Velasco M, Velasco F, Velasco A L, Boleaga B, Jimenez F, Brito F, Marquez I
Unit of Stereotactic Neurosurgery, General Hospital of Mexico SS, Mexico City.
Epilepsia. 2000 Feb;41(2):158-69. doi: 10.1111/j.1528-1157.2000.tb00135.x.
To investigate the clinical, electroencephalographic (EEG), and histopathologic effects of subacute electrical stimulation of the hippocampal formation or gyrus (SAHCS) on 10 patients with intractable temporal lobe seizures.
Bilateral, depth, hippocampal or unilateral, subdural, basotemporal electrodes were implanted in all 10 patients for a topographic diagnosis of the site and extent of the epileptic focus before a temporal lobectomy. In all patients, antiepileptic drugs (AEDs) were discontinued from 48 to 72 h before a program of continuous SAHCS, which was performed for 2-3 weeks. Stimulation parameters were biphasic Lilly wave pulses, 130/s in frequency, 450 micros in duration, and 200-400 microA in amplitude. The stimuli were delivered 23 of every 24 h for the 2-3-week SAHCS period. The effects of SAHCS on the number of clinical seizures per day and the percentage of interictal EEG spikes per 10-second samples of maximal paroxysmal activity at the epileptic focus were determined daily during the 16 days of SAHCS. At the completion of this program, patients underwent an en bloc temporal lobectomy, and the histopathologic effects of SAHCS on the stimulated tissue were analyzed by means of light-microscopy studies.
In seven patients whose stimulation electrode contacts were placed within the hippocampal formation or gyrus and who experienced no interruption in the stimulation program, SAHCS abolished clinical seizures and significantly decreased the number of interictal EEG spikes at the focus after 5-6 days. The most evident and fast responses were found by stimulating either the anterior pes hippocampus close to the amygdala or the anterior parahippocampal gyrus close to the entorhinal cortex. Other surface, hippocampal, and basotemporal EEG signs predicted and accompanied this antiepileptic response. These included an electropositive DC shift and monomorphic delta activity at the medial hippocampal and parahippocampal regions, and a normalization of the background EEG activity and signs of slow-wave sleep in surface. depth, and subdural regions. In contrast, no evident antiepileptic responses or no responses at all were found in three patients when stimulation was either interrupted or when it was administered outside the hippocampus. Light microscopy analysis of the stimulated hippocampal tissue showed histopathological abnormalities attributable to the depth-electrode penetration damage or to the pial surface reaction to the subdural, Silastic electrode plate. However, no evident histopathological differences were found between the stimulated and nonstimulated hippocampal tissue.
SAHCS appears to be a safe procedure that can suppress temporal lobe epileptogenesis with no additional damage to the stimulated tissue.
研究海马结构或海马回亚急性电刺激（SAHCS）对10例顽固性颞叶癫痫患者的临床、脑电图（EEG）及组织病理学影响。
10例患者均植入双侧深部海马电极或单侧硬膜下基底颞叶电极，用于在颞叶切除术前行癫痫灶部位及范围的定位诊断。所有患者在进行连续SAHCS程序前48至72小时停用抗癫痫药物（AEDs），SAHCS持续2至3周。刺激参数为双相利利波脉冲，频率130次/秒，持续时间450微秒，幅度200 - 400微安。在2至3周的SAHCS期间，每24小时中有23小时进行刺激。在SAHCS的16天内，每日测定SAHCS对每日临床发作次数以及癫痫灶每10秒最大阵发活动间期EEG棘波百分比的影响。该程序结束后，患者接受整块颞叶切除术，并通过光学显微镜研究分析SAHCS对受刺激组织的组织病理学影响。
7例刺激电极触点置于海马结构或海马回内且刺激程序未中断的患者，SAHCS在5至6天后消除了临床发作，并显著减少了癫痫灶处的发作间期EEG棘波数量。通过刺激靠近杏仁核的海马前部足或靠近内嗅皮质的海马旁回前部，发现了最明显和快速的反应。其他表面、海马及基底颞叶EEG征象预示并伴随了这种抗癫痫反应。这些征象包括海马内侧和海马旁回区域的正向直流偏移和单形δ活动，以及表面、深部和硬膜下区域背景EEG活动的正常化和慢波睡眠征象。相比之下，3例患者在刺激中断或刺激位于海马外时，未发现明显的抗癫痫反应或根本没有反应。对受刺激海马组织的光学显微镜分析显示，组织病理学异常归因于深部电极穿透损伤或硬膜下硅橡胶电极板对软脑膜表面的反应。然而，在受刺激和未受刺激的海马组织之间未发现明显的组织病理学差异。
SAHCS似乎是一种安全的方法，可抑制颞叶癫痫发作，且不会对受刺激组织造成额外损伤。
