Session 10: Superior oblique paresis

Transactions 29th European Strabismological Association Meeting – de Faber (ed) © 2005 European Strabismological Association, ISBN 04 1537 211 9

Superior oblique palsy: a ten year survey

Majid Farvardin & Alireza Alavi

Shiraz University of Medical Sciences, Shiraz, Iran

ABSTRACT:

Purpose: To evaluate the characteristics and surgical outcome of unilateral superior oblique palsy (SOP).

Patients and methods: Charts of 114 patients with SOP referring to our center from 1993 to 2003 were reviewed retrospectively.

Results: Vertical deviations ranged from 0 to 35 (mean:16.4 0.7) in primary position. As the first step 16.6% of surgeries were Inferior oblique (IO) myectomy, 10.5% IO recess, 56% anterior transposition of IO (ATIO), 1% Harada-Ito (HI) and in 15.7% two muscle surgery was done primarily and contralateral inferior rectus recess(CLIRR) plus ATIO (12.4%)was the most common. Success, defined as deviation 7 in primary position and 10 in adduction gazes was seen in 84% after the first and in 92% after the second operation. The deviation in primary position decreased to – 5 to 12 (mean; 2.4 0.4) after the first operation.

Conclusion: Based on the mentioned data we conclude that with surgery of the IO muscle, SOP can be effectively treated in a majority of patients.

1INTRODUCTION

Superior oblique palsy (SOP) is the most common cause of vertical strabismus encountered in the clinical practice. Both acquired and congenital palsies are common. Clinical presentation depends on several factors including etiology, severity of neural damage, age of onset and the duration of the paresis. Many patients with acquired superior oblique palsies recover spontaneously, so in acquired palsies the patients should be observed for at least 9–12 months1. Several studies have evaluated the effects of different muscle surgeries in superior oblique palsy, here we report the results of surgical management of 114 cases of unilateral SOP, treated with various inferior oblique (IO) weakening procedures.

2SUBJECTS & METHODS

We conducted a retrospective chart study of 128 patients who underwent surgical correction of superior oblique paresis at Khalili Hospital, Shiraz University of Medical Sciences, Shiraz, IRAN between 1993 to 2003. All patients who had adequate preoperative information and at least three months of post-op follow up were included in the study. Overall 114 patients were enrolled in the study criteria for diagnosis of unilateral SOP included:

A Hyperdeviation in primary position

B At least 2 increase in hyperdeviation with contralateral gaze

C Positive Bielschowsky head tilt test with 5 increase of hyperdeviation with ipsilateral head tilt D Any evidence of underaction of the involved superior oblique and/or overaction of ipsilateral

inferior oblique muscle

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Table 1. The result and success rate of various inferior oblique weakening procedures.

Congenital superior oblique palsy was considered if the patient had history of eye deviation and head tilt since infancy, also reviewing old photographs.The palsy was considered traumatic in the case of any pertinent history of trauma. Age, sex and probable causes were recorded. Each patient was questioned about any possible symptom, ie. presence or absence of diplopia, asthenopia and any possible previous surgery. Best corrected visual acuity was determined in all cases. Amblyopia was diagnosed if at least a two line difference in best corrected visual acuity (BCVA) was present between the two eyes. During examination presence or absence of any abnormal head posture, ie. head tilt and head turn, and facial asymmetry was taken into consideration. Measurements of deviation in primary position and diagnostic positions were performed with the alternate prism cover test. Double Maddox rod testing was performed in all cooperative patients. Presence or absence of inferior oblique overaction and V-pattern was noted. The type and the number of surgeries performed were specified. Surgical procedures included inferior oblique weakening procedures (disinsertion, myectomy, recession or anterior transposition), Harada-Ito procedure; contralateral inferior rectus recess (CLIRR) and ipsilateral superior rectus recess (ILSRR). The results of the surgeries was considered as excellent, good and poor depending on the amount of post-op vertical deviation in primary position to be 3 , 4–7 and 7 . A successful surgical out come was defined as a good result (i.e. 7 deviation in primary position) plus 10 deviation in all adduction positions.

3RESULTS

Charts of 114 cases of unilateral superior oblique palsy (SOP) were reviewed. The length of follow up was 3 months to 10 years (mean 9 month, SD 1.41)Among these cases 54 (47%) were male and 60 (53%) were female and 53 (46.5%) had left SOP and 61 (53.5%) had right superior oblique palsy. The age range of patients was 0.5–50 years (mean 13.6, SD 9.4). Etiology was congenital in 66 patients (58%), traumatic in 20 patients (17.5%) and unknown in 28 patients (24.5%). Head tilt was seen in 67 (59%), Face turn was present in 26 (23%) & diplopia in 23 (20%). Amblyopia was encountered in 17 (15%), 10 (59%) of which were in the normal eye( the so called fallen eye syndrome). 101 (88.5%) of the patients had some degrees of inferior oblique overaction. Over all 125 vertical muscle surgeries were performed in the patients (11 (8.8%) of which were reoperations), 104 (83%) single muscle surgery and 21 (17%) combined muscle surgeries were performed. Anterior transposition of the inferior oblique muscle (ATIO) in 62 (56%)was the most frequent surgery performed, followed by inferior oblique (IO) myectomy in 18 (16.6%), inferior oblique recess in 12 (10.5%) and Harada-Ito in 1 (0.9%)The mean angle of pre-operative vertical deviation in the primary position was 0–35 PD (mean 16.4, SD 7.3) which decreased to 15 PD to 12 PD (mean 2.4, SD 3.6) after the 1st operation. The result and the success rate of various inferior oblique weakening procedures and combined contralateral inferior rectus recession plus anterior transposition of IO are shown in table 1 and table 2 respectively.

Overall we had good results in 97 (85%) of the patients after the 1st operation which improved to 106 (93%)after the second operation, similarly success rate was 96 (84%) after the 1st & 2nd operation respectively. The most significant complication in our patients was 5 cases (4.4%) of anti-elevation syndrome after anterior transposition of IO muscle. Other less clinically significant

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Table 2. The result and success rate of combined contralateral inferior rectus recess and anterior transposition of inferior oblique muscle.

complications were the fullness of lower lid after anterior transposition of IO muscle and minor lid changes after vertical rectus muscle surgeries.

4DISCUSSION

Surgical management of SOP depends on the laterality, the degree of superior oblique muscle underaciton and type of the muscle sequelae that has developed. It is generally believed that a V-pattern exotropia on up-gaze is usually associated with IOOA & can be treated with IO weakening procedures. However in the case of significant SO underaction, particularly if there is a V-pattern esotropia on down gaze a strengthening of SO muscle is indicated. Insuperable cyclotorsion also requires strengthening of the SO muscle. Most authors recommend that up to 15–20 PD hypertropia in primary position can often be successfully corrected by recession of the inferior oblique, while any deviation exceeding 20 PD requires additional recession of the ipsilateral superior rectus or contralateral inferior rectus depending on the nature of the muscle sequelae1. The role of SO tuck in managment of superior oblique palsy remains controversial. In several reports no correlation could be found between the size of the tuck and the amount of deviation corrected3,5. It has been suggested that other factors such as laxity of SO tendon and the amount of preoperative deviation are also important in influencing the outcome of SO tuck procedure. Simons et al in their series reported a 50% lower reoperation rate with SO tuck however they had a high rate of surgical Brown syndrome (61%),which in their opinion could be reduced with adjustment of the magnitude of SO tuck based on SO tendon laxity5. In contrary to their opinion, many surgeons feel that the complications of SO tuck outweight the advantages. Infact recent treatment protocols warrant SO tuck only in the case of marked SO tendon laxity during exaggerated SO tendon traction test2,4. This study shows our experience of treating superior oblique palsy with various IO weakening and vertical rectus muscle procedures. A single corrective surgery was successful in 96 patients (84%) while we had good results in 97 patients (85%). These figures improved to 105(92%) and 106(93%) after the second surgery, which are comparable to the results of previous studies1. According to the mentioned results we recommend IO weakening procedures combined with a vertical rectus muscle surgery (in more severe cases) for treating SO palsy. These procedures have comparable results to the SO tuck, need less expertise, are more predictable and have lower complication rates. In our experience up to 25 hyperdeviation in the primary position could be treated with ATIO alone and for any extra-deviation we recommend rectus muscle surgeries depending on the nature of the deviation. In our opinion superior oblique surgery is indicated only if 10 excyclotorsion is present, in which a Harada-Ito procedure is probably preferable.

5CONCLUSION

In this study our 10 years experience in treating SOP with various IO weakening procedures was reviewed. The surgical outcome was quite comparable to the SO tuck, but on the other hand we had

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a much lower complication rate. So it seems that inferior oblique weakening is an acceptable treatment for superior oblique palsy and one do not necessarily have to operate superior oblique muscle unless there is a significant excyclotorsion.

REFERENCES

1.Ansons, A. M., Davis, H.: Neurogenic palsies. In Diagnosis and Management of Ocular Motility Disorders, 3rd ed, p 377.Oxford, Blackwell Science, 2001.

2.Helveston, E. M., Mora, J. S., Lipsky, S. N., et al: Surgical treatment of superior oblique palsy. Trans Am Ophthalmol Soc 1996; 94:315.

3.Morris, R. J., Scott, W. E., Keech R. V.: Superior oblique tuck surgery in the management of superior oblique palsies. J Pediatr Ophthalmol Strabismus 1992; 29: 337–346.

4.Plager, D. A., Superior oblique palsy and superior oblique myokimia. In: Rosenbaum A. L., Santiago A. P., ed. Clinical Strabismus Management. Philadelphia: W. B. Saunders; 1999; chap 15, 219–229.

5.Simons, B. D., Saunders, T. G., Siatkowski, R. M., et al: Outcome of surgical management of superior oblique palsy: A study of 123 cases. Binocular Vis and Strabismus 1998; 13(4): 273–282.

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