Assessment committee: Professor Kirsten Møller MD PhD DMSc, Rigshospitalet, Denmark (Chair), Professor Andreas Schulze-Bonhage MD PhD, Albert-Ludwigs-Universität, Germany, and Clinical Lecturer Antonio Valentin MD PhD, Kings College London, United Kingdom
Principal Supervisor: Associate Professor Lars H Pinborg MD DMSc, Rigshospitalet, Denmark
Co-supervisors: Professors Sándor Beniczky, Olaf B Paulson, Stefan Posse, Henrik BW Larsson, Troels W Kjær
In patients with drug-resistant epilepsy and an expected focal origin of the seizures, surgery is an option that may cure the disease and improve quality of life. However, identification of the tissue necessary to be removed to render the patients seizure-free, the epileptogenic zone (EZ), may be one of the most complicated multimodal and interdisciplinary evaluation processes in medicine. Epilepsy surgery has been performed on a regular basis in Denmark since 1993, but outcomes in the adult population have not been systematically evaluated until now.
The goals of the present thesis were to: 1) Evaluate the outcomes of the Danish epilepsy surgery program, e.g. are the patients referred according to the recommendations from the International League Against Epilepsy? does the Danish results correspond to international standards? and is the change in cognitive function affected by the surgical approach? 2) Investigate the use of new EEG based methods with potential added value in the evaluation process aiming to identify the EZ by 2.a) further development of concurrent EEG and functional MRI (EEG-fMRI) and 2.b) evaluation of the clinical utility of low-density (LD) vs. high-density (HD) electrical source imaging (ESI).
The results of the Danish epilepsy surgery program were found to be comparable to international standards but international recommendations for referral of drug-resistant patients to surgical evaluation were not all fulfilled. In patients with hippocampal sclerosis, selective amygdalohippocampectomy resulted in sustained “freedom from disabling seizures” and better memory function compared with patients operated with a temporal lobe resection.
Our EEG-fMRI results was not of use in the epilepsy surgery evaluation but showed that it is safe to perform concurrent HD EEG and high-speed fMRI which is usable in other fields. In total LD and HD ESI lead to a change in clinical decision in 34% of patients evaluated for epilepsy surgery. Changes were seen in more patients based on HD ESI than based on LD ESI (p<0.001). We are currently awaiting data from intracranial registrations and 1-year follow-up in patients where the decision was changed.
The failure to fulfil international recommendations for referral of drug-resistant patients to epilepsy surgery evaluation led to the establishment of an information campaign targeting medical personnel, patients and their relatives. The promising results of ESI has led to implementation of the low-cost high-efficient LD ESI modality as a routine investigation in epilepsy surgery evaluation. HD ESI will be offered to a subset of challenging cases.