THREE SUBTYPES OF TEMPORAL LOBE EPILEPSY: Clinical and Electrophysiological Characteristics of Medial, Anterior neocortical, and posterior lateral TLE

Lee, Sang Kun; Kim, Joo Yong; Lee, Kwang Woo; Roh, Jae Kyu; Myung, Ho Jin

Abstract

BACKGROUND: The clinical differentiation of hippocampal and neocortical temporal lobe epilepsy has practical value. And there seems no report concerning the clinical difference between anterior and posterior neocortical TLE. This study aims to determine whether there are important clinico-electrical differences between patients with hippocampal sclerosis(medTLE; MTLE) and those with anterior lateral temporal epileptogenic zone(anterior lateral TLE; ALTLE) and posterior lateral temporal one(posterior lateral TLE; PLTLE).
METHODS
The case histories, interictal EEG, ictal semiology, ictal EEG, and memory lateralization in Wada test were compared statistically in the three groups (30 MTLE, 16 ALTLE, and 11 PLTLE). Lateral TLE(LTLE) was diagnosed when the radiologic studies showed discrete lesions lateral to collateral sulcus or the results of invasive study confirmed massive epileptogenic zones in the lateral temporal lobe. Whether the epileptogenic zone was located on the anterior or posterior to the line across the interpeduncular fossa of the midbrain made the differentiation between ALTLE and PLTLE.
RESULTS
A history of febrile convulsion was more common in MTLE patients(p<0.001). An aura with auditory or visual components was unique in ALTLE and PLTLE. Oroalimentary and hand automatisms occurred more frequently in MTLE, while secondary GTCS and version were more frequent in PLTLE(p<0.01). Onset of secondary GTCS and version occurred later in seizures of MTLE(p<0.05). Memory lateralization in Wada test was highly possible in MTLE and PLTLE(p<0.01). Irritative zone was located on the posterior temporal electrode in 4 of 11 patients with PLTLE. Ictal onset with rhythmic beta activity was not observed in MTLE.
CONCLUSION
There are a number of clinico-electrical differences among MTLE, ALTLE, and PLTLE.