Katayama M, Kohara N, Kaji R, Kojima Y, Shibasaki H, Kimura J
Department of Neurology, Kyoto University Hospital, Japan.
Electroencephalogr Clin Neurophysiol. 1996 Oct;101(5):446-52.
Patients with blepharospasm may have selective sensitivity to photic stimuli, for their symptoms are often aggravated after exposure to brightness. To investigate the pathophysiology underlying this phenomenon, we compared the effects of electric and photic conditioning on electrically-evoked blink reflex in 21 patients with blepharospasm and 11 age-matched control subjects. With electric conditioning, R1 was facilitated at inter-stimulus intervals (ISIs) of up to 100 ms in both groups. R2 was inhibited at all ISIs longer than 20 ms in the normals, but to a much lesser extent in the patients, suggesting increased excitability of the multi-synaptic reflex pathway. Compared to electric conditioning, photic conditioning was less potent in inhibiting R2 in the normals. In contrast, photic conditioning in the patients produced R2 inhibition as powerful as electric conditioning. These findings indicate that, in patients with blepharospasm, photic input has a relatively more profound inhibitory effect on the test blink reflex than electric conditioning as compared with normal subjects. The greater susceptibility of the brainstem interneurons to photic conditioning in blepharospasm may be related to the clinically-observed light sensitivity.
眼睑痉挛患者可能对光刺激有选择性敏感，因为他们的症状常在暴露于强光后加重。为了研究这一现象背后的病理生理学机制，我们比较了电刺激条件作用和光刺激条件作用对21例眼睑痉挛患者及11例年龄匹配的对照受试者的电诱发眨眼反射的影响。在电刺激条件作用下，两组在刺激间隔（ISI）长达100毫秒时R1均得到易化。在正常受试者中，所有长于20毫秒的ISI时R2均被抑制，但在患者中抑制程度要小得多，提示多突触反射通路兴奋性增加。与电刺激条件作用相比，光刺激条件作用对正常受试者R2的抑制作用较弱。相反，患者的光刺激条件作用产生的R2抑制作用与电刺激条件作用一样强。这些发现表明，与正常受试者相比，在眼睑痉挛患者中，光刺激输入对测试眨眼反射的抑制作用相对电刺激条件作用更为显著。脑干中间神经元对眼睑痉挛患者光刺激条件作用的更高敏感性可能与临床上观察到的光敏感有关。
