深腦刺激術對大鼠顳葉癲癇之影響

Abstract

癲癇（epilepsy）為一種慢性腦病變而導致大腦產生反覆性且無預警的不正常放電，進而影響正常功能而造成知覺或動作上的異常與改變的疾病。而又可以粗略分為泛發性發作型（generalized seizures）癲癇與局部性發作型（partial seizures）癲癇。其中顳葉癲癇（temporal lobe epilepsy , TLE）為在成人常見的局部性發作型癲癇，依其原發處可分為位於顳葉中層結構，如海馬迴（hippocampus） 、杏仁核（amygdala）以及內鼻皮質（entorhinal cortex）的內側顳葉癲癇（mesial temporal lobe epilepsy , MTLE）以及顳葉旁側結構，如新皮層（neocortex）的外側顳葉癲癇（lateral temporal lobe epilepsy , LTLE） 。臨床上在顳葉型癲癇的病人常在發作之前產生知覺、嗅覺或聽覺的異常先兆（aura） ，而隨著癲癇發作的程度，開始產生在動作上的改變，如在口部或面部上的自動症（automatism）現象、或是頭部歪斜、甚至全身肌肉收縮導致的四肢抽搐情形。在實驗 Wistar 大鼠的左杏仁核做一重複性的電流刺激術（kindling）可做為模擬顳葉型癲癇之模型，其特色為改變原發處的神經細胞放電模式進而產生突觸長期增益而造成顳葉型癲癇迴路上的鞏固。隨著漸進式的神經迴路異常於植入不同腦區的電極可紀錄到癲癇波（epileptiform discharges） 。再根據 Racine 所訂出之不同程度行為表現：stage 1、面部與口部抽動。stage 2、頭部動作。stage 3、前肢單肢抽動。stage 4、後肢站立且前肢雙肢抽動。Stage 5、失去平衡能力摔倒抽搐。可發現癲癇的活動主要反應在癲癇波增長、能量增大，如 delta band（1-5 Hz）與 gamma band（30-50 Hz）、以及腦區之間的同調性增加等。此外，利用深腦刺激術（deep brain stimulation, DBS）對 kindling 的protocol 以及 fully kindled 後之癲癇發作做干擾，亦可觀察到其所產生之影響。

Epilepsy is divided into two main categories: generalized and partial seizures.Temporal lobe epilepsy (TLE) may be one of the most common simple partial seizures. The International League Against Epilepsy (ILAE) recognizes two main types of temporal lobe epilepsy . Mesial temporal lobe epilepsy (MTLE) arises from the hippocampus or the amygdala which are located in the inner aspect of the temporal lobe. Lateral temporal lobe epilepsy (LTLE), the less prevalent type, arises from the neocortex at the outer surface of the temporal lobe. Patients with TLE may experience auras including sensation changes before seizures, which could evolve into oral, lip smacking, chewing automatisms, head deviation, and/or convulsion subsequently. Kindling models of TLE has been a useful tool in the study of epileptogenesis from a precise focus to other brain regions in rats. During the seizures, we can also evaluate rats’ behavior according to Racine’s stages: stage 0) normal behavior; stage 1) facial clonus, mouth clonus; stage 2) head nodding; stage 3) unilateral forelimb clonus; stage 4) bilateral forelimb clonus with rearing; stage 5) rearing and falling. Main characteristics of kindling based on the seizure duration elongated, the power of delta (1-5 Hz) and gamma (30-50 Hz) increased as well as the coherency of brain regions intense. Deep brain stimulation (DBS) is a candidate therapy for epileptic seizures which cannot be controlled by medications. We have applied DBS during kindling procedure on both normal and fully kindled rats to investigate its effects on seizure characteristics of epileptogenesis and already developed into epilepsy.