Journal of Pediatric Ophthalmology and Strabismus

Short Subjects 

Pathological Examination of Plicated Medial Rectus Muscle for Treatment of Re-recurrent Exotropia

Hussain Rao; Vivekanand Singh, MD; Laura Plummer, MD; Justin D. Marsh, MD

Abstract

Plication and resection are surgical procedures commonly used for the treatment of strabismus. Further studies are needed to understand the postoperative effects of plication on muscle tissue. This case report examines a pathological section of a plicated medial rectus muscle, revealing myocyte injury and replacement with fibroconnective tissue. [J Pediatr Ophthalmol Strabismus. 2018;55:e20–e21.]

Abstract

Plication and resection are surgical procedures commonly used for the treatment of strabismus. Further studies are needed to understand the postoperative effects of plication on muscle tissue. This case report examines a pathological section of a plicated medial rectus muscle, revealing myocyte injury and replacement with fibroconnective tissue. [J Pediatr Ophthalmol Strabismus. 2018;55:e20–e21.]

Introduction

Resection and plication of the extraocular muscle are two commonly used strabismus procedures designed to shorten the length of the active muscle. Resection involves removing a segment of the muscle and reattaching it to its original insertion on the sclera, and plication consists of folding the muscle on itself and suturing a posterior portion of the muscle anteriorly at the insertion. Because plication does not require disinsertion of the muscle, there is a theoretical advantage of preserving anterior ciliary circulation, therefore decreasing the risk of developing anterior segment ischemia.1 Despite this potential benefit, there is concern that plication may be less successful than resection.2 Further study is necessary to understand the postoperative effects that plication has on muscle tissue. We present the first report of a pathological examination of a plicated extraocular muscle.

Case Report

A 7-year-old girl presented to our clinic with intermittent exotropia of the left eye of 25 prism diopters (PD) at distance and near with full ductions of both eyes. She subsequently underwent left lateral rectus recession of 9 mm. Approximately 6 months postoperatively, she had recurrence of intermittent exotropia with a distance deviation of 18 PD and near deviation of 20 PD. Due to the patient's recurrent exotropia, a left medial rectus plication of 6 mm was performed using a polygalctin (Vicryl; Ethicon, Inc., New Brunswick, NJ) suture. Despite initial good alignment, the exotropia had returned by 5 months postoperatively with deviations of 20 PD at distance and 25 PD at near. The patient underwent 7-mm resection of the previously plicated medial rectus muscle and the excised muscle was sent to pathology for review (Figures 12).

Microscopic examination of a plicated medial rectus muscle at 4× magnification. Hematoxylin–eosin stained specimen with a dotted line separating viable muscle (above and right) from fibrotic and scarred muscle tissue (below and left). Solid rectangle denotes area magnified in Figure 2. White rectangle denotes area shown in Figure 3.

Figure 1.

Microscopic examination of a plicated medial rectus muscle at 4× magnification. Hematoxylin–eosin stained specimen with a dotted line separating viable muscle (above and right) from fibrotic and scarred muscle tissue (below and left). Solid rectangle denotes area magnified in Figure 2. White rectangle denotes area shown in Figure 3.

Microscopic examination of a plicated medial rectus muscle at 10× magnification denoted by solid line (magnified image from Figure 1). Hematoxylin–eosin stained specimen. Small arrows point to contraction bands in viable muscle and large arrows point to fibrotic muscle.

Figure 2.

Microscopic examination of a plicated medial rectus muscle at 10× magnification denoted by solid line (magnified image from Figure 1). Hematoxylin–eosin stained specimen. Small arrows point to contraction bands in viable muscle and large arrows point to fibrotic muscle.

Pathological examination of the muscle tissue revealed a partially fibrotic viable striated muscle. The muscular tissue was free of inflammatory cell infiltrates or granuloma. The viable muscle fibers showed areas of loss of striations and focal atrophy. Immunohistochemistry revealed fibrotic tissue replacing muscle fibers, as evidenced by rare desmin-positive residual fibers surrounded by fibroconnective tissue (Figure 3). The patient subsequently did well after resection and exhibited esotropia of 6 PD at both distance and near 2 years after her last surgery.

Desmin immunohistochemistry at 100× magnification. The lower left half of the field shows a positively stained viable muscle. The upper right half shows occasional positive fibers surrounded by fibrotic tissue.

Figure 3.

Desmin immunohistochemistry at 100× magnification. The lower left half of the field shows a positively stained viable muscle. The upper right half shows occasional positive fibers surrounded by fibrotic tissue.

Discussion

To our knowledge, this is the first reported pathological specimen of a plicated extraocular muscle as a treatment for strabismus. Our patient underwent resection of a previously plicated medial rectus muscle after intermittent exotropia recurred a second time. Despite multiple surgeries in a relatively short time frame, we have no reason to suspect the extraocular muscle was abnormal initially, given the comitance of the strabismus and full ductions. Some studies have suggested that plication surgery is a superior alternative to resection surgery due to the preservation of anterior ciliary vessels, decreased inflammation, and less surgical trauma to muscle tissue.2 Other studies have suggested that plication may have a lower success rate than resection.3 This case report demonstrates muscle trauma that can occur postoperatively after plication. Desmin is a muscle-specific protein and helps form intermediate filaments in the muscle fibers. Pathological examination of the resected tissue revealed a loss of desmin-positive tissue, which was replaced by fibroconnective tissue. This case demonstrates that a loss of muscle fibers can occur after plication, which may repair by laying down fibroconnective tissue. This fibroconnective tissue may lead to less predictable results when compared with normal muscle tissue.

It is possible that differing plication techniques are responsible for the variable results seen in recent studies. Perhaps some specific surgical techniques are less likely to result in significant myocyte damage in areas of viable muscle. It is also possible that muscle resection has the potential to cause similar myocyte damage, as seen in this case. Regardless, we suspect that some cases of recurrent strabismus after muscle plication are due to myocyte damage that, once the anchoring suture resorbs, manifests as a return to the presenting strabismus pattern if the overlying muscle is damaged. Although plication offers some unique advantages to resection, we encourage surgeons to consider both options carefully before selecting a surgical plan. Further studies, specifically looking at extraocular muscle remodeling after plication, may help to determine risk factors for the recurrence of strabismus.

References

  1. Oltra EZ, Pineles SL, Demer JL, Quan AV, Velez FG. The effect of rectus muscle recession, resection and plication on anterior segment circulation in humans. Br J Ophthalmol. 2015;99:556–560. doi:10.1136/bjophthalmol-2014-305712 [CrossRef]
  2. Chaudhuri Z, Demer JL. Surgical outcomes following rectus muscle plication. JAMA Ophthalmol. 2014;132:579–585. doi:10.1001/jamaophthalmol.2013.8188 [CrossRef]
  3. Alkharashi M, Hunter DG. Reduced surgical success rate of rectus muscle plication compared to resection. J AAPOS. 2017;21:201–204. doi:10.1016/j.jaapos.2017.05.012 [CrossRef]
Authors

From Children's Mercy Hospital and Clinics, Kansas City, Missouri (VS, LP, JDM); and the University of Missouri–Kansas City, Kansas City, Missouri (HR).

The authors have no financial or proprietary interest in the materials presented herein.

Correspondence: Hussain Rao, University of Missouri–Kansas City, 2411 Holmes Street, Kansas City, MO 64108. E-mail: hr6cb@mail.umkc.edu

Received: February 21, 2018
Accepted: June 20, 2018
Posted Online: August 29, 2018

10.3928/01913913-20180802-03

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