双侧不对称上睑下垂的“落幕征”

上次关于腱膜性上睑下垂的英文译文中提到，双侧不对称上睑下垂患者人为提升下垂严重的眼睑后，相对轻的上睑下垂眼会出现明显的上睑下垂加重，这是因为亨利法则。

网上找的一个典型的示教视频，神经学上称此“落幕征”。

The curtain sign (enhanced ptosis) is one of the many eye signs of myasthenia gravis. Hering’s law of reciprocal innervation states that the extraocular muscles receive equal bilateral innervation. In MG, extraocular involvement is variable and asymmetric leading to ptosis that is bilateral but often unequal. Both lids receive the same level of innervation and firing is maximal attempting to hold the lids open. The lid less involved by the disease process is open wider. Manually elevating the more ptotic lid sends a signal to the less ptotic lid that it can relax a bit and the ptosis increases. The manual elevation of the more ptotic lid causes the level of firing to decrease and the previously less ptotic lid suddenly collapses (Video). Manually raising the more ptotic lid causes increased ptosis on the opposite side.

Enhanced ptosis has also been reported in LEMS.

Video courtesy of Dr. Stephen Reich, Department of Neurology, University of Maryland