Abstracts

Ictal SPECT imaging is detecting the seizure onset zone in patients with localization related epilepsy. This is particularly important in presurgical evaluation of epilepsy. [underline]S[/underline]ubtraction [underline]i[/underline]ctal/interictal [underline]S[/underline]PECT [underline]co[/underline]-registered with [underline]M[/underline]RI (SISCOM) has been shown to considerably increase sensitivity and specificity of ictal SPECT. The aim of this study was to evaluate SISCOM prospectively in patients who are undergoing presurgical evaluation but with either non-lesional MRI or discordant findings.
Endpoint of study was
1) to generate a hypothesis for intracranial electrode implantation and
2) to compare SISCOM activation to the gold standard (intracranial EEG or post surgical 2 y outcome)., Between June 2000 and December 2003 all patients with drug resistant epilepsy undergoing presurgical evaluation meeting the following inclusion criteria were included in the study:
- non lesional MRI incl. postoperative non-lesional MRI (re-evaluation) or
- discordant results in basic assessment (history, video-EEG-monitoring, neuropsychology, MRI) where intracranial electrode recording was not absolutely necessary.
Ictal HMPAO or ECD SPECT (both in stable forms) was injected whilst video-EEG-monitoring via a remote controlled injector. Interictal SPECT was injected after a 24-48 hours seizure free interval. SISCOM was calculated on a PC workstation using Analyze software (Analyzedirect Inc, KS, US)., 171 patients were included in the study. 130 patients had all in all 158 SPECT injections. A hypothesis was successfully generated in 77 patients. 50% of those patients had non-lesional MRI, further 8% only possible MRI lesion. 44 patients underwent intracranial electrode implantation and/or epilepsy surgery. Generation of hypothesis was more likely after partial seizures than after generalized seizures (65% vs. 46%). SISCOM activation was concordant to ECoG or site of surgery in 76% and in 80% of patients respectively. Post surgical outcome (n=25) was 60% Engel class I, 24% Engel class II and 16% Engel class III., To our knowledge, this is the first completed prospective SISCOM study.
- in 60% hypothesis for intracranial electrode implantation successfully generated.
- Concordance to ECoG or site of surgery and outcome was high.
- 19% of patients injected underwent epilepsy surgery but with a promising good outcome.
These results are encouraging that prospective SISCOM is generating a hypothesis of seizure onset zone in most patients, either as hypothesis for intracranial electrode implantation or as marker for site of surgery. Larger groups of patients undergoing surgery and follow up are necessary to further assess the value of this time consuming and expensive investigation.,