1 1 3 1 3 3 2 2 1 3 2 1 1 2 3 Epilepsy Surgery for Refractory Focal Epilepsy based on the Analysis of High Frequency Oscillations with Intracranial Electroencephalography A Case Report Akihiko Kondo, M.D. 1, Tomoyuki Akiyama, M.D. 3, Takashi Agari, M.D. 1, Makio Oka, M.D. 3, Yoshinori Kobayashi, M.D. 3, Yumiko Hayashi, M.D. 2, Takashi Shibata, M.D. 2, Yukei Shinji, M.D. 1, Katsuhiro Kobayashi, M.D. 3, Harumi Yoshinaga, M.D. 2, and Isao Date, M.D. 1 1 Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2 Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 3 Department of Child Neurology, Okayama University Hospital Intracranial electroencephalography IEEG is useful as an evaluation component of resective surgery when the results of noninvasive tests are incongruent in patients with refractory neocortical epilepsy. High frequency oscillations HFOs 80 Hz have recently been recognized as having a strong relationship to the epileptogenic zone, and the complete resection of HFOs has been considered a favorable prognostic indicator for surgical outcome. It is sometimes difficult, however, to comprehend dynamic changes in ictal HFOs recorded via subdural electrodes. We performed surgical treatment on a medically intractable patient diagnosed with occipital lobe epilepsy after analyzing the patient s HFOs with IEEG using the original program. The patient has achieved seizure free status one year after surgery. Our method of creating a brain surface topographic map of interictal HFOs and a topographic movie of ictal HFOs was useful for easy understanding of seizure onset zone and epileptic HFOs propagation. It may also be helpful for determining the necessary extent of surgical resection to include the epileptogenic zone, thus promoting better postsurgical seizure outcomes. Received May 20, 2014 accepted August 12, 2014 Key words neocortical epilepsy, respective surgery, high frequency oscillations, intracranial electroencephalography, topographic map Jpn J Neurosurg Tokyo 24 32 39, 2015 700 8558 2 5 1 Address reprint requests to Akihiko Kondo, M.D., Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2 5 1 Shikata cho, Kita ku, Okayama shi, Okayama 700 8558, Japan 32 24 1 2015 1
Fig. 1 T2 weighted MRI shows atrophic gyri with hemosiderin deposition in bilateral occipital and parietal lobes arrows. Old hemorrhagic lesions were suspected. high frequency oscillations HFOs 8 21 25 27 HFO 25 5 1 11 40 1 1 9 18 25 Hz 5 10 sampling rate 645.8 Hz high pass 0.1 Hz bandwidth 200 Hz sporadic spike target dipole cluster goodness of fit 95 2 T2 4 Fig. 1 SPECT Fig. 2 Jpn J Neurosurg VOL. 24 NO. 1 2015. 1 33
Fig. 2 FDG PET shows hypometabolism of the lesions in the right occipital and parietal lobes yellow arrows. Fig. 3 Skull x ray showing the location of intracranial electrodes Left Anteroposterior view. Right Lateral view. Right occipital areas are covered with subdural grid electrodes extending in three different directions medial side, lateral side, and base. Additionally, the right parietal and temporal areas are covered with subdural grid electrodes. One strip electrode is placed on the left parieto occipital area. 3 3 1 Fig. 3 Neurofax EEG 1100 1 khz bandpass filter 0.016 300 Hz HFO HFO MAT- LAB Akiyama 3 4 1 HFO 5 80 Hz 38 34 24 1 2015 1
Fig. 4 Topographic maps showing the rate of interictal HFO in the right cerebral hemisphere Left medial view, Right lateral view The color bar indicates the rate of HFO over a five minute period. interquartile range IQR HFO 75 3 IQR 32 ms HFO HFO 1 MRI CT 3D 2 HFO 10 30 Hz HFO HFO 3D 1 4 1 HFO Fig. 4 HFO Fig. 5 HFO HFO Fig. 6 2 subclinical ictal EEG small spike 18 25 Hz 5 10 Fig. 6 Fig. 7 2 3 1 70 Hz Jpn J Neurosurg VOL. 24 NO. 1 2015. 1 35
t 0.0s t 0.5s t 1.5s t 1.0s t 2.0s t 2.5s Fig. 5 Snapshots from a topographic movie medial view showing that HFOs at seizure onset appear predominantly from the medial area surrounding the right occipital lesion. HFO subsequently propagates in the direction of the base and lateral side in the right occipital lobe 1.0 seconds after seizure onset, and then reappear from the medial area. Fig. 6 Brain surface maps showing the positions of subdural electrodes Left medial view, Right lateral view Circles blue contact points of subdural electrodes, Open circles magenta interictal spikes, Stars yellow interictal HFOs, Open boxes red ictal HFOs, Asterisks white old hemorrhagic lesions, Watery curves resection margin により高いサンプリング周波数での記録を用いた 80 に記録される 当初はマイクロ電極を用いた頭蓋内脳波 Hz 以上の HFO の解析も可能となった 近年では てん 記録で報告されたが6 後に臨床で用いられるマクロ電 かんに関連した HFO はてんかん焦点の新たなマーカー 極でも記録可能なことが示された7 16 22 その後 発作 1 5 10 13 15 として考えられるようになってきた Fig. 8 間欠時 HFO の出現頻度は発作起始部位内のほうが部位 外よりも高いことが示され 発作間欠時 HFO は発作起 36 1 発作間欠時 HFO 始部位あるいはてんかん原性領域のマーカーであると考 発作間欠時 HFO は てんかん性棘波と同様に間欠的 えられるようになった9 12 脳外誌 24 巻 1 号 2015 年 1 月
Fig. 7 Right occipital craniotomy and corticectomy of the lesion responsible for generating the patient s HFOs Left brain surface of right occipital lobe covered with subdural grid electrodes, Middle pre resection view of brownish yellow lesion, Right post resection view. O occipital lobe, T temporal lobe, P parietal lobe, M midline さらに焦点切除術後の発作予後との関連において 発 作間欠時 HFO が頻発する部位の切除割合が術後成績と All epilepsies Seizure semiology 相関することが示された4 14 26 一方で てんかん性棘 波ではそのような関連は認められず また発作起始部位 の切除割合と術後成績も相関しなかったことから HFO Scalp EEG MRI SPECT PET fmri MEG Medication Intracranial EEG が棘波や発作起始部位よりも優れた予後予測マーカーで あることも示唆されている4 14 HFO 本症例においても発作間欠時 HFO が病変部周囲より 高頻度に出現しており 切除範囲に含めるように術前計 画を立て 焦点切除を行った Refractory epilepsies Surgery Epileptogenic zone 2 発作時 HFO てんかん発作の際にも HFO が認められ 主に発作開 始初期の HFO が解析される 当初は 250 Hz までの HFO が報告されたが のちに 250 Hz 以上の HFO も検 出された16 新皮質てんかんで 発作時に 200 Hz 以上の HFO が検出された領域内のさらに限局した領域に 低振 幅な 1 khz 以上の HFO も確認された23 一方 内側側 頭葉てんかんでは 臨床発作の開始直前から発作時にか Fig. 8 Depiction of the presurgical diagnostic process as it is performed in most epilepsy centers HFOs appear to be excellent markers for the epileptogenic zone. Certain patients with complicated and refractory seizures benefit from the identification of HFOs in intracranial EEG. Figure modified from that of Jacobs et al. けて海馬にて HFO 500 800 Hz が検出され これが てんかん原性領域と相関するとの報告や17 HFO 200 時 HFO は右後頭葉の一部に非常に限局して出現し そ Hz 以上 が海馬硬化と強く相関するとの報告があり の後病変部周囲に急激に波及することを動的変化として 術後成績との関連も示唆されている24 捉えることができた この点において 切除範囲の術前 新皮質てんかんにおいて 発作時 HFO も発作間欠時 計画を立てるうえでカラーマップ動画は有用であった HFO と同様にその出現領域を切除範囲に含むことが 良 好な術後成績に相関するとされている11 18 20 さらに発 20 3 HFO 解析の限界と対策 作中の HFO の伝播様式の把握も重要であるが 動的 HFO は発作起始部位等の限られた場所から発生する 変化が複雑な場合もあり カラーマップ動画による視覚 ため 脳の深部構造など 電極でカバーしきれない領域 化が理解を容易なものにし得る 2 3 本症例では発作開始 や狭い領域から生じる HFO は見逃される可能性があ Jpn J Neurosurg VOL. 24 NO. 1 2015. 1 37
HFO HFO HFO HFO 4 5 mm MRI PET SPECT MEG HFO HFO HFO 1 HFO HFO HFO HFO HFO 19 HFO HFO HFO HFO HFO HFO 1 Akiyama T, Otsubo H, Ochi A, Ishiguro T, Kadokura G, Ramachandrannair R, Weiss SK, Rutka JT, Carter Snead O 3rd Focal cortical high frequency oscillations trigger epileptic spasms confirmation by digital video subdural EEG. Clin Neurophysiol 116 2819 2825, 2005. 2 Akiyama T, Otsubo H, Ochi A, Galicia EZ, Weiss SK, Donner EJ, Rutka JT, Snead OC 3rd Topographic movie of ictal high frequency oscillations on the brain surface using subdural EEG in neocortical epilepsy. Epilepsia 47 1953 1957, 2006. 3 Akiyama T, Chan DW, Go CY, Ochi A, Elliott IM, Donner EJ, Weiss SK, Snead OC 3rd, Rutka JT, Drake JM, Otsubo H Topographic movie of intracranial ictal high frequency oscillations with seizure semiology epileptic network in Jacksonian seizures. Epilepsia 52 75 83, 2011. 4 Akiyama T, McCoy B, Go CY, Ochi A, Elliott IM, Akiyama M, Donner EJ, Weiss SK, Snead OC 3rd, Rutka JT, Drake JM, Otsubo H Focal resection of fast ripples on extraoperative intracranial EEG improves seizure outcome in pediatric epilepsy. Epilepsia 52 1802 1811, 2011. 5 Allen PJ, Fish DR, Smith SJ Very high frequency rhythmic activity during SEEG suppression in frontal lobe epilepsy. Electroencephalogr Clin Neurophysiol 82 155 159, 1992. 6 Bragin A, Engel J Jr, Wilson CL, Fried I, Buzsáki G High frequency oscillations in human brain. Hippocampus 9 137 142, 1999. 7 Bragin A, Wilson CL, Staba RJ, Reddick M, Fried I, Engel J Jr Interictal high frequency oscillations 80 500 Hz in the human epileptic brain entorhinal cortex. Ann Neurol 52 407 415, 2002. 8 Bragin A, Engel J Jr, Staba RJ High frequency oscillations in epileptic brain. Curr Opin Neurol 23 151 156, 2010. 9 Crépon B, Navarro V, Hasboun D, Clemenceau S, Martinerie J, Baulac M, Adam C, Le Van Quyen M Mapping interictal oscillations greater than 200 Hz recorded with intracranial macroelectrodes in human epilepsy. Brain 133 33 45, 2010. 10 Fisher RS, Webber WR, Lesser RP, Arroyo S, Uematsu S High frequency EEG activity at the start of seizures. J Clin Neurophysiol 9 441 448, 1992. 11 Fujiwara H, Greiner HM, Lee KH, Holland Bouley KD, Seo JH, Arthur T, Mangano FT, Leach JL, Rose DF Resection of ictal high frequency oscillations leads to favorable surgical outcome in pediatric epilepsy. Epilepsia 53 1607 1617, 2012. 12 Jacobs J, LeVan P, Chander R, Hall J, Dubeau F, Gotman J Interictal high frequency oscillations 80 500 Hz are an indicator of seizure onset areas independent of spikes in the human epileptic brain. Epilepsia 49 1893 1907, 38 24 1 2015 1
2008. 13 Jacobs J, Levan P, Châtillon CE, Olivier A, Dubeau F, Gotman J High frequency oscillations in intracranial EEGs mark epileptogenicity rather than lesion type. Brain 132 1022 1037, 2009. 14 Jacobs J, Zijlmans M, Zelmann R, Chatillon CE, Hall J, Olivier A, Dubeau F, Gotman J High frequency electroencephalographic oscillations correlate with outcome of epilepsy surgery. Ann Neurol 67 209 220, 2010. 15 Jacobs J, Staba R, Asano E, Otsubo H, Wu JY, Zijlmans M, Mohamed I, Kahane P, Dubeau F, Navarro V, Gotman J High frequency oscillations HFOs in clinical epilepsy. Prog Neurobiol 98 302 315, 2012. 16 Jirsch JD, Urrestarazu E, LeVan P, Olivier A, Dubeau F, Gotman J High frequency oscillations during human focal seizures. Brain 129 1593 1608, 2006. 17 Kobayashi K, Agari T, Oka M, Yoshinaga H, Date I, Ohtsuka Y, Gotman J Detection of seizure associated high frequency oscillations above 500 Hz. Epilepsy Res 88 139 144, 2010. 18 Modur PN, Zhang S, Vitaz TW Ictal high frequency oscillations in neocortical epilepsy implications for seizure localization and surgical resection. Epilepsia 52 1792 1801, 2011. 19 Nariai H, Matsuzaki N, Juhász C, Nagasawa T, Sood S, Chugani HT, Asano E Ictal high frequency oscillations at 80 200 Hz coupled with delta phase in epileptic spasms. Epilepsia 52 e130 134, 2011. 20 Ochi A, Otsubo H, Donner EJ, Elliott I, Iwata R, Funaki T, Akizuki Y, Akiyama T, Imai K, Rutka JT, Snead OC 3rd Dynamic changes of ictal high frequency oscillations in neocortical epilepsy using multiple band frequency analysis. Epilepsia 48 286 296, 2007. 21 Staba RJ, Stead M, Worrell GA Electrophysiological biomarkers of epilepsy. Neurotherapeutics 11 334 346, 2014. 22 Urrestarazu E, Jirsch JD, LeVan P, Hall J, Avoli M, Dubeau F, Gotman J High frequency intracerebral EEG activity 100 500 Hz following interictal spikes. Epilepsia 47 1465 1476, 2006. 23 Usui N, Terada K, Baba K, Matsuda K, Nakamura F, Usui K, Tottori T, Umeoka S, Fujitani S, Mihara T, Inoue Y Very high frequency oscillations over 1000 Hz in human epilepsy. Clin Neurophysiol 121 1825 1831, 2010. 24 Usui N, Terada K, Baba K, Matsuda K, Nakamura F, Usui K, Yamaguchi M, Tottori T, Umeoka S, Fujitani S, Kondo A, Mihara T, Inoue Y Clinical significance of ictal high frequency oscillations in medial temporal lobe epilepsy. Clin Neurophysiol 122 1693 1700, 2011. 25 Worrell G, Gotman J High frequency oscillations and other electrophysiological biomarkers of epilepsy clinical studies. Biomark Med 5 557 566, 2011. 26 Wu JY, Sankar R, Lerner JT, Matsumoto JH, Vinters HV, Mathern GW Removing interictal fast ripples on electrocorticography linked with seizure freedom in children. Neurology 75 1686 1694, 2010. 27 Zijlmans M, Jiruska P, Zelmann R, Leijten FS, Jefferys JG, Gotman J High frequency oscillations as a new biomarker in epilepsy. Ann Neurol 71 169 178, 2012. 1 HFO HFO HFO 1 HFO HFO 24 32 39 2015 Jpn J Neurosurg VOL. 24 NO. 1 2015. 1 39
100 40 24 1 2015 1