Case Report: Case 14

This case is about an 11 month old boy, presented with inward deviation of his right eye since birth. He was a premature child (29 weeks). No history of pain, vomiting or trauma associated with strabismus / neurological. Work-up was unremarkable, His twin brother was normal

Case Presenters:

Dr. Luis Eduardo M. Rebouças de Carvalho, MD., is the Ophthalmologist In-Chief at the Strabismus Department of the Santa Casa de São Paulo Medical School at Santa Casa de São Paulo, Brazil. Dr. Carvalho obtained his Degree from the Faculdade de Medicina ABC 1987 (Medical School ABC Foundation), following which he did his Residency from the Santa Casa de Miseriçórdia de São Paulo / Brazil (1988-1990). He then went on to pursue a Fellowship at the Santa Casa de Misericórdia de São Paulo / Brazil (1990-1993). Dr. Carvalho then went on to do his Postgraduate course at the UNIFESP / EPM (Paulista Medical School) São Paulo / Brazil (1993-1995), following which he underwent a Doctorate Degree at the University of São Paulo Medical School, USP, Brazil (2005-2007)

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Status: CASE CLOSED

Members’ Responses:

1) Whether they would recommend an MRI of the Brain prior to the surgical procedure:
30.00% feel it is Indispensable; 62.50% felt it is Useful but not indispensable. The remaining 7.50% would
not recommend pre-surgical MRI due to the risks of general anaesthesia.

2) What is your preferred surgical technique for VI Nerve palsy?
21.25% replied saying Carlson Jampolsky, 38.75% preferred Superior rectus transposition
combined with Medial Rectus recession, 31.25% opted for Vertical muscle transposition
augmented with lateral fixation (Foster) & 8.75% would use the Nishida Muscle Transposition
surgical technique.

3) What is the occlusive treatment regime proposed for this case?
42.50% said they patch for 2 hours / day, 36.25% opted for 4 hours / day patching, 17.50% said
they do 6 hours of patching / day & the remaining 3.75% said they’d opt for 8 or more hours of
patching /day.

Experts Panel

Our Experts for Case 14 are Dr. Cameron Parsa, Dr. Craig Donaldson & Dr. Kanwar Mohan In addition to answering the questions posed to our members, our Experts were also asked the following questions: 4) Do you think that VI Nerve palsy is a benign entity? 5) What is your approach to diagnose and treat a patient with VI Nerve palsy pattern?

Kanwar Mohan- view bio

1) Do you feel recommending MRI image study prior to the surgical procedure is:
a) Indispensable
b) Useful but not indispensable
c) I would not recommend prior MRI image due the anesthesia damage
My answer is ‘b’. Due to a very large esotropia, absence of abduction and no narrowing of palpebral fissure in adduction, I would consider the diagnosis of 6th nerve palsy. No history of trauma, and the absence of signs and symptoms of raised intracranial pressure make me strongly think ‘Congenital’ as the etiology of 6th nerve palsy in this child. Though MRI image study will not help in the management of this case, it will help in finding out any congenital etiology such as the absence of 6th nerve, and any associated intracranial congenital anomaly. Thus MRI image study will be useful but not indispensable, and I would feel recommending it prior to surgical procedure in this child.

2) What is your preferred surgical technique for VI Nerve palsy?
a) Carlson Jampolsky
b) Superior rectus transposition combined with Medial Rectus recession
c) Vertical muscle transposition augmented with lateral fixation (Foster)
d) Nishida Muscle Transposition
My answer is ‘d’. My preferred surgical technique for 6th nerve palsy is Nishida muscle transposition without tenotomy and muscle splitting. There is less interference with the anterior segment circulation with this procedure because there is no tenotomy, no muscle splitting, only one third of the muscle width is ligated, and the muscle sutures are placed apart from the anterior ciliary vessels. Thus there is a less risk of anterior segment ischemia and this procedure is safe. In addition, the chances of development of a vertical imbalance are much less because the vertical action of the superior and inferior rectus muscles is not affected. Therefore, I prefer this procedure for treating 6th nerve palsy.

3) What is the occlusive treatment option proposed for this case?
a) 2 hours / day
b) 4 hours / day
c) 6 hours / day
d) 8 or more hours /day
My answer is ‘d’. I believe and follow that a full-time occlusion gives a faster and better improvement in vision as compared to some hours of occlusion. Hence I would advise at least 8 or more hours of occlusion per day in this child.

4) Do you think that VI Nerve palsy is a benign entity?
I do not think that 6th nerve palsy is a benign entity in all situations. Patients with 6th nerve palsy due to medical conditions such as diabetes, hypertension etc. do not require neurological investigations, and I would consider it a benign entity in these patients. However, patients with 6th nerve palsy due to head trauma require a neurological work up and neuro imaging studies to assess the extent of craniocerebral injury, and I would not consider it a benign entity in this situation. In the absence of medical conditions mentioned above, a 6th nerve palsy may be a sign of serious intracranial pathology, and I would not consider it a benign entity in such patients, and would order neurological investigations.

5) What is your approach to diagnose and treat a patient with VI Nerve palsy pattern?
My approach to diagnose a 6th nerve palsy is as follows :
I would make a diagnosis of 6th nerve palsy if a patient has the following cardinal signs :
i. Esotropia in primary position and increasing in the gaze of the involved lateral rectus muscle
ii. Limitation of abduction
iii. Head turn to the side of the involved lateral rectus muscle
iv. Presence of uncrossed diplopia with more separation of images in the gaze of the involved lateral rectus muscle
v. Absence of narrowing of palpebral fissure in adduction, and esotropia proportionate to the extent of abduction limitation would differentiate it from the Duane’s Syndrome.
My approach to treat a 6th nerve palsy
i. I would assess visual acuity to detect amblyopia in younger children and if present, would treat it with occlusion therapy.
ii. I would advise occlusion of the normal eye to give relief from diplopia and to avoid development of contracture of the medial rectus muscle, and would wait for at least 6 months for a natural recovery. In the waiting period, I would do measurement of esotropia, assessment of abduction improvement, and diplopia charting to assess the extent of separation of diplopic images every 2 months. If there is no improvement at all after 6 months or no further improvement for consecutive 6 months, I would consider surgical intervention as follows:
a. Partially recovered 6th nerve palsy – I would do forced duction test (FDT) to assess the stiffness of the medial rectus muscle, and perform conventional medial rectus recession and lateral rectus resection depending upon the amount of esotropia. If the medial rectus muscle is tight, I would reduce the amount of recession by 1-2 mm.
b. Unrecovered 6th nerve palsy – I would do FDT to assess medial rectus muscle stiffness. Then I would do Nishida procedure without tenotomy and splitting, and would add medial rectus muscle recession if this muscle is tight or esotropia is more than 40 prism diopters.

Craig Donaldson- view bio

1) Do you feel recommending MRI image study prior to the surgical procedure is:
a) Indispensable
b) Useful but not indispensable
c) I would not recommend prior MRI image due the anesthesia damage
Indispensable in this case, given the significant risk of accompanying intracranial pathology. For example, intraventricular haemorrhage associated with prematurity.

2) What is your preferred surgical technique for VI Nerve palsy?
a) Carlson Jampolsky
b) Superior rectus transposition combined with Medial Rectus recession
c) Vertical muscle transposition augmented with lateral fixation (Foster)
d) Nishida Muscle Transposition
None of these. I would perform a half tendon superior and inferior rectus transposition with Foster type augmentation suture and medial rectus recession (with adjustable in older patients).

3) What is the occlusive treatment option proposed for this case?
a) 2 hours / day
b) 4 hours / day
c) 6 hours / day
d) 8 or more hours /day
It depends on whether he has adopted an abnormal head posture. If he has an AHP then the role of patching is probably less important from an amblyopia point of view. If there is no AHP then I would patch according to the vision recorded.

4) Do you think that VI Nerve palsy is a benign entity?
No, I do not think 6th nerve palsy is necessarily a benign entity. If we are talking about congenital 6th nerve palsy, it depends on the clinical scenario. Many congenital 6th nerve palsies resolve spontaneously and are likely secondary to transient raised intracranial pressure. Persisting dense congenital 6th nerve palsies are frequently associated with other intracranial abnormalities. For example, in this case the patient is premature and there is a risk of intraventricular haemorrhage, periventricular leukomalacia, hydrocephalus and cerebral palsy. Imaging of affected patients can be very important in so far as ruling out intracranial pathology and also in helping establish the diagnosis. It may be difficult to distinguish between congenital 6th nerve palsy and Duanes RS 1. Imaging may identify an atrophic lateral rectus muscle (6th NP) or absence of the abducens nucleus (DRS 1).

5) What is your approach to diagnose and treat a patient with VI Nerve palsy pattern?
My approach to diagnosing and treating a patient with a 6th nerve palsy pattern is as mentioned dictated to by the clinical scenario. In all newborns with this pattern of palsy a prenatal and birth history is essential. If the prenatal and birth history and ophthalmic examination is otherwise normal with some historical evidence of improving abduction in the first 2-3 weeks after birth I will observe without investigation, expecting further spontaneous improvement. I commence patching of the non-affected eye for 2-4 hours per day until resolution. If the infant has an abnormal history (e.g. significant prematurity), other physical abnormalities or persisting 6th nerve palsy I will organise neuroimaging as well as formal neurological review. Patching for 2-4 hours per day of the non-affected eye is also commenced. I have not found Botox to the medial rectus muscle to alter the eventual outcome in patients I have treated with 6th nerve palsy. If patients are able to generate saccades beyond the midline I will perform a resect/recess procedure. For denser palsies my operation of choice is a half tendon superior and inferior rectus transposition with augmentation suture and medial rectus recession.

Cameron Parsa- view bio

1) Do you feel recommending MRI image study prior to the surgical procedure is:
a) Indispensable
b) Useful but not indispensable
c) I would not recommend prior MRI image due the anesthesia damage
I would not recommend MR imaging prior to surgery. The clinical exam should suffice to determine if the 6th nerve palsy is isolated or not.

2) What is your preferred surgical technique for VI Nerve palsy?
a) Carlson Jampolsky
b) Superior rectus transposition combined with Medial Rectus recession
c) Vertical muscle transposition augmented with lateral fixation (Foster)
d) Nishida Muscle Transposition
For a complete 6th nerve palsy as in this case, I would recommend a vertical rectus muscle transposition surgery, using adjustable suture technique. To augment the effect of the transposed muscles, I would place the tendon of the superior rectus muscle closer to the inferior insertion edge of the lateral rectus muscle, in hang-back fashion, and the tendon of the inferior rectus muscle closer to the superior insertion edge of the lateral rectus muscle (“crossed-fixation” as described by Guyton and colleagues, reference #1) to bring both vertical muscle bellies closer to the globe equator for maximal abductive “spring” effect. With such full tendon transposition, recession of the medial rectus muscle may sometimes be eluded.

3) What is the occlusive treatment option proposed for this case?
a) 2 hours / day
b) 4 hours / day
c) 6 hours / day
d) 8 or more hours /day
I would recommend approximately 4 hours of patching of the left eye per day until the amblyopia is resolved.

4) Do you think that VI Nerve palsy is a benign entity?
If isolated and present at birth, generally yes, with nearly all recovering spontaneously, this rare case excepted. However, I may inquire as to whether any predisposing factors for thrombus formation in the mother during pregnancy, via history (i.e. fainting, dehydration) as well as blood tests for Factor V Leiden mutation, anti-phospholipid antibodies, etc. to determine if maternal risk factors exist for micro-emboli to form during pregnancy and lodge in the nerve blood supply. I would particularly emphasize this is any other apparently isolated, sporadic congenital malformations also present in the child or direct relatives. In such case, future pregnancies may take such information into account with steps taken to reduce susceptibility to micro-emboli formation.

5) What is your approach to diagnose and treat a patient with VI Nerve palsy pattern?
I would first insure no other associated clinical signs to make one suspect a particular cause for the condition. I would then await spontaneous improvement in the first weeks to months of life.
To assess nerve recovery, I would particularly take care to compare the velocity of saccades of each eye moving in the same direction to see whether small but quick saccadic movements are possible despite the restricted abduction of the affected eye. If so, this would indicate residual VI nerve function/recovery with further abductive movement simply blocked mechanically by a contracted medial rectus muscle. If any nerve function can hence so be noted, a horizontal muscle recess-resect procedure would be the procedure of choice.
Prior to any surgery, I would also first perform occlusion therapy of the unaffected eye for two reasons: a) to reduce amblyopia prior to the surgical procedure, as well as to, b) help make more manifest any residual abductive ability of the lateral rectus muscle with gradual stretching and lengthening of the medial rectus muscle and a decrease in the angle of strabismus. If extreme inturning of the eye precludes such determination, the injection of botulinum toxin could be envisioned as performed here. If, nonetheless, no lateral rectus muscle function can be noted, as was the case here, vertical rectus muscle transposition would indeed be indicated.
My favored surgical procedure for a complete 6th nerve palsy would be a full-tendon transposition of the vertical muscles. Fornix incisions would better preserve conjunctival blood supply to the anterior segment. I might also attempt ciliary vessel sparing techniques as further “back-up” against anterior segment ischemic syndrome, though hardly ever necessary in such young children with normal blood vasculature. Crossed fixation of the vertical muscles, placing the superior rectus muscle near the inferior edge of the lateral rectus muscle insertion, and placing the inferior rectus muscle near the superior edge of the lateral rectus muscle insertion as described by Guyton and colleagues (reference #1) permits a Foster-like augmented effect of the transposed muscles, while still permitting adjustable suture techniques to be used, if available, under propofol sedation for infants to minimize chances of inducing a vertical deviation. With full vertical rectus tendon transposition and hence the increased abductive “spring” effect obtained, I may, in most cases, forgo medial rectus muscle recession altogether and instead inject botulinum toxin at the time of surgery, or post-operatively, if necessary.

Education Case Report Quiz & Expert Opinions

Other Cases:

    Bi-monthly, we present a survey based medical quiz to our members. We request them to answer the question(s) asked by selecting one of the options provided at the end of the presentation. The case presentation is also sent to a few established / renowned ophthalmologists asking them for their opinion.

    As both sets of these opinions are important, we compile them for each case and include it in the next newsletter.

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