Höffken Oliver, Stude Philipp, Lenz Melanie, Bach Michael, Dinse Hubert R, Tegenthoff Martin
Department of Neurology, Ruhr-University Bochum, BG-Kliniken Bergmannsheil, Bochum, Germany.
Eur J Neurosci. 2009 Aug;30(4):714-20. doi: 10.1111/j.1460-9568.2009.06859.x. Epub 2009 Aug 10.
Migraine is a common ictal disorder with an interindividual heterogeneous characteristic, whose underlying mechanisms remain elusive. On the one hand migraine is associated with abnormal cortical hyperexcitability. On the other hand, studies reported lower amplitudes of visual-evoked potentials (VEPs) and concluded that low preactivation levels imply decreased excitability. Here we measured visual cortex excitability and paired-pulse suppression in subjects suffering from migraine without aura and in a group of aged- and gender-matched healthy subjects to address the relation between activation levels and excitability. To that aim, we analysed amplitudes of VEPs and paired-pulse suppression evoked by a paired-pulse stimulation paradigm using stimulus onset asynchronies (SOAs) between 80 and 133 ms. We found that in migraineurs in the interictal state the amplitudes of the first VEP were reduced as compared with healthy subjects by approximately 20%. In the case of paired-pulse suppression comparable to healthy controls, the second response amplitude should be reduced as well, which was not the case. Instead, the ratio between the first and second VEP was higher than in healthy controls and did not depend on SOA in the range tested, which demonstrates reduced paired-pulse suppression and therefore implicates increased cortical excitability. Our data show that in migraineurs VEPs were reduced presumably due to reduced activation levels. However, paired-pulse suppression using short SOAs in the range of 100 ms or less was even higher than in normal subjects. Thus, our data show that signatures of both hyper- and hypoexcitability can be found depending on stimulation condition.
偏头痛是一种常见的发作性疾病，具有个体间异质性特征，其潜在机制仍不清楚。一方面，偏头痛与异常的皮层兴奋性过高有关。另一方面，研究报告视觉诱发电位（VEP）的波幅较低，并得出低预激活水平意味着兴奋性降低的结论。在这里，我们测量了无先兆偏头痛患者以及一组年龄和性别匹配的健康受试者的视觉皮层兴奋性和双脉冲抑制，以探讨激活水平与兴奋性之间的关系。为此，我们分析了使用80至133毫秒的刺激起始异步（SOA）的双脉冲刺激范式诱发的VEP波幅和双脉冲抑制。我们发现，在发作间期的偏头痛患者中，第一个VEP的波幅与健康受试者相比降低了约20%。在双脉冲抑制与健康对照相当的情况下，第二个反应波幅也应降低，但实际并非如此。相反，第一个和第二个VEP之间的比率高于健康对照，并且在所测试的范围内不依赖于SOA，这表明双脉冲抑制降低，因此意味着皮层兴奋性增加。我们的数据表明，在偏头痛患者中，VEP降低可能是由于激活水平降低。然而，使用100毫秒或更短范围内的短SOA的双脉冲抑制甚至高于正常受试者。因此，我们的数据表明，根据刺激条件，可以发现兴奋性过高和过低兴奋的特征。
