Levator Muscle and Its Aponeurotic Maldevelopment in Congenital Ptosis

Overview

this study reports the incidence of levator muscle dysgenesis among patients with simple congenital myogenic ptosis. In addition, the study aims to describ the nature of the dysgenesis, including the gross appearance of the muscle intraoperatively as well as the histopathological features under the microscope, correlation between the degree of dysgenesis and the preoperative ptosis assessment, and evaluation of the surgical outcome after levator muscle resection. Also, this research aims to shed light on the role of aponeurotic developmental anomalies, specifically fibrotic changes and maldevelopment in the pathogenesis of simple congenital ptosis.

Despite the general agreement on the myogenic etiology of simple congenital ptosis, the exact pathogenesis of the levator palpebrae superioris (LPS) muscle remains controversial. This debate stems from confusing pathological changes within the LPS; while childhood ptosis is commonly attributed to muscle dystrophy , other reports have identified criteria consistent with dysgenesis. Consequently, the majority of published literature has focused on these muscle belly changes-supporting either the dysgenesis or dystrophy theories-or on neural etiologies in cases associated with superior rectus paresis or the Marcus Gunn jaw-winking phenomenon. However, congenital ptosis may also arise from mechanical or aponeurotic factors which are frequently overlooked. Aponeurotic disinsertion or dehiscence is a well-recognized cause of acquired (involutional or traumatic) ptosis and is classically corrected by the repair technique first described by Quickert. While typically associated with adults, congenital aponeurotic defects do exist; Anderson and Gordy attributed these to a failure of the levator aponeurosis (LA) to correctly insert into the tarsus. Despite this, reports exploring LA fibrotic changes in congenital cases remain scarce. Congenital aponeurotic maldevelopment is an estab- lished yet underreported entity of congenital ptosis. It could be suspected clinically with high crease position, lower lid position on downgaze and presence of corneal hue. The investigators have observed fibrotic changes within the LA, or fibrous bands anchoring the LA to surrounding structures, during resection in patients with simple congenital ptosis.