J Korean Neurosurg Soc.  2012 Nov;52(5):466-471. 10.3340/jkns.2012.52.5.466.

Magnetoencephalography Interictal Spike Clustering in Relation with Surgical Outcome of Cortical Dysplasia

• Jeong W
• Chung CK
• Kim JS

• KMID: 2018253
• DOI: http://doi.org/10.3340/jkns.2012.52.5.466

Abstract

OBJECTIVE
The aim of this study was to devise an objective clustering method for magnetoencephalography (MEG) interictal spike sources, and to identify the prognostic value of the new clustering method in adult epilepsy patients with cortical dysplasia (CD).
METHODS
We retrospectively analyzed 25 adult patients with histologically proven CD, who underwent MEG examination and surgical resection for intractable epilepsy. The mean postoperative follow-up period was 3.1 years. A hierarchical clustering method was adopted for MEG interictal spike source clustering. Clustered sources were then tested for their prognostic value toward surgical outcome.
RESULTS
Postoperative seizure outcome was Engel class I in 6 (24%), class II in 3 (12%), class III in 12 (48%), and class IV in 4 (16%) patients. With respect to MEG spike clustering, 12 of 25 (48%) patients showed 1 cluster, 2 (8%) showed 2 or more clusters within the same lobe, 10 (40%) showed 2 or more clusters in a different lobe, and 1 (4%) patient had only scattered spikes with no clustering. Patients who showed focal clustering achieved better surgical outcome than distributed cases (p=0.017).
CONCLUSION
This is the first study that introduces an objective method to classify the distribution of MEG interictal spike sources. By using a hierarchical clustering method, we found that the presence of focal clustered spikes predicts a better postoperative outcome in epilepsy patients with CD.

Keyword

Epilepsy; Cortical dysplasia; Magnetoencephalography; Hierarchical clustering; Surgical outcome

MeSH Terms

Adult
Epilepsy
Follow-Up Studies
Humans
Magnetoencephalography
Malformations of Cortical Development
Retrospective Studies
Seizures

Figure

• 

  Fig. 1 Hierarchical dendrogram (A) and equivalent current dipoles on MR images (B) for Patient #10. The individual spike sources (n=20) are represented along with the vertical axis. The ⊃-shaped lines connect the spike objects that are combined at each aggregation stage.

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