The contribution of an intraarterial electroencephalographic study in patients with deep epileptogenic foci

OBJECTIVES: To evaluate the diagnostic efficacy of an intra-arterial electroencephalographic recording and determine which patients obtain most benefit from this technique, to compare the results obtained using other recording techniques and to establish a standard for recording. PATIENTS AND METHODS: We made 64 intra-arterial recordings in 30 patients from one of three groups: persons with drug-resistant temporal epilepsy; patients with epileptic seizures of any type who required cerebral arteriography and patients whose illness required selective anteriography for any reason. We used a Seeker 10 guide-wire, the end of which acted as an electrode and a 2 minute recording was made. The position of the electrode varied depending on the site of the patients disorder. Activity was simultaneously measured with surface electrodes. Using the chi squared non-parametric test, we analysed the efficacy of the test. The paired t test was used to establish the concordance between observers. We compared the results obtained from the intra-arterial EEG with the simultaneous surface recording. RESULTS: We found three types of electroencephalographic patterns. The commonest was defined by the presence of high-voltage multi-spiked acute waves. The sensitivity of the test was 93.33%, the specificity was 80% and the overall value of the test was 86.66%. The chi squared test showed its reliability in the diagnosis of deep epileptogenic foci. There was high concordance between the observers in the study. No complications were seen in the patients in this study. CONCLUSION: The intra-arterial EEG recording is a semiinvasive test which may be useful in a selected group of patients and has high sensitivity and specificity.