Experts’ opinion – Case 7

In addition to answering the questions posed to our members, our Experts were also asked the following questions:
1) Assuming the medial rectus was adherent to the orbital defect, would you expect a positive forced duction test?
2) What would be the optimal time for surgery?
3) If the muscle had been transected and a large segment were missing or destroyed, what would be your surgical approach?

Dr. Andrea Molinari

In my opinion, this represents an atypical case of congenital left IV nerve palsy with superior rectus overaction / contracture syndrome. Congenital IV nerve palsy can manifest in many ways in a wide clinical spectrum, especially if it is as long standing as in this patient. She has all the features of superior rectus overaction / contracture syndrome: hypertropia in all gaze positions, hypertropia of more than 15 diopters in primary position, hypertropia that is larger in abduction, contralateral superior oblique overaction and a very positive head tilt test. She does not display many features of congenital IV nerve palsy: facial asymmetry is not pronounced, she exhibits a face turn instead of a head tilt, and she has no inferior oblique overaction. However, in my experience inferior oblique overaction is not invariably present in cases of IV nerve palsy.
I have seen very few cases of isolated inferior oblique palsy, most of them following trauma. I have not encountered or seen reports of congenital inferior oblique palsy; therefore, I do not think that this is the correct diagnosis in this case.

The surgical strategy in this patient seemed perfectly adequate to me. Patients with superior rectus overaction/contracture syndrome require a weakening procedure of this muscle. The right superior oblique overaction was correctly addressed with a posterior tenectomy. In a binocular patient, this is a safer procedure for weakening the overacting superior oblique. The moderate lateral rectus recession was perfectly adequate for her small exotropia.

 

Dr. Elias Traboulsi

This case is about a 32-year-old lady who presented with Anomalous Head Posture – We are not told how long she has had it. She is also amblyopic in her left eye and fixates with her palsied right eye in abduction with a left face turn, keeping her right eye away from the adducted position.

(1) How do you explain this pattern?
IO palsy

(2) Which procedure do you prefer for weakening SOOA?
SO tendon elongation

3) How do you explain the Head Tilt Test difference?
IO palsy, but cannot exclude some contracture of LSR as patient is fixating with OD and LHT is chronic. LHT is larger in downgaze also supporting a tight LSR.

(4) Do you think that IO palsy is a benign entity?
IO is a benign entity in the sense that patients with IO palsy do not have brain tumors or myasthenia gravis. See series by Pollard ZF. Diagnosis and treatment of inferior oblique palsy. J Pediatr Ophthalmol Strabismus. 1993 Jan-Feb;30(1):15-8.

(5) What is your approach to treat a patient with IO palsy pattern?
If the horizontal and vertical deviations are small (<10 PD), I would proceed with weakening the SO (tendon lengthening procedure) first. I would reassess and treat residual XT or HT with rectus recession as a second stage procedure. If they are larger, especially if there is evidence of a tight SR, I would proceed as the surgeon did in this case and address those deviations all at once.

 

Dr. Fay Cruz

(1) How do you explain this pattern?
IO palsy; the patient presented with a limited adduction on elevation of the right eye, no restriction was noted on forced duction, an overacting superior oblique and fulfills the three step test for an inferior oblique palsy on the right eye

(2) Which procedure do you prefer for weakening the SOOA?
SO tenectomy; SO tenectomy on the right eye and an SR recession on the contralateral eye will address the hypertropia as well as the A- pattern

(3) How do you explain the Head tilt test difference?
IO palsy

(4) Do you think the IO palsy is a benign condition?
As stated in the clinical strabismus management book by Rosenbaum and Santiago, IO palsy is
usually idiopathic and benign in nature. The MRI results of the patient was also negative.

(5) What is your approach to treat a patient with IO palsy pattern?
The management of the case is dependent on the spread of comitance and the severity of
the oblique dysfunction. In the case presented, I will follow the same procedure.

 

Dr. Federico Velez

(1) How do you explain this pattern?
There are several diagnostic possibilities. Patient has right under elevation all gazes worse in adduction, right over depression more in adduction and the left eye shows limited downgaze in all gazes worse in abduction. Right inferior oblique weakness, right superior oblique overreaction, left superior rectus overaction, left inferior rectus muscle weakness can all create very similar patterns with similar torsion. If I value, the Bielschowsky (which in chronic deviations can mislead the diagnosis) then it is unlikely that this patient has a left inferior rectus muscle paresis leaving me with 3 possible diagnoses. The horizontal pattern in my opinion does not help with the final diagnosis. Interestingly the surgeon indicates that the forced duction test was negative. If correct then the most likely diagnosis is a right inferior oblique paresis. However, this won’t explain the left hypertropia in right gaze. I would have expected no left hypertropia in right gaze. One limitation of the forced duction test is an overacting not tight muscle. So a superior oblique overaction and superior rectus overaction can again explain the pattern here presented without necessarily having a positive forced duction test which I will see in patients with muscle contracture not necessarily an overacting muscle. The diagnosis of inferior oblique palsy is doubted by some strabismologists. If the problem is the innervational I see two possible locations, 3rd nerve nucleus where there is a specific representation for the inferior oblique, or in the orbit after the inferior branch of the 3rd nerve left branched to the inferior oblique. A muscle hyopoplasia as has been published (Ela Dalman et all J AAPOS) can explain the finding of under elevation in adduction, intorsion, a pattern. But still in my opinion wont explain the left hypertropia in right gaze. Except if there is a secondary overaction of the left superior rectus muscle either primary or secondary causing limitation to downgaze rotation of the left eye worse in abduction, a pattern, underaction of the ipsilateral antagonist inferior rectus muscle with over action of the contralateral antagonist muscle superior oblique.
(2) Which procedure do you prefer for weakening the SOOA?
My decision is based on the amount of deviation in primary position, the forced duction test and whether I am operating or not on another vertical muscle. Deviations of less than 5 PD, I perform posterior tenectomy. If the forced duction test is positive and the deviation ranges between 5-10 PD, I rather do a lengthening procedure either z lengthening or spacer; if the deviation is larger than 5 PD with negative forced duction test and patients with more than 10 PD of deviation in primary position, I add a second vertical muscle to for example a posterior tenectomy.

(3) How do you explain the Head tilt test difference?
For this patient all 3 options are possible and a final diagnosis is not possible based on the Bielschowsky manoeuvre. In my opinion (not necessary because the surgical treatment was appropriate) the only test I would have considered was a high resolution MRI of the orbit.

(4) Do you think the IO palsy is a benign condition?
It will be exceptional for a malignant orbital lesion or brain lesion including a malignant lesion or an aneurysm to present as an isolated inferior oblique muscle palsy. There could be 3rd nerve neuromas that could potentially affect the branch to the inferior oblique or a brain stem vascular lesion or inflammatory condition affecting the nucleus to the inferior oblique but I believe more inferior oblique palsies are related to congenital abnormalities that decompensate overtime just like most non-traumatic (normal brain imaging) superior oblique paresis.

(5) What is your approach to treat a patient with IO palsy pattern?)
I consider imaging as I usually recommend for all patients who present with a new onset cyclovertical deviation. Surgery depends on the deviation but usually involves ipsilateral superior oblique muscle weakening plus a contralateral superior recuts muscle weakening procedure. In some cases, I consider strengthening the contralateral inferior rectus muscle.

 

Dr. Massimiliano Serafino

(1) How do you explain this pattern?
III nerve paresis; In my opinion she has a paresis of IO and MR in RE. This could explain her pattern:
– XT in primary position
– more XT in left gaze (15PD)
– left head turn
– stereopsis in right gaze (6PD)
– A pattern (relative SO overaction)
The intorsion in the left eye could be explained with a SR contracture. In primary SO overaction there is no head tilt

(2) Which procedure do you prefer for weakening SOOA?
SO tenectomy; In this case I am not scared about postoperative IO overaction because IO is paretic. So my favourite approach would be the SO tenectomy.

(3) How do you explain the Head Tilt Test difference?
IO palsy; Patient with IO palsy has an objective intorsion (as shown in this case). This means patient could have a head tilt on the same side of the affected eye (in our case could be right head tilt). If you perform an HTT on the opposite side (left tilt) the right eye will have a slight extorsion. The 2 muscles that can extort the eye are IO and IR; the IO is paretic than the IR will contract and the eye will go down. This explains why our patient has a left HT (20PD) during HTT (Left tilt)

(4) Do you think that IO palsy is a benign entity?
IO palsy is rare and idiopathic. The exact cause is unknown and has not been associated with any neurological abnormalities.

(5) What is your approach to treat a patient with IO palsy?
I would treat only patient with diplopia, moderate to severe abnormal head posture and vertical deviation in primary position. My approach is superior oblique weakening procedure alone or associated with controlateral superior rectus muscle recession if vertical deviation is more than 10PD.

 

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