Subdural interhemispheric grid electrodes for intracranial epilepsy monitoring: feasibility, safety, and utility: clinical article.
OBJECTIVE
Intracranial monitoring for epilepsy has been proven to enhance diagnostic accuracy and provide localizing information for surgical treatment of intractable seizures. The authors investigated their experience with interhemispheric grid electrodes (IHGEs) to assess the hypothesis that they are feasible, safe, and useful.


METHODS
Between 1992 and 2010, 50 patients underwent IHGE implantation (curvilinear double-sided 2 × 8 or 3 × 8 grids) as part of arrays for invasive seizure monitoring, and their charts were retrospectively reviewed.


RESULTS
Of the 50 patients who underwent intracranial investigation with IHGEs, 38 eventually underwent resection of the seizure focus. These 38 patients had a mean age of 30.7 years (range 11-58 years), and 63% were males. Complications as a result of IHGE implantation consisted of transient leg weakness in 1 patient. Of all the patients who underwent resective surgery, 21 (55.3%) had medial frontal resections, 9 of whom (43%) had normal MRI results. Localization in all of these cases was possible only because of data from IHGEs, and the extent of resection was tailored based on these data. Of the 17 patients (44.7%) who underwent other cortical resections, IHGEs were helpful in excluding medial seizure onset. Twelve patients did not undergo resection because of nonlocalizable or multifocal disease; in 2 patients localization to the motor cortex precluded resection. Seventy-one percent of patients who underwent resection had Engel Class I outcome at the 2-year follow-up.


CONCLUSIONS
The use of IHGEs in intracranial epilepsy monitoring has a favorable risk profile and in the authors' experience proved to be a valuable component of intracranial investigation, providing the sole evidence for resection of some epileptogenic foci.
Section of Neurosurgery, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, USA.
Kimon
K
Bekelis
Tarek A
TA
Radwan
Atman
A
Desai
Ziev B
ZB
Moses
Vijay M
VM
Thadani
Barbara C
BC
Jobst
Krzysztof A
KA
Bujarski
Terrance M
TM
Darcey
David W
DW
Roberts
D000293:Adolescent; D000328:Adult; D002648:Child; D004567:Electrodes, Implanted / Q000009:adverse effects; D004569:Electroencephalography / Q000379:methods; D017034:Epilepsy, Frontal Lobe / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D005240:Feasibility Studies; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000009:adverse effects / Q000379:methods*; D009483:Neuropsychological Tests; D012189:Retrospective Studies; D012640:Seizures / Q000175:diagnosis / Q000503:physiopathology; D013355:Subdural Space; D013530:Surgical Wound Infection / Q000209:etiology; D016896:Treatment Outcome; D014741:Video Recording