LOCALIZING VALUE OF ICTAL MEG IN NEOCORTICAL EPILEPSY
Abstract number :
3.187
Submission category :
Year :
2002
Submission ID :
1497
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Gregory L. Barkley, Brien J. Smith, Erasmo A. Passaro, Daniela N. Minecan, Kost V. Elisevich, Karen M. Mason, Susan M. Bowyer, Norman Tepley. Neurology, Henry Ford Health System, Detroit, MI; Neurosurgery, Henry Ford Health System, Detroit, MI; Neurology,
RATIONALE: To investigate the localizing value of ictal MEG recordings in patients with neocortical epilepsy
METHODS: As part of the presurgical evaluation of patients with intractable localization-related epilepsy of neocortical orign, MEG recordings lasting at least thirty minutes were recorded using a 148-magnetometer whole head MEG in a magnetically shielded room. Thirty-two channel digital EEG recordings were simultaneously collected. Seizures and interictal spikes on MEG were analyzed using single equivalent current dipole modeling and mapped onto the patient[ssquote]s coregistered MRI. MEG localization was compared to other presurgical diagnostic testing and postsurgical outcome in those who have had surgical resections.
RESULTS: We have recorded seizures in 6 patients, 8 to 31 years old, with neocortical epilepsy. Three of them have had resective surgery. On neuroimaging, two of the patients had a focal area of cortical dysplasia and one had generalized atrophy, worse in the hemisphere of ictal onset. Ictal MEG localizations were confirmed by subsequent intracranial EEG monitoring. One patient had a left frontotemporal lobe resection, one had a left temporoparietal resection sparing part of the epileptic focus, which extended into language cortex, and one had a left paracentral lobule resection. Prior to surgery each of the three patients was averaging 10-40 seizures per day. All three have had a dramatic improvement in seizures with simple partial seizures but no complex partial or secondarily generalized seizures in two and only two seizures in the past year in the third. Two of the three other patients are scheduled for intracranial monitoring and the third has declined surgery.
CONCLUSIONS: Ictal MEG has been useful in determining the site of implantation of intracranial electrodes and has accurately predicted the site of ictal onset in those who have had intracranial monitoring. Resection of the MEG ictal zone has been associated with good surgical outcome. Ictal MEG and concordant noninvasive diagnostic studies may some day replace intracranial EEG monitoring in selective patients with neocortical lesions.
(Disclosure: Grant - Norman Tepley: 4D Neuroimaging)