PMC4533458_01
A: Coronal short T1 inversion recovery (STIR) images revealed an isointense mass below the left frontal lobe (arrows) and mild cortical hyperintensity that extended to the left anterior perforated substance (arrowheads). B: Axial fluid attenuated inversion recovery (FLAIR) image showing the area of hyperintensity in the left basal frontal area (arrowheads). C: Sagittal T1 weighted image showing the definitely enlarged olfactory nerve under the anterior perforated substance (arrow).
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F1
T1 inversion recovery (STIR) imaging, mild cortical hyperintensity was observed with obscured sulci around the left orbital gyrus (Fig. 1). The enlarged ipsilateral olfactory nerve was also detected (Fig. 1). The affected nerve ranged from the olfactory trigone to the olfactory bulb. Moreover, the enlarged olfactory nerve was connected to the affected basal frontal lobe including the anterior perforated substance (Fig. 1).
Intraoperative electrocorticography demonstrating abnormal sharp waves originating from the basal frontal area. This was performed using a 5 x 4 grid of electrodes placed on the prefrontal cortex and three sets of 4 x 1 electrodes on the basal frontal area. During the procedure, the end-tidal sevoflurane concentration was continued at 2.8% and end-tidal CO2 was maintained at 30 tmmHg.
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F2
An abnormal sharp wave originating from the orbitofrontal cortex was found (Fig. 2).
A: Intraoperative view thorough a left frontal craniotomy. White arrows indicate the left enlarged olfactory nerve adjacent to the left optic nerve under the partially resected basal frontal area. B: Neuronal Nuclei (NeuN) staining of resected left orbital gyri. The columnar organization of the enlarged dysmorphic neurons can be seen in the lower right portion of the figure. Scale bar: 300 mm.
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F3
A definitely enlarged olfactory nerve was also detected (Fig. 3). The final pathological diagnosis of resected basal frontal area was FCD type IIa (Fig. 3).
Postoperative magnetic resonance imaging (MRI) showing subtotal resection of the affected left basal frontal area. The arrow indicates the preserved left olfactory nerve, and the arrowheads indicate the preserved anterior perforated substance.
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F4
Postoperative MRI indicated successful resection of the lesion affected with FCD (Fig. 4).