms associated with various genetic mutations.

Patients with refractory temporal seizures are candidates for surgical treatment. The detection of a structural lesion on MRI is related to poorer pharmacological control but better surgical results. However, when MRI is negative, other more expensive and invasive investigations must be considered. Therefore, studying these cases always requires a specific protocol and, frequently, a personalized diagnostic strategy, so the appropriate use of the different radiological techniques is essential. Structural MRI is the principal radiological technique in both diagnostic and presurgical settings, although functional imaging is required when the MRI is inconclusive. Findings from imaging should always be interpreted considering the EEG data, and patients with refractory seizures should be managed by multidisciplinary teams in specialized units.

This publication is endorsed by: European Society of Neuroradiology (www.esnr.org).