Journal of Clinical and Aesthetic Dermatology

APR 2018

An evidence-based, peer-reviewed journal for practicing clinicians in the field of dermatology

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50 JCAD JOURNAL OF CLINICAL AND AESTHETIC DERMATOLOGY April 2018 • Volume 11 • Number 4 C A S E S E R I E S Case 1. A 38-year-old man presented with a history of congenital ptosis of the left eye. This patient had two previous surgeries to repair ptosis, with the most recent one being eight years previously, with recurrence after both procedures (Figure 2, A1). Botulinum toxin was administered (Figure 2, A2), including two units injected into the pre-tarsal orbicularis of the left eye. On examination six weeks after the botulinum toxin injection, MRD had increased in the left eye by 0.993mm. The tarsal platform show difference also decreased by 0.149mm (Figure 2, A3). Case 2. A 71-year-old woman with a history of thyroid-associated orbitopathy presented with left-sided ptosis appearing greater than right-sided ptosis. On examination, the left MRD was 1.85mm (Figure 2, B1) compared to a right MRD of 2.77mm. Botulinum toxin was injected (Figure 2, B2), including two units injected into the lateral and medial pre-tarsal orbicularis of the left eye. Eight weeks after the botulinum toxin injection, MRD had increased in the left eye by 0.919mm (Figure 1, B3). Case 3. A 55-year-old woman presented with right-sided ptosis (Figure 2, C1). Botulinum toxin was injected (Figure 2, C2), including two units to the lateral and one unit to the medial right pre-tarsal orbicularis, as well as one unit to the right frontalis. Eleven weeks after the botulinum toxin injection, MRD had increased in the left eye by 0.83mm and the size of the palpebral fissure had increased by 1.048mm. The tarsal platform show difference also had decreased by 2.044mm (Figure 2, C3). DISCUSSION Botulinum toxins are neuromuscular- blocking agents produced by the bacteria Clostridium botulinum. They weaken targeted muscles by inhibiting the release of acetylcholine from the presynaptic terminal of the neuromuscular junction. 3 In this small case series, we found that neurotoxin application to the pre-tarsal orbicularis was effective in raising eyelid position and decreasing TPS asymmetry. The orbicularis oculi muscle is divided into three segments: pre-tarsal, pre-septal, and orbital (Figure 1). 5 Anatomic studies have shown that each segment of the muscle plays a specific role in eyelid physiology. 5 The orbital portion is involved in forceful and sustained closure, the pre-septal portion closes the eyelid during a blink, and the pre-tarsal orbicularis is postulated to play a role in lid margin tone. 5 Ptosis pathophysiology is complex and cannot be perfectly explained by a simple model of discordance between the eyelid protractors and retractors. The botulinum toxin injections are hypothesized to work by weakening the pre-tarsal orbicularis selectively, tending toward a balance of force favoring retraction. This would be similar to the eyelid position dysregulation found in patients with facial nerve palsy. 6 While the MRD improvements provided patients with substantial aesthetic enhancements, the effectiveness of botulinum toxin for functional ptosis is still uncertain. Our case series shows just under 1mm of improvement. More severe ptosis might not respond to botulinum toxin in such a fashion and thus requires further study. The effects of botulinum toxins tend to be dose-dependent. 7 As such, injecting increased doses of botulinum toxins into the pre-tarsal orbicularis could potentially yield greater improvements in MRD. However, larger doses could induce other complications, including lagopthalmos, exposure keratitis, and even worsening ptosis if the toxin diffuses to the Mueller/levator complex. Addressing periorbital asymmetry with botulinum toxins must be tailored to each patient, and involves the treatment of several areas, requiring a targeted approach with a thorough understanding of the muscles involved. Treatment in this region commonly involves addressing the protractor muscles aimed at elevating the brow. An argument can FIGURE 1. A) Sagittal cross-section of the upper lid illustrates the three divisions of the orbicularis oculi muscle, highlighted in pink: "A" denotes the region of the pre-tarsal orbicularis, "B" denotes the region of the pre-septal orbicularis, and "C" denotes the orbital portion of the orbicularis oculi. The level of the injection site for addressing mild ptosis is shown approximately 2mm above the lash line. B) Coronal illustration of the anatomy of the orbicularis oculi muscle is pictured here; "A" denotes the region of the pre-tarsal orbicularis, "B" denotes the region of the pre-septal orbicularis, and "C" denotes the orbital portion of the orbicularis oculi. The injection sites for addressing mild ptosis are denoted by the two X marks, 2mm above the lash line over the medial limbus and lateral limbus. A B

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