Abstracts

Rationale: Evaluation of patient with intractable epilepsy, cavernous angioma and ictal asystole, treated with cavernoma and epileptic focus resection after placement of indwelling intracranial electrodes, followed by pathological study of resected specimens.Methods: Case: A 40-year-old man experienced epileptic seizures since the age of 20. Usually preceded by abnormal sensation in his right arm, he presented with complex partial seizures leading to ictal asystole and rapid impairment of consciousness after the seizure has stopped. Initial seizure frequency was about 4–5 times per year, but gradually worsened to once a month. On the continuous scalp EEG/video, epileptic discharges originated from left Sp, Fp, and aT. MRI results revealed a cavernous angioma on the orbital surface of the left frontal lobe. Temporal lobe epilepsy was suspected based on seizure semiology and EEG findings. Since ictal asystole occurred with seizures, indwelling intracranial electrodes were inserted, and the origin of the seizures and the propagation were identified. As pathological study, immunohistochemistry for primary antibodies was performed (Table1).Results: Two intracranial electrode arrays were placed: on the frontal cortex, adjacent to the lesion, and on the temporal lobe, covering from the tip to the parahippocampal gyrus. Seizure video EEG after intracranial electrodes placement showed seizure origin from the lateral orbital surface of the left frontal lobe (where the cavernous angioma located), propagating centrifugally. Simultaneously on the electrocardiogram, heart rate gradually decreased to extreme bradycardia, and an ictal asystole was recorded. Clinically with cardiac syncope, the patient became unconscious 18-25 seconds after seizure onset. In addition to the standard EEG recording band, we used high frequency bands (80–120 Hz), aiming at the detection of high frequency oscillation (HFO) areas. We included those locations in the planned resection - the base of the left frontal lobe and temporal tip, including cortex where spikes were identified on the EEG together with the cavernous angioma. Histological and immunohistochemical study: There was widespread diffusion of iron and reactive astrocytes in the removed tissues surrounding the cavernous angioma, where a strong immune reaction to HMGB1 and TLR4 together with microglia proliferation and activation were seen. In the cortical gray matter where spikes were identified on the EEG, the oxidative stress marker 4-HNE together with HMGB1 and TLR4-positive neurons were confirmed over a wider area surrounding the angioma.Conclusions: It was speculated that oxidative stress spread through activated microglia and reactive astrocytes, due to the action of neuron-neuron and astro-neuron interactions, is related to epileptogenesis. However, in order to identify the relationship of inflammatory cytokines to epileptogenic transformation, a more detailed electrophysiological examination in parallel with histopathological evaluation will be required.