Subdural Electrodes in the Speech-Dominant Hemisphere in Neocortical Epilepsies.
Abstract number :
3.187
Submission category :
Year :
2001
Submission ID :
2703
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
H.J. Meencke, MD, Prof., Epilepsy Center Berlin-Brandenburg, Epilepsy Center Berlin, Berlin, Germany; H.B. Straub, MD, Epilepsy Center Berlin-Brandenburg, Epilepsy Center Berlin, Berlin, Germany; C. Dehnicke, MD, Epilepsy Center Berlin-Brandenburg, Epilep
RATIONALE: Patients with drug-resistant epilepsies with seizure onset in eloquent neocortical areas in surface EEG studies were subsequently studied invasively with subdural electrodes. We studied the prognostic significance for postoperative seizure outcome of (1) histology, (2) extend of resection, defined by overlap of seizure onset zone and eloquent area and (3) extend of resection of the irritative zone.
METHODS: From 426 patients in preoperative non-invasive video-EEG-intensive-monitoring 57 patients got invasive subdural grid-electrode studies. 28 of them were on the speech-dominant side. 26 had a complete study (12 female, 14 male).The age was between 8 and 60 years with median 30 years, the follow up between 1 and 6 years median 2.4 years.
RESULTS: The location of the subdural grid-electrodes was in 16 cases infrasylvian, 4 cases infra- and suprasylvian central, 5 cases suprasylvian central and 1 case frontal infrasylvian. 25 patients got neocortical resections. 2 cases were rejected and 1 case had only MST. The overall postoperative outcome is class I: 65.4 %, class II: 15.4 %, class III: 11,5 %, class IV: 7.7 %. Cases with single pathology had 81 % class I, whereas cases with dual pathology only 50 % class I. The worst outcome had cases with hippocampal sclerosis and neocortical pathology. Cases with clear separation of seizure onset zone and eloquent cortex had 83 % class I, whereas cases with dominant overlap only 50 % class I. The analysis showed the predominant prognostic value of the extend of the resection of the seizure onset zone and not the irritative zone characterized by after discharge and interictal spiking.
CONCLUSIONS: Subdural grid-electrodes are indicated for separation of seizure onset zone and eloquent cortex. The extend of resection limited by the overlap of epileptogenic area and eloquent cortex defines the postoperative result. The resection of the seizure onset zone is more important than the resection of the irritative zone. Dual pathology is a negative prognostic factor. Hippocampal sclerosis together with neocortical lesions seems to be worse.