PMC4307874_01
Consecutive CT scan, MR images, and skull X-ray with depth electrodes. (A, B) CT scan (A) and coronal MRI (B) acquired at the start of the seizures. A hematoma is seen in the left medial temporal lobe. (C) Coronal MRI after hematoma evacuation in the first surgery. The arrow indicates the parahippocampal gyrus located mesially to the surgical cavity. (D) Lateral skull X-ray shows the bilateral intracranial electrodes inserted via the occipital lobes. The left and right depth electrodes feature 10 and 6 contacts, respectively. Both depth electrodes are stereotactically located from the hippocampus to the amygdala. (E) The fusion image of MRI and CT identifies the location of L2 of the left depth electrode. The arrow indicates L2 placed in the inferomedial part of the previous surgical cavity. (F) Coronal MRI after the third surgery. The arrow indicates the cavity of the resected left prepiriform cortex and the residual mesial-cortical part of the amygdala.
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Computed tomography (CT) showed a small hemorrhage in the left mesial temporal lobe (Fig. 1A). Magnetic resonance imaging (MRI; Fig. 1B) showed a fresh 20-mm diameter hemorrhage in the left amygdala. Magnetic resonance imaging showed the prior surgical resection in the lateral-basal part and residual tissue in the mesial-cortical portion of the amygdala (Fig. 1C). We stereotactically placed two depth electrodes in the bilateral amygdalae and hippocampi via the occipital lobes of the patient at the age of 42 years (Fig. 1D). The ictal and interictal zones were identified in the left prepiriform cortex and the residual mesial-cortical part of the amygdala on the second postoperative MRI (Fig. 1C). Using an intraoperative navigation system (Fig. 1E), we aspirated the left prepiriform cortex and the residual mesial-cortical part of the amygdala. Resection ended when the arachnoid membrane of the parahippocampal gyrus was exposed (Fig. 1F).
Intracranial EEG findings. The 16 monopolar contacts of the bilateral depth electrodes are comprised of 10 contacts (red) in the left hemisphere and 6 contacts (blue) in the right hemisphere. Both depth electrodes are stereotactically located from the hippocampus to the amygdala via occipital lobes (Fig. 1D). Three interictal spikes are seen from L1 to L3 (closed circles). Two brackets indicate ictal low-amplitude fast activities (around 40 Hz) lasting around 10 s in duration each. These short-duration fast activities occurred frequently during sleep. When the ictal low-amplitude fast activities lasted longer than 20 s, the patient awoke and complained of a foul odor (sampling rate: 2 kHz; LFF, 1.59 Hz; HFF, 600 Hz).
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While he was asleep, ictal low-amplitude fast (around 40 Hz) appeared only at electrodes L1, L2, and L3 in the anterior contacts placed in the mediocortical part of the amygdala (Fig. 2).