Functional neurosurgery in the treatment of epilepsy in The Netherlands. Aspects of presurgical evaluation and the contribution of subdural and stereotactically implanted depth electrodes in the Dutch Workgroup for Functional Surgery.

In the Netherlands all patients who are considered candidates for surgical treatment of their epilepsy are referred to the Dutch Workgroup for Functional Neurosurgery. Resective neurosurgery in partial epilepsy is a focus of special interest of national health authorities. Annually 15-20 patients can now be operated upon. Presurgical evaluation includes a.o. 18/FDG PET. For depth-EEG recording a specially designed method of "Combined Subdural and Depth-EEG Recording" is used which has been described previously. 70 patients underwent depth-EEG recording with the combined method. In 4.2% of the patients there were transient complications, in 1.4% there was a possibly permanent slight neurological deficit caused by the method. Fifty-six patients were evaluated at least one year after their surgical treatment (median follow-up 3 years). In the frontal lobe group comprising 9 patients 56% were seizure-free, 76% benefited from the treatment. In the temporal lobe group with 47 patients 68% were seizure-free and 92% benefited. No patient deteriorated from the resection. Permanent morbidity was nil.