Journal Pre-proof Temporal transposition of the split medial rectus muscle when the medial rectus is the sole functioning rectus muscle Chong-Bin Tsai, MD, PhD, Chien-Liang Fang, MD, Ming-Shan Chen, MD PII: S1091-8531(19)30542-7 DOI: https://doi.org/10.1016/j.jaapos.2019.10.003 Reference: YMPA 3108 To appear in: Journal of AAPOS Received Date: 5 August 2019 Revised Date: 25 September 2019 Accepted Date: 7 October 2019 Please cite this article as: Tsai C-B, Fang C-L, Chen M-S, Temporal transposition of the split medial rectus muscle when the medial rectus is the sole functioning rectus muscle, Journal of AAPOS (2019), doi: https://doi.org/10.1016/j.jaapos.2019.10.003. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. 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Temporal transposition of the split medial rectus muscle when the medial rectus is the sole functioning rectus muscle Chong-Bin Tsai, MD, PhD,a,b Chien-Liang Fang, MD,c,d and Ming-Shan Chen, MDe,f Author affiliations: a Department of Ophthalmology, Ditmanson Medical Foundation Chiayi Christian Hospital, Chiayi City, Taiwan; bDepartment of Optometry, College of Medical and Health Science, Asia University, Taichung, Taiwan; cDivision of Plastic and Reconstruction Surgery, Department of Surgery, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chia-Yi City, Taiwan; dDepartment of Food Nutrition and Health Biotechnology, College of Medical and Health Science, Asia University, Taichung City, Taiwan; eDepartment of Anesthesiology, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chia-Yi City, Taiwan; fDepartment of Biotechnology, Asia University, Taichung City, Taiwan Presented at the 40th Meeting of the European Strabismological Association, Helsinki, Finland, June 5-8, 2019. Submitted August 5, 2019. Revision accepted October 7, 2019. Correspondence: Chong-Bin Tsai, MD, PhD, Department of Ophthalmology, Ditmanson Medical Foundation Chiayi Christian Hospital. No. 539 Zhongxiao Road, East District, Chiayi City 60002, Taiwan (email: [email protected]). Word count: 1,227 Multiple cranial nerve palsies often lead to complex clinical presentations. We report 2 cases in which a combination of multiple palsies resulted in paralytic esotropia with the medial rectus being the sole functioning rectus muscle. Both cases were treated with temporal transposition of split medial rectus. Multiple simultaneous cranial nerve palsies often lead to complex clinical presentations. A partial oculomotor nerve palsy involving both the superior rectus and the inferior rectus muscles combined with a complete abducens nerve palsy can result in a paralytic esotropia, with the medial rectus muscle becoming the sole functioning rectus muscle. This condition mimics the clinical picture of complete oculomotor nerve palsy, which can be managed with a medial transposition of the split lateral rectus (MTSLR) technique.1-4 For this reason, one might reasonably treat this condition by transposing the medial rectus muscle temporally. We describe 2 cases of partial oculomotor nerve palsy and complete abducens nerve palsy that presented at Chiayi Christian Hospital and were managed using a novel technique wherein the medial rectus muscle is split, and both halves are transposed temporally. Case Reports Case 1 A 27-year-old man presented with horizontal diplopia after a traffic accident that resulted in a skull base fracture 9 months earlier. On examination, visual acuity was 20/50 in the right eye and 20/25 in the left eye. The right eye was ptotic. Ocular motility testing revealed deficits in elevation, depression, and abduction of the right eye. Prism cover testing showed an esotropia of 45∆ in primary position. The function of right medial rectus could be identified during attempted adduction. The right superior oblique seemed functional, as indicated by increased depression with slight intorsion in downgaze. Aberrant reinnervation of right levator palpebrae superioris was detected during attempted adduction (Figure 1A). The patient underwent temporal transposition of the split medial rectus muscle (TTSMR) in the right eye under general anesthesia. A fornix conjunctival incision was made in the nasal quadrant. Two radial conjunctival incisions were made in the superior- and inferior-temporal quadrants. The medial rectus muscle was not tight on intraoperative forced duction testing. The medial rectus muscle was identified and split into two halves up to 25 mm from its insertion. Each half of split medial rectus muscle was secured with a double-armed 5-0 polyester suture and then detached. A Gass muscle hook was placed in the superior-temporal conjunctival incision and passed nasally under the superior rectus muscle. The upper medial rectus sutures were passed through the opening in the Gass hook, and the hook was retracted to transpose the sutures temporally. The insertion of superior oblique tendon was isolated with a small muscle hook. Again, the Gass hook was passed posterior to the insertion of superior oblique tendon and then retracted to transpose the upper medial rectus sutures temporally. The Gass hook was placed in the inferior-temporal conjunctival incision and passed nasally under the inferior rectus muscle. The inferior medial rectus sutures were passed through the opening in the Gass hook and the hook was retracted to transpose the sutures temporally. The transposed halves were reattached at 8 mm posterior to the insertion of lateral rectus muscle with nonadjustable 5-0 polyester sutures. The globe was in a slightly exotropic position at the end of the surgery (Figure 2). The patient remained orthotropic in the primary position after 8 months of follow-up (Figure 1B). Postoperative magnetic resonance imaging (MRI) confirmed that the right medial rectus muscle was split in halves and transposed temporally (eSupplement 1, available at jaapos.org). Case 2 A 59-year-old woman presented with esodeviation and ptosis in her left eye, after 2 pituitary tumor surgeries 1 year ago. On examination, visual acuity was 20/20 in the right eye and 20/30 in the left eye. Ocular motility testing showed deficits in elevation, depression, and abduction of the left eye. Prism cover testing showed a left esotropia of 60∆ and hypertropia of 30∆ in primary position. The patient underwent TTSMR as described above. The medial rectus was tight on intraoperative forced duction testing. The globe was in a slightly exotropic position at the end of surgery. However, the patient developed an exotropia of 30∆ and hypertropia of 10∆ in the left eye 3 days postoperatively; revision surgery was performed 1 month later. The superior half of the split medial rectus was found adhered tightly to the superior oblique tendon. Both halves of the split medial rectus were detached and reattached at 20 mm from the limbus for the superior half and 16 mm from limbus for the inferior half. Ten units of botulinum toxin were injected at the superior temporal quadrant to further weaken the superior half of the split medial rectus. At 4 months’ follow-up the patient continued to have an exotropia of 20∆ and hypertropia of 18∆ hypertropia (eSupplement 2, available at jaapos.org). Discussion In the rare event that the medial rectus becomes the only functioning rectus muscle, temporal transposition of the muscle will reduce the adducting force and create abducting force. Determining the optimal reattachment site for the medial rectus muscle on the temporal half of the globe is crucial for the final ocular alignment. Because our search of the literature yielded no reports on this procedure, we sought hints for surgical design in reports on MTSLR. In MTSLR, the transposed halves of the lateral rectus muscle have been attached to the superior-nasal globe,1 20 mm from the limbus and posterior to the nasal vortex veins,2 1 mm posterior to the edges of medial rectus insertion,3 and adjacent to the medial rectus insertion with adjustable suture.4 Improved postoperative results in MTSLR guided the development of our procedure. Taking into account the MTSLR experience, geometric calculations5, and magnetic resonance imaging estimation6, we estimated that the medial rectus muscle should be reattached 8 mm from the lateral rectus insertion. This location worked well in our case 1 but resulted in overcorrection in case 2. The medial rectus tightness in case 2 might have caused the overcorrection. The muscle should be split as posteriorly as possible to facilitate the transposition and reduce the hindering effect of the pulley system. The management of the oblique muscles is important in transposition of the rectus muscles. Transposing routes both posterior to and anterior to the oblique muscles have been reported in MTSLR.3,7,8 Because the inferior oblique tendon inserts closer to the lateral rectus border than does the superior oblique tendon, the insertion of the inferior oblique tendon will not hinder the path of temporal transposition, although the superior oblique tendon will. In our technique, transposing the superior half posterior to the superior oblique tendon is recommended but not necessary for the inferior half of the split medial rectus muscle to be posterior to the inferior oblique tendon. TTSMR is a novel technique for the management of the condition represented by our 2 cases. Surgeons should be cautious, however, in treating patients with long-term medial rectus contracture, in which cases excessive tension after transposition will probably lead to overcorrection. An alternative approach in these cases is to use a distal split stump of the medial rectus to increase the length of the shortened lateral rectus in MTSLR.9 Patients should be advised regarding the possibility of reduced vision from choroidal effusion or optic nerve compression, as in the MTSLR. Finally, more experience is necessary to determine the appropriate reattachment site for transposition before widespread adoption of this TTSMR procedure be considered. References 1. Taylor JN. Surgical management of oculomotor nerve palsy with lateral rectus transplantation to the medial side of globe. Aust N Z J Ophthalmol 1989;17:27-31. 2. Kaufmann H. “Lateralis splitting” in total oculomotor paralysis with trochlear nerve paralysis [in German]. Fortschr Ophthalmol 1991;88:314-16. 3. Gokyigit B, Akar S, Satana B, Demirok A, Yilmaz OF. Medial transposition of a split lateral rectus muscle for complete oculomotor nerve palsy. J AAPOS 2013;17:402-10. 4. Shah AS, Prabhu SP, Sadiq MA, Mantagos IS, Hunter DG, Dagi LR. Adjustable nasal transposition of split lateral rectus muscle for third nerve palsy. JAMA Ophthalmol 2014;132:963-9. 5. Levin LA, Kaufman PL. Adler’s Physiology of the Eye: Clinical Application. 11th ed. Edinburgh; New York: Saunders/Elsevier; 2011. 6. Chaudhuri Z, Demer JL. Magnetic resonance imaging of bilateral split lateral rectus transposition to the medial globe. Graefes Arch Clin Exp Ophthalmol 2015;253:1587-90. 7. Erbagci I, Oner V, Coskun E, Okumus S. A new surgical treatment option for chronic total oculomotor nerve palsy: a modified technique for medial transposition of split lateral rectus muscle. J Pediatr Ophthalmol Strabismus 2016;53:150-54. 8. Aygit ED, Inal A, Ocak OB, et al. Simplified approach of Gokyigit's technique for complete cranial nerve third palsy. Int Ophthalmol 2019;39:111-16. 9. Bagheri A, Feizi M, Sahebghalam R, Yazdani S. Lateral rectus-medial rectus union: a new surgical technique for treatment of complete third nerve palsy. J Pediatr Ophthalmol Strabismus 2019;56:10-18. Legends FIG 1. Clinical photographs of case 1. A, Before surgery. B, Eight months after surgery: the right eye showed aberrant reinnervation with attempted adduction. FIG 2. Splitting and transposition of the medial rectus muscle to the lateral rectus muscle area. A, Right eye (surgeon’s view). The medial rectus muscle is split up to 25 mm from its insertion, and each half is secured with a double-armed 5-0 polyester suture. B, A Gass muscle hook is placed in the superior-temporal conjunctival incision and passed nasally under the superior rectus muscle. The upper medial rectus sutures are passed through the opening in the Gass hook. C, The Gass hook is retracted to transpose the sutures temporally. D, The Gass hook is placed in the inferior-temporal conjunctival incision and passed nasally under the inferior rectus muscle. The inferior medial rectus sutures are passed through the opening in the Gass hook. E, The Gass hook is retracted to transpose the sutures temporally. F, The transposed superior half of the medial rectus muscle (arrow) is reattached 8 mm posterior to the insertion of lateral rectus muscle (arrowhead). G, The transposed inferior half (arrow) is reattached 8 mm posterior to the insertion of lateral rectus muscle (arrowhead). H, The globe is in a slightly exotropic position at the end of surgery.