Ictal clinical and scalp-EEG findings differentiating temporal lobe epilepsies from temporal 'plus' epilepsies

Abstract

Temporal 'plus' epilepsies are characterized by seizures involving a complex epileptogenic network including the temporal lobe and the closed neighboured structures such as the orbito-frontal cortex, the insula, the frontal and parietal operculum and the temporo-parieto-occipital junction. Temporal 'plus' epilepsies are currently identified by means of intracerebral electrodes but whether their diagnosis can be suspected non-invasively has not been evaluated yet. The aim of this retrospective study was to address this issue in 80 consecutive patients who were thought to suffer from non-lesional temporal lobe seizures which finally proved, on the basis of stereotactic intracerebral EEG (SEEG) recordings, to be 'purely' temporal (TL group, n = 58) or temporal 'plus' (T+ group, n = 22). Our results showed that the two groups of patients were difficult to differentiate on the basis of general clinical features or MRI data. Even the presence of hippocampal sclerosis did not distinguish the two groups. Conversely, both ictal clinical symptoms and scalp-EEG findings significantly differentiated TL from T+ patients. Patients with TL epilepsies more frequently presented an ability to warn at seizure onset (P = 0.003), an abdominal aura (P = 0.05), gestural automatisms (P = 0.04) and a post-ictal amnesia (P = 0.02). Patients suffering from T+ epilepsies more frequently had gustatory hallucinations (P = 0.02), rotatory vertigo (P = 0.02) and auditory illusions (P = 0.02) at seizure onset; they exhibited more frequently contraversive manifestations of the eyes and/or head (P = 0.001), piloerection (P = 0.03) and ipsilateral tonic motor signs (P = 0.05), and they were more often dysphoric in the post-ictal phase (P = 0.0001). Cluster analysis mainly indicated that some associations of symptoms were relevant for differentiating TL cases from T+ cases. Interictal EEG of T+ patients more frequently exhibited bilateral or precentral abnormalities, while ictal EEG more frequently pointed over the anterior frontal, temporo-parietal and precentral regions. Neither TL interictal spikes, nor TL ictal EEG onset, allowed us definitely to rule out the possibility of T+ epilepsies. Our findings may be useful for identifying, among patients suffering from 'atypical' non-lesional TL epilepsies, those who should undergo invasive recordings before surgery.

18FDG‐PET in different subtypes of temporal lobe epilepsy: SEEG validation and predictive value

“…In most cases, a time-frequency representation of signals (spectrogram computed from short-term fast Fourier transform) was used to accurately determine the beginning of the rapid activity. 16 Subtypes of TLE were defined according to the current categories proposed in previous studies: 8,9,17 (1) mesial TLE, in which the EZ is limited to the mesial temporal lobe; (2) lateral TLE, in which the EZ is limited to the temporal neocortex; (3) "temporal plus," in which the EZ extends to the adjacent cortex (operculoinsular, orbitofrontal, or temporooccipital region). We also defined bilateral TLE when the EZ was found to be bilateral (characterized by seizures starting either from one or the other side or seizures starting immediately or rapidly <1 s on both temporal lobes).…”

“…Invasive and noninvasive presurgical investigations have thus permitted to identify TLE with distinct EZ (and propagation pathways; mesial, lateral or temporal plus subtypes, bilateral), leading to distinct temporal resections. 8,9 Among the noninvasive evaluation, interictal 18 FDG-PET, which evaluates the cerebral metabolic rate for glucose (CMRGlc), visually demonstrates temporal hypometabolism (unilateral or bilateral asymmetric) in >70% of patients with refractory epilepsy. 10 Using quantitative analysis, detection of significant temporal lobe hypometabolism may exceed 90% in these patients.…”

The interictal dysphoric disorder of epilepsy: Legend or reality?

“…In fact, the identification of patients with PDS may be relevant in terms of localizing and prognostic value. In fact, post-ictal mania seems to be associated with frontal, non-dominant involvement [37,38] and is associated with a poor prognosis after surgery identifying temporal lobe "plus" patients [38]. In this regard, a specific clinical instrument for the evaluation of IDD and PDS has been developed, namely the Interictal Dysphoric Disorder Inventory (IDDI) [20].…”

Hippocampal sclerosis: pathogenesis, clinical features, diagnosis, and treatment

“…Интериктальная эпиактивность чаще локализуется билатерально в височных областях или в предцентраль-ном регионе. Иктально эпиактивность при «темпораль-ных плюс» формах чаще отмечается в переднелобных, темпоропариетальных и предцентральных областях [24]. Дифференциальная диагностика височной эпилепсии от «височной эпилепсии плюс», проводимая квалифициро-ванным эпилептологом, является ключевой в планирова-нии хирургического вмешательства и прогнозировании исхода лечения.…”