Abstracts

Rationale: The concept of temporal “plus” epilepsy was introduced to define this group of patients with temporal lobe (TL) semiology and electrophysiological characteristics, but poor results after standard TL resections. These patients are believed to have widespread epileptogenicity, which includes TL and extra-TL structures. To address the issue if the existence of temporo-frontal epilepsy explains some of the surgical failure in patients with a diagnosis of TL epilepsy, we reviewed a series of patients investigated with intracranial SEEG recordings exploring simultaneously the temporal and frontal lobe (FL) structures. Methods: 103 patients were studied between 2000 and 2006 with SEEG electrodes. Patients were included in the study if: a) they had intracranial electrodes sampling at least TL structures and orbito-frontal and lateral frontal regions; b) clinical and scalp EEG features at least suggestive of a temporal or temporo-frontal seizure origin; c) high-quality MRI; and d) adequate follow-up. We correlated the seizure onset and propagation patterns with surgical outcome. Results: Nineteen patients fulfilled the criteria (11 male; mean age at evaluation, 33yrs (range, 17-45); mean age at seizure onset, 15yrs (range, 1-34)). Surface EEGs were temporal in 8 patients, FT in 7, generalized or diffuse in 2 and frontal only or normal in one each. MRI was normal in 9 patients and revealed structural abnormalities in 10: neocortical FT in 6, hippocampal in 4 and colpocephaly in one. SEEG studies were unilateral in 9 patients and bilateral in 10. Twenty-seven patterns of seizure onset were recorded (mean number of seizures per patient, 19.7; range, 2-76): 18 were temporal with no or late frontal propagation in 7, and with early frontal propagation in 11; 7 were frontal with no or late temporal propagation in 2, and early temporal propagation in 5; and 2 were FT with no further propagation. Fifteen patients had surgery including 12 who underwent TL resections only: 5 had a satisfactory outcome including 4 with a temporal seizure onset and no or late frontal propagation, while 7 had a poor outcome including 6 with a temporal onset and immediate or early frontal propagation. Conclusions: Epileptic patients with temporo-frontal features often represent cases of regional or widespread epileptogenecity and surgical outcome after temporal resection only is often unsatisfactory. The frontal and anterior temporal lobe structures form a functional unit through which the epileptic activity propagates. The complexity of their connections makes it difficult to identify the characteristic clinical phenomena which are the direct result of a local epileptic activation and to distinguish them from those arising from propagation. Moreover, the interpretation of the electrical activity measured can be limited by the approach used to introduce the electrodes.