Kobayashi Eliane, Bagshaw Andrew P, Grova Christophe, Dubeau François, Gotman Jean
Montreal Neurological Institute and Hospital, McGill University, Canada.
Hum Brain Mapp. 2006 Jun;27(6):488-97. doi: 10.1002/hbm.20193.
Simultaneous electroencephalogram/functional magnetic resonance imaging (EEG-fMRI) during interictal epileptiform discharges can result in positive (activation) and negative (deactivation) changes in the blood oxygenation level-dependent (BOLD) signal. Activation probably reflects increased neuronal activity and energy demand, but deactivation is more difficult to explain. Our objective was to evaluate the occurrence and significance of deactivations related to epileptiform discharges in epilepsy. We reviewed all EEG-fMRI studies from our database, identified those with robust responses (P = 0.01, with > or =5 contiguous voxels with a |t| > 3.1, including > or =1 voxel at |t| > 5.0), and divided them into three groups: activation (A = 8), deactivation (D = 9), and both responses (AD = 43). We correlated responses with discharge type and location and evaluated their spatial relationship with regions involved in the "default" brain state (Raichle et al. [2001]: Proc Natl Acad Sci 98:676-682]. Deactivations were seen in 52/60 studies (AD + D): 26 related to focal discharges, 12 bilateral, and 14 generalized. Deactivations were usually distant from anatomical areas related to the discharges and more frequently related to polyspike- and spike-and-slow waves than to spikes. The "default" pattern occurred in 10/43 AD studies, often associated with bursts of generalized discharges. In conclusion, deactivations are frequent, mostly with concomitant activation, for focal and generalized discharges. Discharges followed by a slow wave are more likely to result in deactivation, suggesting neuronal inhibition as the underlying phenomenon. Involvement of the "default" areas, related to bursts of generalized discharges, provides evidence of a subclinical effect of the discharges, temporarily suspending normal brain function in the resting state.
发作间期癫痫样放电期间同步进行脑电图/功能磁共振成像（EEG-fMRI）可导致血氧水平依赖（BOLD）信号出现正向（激活）和负向（失活）变化。激活可能反映神经元活动和能量需求增加，但失活则更难解释。我们的目的是评估癫痫中与癫痫样放电相关的失活的发生情况及意义。我们回顾了数据库中所有的EEG-fMRI研究，确定那些有强烈反应的研究（P = 0.01，有≥5个连续体素，|t|> 3.1，包括≥1个体素，|t|> 5.0），并将它们分为三组：激活组（A = 8）、失活组（D = 9）和既有激活又有失活组（AD = 43）。我们将反应与放电类型和位置进行关联，并评估它们与参与“默认”脑状态的区域的空间关系（Raichle等人[2001]：美国国家科学院院刊98：676 - 682）。在52/60项研究（AD + D）中观察到失活：26项与局灶性放电相关，12项双侧性，14项全身性。失活通常远离与放电相关的解剖区域，并且与多棘波和棘慢波相关的情况比与棘波相关的情况更常见。“默认”模式出现在10/43项AD研究中，通常与全身性放电的突发相关。总之，对于局灶性和全身性放电，失活很常见，大多伴有激活。随后出现慢波的放电更有可能导致失活，提示神经元抑制是潜在现象。与全身性放电突发相关的“默认”区域的参与，为放电的亚临床效应提供了证据，即在静息状态下暂时中止正常脑功能。
