Zhang Minchen, Zhou Rong, Gao Weicheng
Department of Plastic and Cosmetic Surgery, The Affiliated Friendship Plastic Surgery Hospital of Nanjing Medical University, No.146, Han-zhong Road, Nanjing, Jiangsu 210029, PR China.
Department of Plastic and Cosmetic Surgery, The Affiliated Friendship Plastic Surgery Hospital of Nanjing Medical University, No.146, Han-zhong Road, Nanjing, Jiangsu 210029, PR China.
Med Hypotheses. 2020 Dec;145:110341. doi: 10.1016/j.mehy.2020.110341. Epub 2020 Oct 9.
Previous studies have suggested that the senile ptosis is mostly aponeurotic ptosis. Aponeurotic ptosis, the most common cause of acquired ptosis in elderly adults, results from disinsertion or dehiscence of the levator aponeurosis from the tarsal plate. Müller's Muscle is located below the levator aponeurosis, and its main function is to contribute to a few millimeter in upper eyelid elevation. In recent years, studies have shown that Müller's Muscle plays a more important role in the eye-opening process than previously reported. There are few reports on the changes of smooth muscle component with age in Müller's Muscle. As far as we know, it has not been written up previously. Through histological study on Müller's Muscle of Chinese cadaver specimens, we found that Müller's Muscle contained obvious smooth muscle components above the upper edge of the tarsus in the specimen of a child. However, in elderly specimens, we observed that the smooth muscle components decreased gradually even faded away from originated inferior branch of levator superioris muscle to upper margin of tarsus. We hypothesized that the number of smooth muscle components in Müller's Muscle gradually decreases, with the increase of age, which further affects the function of Müller's Muscle in assisting levator muscle, and further causes or aggravates ptosis. Our hypothesis needs to be further verified by more autopsy histological studies of different ages and genders, so as to provide a new idea for the clinical diagnosis and treatment of ptosis.
以往研究表明，老年性上睑下垂大多为腱膜性上睑下垂。腱膜性上睑下垂是老年人后天性上睑下垂最常见的原因，由提上睑肌腱膜从睑板的附着分离或裂开所致。米勒肌位于提上睑肌腱膜下方，其主要功能是在上睑抬高时贡献几毫米的提升力量。近年来，研究表明米勒肌在睁眼过程中发挥的作用比之前报道的更为重要。关于米勒肌中平滑肌成分随年龄变化的报道较少。据我们所知，此前尚无相关论述。通过对中国尸体标本的米勒肌进行组织学研究，我们发现，在儿童标本在儿童标本中，米勒肌在睑板上缘上方含有明显的平滑肌成分。然而，在老年标本中，我们观察到平滑肌成分逐渐减少，甚至从提上睑肌的起始下支到睑板上缘逐渐消失。我们推测，随着年龄的增长，米勒肌中平滑肌成分的数量逐渐减少，这进一步影响了米勒肌辅助提上睑肌的功能，进而导致或加重上睑下垂。我们的推测需要通过更多不同年龄和性别的尸检组织学研究进一步验证，以便为上睑下垂的临床诊断和治疗提供新思路。
