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Recently, Boniface and Antoun1reported endovascular EEG during intra-arterial amobarbital tests using an endovascular guide wire as the different electrode for bipolar recordings against an extracranial surface electrode (T3) or an average reference. They concluded that their technique was feasible to identify intracranial epileptiform discharges and was less invasive than other intracranial EEG methods with the advantage that it was possible to move the guide wire between different intracranial sides. They also mentioned “the potential to achieve more in a bipolar format when the electrical characteristics of the electrode are optimised”.
Our experience with this technique2 prompted us to use a multilead catheter developed for cardiological examinations (PathfinderTM, Cardima, 47201 Lakeview Boulevard, Fremont, CA 94538, USA) with eight pairs of electrodes (electrode length 0.5 mm, interelectrode spacing 2 mm; electrode pair spacing 6 mm). This allows bipolar recording simultaneously from each electrode to an extracranial surface electrode (FZ) (figure). Our endovascular EEG shows pulse artefacts in some leads, which are a common problem of this technique,1-3 but they were less pronounced than other recordings.1 Using the tip of the guide wire as the different electrode, as done by previous groups,1-3 has the disadvantage that recordings are achieved from a single area at one time only and that the guide wire has to be moved to record from other parts of the temporal lobe. The catheter we used, however, provides simultaneous recordings from 16 different points over a length of 72 mm of the temporal lobe. Such a technique may be of interest during pharmacological activation of epileptogenic foci with short acting barbiturates,4 and especially during the intracarotid amobarbital test, as this test is routinely performed during presurgical evaluation of patients with medically intractable temporal lobe epilepsy and is known to activate the epileptic focus in more than half of the patients.5 The clinical use of this technique awaits further evaluation in an appropriate number of patients.