Temporal Plus Epilepsies I: Prevalence in Epilepsy Surgery Patients.
Abstract number :
2.289
Submission category :
Year :
2001
Submission ID :
1206
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
P. Kahane, MD, Neurology, Grenoble Hospital, France; J. Isnard, MD, Neurology, Lyon Hospital, France; D. Hoffmann, MD, Neurosurgery, Grenoble Hospital, France; M. Guénot, MD, Neurosurgery, Lyon Hospital, France; C. Barba, MD, Neurology, Grenoble Hospital,
RATIONALE: There are increasing evidences that some drug resistant partial epilepsies of temporal lobe origin may in fact involve an epileptogenic zone which extend outside the boundaries of standard temporal lobectomy. We propose to refer to the latter as [dsquote]temporal plus epilepsies[dsquote], and suggest that these epilepsies could account for some failures of standardized temporal lobe surgery. The first part of this retrospective and multicentric study aimed at assessing the frequency and characteristics of temporal plus epilepsies.
METHODS: Out of 368 epileptic patients operated in our centers between 1990 and 1998, 248 benefited from stereotactic intracerebral EEG (SEEG) recordings before surgery, of whom we selected the 182 patients who subsequently underwent a surgical resection that included at least part of the temporal lobe structures. We then reviewed the SEEG findings of these 182 patients in order to identify those with an epileptogenic zone (EZ) extending outside the boudaries of a standard temporal lobectomy (temporal plus epilepsy), and those with a typical temporal lobe epilepsy (TLE).
RESULTS: We found 60 patients who met our criteria of temporal plus epilepsy. These include 28 patients whose epileptogenic zone extended to the posterior temporal cortex, behind the boundary of standard temporal lobectomy, or to the temporo-parieto-occipital junction (T-Posterior 47%), 21 where the EZ included the frontobasal and/or the orbitofrontal cortex (T-Frontal 35%), and 11 patients whose EZ extended to various aspects of the perisylvian area, including the insula as well as the frontal and parietal operculum (T-Perisylvian 18%). Temporal plus epilepsies were more frequently cryptogenic or symptomatic (25% and 43% respectively) than TLE (11% and 25% respectively). This was even more true for the T-Posterior subtype where cryptogenic and symptomatic etiologies accounted for 36% and 54% of cases, respectively. Conversely, hippocampal sclerosis (HS) was more frequent in TLE (64%) than in temporal plus epilepsy (30%), with the exception of T-Perisylvian epilepsy (73% of HS).
CONCLUSIONS: Temporal plus epilepsies represent a significant proportion of epilepsy surgery candidates (60/368 in this series : 16%). Among our patients contemplating a temporal lobe surgery, 21% (60/281) suffered from an epileptogenic zone extending outside the boudary of a standard temporal lobectomy, including 18 patients with MRI signs of HS. The therapeutic impact of correctly identifying this population will be discussed in the surgical results section of this series (Ryvlin et al. Temporal plus epilepsy part II : surgical results).