PMC4308033_01
Ictal EEG with both left frontal spike and wave discharges (A), and generalized attenuation with superimposed beta, maximal right frontal (B); MRI with bifrontal encephalomalacia, Right > Left (C, D); SISCOM with patchy frontoparietal uptake (E, F).
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On at least 2 occasions, these progressed to clonic movements of the right face (Figs. 1A-B). A brain MRI showed bilateral frontal encephalomalacia, maximal right (Figs. 1C-D), while patchy areas of bilateral frontoparietal uptake were seen on SISCOM (Figs. 1E-F).
Initial surgical evaluation with bilateral subdural (A) and depth electrode placement, including the anterior cingulate gyrus, coronal (B), axial (C). Subsequent left hemispheric subdural electrode placement over the lateral and mesial frontal regions (D). 3-D (3-Dimensional) representations of the brain surface and electrodes were created with Freesurfer (surfer.nmr.mgh.harvard.edu) and Curry 6 (neuroscan.com/curry.cfm) software. The primary brain volume (light gray) was automatically segmented with Freesurfer using a pre-operative 1.5T T1-weighted 3-D Fast Spoiled Gradient-Recalled-Echo (FSPGR) sequence. Frontal lobe lesions not included by Freesurfer were manually segmented with Curry 6 (dark gray) from the 3-D FSPGR. Electrode locations were obtained from a post-operative CT and were coregistered with the above volumes using Curry 6.
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Bilateral frontal subdural electrodes were implanted over the encephalomalacic region, along with the interhemispheric fissure (yellow) and orbitofrontal (red) and lateral frontal regions (green) (Fig. 2A). Four 6-contact depth electrodes (3 left, 1 right) were implanted in the frontal lobes (purple) (Fig. 2A). On the left, one electrode was placed with the long axis parallel to the middle frontal gyrus, with distal contacts corresponding to the anterior cingulate cortex (Figs. 2B-C), and the other two were aimed mesially and laterally from the lateral convexity. The patient was taken back to the OR, and left-sided grid and strips were placed over the lateral convexity and the interhemispheric fissure (Fig. 2D).
Post-surgical MRI with resection in the left mesial frontal region (A) and anterior corpus callosotomy (B); Selected pre- and postoperative neuropsychological test scores (Table). Reliable Change Index (RCI) scores were generated, and postoperative test scores exceeding the critical 90 percent confidence interval are indicated. If available, data pertaining to test-retest reliability within a non-surgical epilepsy sample was utilized to generate RCI calculations; otherwise, published normative data was utilized.
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Neuropsychological testing revealed diffuse cognitive deficits, predominantly involving attention, executive function, and psychomotor speed (see preoperative scores in Fig. 3). Postoperative MRI and neuropsychological test scores one year after surgery are shown in Fig. 3.