THERAPEUTIC IMPLANTATION OF INTRACRANIAL ELECTRODES
Abstract number :
2.457
Submission category :
Year :
2003
Submission ID :
1074
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
Tracy Butler, Carl Bazil, Robert Goodman, Lawrence Hirsch, Linda Leary, Steven Karceski, Martha Morrell Comprehensive Epilepsy Center, Columbia University, New York, NY
Changes in both local and large-scale neuronal networks underly epileptogenesis in experimental animals, and likely play a key role in the development of intractable epilepsy in humans. Clinical trials of epilepsy surgery demonstrate that removal of a defined seizure focus within a disordered local network is therapeutic, while the success of vagal nerve stimulator and corpus callosotomy (a procedure which not only limits seizure spread, but reduces seizure frequency) indicates that alterations in large-scale networks may also result in significant clinical improvement via modulation of putative inhibitory and excitatory networks remote from any presumed seizure focus.
Implantation of intracranial electrodes provides another model for exploring the role of disordered neuronal networks in epilepsy. Surgical placement of subdural, epidural and depth electrodes is associated with variable degrees of brain trauma. In some cases, this trauma may serve to disrupt dysfunctional brain circuits contributing to seizure generation or propagation, resulting in clinical improvement.
As a preliminary, retrospective, descriptive study, we identified four patients since 1996 who did not undergo resective surgery, but whose seizure frequency decreased markedly after intracranial electrode implantation.
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While only limited conclusions can be drawn from anecdotal data, it is clear that some epilepsy patients improve after placement of intracranial electrodes, without need for resective surgery. Based on these four patients, it appears possible that perioperative complications may be associated with improved seizure frequency, perhaps via disruption of epileptogenic neuronal networks, as discussed above. Other relevant factors may include corticosteroid use, general anesthesia, blood-brain barrier disruption, stress-related hormonal and cytokine influences, and placebo effect. These factors should be considered when assessing the effectiveness of epilepsy surgery, which likely benefits patients by means beyond simple removal of a small region of epileptic tissue.