Article
Investigation of stereoencephalography electrode placement techniques in patients with refractory focal epilepsy: study protocol for a single-blinded randomised case control parallel group trial
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Authors
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Vejay N. Vakharia
- National Hospital for Neurology & Neurosurgery, Department of Experimental Epilepsy, London, United Kingdom
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Andrew Mcvoy
- National Hospital for Neurology & Neurosurgery, Department of Experimental Epilepsy, London, United Kingdom
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Anna Miserocchi
- National Hospital for Neurology & Neurosurgery, Department of Experimental Epilepsy, London, United Kingdom
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Roman Rodionov
- National Hospital for Neurology & Neurosurgery, Department of Experimental Epilepsy, London, United Kingdom
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Sebastien Ourselin
- National Hospital for Neurology & Neurosurgery, Department of Experimental Epilepsy, London, United Kingdom
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John Duncan
- National Hospital for Neurology & Neurosurgery, Department of Experimental Epilepsy, London, United Kingdom
| Published: | June 9, 2017 |
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Outline
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Objectives: To determine the optimal surgical technique for Stereoencephalography (SEEG) electrode insertion. SEEG was first described by Talairach and Bancaud (1965) and is a key feature of presurgical evaluation of patients with refractory focal Epilepsy. The procedure involves the stereotactic placement of 8-16 electrodes within predefined brain targets to help determine the seizure onset zone prior to definitive surgical resection. Current techniques involve the use of a stereotactic frame, frameless neuronavigation systems and robotic trajectory guidance systems. The main complications associated with this technique are haemorrhage and infection. To date there are no published prospective control studies comparing different SEEG techniques.
Methods: We are initiating a single blinded randomised case control parallel group single centre trial comparing SEEG electrode insertion between the currently used frameless neuronavigation system (Vertek arm, Medtronic) and a robotic trajectory guidance system (iSYS1, Medizintechnik GmbH). The primary outcome is to compare the operative time for electrode bolt insertion between the two techniques. The secondary outcomes are to compare:
a. Accuracy of SEEG depth electrode placement, as assessed by skull entry point, error of angle of implantation of intracranial bolt and distance of the actual electrode tip compared to the target point as defined by the preoperative plan and target region sampled.
b.Incidence of clinically significant and non-clinically significant radiologically detected post-operative haemorrhages
c.Infection rate
d. New post-operative neurological deficits
Discussion: SEEG electrode placement using stereotactic frame based methods are cumbersome and time consuming. High-volume centres have developed frameless systems at the relative expense of accuracy. Robotic trajectory guidance systems have been proposed to provide the benefits of frameless techniques with accuracies comparable to frame-based systems. We have performed pre-clinical studies recreating implantations on patient specific 3D printed phantoms which support this. Cumulative summation analysis revealed a minimal learning curve and superior entry and target point accuracies with the iSYS1 system. A meta-analysis of the literature revealed only poor quality (level 3) clinical evidence comparing the different SEEG techniques.
Conclusion: It is important that new techniques are compared to the previous ‘gold-standard’ through well designed and methodologically sound studies before they are introduced into widespread clinical practice. To our knowledge this would be the first randomised control trial comparing SEEG techniques.
