Upper Eyelid Ptosis During Neuromodulator Injections—An Exploratory Injection and Dissection Study

Background: Aesthetic neuromodulator injections of the upper face are frequently performed to temporarily block muscular actions of the periorbital muscles to ultimately reduce skin rhytids. However, the adverse event rate in the literature for toxin-induced blepharoptosis ranges from 0.51% to 5.4%. Objective: To identify access pathways by which injected neuromodulator product can travel from extra-to intra-orbital and therefore affect the levator palpebrae superioris muscle. Methods: Nine non-embalmed human body donors were investigated in this study with a mean age at death of 72.8 (16.1) years. The 18 supraorbital regions were injected in 28 times (14 for supratrochlear and 14 for supraorbital) with 0.5 cc, whereas eight cases (four for supratrochlear and four supraorbital) were injected with 0.1 cc of colored product. Anatomic dissections were conducted to identify structures stained by the injected color. Results: The results of this injection-and dissection-based study revealed that both the supratrochlear and the supraorbital neurovascular bundles are access pathways for injected neuromodulator products to reach the intra-orbital space and affect the levator palpebrea superioris muscle. Out of 36 conducted injection passes, seven (19.44%) resulted in affection of the sole elevator of the eyelid of which 100% occurred only at an injection volume of 0.5 cc and not at 0.1 cc. Conclusion: Clinically, the results indicate that a low injection volume, a superficial injection for the supraorbital location, and angling the needle tip away from the supratrochlear foramen (toward the contralateral temple) when targeting the corrugator supercilii muscles, can increase the safety profile of an aesthetic toxin glabellar treatment.