J Korean Neurosurg Soc.  2014 Sep;56(3):248-253. 10.3340/jkns.2014.56.3.248.

Emerging Surgical Strategies of Intractable Frontal Lobe Epilepsy with Cortical Dysplasia in Terms of Extent of Resection

• Shin JH
• Jung NY
• Kim SP
• Son EI

• KMID: 2339965
• DOI: http://doi.org/10.3340/jkns.2014.56.3.248

Abstract

OBJECTIVE
Cortical dysplasia (CD) is one of the common causes of epilepsy surgery. However, surgical outcome still remains poor, especially with frontal lobe epilepsy (FLE), despite the advancement of neuroimaging techniques and expansion of surgical indications. The aim of this study was to focus on surgical strategies in terms of extent of resection to improve surgical outcome in the cases of FLE with CD.
METHODS
A total of 11 patients of FLE were selected among 67 patients who were proven pathologically as CD, out of a total of 726 epilepsy surgery series since 1992. This study categorized surgical groups into three according to the extent of resection : 1) focal corticectomy, 2) regional corticectomy, and 3) partial functional lobectomy, based on the preoperative evaluation, in particular, ictal scalp EEG onset and/or intracranial recordings, and the lesions in high-resolution MRI. Surgical outcome was assessed following Engel's classification system.
RESULTS
Focal corticectomy was performed in 5 patients and regional corticectomy in another set of 5 patients. Only 1 patient underwent partial functional lobectomy. Types I and II CD were detected with the same frequency (45.45% each) and postoperative outcome was fully satisfactory (91%).
CONCLUSION
The strategy of epilepsy surgery is to focus on the different characteristics of each individual, considering the extent of real resection, which is based on the focal ictal onset consistent with neuroimaging, especially in the practical point of view of neurosurgery.

Keyword

Epilepsy surgery; Frontal lobe epilepsy; Cortical dysplasia

MeSH Terms

Classification
Electroencephalography
Epilepsy
Epilepsy, Frontal Lobe*
Humans
Magnetic Resonance Imaging
Malformations of Cortical Development*
Neuroimaging
Neurosurgery
Scalp

Figure

• 

  Fig. 1 Schematic drawings for 3 categories of surgical strategies; each circle indicates the extent of cortical resection based on surgical strategies as stated on Table 1. A : Focal corticectomy. B : Regional corticectomy. C : Partial functional lobectomy.

• 

  Fig. 2 Illustration of case 10 with focal corticectomy with intracranial recordings. Patient is a 41-year-old male; 15-year history of complex partial seizures characterized by hypermotor seizure with right arm tonic posture and loud vocalization. The video-EEG evaluation revealed no definitive ictal onset. Brain MR showed subtle high signal change on the left middle frontal gyrus (A : stared). Invasive intracranial monitoring (Grid) demonstrates rhythmic alpha activity over left centroparietal area intermingled with muscle artifacts during ictal period and very frequent small spikes on the left frontal area (Fp1, F3) during interictal period (B). The extent of corticectomy was planned based on the ictal onset of intracranial recordings (C : pink circle of areas 6, 14, 15 on Grid). Patient belongs to Engel class I with a follow-up of 1 year.

• 

  Fig. 3 Illustration of case 7 with focal corticectomy without intracranial recordings. Patient is a 13-year-old male; seizure onset at 4 years of age was characterized by nocturnal seizure attack with head rotation to right and dystonia of right arm. Video EEG demonstrates left frontal ictal and interictal EEG discharges consistent with his semiology. MRI shows abnormal focal thickening of the cortex in the left superior frontal gyrus (A : stared). PET scan revealed focal hypometabolism at left frontal cortical area consistent with MR findings (B : arrows). Focal corticectomy was performed on left superior frontal gyrus under ECoG guide without intracranial recordings. Postexcisional ECoG reveales no residual spikes, and pathology revealed cortical dysplasia type IIb (C). Two years after surgery, he belongs to Engel class I.

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