Service de Neurologie et Explorations Fonctionnelles du Système Nerveux, CHU Rangueil, 31059 Toulouse Cedex 9, France.
J Neurol Neurosurg Psychiatry. 2010 Sep;81(9):978-84. doi: 10.1136/jnnp.2009.190223. Epub 2010 Jun 30.
Photophobia is an abnormal sensitivity to light experienced by migraineurs and is perhaps caused by cortical hyperexcitability. In clinical studies, an inter-relation between light perception and trigeminal nociception has been demonstrated in migraineurs but not in controls. The purpose of the study was to verify this interaction by functional imaging.
The authors used H(2)O(15) positron emitting tomography (PET) to study the cortical responses of seven migraineurs between attacks and the responses of seven matched control subjects to luminous stimulations at three luminance intensities: 0, 600 and 1800 Cd/m(2). All three intensities were both with and without concomitant trigeminal pain stimulation. In order to facilitate habituation, the stimulations were started 30 s before PET acquisitions.
When no concomitant pain stimulation was applied, luminous stimulations activated the visual cortex bilaterally in migraineurs (specifically in the cuneus, lingual gyrus and posterior cingulate cortex) but not in controls. Concomitant pain stimulation allowed visual cortex activation in control subjects and potentiated its activation in migraineurs. These activations by luminous stimulations were luminance-intensity-dependent in both groups. Concomitant stimulation by pain was associated with activation of the posterior parietal cortex (BA7) in migraineurs and controls.
The study shows the lack of habituation and/or cortical hyperexcitability to light in migraineurs. Moreover, the activation by light of several visual cortex areas (including the primary visual cortex) was potentiated by trigeminal pain, demonstrating multisensory integration in these areas.
畏光是偏头痛患者对光异常敏感的一种表现，可能是皮质过度兴奋所致。在临床研究中，偏头痛患者的光感觉和三叉神经痛觉之间存在相互关系，但在对照组中则没有。本研究旨在通过功能成像来验证这种相互作用。
作者使用 H(2)O(15)正电子发射断层扫描 (PET) 研究了 7 名偏头痛发作间期患者和 7 名匹配对照者对三种亮度（0、600 和 1800 Cd/m(2)）光刺激的皮质反应。三种亮度均伴有和不伴有三叉神经疼痛刺激。为了促进适应，刺激在 PET 采集前 30 秒开始。
当没有同时进行疼痛刺激时，光刺激在偏头痛患者双侧激活了视觉皮质（特别是在楔叶、舌回和后扣带回皮质），但在对照组中则没有。同时进行疼痛刺激使对照组的视觉皮质激活，并增强了偏头痛患者的激活。在两组中，这些光刺激的激活都与亮度强度有关。同时进行疼痛刺激与偏头痛患者和对照组的后顶叶皮质（BA7）的激活有关。
本研究表明偏头痛患者对光缺乏适应和/或皮质过度兴奋。此外，三叉神经疼痛增强了光对几个视觉皮质区域（包括初级视觉皮质）的激活，证明了这些区域的多感觉整合。
