Occipital Lobe Epilepsy in Children: Pre-operative Evaluation with Magnetoencephalography and Surgical Outcomes

George M. Ibrahim, MD1, Gregory Albert, MD, MSc1, Aria Fallah, MD1, Hiroshi Otsubo, MD, PhD1, Ayako Ochi, MD, PhD1, Tomoyuki Akiyama, MD, PhD1, Elizabeth Donner, MD1, Shelly Weiss, MD1, O. Carter Snead, MD1, James Drake, MD1, James Rutka, MD, PhD1

1Toronto, Canada

Keywords: seizures, occipital lobe, magnetoencephalography, outcome, epilepsy

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Abstract

     Occipital lobe epilepsy (OLE) can be difficult to localize due to the deep anatomical location of the occipital lobe and the possibility of rapid distant propagation of seizures.
     We present our single-institution experience in the surgical management of OLE, the first such series to include routine use of magnetoencephalography (MEG) in pre-operative evaluation.
     Forty-one patients met inclusion criteria for the study with a mean follow-up of 3.1 years.
     Retrospective chart review was performed from 2000 to 2010 to identify patients that met selected criteria for OLE. Clinical, imaging and electrophysiological information was reviewed. Patients were analyzed in two categories: isolated OLE and extended OLE (parietooccipital, temporooccipital, and temporoparietooccipital localizations).
     Patients with extended OLE had younger ages at seizure onset and different seizure semiologies compared with those with isolated OLE. None of the patients with isolated OLE underwent insertion of subdural grid electrodes for localization of the epileptogenic zone compared with 77% of those with extended OLE (p<0.001). Overall, 68% of children with OLE achieved satisfactory seizure outcomes. Neither seizure location nor grid insertion was associated with surgical outcome, but more MEG dipoles in the non-epileptogenic occipital lobe correlated with unsatisfactory seizure outcome (p=0.06).
     This is a retrospective study.
     In this single-institution series of 41 patients with OLE with a mean 3.1-year follow-up, 68% of patients achieved satisfactory seizure control.
     MEG may play a role in the evaluation, surgical planning and prognostication of surgical outcomes in children with OLE.


Acknowledgements

Project Roles:

G. Ibrahim (), G. Albert (), A. Fallah (), H. Otsubo (), A. Ochi (), T. Akiyama (), E. Donner (), S. Weiss (), O. Snead (), J. Drake (), J. Rutka ()