Rectus Transposition Surgery Research Articles

Superior Rectus Transposition Surgery: Safety, Efficacy, and Place in Therapy.

Abduction limitation in esotropic Duane retraction syndrome (DRS), esotropic Mobius syndrome, and sixth nerve palsy is one of the difficult-to-manage problems in strabismus surgery. The procedure of superior rectus transposition (SRT) was introduced by Johnston et al. In this procedure, the superior rectus (SR) muscle is disinserted and sutured adjacent to the insertion of lateral rectus (LR) muscle. The purpose of this review is to explore literature about efficacy and safety of SRT and its usage in strabismus surgery.

Assessment of torsion after superior rectus transposition with or without medial rectus recession for Duane syndrome and abducens nerve palsy

Superior rectus transposition with or without medial rectus recession has been advocated for the treatment of abducens nerve palsy and esotropic Duane syndrome. Early reports have focused mainly on postoperative ocular alignment, but there is concern that superior rectus transposition may induce torsional misalignment. The purpose of this study was to evaluate torsional outcomes after superior rectus transposition surgery using prospective preoperative and postoperative torsional assessments. Prospective measurements were performed on all patients undergoing superior rectus transposition. Preverbal infants were assessed using fundus torsion evaluating the position of the fovea relative to the optic nerve; older children/adults underwent double Maddox rod (DMR) assessment of torsion. A total of 11 subjects met the study inclusion criteria. The etiology of strabismus was an abducens nerve palsy (n = 7) or Duane syndrome (n = 4). For the subjects evaluated by fundus torsion (n = 4), there was no significant change in torsion for 3 (75%). For those subjects undergoing DMR (n = 7), there was a significant change in subjective torsion (4.7 ± 3.8°excyclotorsion vs 0.0° ± 5.0° excyclotorsion; P = 0.004). Esotropic deviation improved significantly for all subjects (39(Δ) ± 23(Δ) vs 6.5(Δ) ± 13(Δ); P = 0.001) and no significant mean vertical deviation postoperatively, although 1 patient had a clinically significant postoperative hypertropia measuring 14(Δ). Abduction also improved significantly (-4.2 ± 0.9 vs -2.8 ± 1, P = 0.0001). In this patient series, superior rectus transposition with medial rectus recession did not have clinically significant induction of torsional diplopia as a result of the procedure.

Connective tissues reflect different mechanisms of strabismus over the life span

Connective tissue pulleys determine extraocular muscle force directions and pulley heterotopy can induce strabismus. The etiology and type of pulley abnormalities vary with patient age, resulting in different but predictable types presentations of strabismus. Magnetic resonance imaging (MRI) was obtained in 95 patients with pulley heterotopy, of whom 56 had childhood-onset pattern strabismus, and was compared with published data on 28 patients aged 69±12years who had sagging eye syndrome. Control data were from age-matched normal controls with no strabismus. Patients with childhood-onset strabismus had intact lateral rectus-superior rectus band ligaments and straight extraocular muscle paths but exhibited pulley array A pattern-associated incyclorotation or V pattern-associated excyclorotation. Rectus transposition surgery collapsed patterns. Patients with sagging eye syndrome exhibited blepharoptosis, superior sulcus defect, and inferolateral displacement of rectus pulleys with elongation of extraocular muscles that followed curved paths. Symmetrical lateral rectus pulley sag was associated with divergence paralysis esotropia; asymmetrical sag > 1mm, with cyclovertical strabismus. Both lateral rectus resection and medial rectus recession treated divergence paralysis esotropia. Partial vertical rectus tenotomy treated cyclovertical strabismus. Childhood onset pulley abnormalities are associated with A or V pattern strabismus and external anatomical features suggest that these pulley defects are probably congenital. Adult onset pulley defects commonly result from age-related tissue involution and external features such as adnexal laxity are also helpful in recognizing involution as a possible etiology of strabismus.

Intraoperative monitoring of torsion to prevent vertical deviations during augmented vertical rectus transposition surgery

Total transposition of the superior and inferior rectus muscle laterally, with augmentation sutures, may be complicated by induction of an undesirable vertical deviation. Induced vertical misalignment may be associated with changes in torsion. We have developed a simple method to monitor intraoperative torsion that may reduce the incidence of vertical deviations. We reviewed consecutive cases of total abducens palsy or esotropic Duane syndrome treated with augmented lateral transposition of the superior and inferior rectus muscles, where the 12 o'clock and 6 o'clock intraoperative positions were initially marked with a dot at the limbus using a surgical pen. The location of the marks was monitored during tying of the augmentation sutures; changes in torsion were monitored intraoperatively. Records of 9 cases of augmented vertical rectus transposition were reviewed. On the basis of intraoperative assessment of torsion, by observing the position of preplaced limbal dots, the inferior rectus augmentation suture was tied less tightly than the superior rectus suture, leaving a gap of 1 to 3 mm between the inferior and lateral rectus muscles in 8 of 9 cases. The augmentation suture was totally removed in 1 case. After these intraoperative adjustments, there was no induced intraoperative torsion, whereas further tightening of the inferior suture induced extorsion. Six weeks postoperatively, 8 of 9 patients did not experience a symptomatic vertical deviation. When performing augmented transposition procedures, intraoperative monitoring of torsion may reduce the incidence of inadvertent vertical deviations and torsion. This technique may also be useful in other cases where correction or avoidance of torsion is needed.

Medial rectus recession following vertical rectus transposition in esotropic Duane's retraction syndrome

Introduction: Augmented vertical rectus transposition surgery (VRT) improves esotropia, torticollis, and abduction in esotropic Duane syndrome. The length-tension curve shows an increased stiffness in the ipsilateral medial rectus muscle in Duanes. Some Duanes patients require medial rectus recession (MRc) following VRT to improve alignment. We aim to characterize these patients, and their post-operative results.

Management of vertical deviations after vertical rectus transposition surgery

To describe options for the management of vertical deviations after vertical rectus muscle transposition surgery (VRT). Retrospective case series including 7 children who underwent VRT for esotropic Duane syndrome and developed the complication of a vertical deviation. Eighty-two consecutive children underwent VRT for Duane syndrome. Seven eyes of 7 patients (4 boys, 3 girls) were found to have induced vertical deviations postoperatively. Average length of follow-up was 12.7 months (range, 3-28 months). Median induced vertical deviation was 10.1(Delta) (range, 8-12). All patients required only one additional surgery to ameliorate the vertical deviation. At final follow-up, the mean vertical tropic deviation was 0. Six patients were operated on within 4 days of VRT. Surgical strategies included recession of one vertical rectus muscle and repositioning of a posterior fixation suture. In children undergoing VRT for esotropic Duane syndrome, the complication of a vertical deviation occurred in 8.5% of cases. The vertical deviation was completely ameliorated in each case by one surgical procedure involving recession of one of the transposed muscles.

Unaugmented Vertical Muscle Transposition Surgery for Chronic Sixth Nerve Paralysis

Introduction: Chronic sixth nerve palsy can cause incapacitating diplopia requiring vertical muscle transposition surgery. Augmentation of surgery, with lateral fixation sutures, medial rectus recession or botulinum toxin injection, is associated with an increased risk of complications. Purpose: Our aim was to evaluate the efficacy and safety of unaugmented full-tendon vertical rectus transposition in chronic sixth nerve paralysis. Methods:Longitudinal study of 21 patients with chronic sixth nerve paralysis of longer than 6 months duration, who underwent superior and inferior recti transposition surgery without medial rectus recession or botulinum toxin injection. Details of surgery, preoperative and postoperative examinations including full orthoptic examination were obtained from an electronic database. Outcomes included the change in angle of deviation, the requirement for further surgery to the medial rectus and postoperative improvement in diplopia. SPSS software (Version 12.0.1, SPSS Inc. Chicago, IL) was used to summarize baseline characteristics and outcomes and to compare preoperative and postoperative deviation (paired t-test). Results: Twenty-one patients (10 (47.6%) men and 11 (52.4%) women) with a mean age of 41 years (range 4 to 74 years) were operated in the period between April 1998 and November 2000. Eighteen patients had unilateral and three had bilateral acquired sixth nerve palsy. Nineteen patients required unilateral surgery and two had bilateral transposition procedures. In patients with unilateral sixth nerve palsy, mean esotropia in primary position before surgery was 46.7 prism-diopters (PD) (95% CI 35.9–57.4 PD) and improved to 14.6 PD after surgery (95% CI 6.4–22.7 PD). The angle of deviation was significantly reduced by an average of 32.1 PD (p < 0.001, paired t-test; 95 % CI 22.6–41.6 PD). Over all, 10 patients (55.6%) had a well-controlled esophoria with a postoperative alignment of within 10 PD of orthophoria without diplopia in the primary position, for distance and near. A further six patients (28.6%) required additional medial rectus recessions to achieve success. The only complication observed was slippage of the inferior rectus in one patient (4.2%), who consequently required further surgery. Conclusion: Botulinum toxin infiltration of the medial rectus in vertical rectus transposition surgery may be unnecessary, incurring cost, additional attendances and interventions for patients. Less than a third of all patients in our series required additional medial rectus recession later.

The efficacy of rectus muscle transposition surgery in esotropic Duane syndrome and VI nerve palsy

Partial tendon transposition was first described by Hummelshein in 1907. Full tendon transposition was reported by Schillinger in 1959. Recently, full tendon transposition with posterior augmentation was reported by Foster in 1997. I will review current thinking concerning the anatomy and physiology of rectus muscle transposition and present our current clinical experience with this procedure in Duane syndrome. A retrospective review of vertical rectus muscle transposition procedures in patients with VI Nerve palsy was performed comparing the postoperative field of single binocular vision, amount of improved abduction, and change in the primary esotropic angle. In addition, a consecutive series of vertical rectus muscle transposition cases for the treatment of esotropic Duane syndrome is presented, evaluating the improvement and head position, abduction, and reduction of the primary position esotropia. In VI Nerve palsy patients, vertical rectus transposition surgery produces 41 degrees to 71 degrees of binocular visual field with 10 degrees to 21 degrees of binocular field in abduction. In esotropic Duane syndrome the surgical procedure produces 42 degrees to 66 degrees of binocular field and a correction of approximately 15 degrees of face turn. Variability in the efficacy of the procedure is related to the degree of ipsilateral medial rectus contracture. Vertical rectus transposition with posterior fixation can create a binocular diplopia-free field of 40 to 70 degrees in patients with VI Nerve palsy and about 40 to 65 degrees in patients with Duane syndrome. Partial rectus muscle transposition is an effective procedure in cases where surgery on multiple rectus muscles has been or will be required. Orbital wall fixation of the lateral rectus muscle is an effective and reversible method to inactivate a lateral rectus muscle and may be useful in cases of Duane syndrome with marked anomalous innervation and severe cocontraction.

Surgical implications of the rectus extraocular muscle pulleys

Purpose Magnetic resonance imaging (MRI) shows that the paths of rectus extraocular muscle bellies remain fixed in the orbit during large ocular rotations, and across large surgical transpositions of their insertions. This stability of muscle paths is due to their passage through pulleys which are coupled to the orbit and located in a coronal plane anterior to the muscle bellies near the equator of the globe. Autopsy studies have shown the pulleys to be fibroelastic sleeves consisting of dense bands of collagen and elastin, suspended from the orbit and adjacent extraocular muscle sleeves by bands of similar composition. Immunohistochemical studies have revealed substantial smooth muscle in the pulley suspensions and in posterior Tenon's fascia. The pulleys function as mechanical origins of the rectus extraocular muscles in the sense of determining extraocular muscle pulling directusons. This study was conducted to determine the theoretical effects of the pulleys on the outcome of rectus transposition surgery. Methods The functional and anatomical evidence for the existence of the rectus extraocular muscle pulleys was reviewed. In two patients, binocular alignment data were collected using the Hess screen test before and after vertical rectus transposition surgeries for lateral rectus paralysis. Paths of the rectus extraocular muscles were determined using high resolution MRI. The OrbitTM 1.5 extraocular biosimulation program was employed to compute theoretical binocular alignment and muscle paths, under alternative conditions including or omitting the pulleys. Results Pulleys are required to account for observed paths of rectus extraocular muscles following transposition surgery. In the absence of pulleys, transposition of the superior and inferior rectus muscles to the lateral rectus insertion for abducens paralysis would result in bizarre ocular misalignments not observed clinically. Conclusions The human orbit contains specialized musculofibroelastic tissues in and just posterior to Tenon's fascia, which serve as pulleys, determining actions of rectus extraocular muscles. These pulleys are located in a roughly coronal plane just posterior to the equator of the globe. Unimpaired pulley function is essential to effective muscle transposition surgery.