PMC5315437_01
The MRI T2 axial sequence obtained about 6 months after the symptom onset showed a small focus of stable hyperintense signal change involving the cortex in the right posterior parafalcine frontal area (yellow arrow), which was not present on the first scan but was present on the second scan. No cortical atrophy or ventriculomegaly was noted on this scan.
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A repeat MRI demonstrated a new small focus of increased T2/FLAIR signal in the right posterior parafalcine frontal area without cortical atrophy or ventriculomegaly, concerning for neoplasm or cortical dysplasia (Fig. 1).
An intraoperative picture showing a resection cavity (indicated with a dotted light blue line) anteromedially within the craniotomy margin. The area of the resection, determined intraoperatively with electrocorticography, included the focal area of the T2/FLAIR hyperintensity noted on the preoperative imaging studies (indicated by a dotted yellow line).
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The areas of the lesion and the adjacent frequently spiking cortex were resected, while preserving the primary motor area (Fig. 2).
Pathologic findings consistent with Rasmussen's encephalitis included perivascular lymphocytic inflammation [A] and microglial nodules [B]. Intermixed T-lymphocytes are highlighted by CD3 immunostaining [C]. Gliosis was present, with the radially arranged spider-like projections of reactive astrocytes highlighted by glial fibrillary acidic protein immunostaining [D]. (hematoxylin-eosin, original magnifications x 40 [A], x 20 [B]; original magnification x 20 [C, D]).
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The pathologic specimen showed encephalitis with gliosis, with foci of perivascular chronic inflammation, microglial clusters, and focal lymphoid aggregates primarily consisting of T-lymphocytes, consistent with RS (Fig. 3).
An intraoperative picture taken after the peri-insular hemispherotomy was completed (taken from the primary surgeon's view and rotated for an easier view). The frontoparietal lobes are shown toward the top of the picture, and the temporal lobe is shown toward the bottom of the picture. The frontoparietal and temporal opercular cortical areas had been resected along the sylvian fissure. Note that all the major blood vessels were preserved to prevent postoperative stroke and resultant edema.
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Several days later, and within 7 months from the initial seizure and 2 months from the initial evaluation in the epilepsy clinic, she underwent right-sided peri-insular functional hemispherotomy (see the descriptions by Villemure et al. for the details of the procedure) and placement of an external ventricular drain (EVD) (Fig. 4).
The postoperative MRI T1 axial sequence obtained about 6 weeks from the hemispherotomy showed expected postsurgical changes, including hemispheric disconnection from the underlying basal ganglia and thalamus as well as disconnection of the insular cortex (yellow arrow).
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The postoperative MRI showed expected postoperative changes, with appropriate hemispheric disconnection (Fig. 5).