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

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.