Velasco M, Velasco F, Velasco A L
Unit for Stereotactic Neurosurgery, General and Children's Hospitals of Mexico SS and UMR, Neurophysiology, National Medical Center, IMSS, Mexico City, Mexico.
J Clin Neurophysiol. 2001 Nov;18(6):495-513. doi: 10.1097/00004691-200111000-00001.
The following two different modulatory procedures to control intractable epileptic seizures are presented: (1) chronic electrical stimulation of the centromedian-thalamic nucleus (ESCM) for control of generalized tonic-clonic seizures and atypical absences, and (2) subacute hippocampal stimulation (SAHCS) and chronic hippocampal stimulation for control of nonlesional temporal lobe seizures. The ESCM antiepileptic effect seems to be the result of activation of a nonspecific reticulothalamocortical system responsible for generalized electrocortical responses (recruiting, desynchronization, negative direct current shifts, and three spike-wave complexes per second). The success of the ESCM procedure depends on the following predictor factors: case selection (primary and secondary tonic-clonic seizures and atypical absences of the Lennox Gastaut syndrome), ventriculographic and electrophysiologic definition of the optimal stereotactic targets (based on the anterior commissure, posterior commissure, and the vertical line perpendicular to the posterior commissure and electrocortical recruiting responses), periodic electrophysiologic monitoring of the reliability of ESCM in the absence of the patient's subjective sensations and with totally internalized subcutaneous stimulation systems (by recording scalp electrocortical recruiting, desynchronizing, and direct current responses), quantitative evaluation of clinical and EEG improvement, and analysis of the ON and OFF effects, taking into account a long-lasting (possibly plastic) effect of ESCM. SAHCS blocks clinical and EEG signs of temporal lobe epileptogenesis with no additional damage of the stimulated hippocampal tissue. Preliminary results suggest that this antiepileptic effect is, at least in part, the result of a physiologic inhibition of the stimulated hippocampal tissue, because after SAHCS the authors found the following: (1) increased threshold and decreased duration, propagation, and blockage of the clinical signs accompanied with the hippocampal afterdischarge; (2) flattening of the hippocampal-evoked response recovery cycles; (3) single photon emission computed tomographic hypoperfusion; and (4) increased concentration of benzodiazepine receptor binding at the stimulated hippocampal region. Chronic hippocampal stimulation persistently blocked temporal lobe epileptogenesis in one patient under open protocols during 24 months with no apparent additional alterations in recent memory.
（1）慢性电刺激中央中核 - 丘脑核（ESCM）以控制全身性强直 - 阵挛性发作和非典型失神发作；（2）亚急性海马刺激（SAHCS）和慢性海马刺激以控制非损伤性颞叶癫痫发作。ESCM的抗癫痫作用似乎是激活了一个负责全身性皮质电反应（募集、去同步化、负向直流偏移以及每秒三个棘波 - 慢波复合波）的非特异性网状丘脑皮质系统的结果。ESCM手术的成功取决于以下预测因素：病例选择（原发性和继发性强直 - 阵挛性发作以及Lennox - Gastaut综合征的非典型失神发作）、基于前连合、后连合以及垂直于后连合的垂线和皮质电募集反应的脑室造影和电生理确定最佳立体定向靶点、在患者无主观感觉且使用完全植入皮下的刺激系统时对ESCM可靠性进行定期电生理监测（通过记录头皮皮质电募集、去同步化和直流反应）、对临床和脑电图改善情况进行定量评估以及分析开/关效应，并考虑ESCM的长期（可能是可塑性的）效应。SAHCS可阻断颞叶癫痫发生的临床和脑电图征象，且不会对受刺激的海马组织造成额外损伤。初步结果表明，这种抗癫痫作用至少部分是受刺激海马组织生理抑制的结果，因为在SAHCS后作者发现：（1）海马放电后临床征象的阈值升高、持续时间缩短、传播和阻断；（2）海马诱发反应恢复周期变平坦；（3）单光子发射计算机断层扫描灌注减低；（4）受刺激海马区域苯二氮䓬受体结合浓度增加。在开放方案下，慢性海马刺激在一名患者中持续24个月阻断了颞叶癫痫发生，且近期记忆无明显额外改变。
