Recession and anterior transposition of the inferior oblique for treatment of superior oblique palsy

One- vs Two- vertical muscle surgery in the management of unilateral superior oblique muscle palsy with hypertropia over 20 PD

Purpose: To compare the surgical outcomes of One- versus Two-vertical muscle surgery in patients with unilateral superior oblique muscle palsy (SOP) with primary position hypertropia (HT) over 20 PD. Patients in Group 1 underwent inferior oblique anterior transposition plus resection (IOATR), while patients in Group 2 underwent inferior oblique anterior transposition (IOAT) along with contralateral inferior rectus (IR) recession. Methods: Medical data of all SOP patients treated by either procedure from 2000 to 2023 in our strabismus center were recruited. We compared surgical outcomes between Group 1 and Group 2 by analyzing HT correction, rate of under-correction, and over-correction. Results: The study included 33 patients in Group 1 and 23 in Group 2. Both groups were similar in age, sex, etiology, affected side, diplopia, and head tilt. Group 2 achieved higher HT correction in all measured gazes. Group 1 had a higher risk of under-correction (18.18% in Group 1 vs 8.69% in Group 2) while Group 2 had a higher rate of over-correction (21.73% vs 0% in Group 1). Conclusion: In patients with severe unilateral SOP, Two-vertical muscle surgery achieved higher amounts of HT correction in all gazes despite a significantly higher risk of over-correction.

Inferior oblique muscle myectomy versus anterior transposition in the management of unilateral superior oblique muscle palsy, a comparative study

Purpose: To evaluate the surgical outcomes of two inferior oblique muscle weakening procedures in the management of unilateral superior oblique muscle palsy (SOP). Methods: Files of all SO palsy patients with 11-20 PD hypertropia (HT) who were treated either by inferior oblique myectomy (IOM) or inferior oblique anterior transposition (IOAT) were retrospectively reviewed. Demographic characteristics such as sex, age, etiology, simultaneous horizontal deviation, and diplopia were noted. The two techniques were compared through HT correction (in the primary position, contralateral gaze, and ipsilateral tilt) and head tilt correction. Subgroup analysis was performed in the moderate group (11-15 PD HT) and large group (16-20 PD HT). Results: This study included 69 patients in the IOM group and 55 patients in the IOAT group. The demographic characteristics of both groups were similar. Although both procedures successfully corrected the abnormal head tilt, IOAT achieved significantly more HT correction compared to IOM (p-value: 0.003). While both techniques were equally effective in the moderate group, IOAT resulted in more primary position HT correction (16.4 vs. 12.9 PD) in the large group. However, anti-elevation syndrome occurred in 5.4% of patients treated by IOAT. Conclusions: IOAT achieved more HT correction compared to IOM, particularly in patients with large preoperative HT. The lower risk of under-correction following IOAT must be weighed against its potential risk of anti-elevation syndrome.

Surgical outcomes of three different weakening procedures of inferior oblique muscle in the treatment of unilateral superior oblique palsy

Background

To compare surgical outcomes and complications of three inferior oblique weakening procedures; Inferior Oblique Myectomy (IOM), Inferior Oblique combined Resection-Anterior Transposition (IORAT) and Inferior Oblique Anterior Transposition (IOAT) in the management of unilateral Superior Oblique (SO) palsy.

Methods

Retrospective review of medical records of all patients with unilateral SO palsy who underwent one of the aforementioned IO weakening procedures at Benha University hospital was performed. Patients were excluded if surgery was bilateral or combined with other vertical muscle surgery. Primary outcome parameters were improvement of Hypertropia (HT) in primary gaze, side gazes, on alternate head turn, Inferior Oblique Overaction (IOOA), Superior Oblique Underaction (SOUA), correction of head tilt and postoperative complications.

Results

The review reveals a total of 65 patients with unilateral SO palsy; 54 congenital and 11 acquired, who met the study criteria and were classified into 3 groups; IOM group (24cases), IORAT group (19cases) and IOAT group (22cases). Compared with IOM, both IORAT and IOAT induced significant correction of HT in primary position, ipsilateral gaze, contralateral head tilt and IOOA. IORAT was significantly more effective than IOAT in correction of HT in ipsilateral gaze and contralateral head tilt while there was no statistical difference between the three groups in correction of HT in ipsilateral gaze, contralateral head tilt and SOUA. Postoperative Anti-elevation was significantly recorded following IORAT (6 cases, 31%) than IOAT (3 cases, 13%) and IOM (one cases, 4%).

Conclusions

The IORAT and IOAT were more superior to IOM in correction of IOOA and HT in the primary position and some other gaze positions. However, superiority of IORAT over the other two procedures should be weighed against its significant association with postoperative underaction of IO muscle and anti-elevation syndrome.

Managing Hypoplasia of the Inferior Rectus Muscle by Inferior Oblique Anterior Transposition in Children

Congenital hypoplasia or aplasia of the inferior rectus muscle is an uncommon condition. The authors present two pediatric patients with hypoplasia of the inferior rectus muscle treated by inferior oblique anterior transposition. The long-term follow-up outcomes of eye position and stereopsis acuity development were favorable. [J Pediatr Ophthalmol Strabismus. 2017;54:e50-e53.].

Combined resection and anterior transposition of the inferior oblique muscle for treatment of large primary position hypertropia caused by unilateral superior oblique muscle palsy

PURPOSE

To evaluate the efficacy of combined resection and anterior transposition of the inferior oblique muscle for treatment of unilateral superior oblique muscle palsy with hypertropia from 20(Δ) to 25(Δ) in primary position.

METHODS

The medical records of consecutive patients operated on for unilateral superior oblique muscle palsy and hypertropia from 20(Δ) to 25(Δ) in primary position were retrospectively reviewed. All patients had overaction of the inferior oblique muscle. The inferior oblique muscle was disinserted and 4 mm of its distal end was resected and transposed to the lateral border of the inferior rectus muscle insertion. The prism and alternate cover test was used to measure hypertropia. Surgical results were evaluated at 6 months' follow-up.

RESULTS

A total of 27 patients were included. The mean hypertropia in primary position was 22.6 ± 0.4(Δ) preoperatively, which decreased to 1.4 ± 0.6(Δ) after surgery. None of the patients developed hypotropia in primary position. Mild limitation of elevation was recorded in 1 patient, and 4 patients developed lower eyelid fullness.

CONCLUSIONS

In this patient cohort, combined resection and anterior transposition of the inferior oblique muscle effectively treated unilateral superior oblique muscle palsy with hypertropia from 20(Δ) to 25(Δ) in primary position.

Does inferior oblique recession cause overcorrections in laterally incomitant small hypertropias due to superior oblique palsy?

AIM

To evaluate the effects of inferior oblique muscle recession (IOR) in cases of laterally incomitant hypertropia <10 prism dioptres (PD) in central gaze thact 2t are clinically consistent with superior oblique palsy (SOP).

METHODS

We retrospectively reviewed patients with SOP and hypertropias <10 PD in central gaze who underwent graded IOR. Primary outcomes were reduction of lateral incomitance and number of overcorrections in central gaze.

RESULTS

Twenty-five patients were included. Mean follow-up was 13.8 months (range 1.4-66). Mean central gaze hypertropia decreased from 5.6±2.1 to 0.2±1.6 PD (p<0.001). Contralateral gaze hypertropia decreased from 15.9±7.6 to 2.3±3.3 PD (p<0.001). Lateral incomitance (central vs contralateral gaze) was 10.3±6.9 PD preoperatively and 2.0±3.0 PD postoperatively (p<0.001). There were two patients overcorrected in central gaze, and one patient overcorrected in downgaze. One patient necessitated further surgery for overcorrection.

CONCLUSIONS

Although small hypertropias can be treated with prisms or small, adjustable inferior rectus recessions, IOR collapses incomitance without causing much overcorrection. IOR is a reasonable treatment for small, laterally incomitant hypertropia due to SOP.

Outcome of unilateral inferior oblique recession

PURPOSE

The aim of this study was to analyze the outcome of unilateral inferior oblique (IO) recession in patients with unilateral or asymmetrical IO overaction in terms of effectiveness, stability, and undesired effects.

METHODS

Fifteen patients with nonparalytic strabismus who underwent unilateral IO recession for unilateral or asymmetric IO overaction and horizontal muscle surgery were included in this study. Nine patients demonstrated asymmetric bilateral IO overaction, whereas 6 had unilateral overaction. All patients underwent IO recession to the Scheie Parks point in one eye, along with conventional horizontal muscle surgery. Clinical outcome assessment included changes in oblique muscle dysfunction in both eyes. Changes in horizontal deviation, V pattern, vertical deviation, and excyclotorsion were also studied.

RESULTS

Satisfactory outcome in terms of oblique muscle function, V pattern, vertical deviation, and cyclodeviation was achieved in all patients with unilateral IO overaction and 7 (77%) patients with bilateral IO overaction. Increased IO overaction in the other eye was noted in 2 patients. Satisfactory outcome in patients with bilateral overaction was related to degree of asymmetry in IO overaction between the 2 eyes.

CONCLUSION

Unilateral IO recession is effective in patients with unilateral IO overaction and selected patients with largely asymmetrical bilateral IO overaction.

Anterior transposition of the inferior oblique muscle for treatment of superior oblique palsy

PURPOSE

Weakening of the inferior oblique muscle is the procedure of primary importance in patients with superior oblique palsy, Knapp's Classes I and III. In this study, the effectiveness of anterior transposition of the inferior oblique muscle in treatment of these patients was evaluated.

METHODS

Sixteen patients with superior oblique palsy, Knapp's Classes I and III, underwent anterior transposition of the inferior oblique muscle. The tip of the disinserted muscle was sutured to the sclera, parallel, and adjacent to the lateral border of the inferior rectus muscle insertion. The prism and alternate cover test measurements were made in all cardinal positions of gaze before and 6 months after surgery.

RESULTS

The mean reduction of hyperdeviation was 15 prism diopters (PD) in the primary position, 23.4 PD in adduction, 26.65 PD in elevation and adduction, and 18.63 PD in depression and adduction. There was no hypotropia in the primary position. Mild limitation of upgaze has occurred in 3 of these patients, and mild fullness of the lower lid was developed by 25%. Postoperative hyperdeviation in the primary position was 5 PD or less in 15 out of 16 patients.

CONCLUSIONS

The anterior transposition of the inferior oblique muscle is very effective in eliminating hyperdeviation in patients with superior oblique palsy, Knapp's Classes I and III. Up to 25 PD reduction of hyperdeviation in the primary position can be achieved. If this type of anterior transposition is used, primary position hypotropia or marked limitation of upgaze possibly will not occur.

Effect of graded anterior transposition of the inferior oblique muscle on versions and vertical deviation in primary position

INTRODUCTION

There are various methods for weakening the inferior oblique muscle; here we describe the results of a graded anterior transposition.

METHODS

Charts of 21 children (37 eyes) who underwent graded anterior transposition of the inferior oblique muscle were reviewed. Graded anterior transposition consisted of reinsertion of the inferior oblique muscle at various points along the temporal aspect of the inferior rectus muscle; the more severe the overaction, the more anterior the placement of the new insertion. In all cases the new inferior oblique insertion line was oriented parallel to the inferior rectus muscle axis. We analyzed the preoperative to postoperative change in inferior oblique overaction (versions) and vertical alignment in primary position.

RESULTS

Postoperatively, 18 of 21 patients had normal versions, 2 patients had -1 underaction of 1 eye, and 1 patient had +1 overaction of both eyes. Eleven patients (15 eyes) had a preoperative vertical deviation in primary position of 4 PD or more. Three of these patients had unilateral congenital superior oblique palsy and a preoperative hypertropia of 20 PD. They underwent unilateral graded anterior transposition with a mean postoperative vertical change of 18 PD. Three patients had asymmetric primary inferior oblique overaction with true hypertropia, 1 patient had amblyopia and primary inferior oblique overaction, and 4 patients had dissociated vertical deviation associated with inferior oblique overaction. All patients had improvement after surgery, with no significant vertical deviation in primary position.

CONCLUSIONS

Graded anterior transposition of the inferior oblique muscle is effective in normalizing versions and correcting vertical deviations in primary position.

The neurofibrovascular bundle of the inferior oblique muscle as the ancillary origin of that muscle

PURPOSE

To establish that the neurovascular bundle (NVB) of the inferior oblique muscle has ligamentous qualities that enable it to function as an ancillary origin to the muscle, particularly after anterior transposition of its insertion.

METHODS

Fresh cadaveric eyes and eyes of surgical patients were studied. Eighteen orbits were dissected to demonstrate the linear course of the NVB and its adjacent fibrous bands. Intact orbits were analyzed histologically, as were autopsy and surgical specimens, to evaluate the capsule of the NVB and the adjacent fibrous bands. The elastic modulus was measured in NVB specimens and in superior oblique tendons. Six eyes in which recurrent inferior oblique muscle overaction developed after an anterior transposition procedure were surgically explored to determine the structure that was serving as its ancillary origin.

RESULTS

Gross anatomic and microscopic studies showed a linear orientation of the NVB,with adjacent fibrous bands anteriorly joining the inferior oblique and inferior rectus muscle capsules. The NVB showed about 50% fibrocollagenous capsule, with the collagen fibers aligned parallel to the NVB. The elastic modulus was highest (stiffest) in the NVB and lowest in the superior oblique tendon. In patients who had undergone anterior transposition operations, the NVB served as the ancillary origin of the inferior oblique muscle.

CONCLUSION

The name of the NVB should be changed to neurofibrovascular bundle because it has a prominent fibrocollagenous capsule and is encased in fibrous tissue bands anteriorly. The neurofibrovascular bundle has a linear course and is relatively stiff. It binds the midposterior portion of the inferior oblique muscle posteriorly. Its ligamentous qualities enable it to function as an ancillary origin for the inferior oblique muscle.

Anterior transposition of the inferior oblique in the treatment of unilateral superior oblique palsy

Anterior transposition of the inferior oblique (ATIO), is an accepted surgical procedure for the treatment of primary inferior oblique overaction and dissociated vertical deviation. Our study was undertaken to see if ATIO could be useful in the treatment of preselected unilateral superior oblique palsy (SOP) patients. Three consecutive patients with unilateral SOP with preoperative primary-position hypertropia averaging 27 delta, Knapp class V, underwent ATIO. The results were excellent and none of these patients developed primary-position hypotropia. Complications of ATIO in our patients consisted of some elevation deficiency, elevation of the lower lid in upgaze, and reduced inferior "scleral show" in the surgically treated eye. We are proposing that ATIO be considered as a beneficial operation in unilateral SOP patients with at least 25 delta of preoperative primary-position hypertropia.

The effect of anterior transposition of the inferior oblique muscle

The effect of anterior transposition of the insertion of the inferior oblique muscle was compared with the results from conventional inferior oblique muscle recession in 50 patients. Even though both groups of patients had a similar degree of overaction preoperatively, postoperative inferior oblique muscle action was weaker (P < .01) and upgaze more limited P < .01) in the anterior transposition group. These data suggest that anterior transposition serves to convert the inferior oblique muscle from an elevator to a depressor on attempted elevation. Because anterior transposition is such a powerful weakening operation, we suggest that it be reserved for patients with moderate to severe inferior oblique muscle overaction. To avoid postoperative hypotropia in upgaze, anterior transposition should be performed in both eyes for bilateral inferior oblique muscle overaction and not unilaterally.