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Abstract
Surgical management of complete third nerve paralysis is a challenge. While several techniques have been described over the years, they result in less than satisfactory outcomes with residual deviations in primary gaze or postoperative drifts. One of the described techniques for management of oculomotor palsy has been medial transposition of the lateral rectus muscle which provides a good surgical alternative but often can result in undercorrection. We describe a modification of the existing technique of medial transposition of the split lateral rectus by force augmentation through the use of equatorial fixation sutures resulting in an improved outcome in primary gaze alignment. The modified technique involves splitting of the lateral rectus into two halves followed by transposing the superior half from below the superior oblique and superior rectus and inferior half from below the inferior oblique and inferior rectus to attach them at the superior and inferior edge of the medial rectus insertion, respectively. This is followed by placing non-absorbable sutures to fix each split belly of the transposed muscles to the sclera at the equator adjacent to the medial rectus such that the split muscles lie nearly parallel to the medial rectus till the equator before reflecting away. These sutures augment the force of the transposed muscles by redirecting the force vectors in the direction of action of the medial rectus. Satisfactory postoperative primary gaze alignment was achieved in three cases of complete third nerve paralysis.
- Treatment Surgery
- Muscles
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Surgical management of complete third nerve paralysis is a formidable challenge. Available surgical options include large recession–resection, orbital fixation, globe anchor and superior oblique transpositions but none provide an adequately satisfactory outcome in all cases.1–5 Common problems include extensive orbital dissection, residual deviations, postoperative drift, abnormal movements and the need for introduction of foreign material. A relatively novel technique is the medial transposition of the split lateral rectus where the muscle is split and transposed close to the medial rectus from behind the globe.6–10 While this procedure significantly improves outcomes in complete oculomotor palsy, residual undercorrections have been reported.9
This paper describes a simple yet effective modification of the medial transposition of split lateral rectus technique in which the transposition is augmented with the application of an equatorial fixation suture which redirects the force vector of the lateral rectus more effectively in the direction of action of the paralysed medial rectus muscle. The modified procedure was performed on three eyes of three patients and resulted in satisfactory outcomes with a good primary gaze alignment. We checked colour vision, contrast sensitivity and performed direct ophthalmoscopy of patients preoperatively and on subsequent follow-up.
The surgery is undertaken through four fornix conjunctival incisions in each quadrant after performing a forced duction test to confirm a free lateral rectus muscle. The lateral rectus is hooked, split in half up to at least 15 mm posteriorly after placing 6-0 Vicryl sutures (Ethicon, Johnson and Johnson, Aurangabad, India). Superior oblique is hooked and posterior tenectomy is done as in conventional surgeries. Posterior tenectomy of superior oblique helps in free movements of the transposed muscle under it, reduces the abduction effect and hence brings out greater correction. The superior half of the split lateral rectus is passed between the superior oblique tendon and sclera. After hooking the superior rectus, split end is passed between it and sclera. To prevent torsion of the transposed muscle, superior end of split muscle is attached medially just above medial rectus insertion and the inferior end is attached 5 mm above it to ensure that the inner surface of the muscle remains towards sclera. Similarly, inferior half is passed between inferior oblique and sclera. Inferior rectus is hooked and sutures are passed between the muscle and sclera. Inferior end is attached just below medial rectus insertion. Equatorial fixation sutures are put 8 mm behind the new insertion of the split muscles with 5-0 Ethibond (Ethicon, Johnson and Johnson, Aurangabad, India) passing them through the transposed ends incorporating 25℅ of the muscle (see online supplementary video). Forced duction is assessed in all directions after the transposition procedure to ensure that the surgery has not resulted in restriction of movement and was observed to be free in all the three cases.
Case 1: a 7-year-old boy presented with severe ptosis and outward deviation of his left eye since birth with no significant medical or surgical history (figure 1A). Vision in right eye was 20/20 and in left eye finger-counting-close-to-face. Diagnosis of left complete third nerve palsy with aberrant regeneration was made and the above procedure performed. Postoperatively at 10 months, exotropia reduced from 90 to 10 prism dioptre (PD) (figure 1B).
Clinical photographs of patient with left eye (OS) complete third nerve palsy. Preoperative (A), and 10 months after surgery (B). There is marked improvement in deviation.
Case 2: a 42-year-old female presented with left exotropia after surgery for optic nerve sheath meningioma 2 years ago (figure 2A). Visual acuity in right eye was 20/20 and hand movement in left eye with left optic atrophy. Primary gaze deviation was 50 PD exotropia, 8 PD hypotropia. Postoperatively at 6 months, there was 12 PD exotropia with 6 PD hypotropia (figure 2B).
Preoperative (A) and postoperative (B) clinical image of patient after transposition surgery.
Case 3: a 22-year-old female gave history of sudden onset exotropia of right eye since 2 years with no history of trauma or medical illness. She presented with diplopia with visual acuity of 20/20 in both eyes and normal fundus findings. MRI brain and orbits did not reveal any abnormality. Systemic investigations came out to be negative as well. Hence a diagnosis of right eye idiopathic complete third nerve palsy was made. She had 60 PD exotropia with14 PD hypertropia (figure 3A). At 3 months postoperatively she had 8 PD exotropia and no vertical deviation (figure 3B).
Preoperative photograph (A) showing right eye exotropia of 60 PD, hypotropia of 14 PD and postoperative photograph (B) showing orthotropia after transposition surgery.
Full tendon transposition of the lateral rectus was initially described by Taylor6 and modified to a split tendon transposition by Kaufmann.7 ,8 Gokyigit et al9 further modified this by reattaching the split ends 2 mm posterior to superior and inferior borders of medial rectus. However, they noted an undercorrection and need for medial rectus strengthening in half their cases. Similarly, Sukhija et al10 reported large residual exotropia in three of their four cases which were operated using a modification of this procedure.
In our series, we reattached the two halves just above and below the insertion of medial rectus along with equatorial fixation sutures using non-absorbable material to augment the action of the transposed muscle (figure 4) resulting in minimum residual exotropia. This also caused the lateral rectus split to extend posterior to globe (figure 5 and online supplementary image), a factor shown to be important for satisfactory alignment in primary gaze.11 Complications like choroidal effusion or retinal detachment, which can occur due to increase in choroidal pressure when attaching the muscle near the vortex veins were not observed in any case.
Representative sketch showing path of transposed muscle. Superior view shows the course under superior oblique (SO) and superior rectus (SR), inferior view demonstrates the path under inferior rectus (IR) and inferior oblique (IO). IO, inferior oblique; IR, inferior rectus; LR, lateral rectus; MR, medial rectus; SO, superior oblique; SR, superior rectus.
Non contrast coomputerised tomography orbit of case 1 showing the split of lateral rectus reaching posterior to the globe (arrow).
Equatorial fixation sutures were first described by Foster12 in Duane syndrome and abducens palsy. The sutures were aimed at augmenting the force of the transposed muscles in these cases. During their usage in the currently described procedure, these sutures act by producing an adducting tonic force by changing the force vectors of the split lateral rectus muscle. This strengthens the effect of the transposition and results in good primary gaze alignment. In previous reports of the transposition procedure, the direction of transposed ends is not parallel to medial rectus muscle but at an angle >45°. This resulted in only a part of the force vector acting to adduct the exotropic eye and resultant residual deviation. Alignment could be improved if the distance between medial rectus muscle and transposed split ends of lateral rectus was reduced or closed. This ‘closing the gap’ effect as described by Foster was brought about by transfixing the transposed split ends of lateral rectus to the sclera adjacent to medial rectus at the equator.12 This form of equatorial fixation sutures has not been previously described for use in patients of third nerve palsy.
One possible limitation of this surgery is a tight forced duction test for the lateral rectus preoperatively where it may not be possible to adequately mobilise the muscle. In such cases alternative procedures like medial periosteal anchoring of globe2–4 or lateral rectus transposition with hang-back technique13 may be more suitable.
To conclude, medial transposition of the split lateral rectus is an effective procedure for tackling complete oculomotor palsy and the modification of augmenting the procedure using an equatorial fixation suture enhances the final outcome.
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
- Data supplement 1 - Online figure
- Data supplement 2 - Online video
Footnotes
Contributors Design and conduct of study (RS, PS); collection of data (DS, MS, RD); analysis and interpretation of data (MS, DS, RD, RS); preparation of manuscript (DS, MS); review and approval of manuscript (PS, RS).
Competing interests None declared.
Patient consent Obtained.
Ethics approval The study was conducted in compliance with the Declaration of Helsinki, and Institutional Ethics subcommittee, All India Institute of Medical Sciences, New Delhi, India.
Provenance and peer review Not commissioned; externally peer reviewed.