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Treatment of Inferior Oblique Paresis With Superior Oblique Silicone Tendon Expander
Treatment of Inferior Oblique Paresis With Superior Oblique Silicone Tendon Expander Marc F. Greenberg, MD and Zane F. Pollard, MD Introduction: Patients with inferior oblique eye muscle paresis may show hypotropia and apparent superior oblique muscle overaction on the side of the presumed weak inferior oblique (IO) muscle. We report 8 such patients successfully treated using unilateral silicone superior oblique (SO) tendon expanders. Methods: Eight consecutive cases over the course of 6 years from the authors’ private practice are described. None had a history of head trauma or a significant neurologic event. All patients showed IO paresis by 3-step test, with incyclotorsion and SO overacton of the hypotropic (paretic) eye. Forced ductions of the hypotropic eye were normal in all cases, and the vertical strabismus was treated with placement of a 7- mm silicone SO tendon expander in the hypotropic (paretic) eye. Results: Mean preoperative primary position hypotropia was 6.5 prism diopters (PD); mean postoperative was 0.5 PD. Seven of 8 patients had resolution of primary position hypotropia, whereas the eighth was reduced. Mean preoperative SO overaction was 3⫹; all patients had postoperative resolution of SO overaction. Of 4 patients with preoperative ocular torticollis, mean preoperative head tilt was 9.3 degrees; mean postoperative tilt was 2.9 degrees. Two patients’ head tilts had resolved, the other 2 showed improvement. All patients showed preoperative incylclotorsion of the hypotropic (paretic) eye; inclyclotorsion resolved in all patients after the placement of a SO tendon expander. Conclusion: The silicone SO tendon expander effectively restores ocular alignment in IO paresis with apparent SO overaction. Associated ocular torticollis can also be improved. (J AAPOS 2005;9:341-345) nferior oblique (IO) paresis is an uncommon form of strabismus characterized by a hypotropia that increases in adduction of the hypotropic (paretic) eye. It also is increased by head tilt away from the side of the hypotropic (paretic) eye. Patients often may show a compensatory ocular torticollis with face turn away from the side of the hypotropic (paretic) eye and head tilt toward the side of the hypotropic (paretic) eye. Although some patients with IO paresis may show marked underaction of the paretic muscle, the patients in this study all showed superior oblique (SO) overaction in the hypotropic (paretic) eye, with prominent depression of that eye on adduction, incyclotorsion of the hypotropic (paretic) eye, and exotropia in downgaze. Numerous procedures have been devised to weaken overacting SO muscles. In 1991, Wright1 described use of a silicone SO tendon expander designed to partially weaken the muscle action. Such graded weakening was
I
From the Eye Consultants of Atlanta, Children’s Healthcare of Atlanta at Scottish Rite, Atlanta, Georgia. Presented at the AAPOS meeting Washington, DC, March 2004. Supported by a grant from the James Hall Foundation. Submitted March 9, 2004. Revision accepted April 4, 2005. Reprint requests: Marc Greenberg, MD, 5445 Meridian Mark Road, Suite 220, Atlanta, GA 30327. Copyright © 2005 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/2005/$35.00 ⫹ 0 doi:10.1016/j.jaapos.2005.04.003
Journal of AAPOS
thought to decrease the risk of causing SO paresis as compared with full SO tenotomy or tenectomy. We have previously reported a series of 71 patients with A-pattern strabismus in which overacting SO muscles were effectively weakened by use of a silicone tendon expander.2 In 66 patients with bilateral SO overaction, collapse of the A patterns and resolution of SO overaction were successful in all cases, with no iatrogenic SO pareses. In the same report,2 5 cases of IO paresis also were reported on briefly; 4 resolved successfully and 1 did have consecutive SO paresis. In this retrospective review, we examine cases of IO paresis treated with unilateral SO tendon expander subsequent to our previous report and report results with specific attention to vertical strabismus, ocular torticollis, cyclotorsion, and SO overaction.
SUBJECTS AND METHODS A retrospective review of both authors’ surgical logs was made to identify all patients with a diagnosis of IO paresis who were treated using SO tendon expanders between 1997 and 2002. Eight consecutive patients were identified. All had a positive 3-step test for IO paresis, as well as incyclotorsion and SO overaction of the hypotropic (paretic) eye. Unless noted, all patients were healthy. None had a history of head trauma or neurologic abnormality. Intraoperative forced duction testing of elevation in adduction revealed no Brown’s syndrome in any patient. All patients had surgical placement of a 7- mm long segAugust 2005
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342 Greenberg and Pollard ment of a 0.75- ⫻ 2-mm #40 silicone retina circling band (Baush and Lomb Surgical, St. Louis, MO) sutured between the severed ends of the SO tendon in the hypotropic (paretic) eye. The SO tendon was cut at least 5 mm nasal to the nasal border of the superior rectus muscle. Two 7-0 Prolene® (Ethicon, Inc., Somervile, NJ) double-armed sutures on a BV-1 needle were used to secure the tendon expander to the severed tendon ends. The #40 retina band used is smaller than the #240 band originally used by Wright1 and is more similar in size to the SO tendon itself. No other simultaneous strabismus surgery was performed. All cases, except case 1, were performed with particular attention to leaving an intact Tenon’s capsule between the tendon expander and the sclera because entering the subTenon’s space while placing a SO tendon expander may result in a severe postoperative sterile orbital inflammatory response and resultant iatrogenic Brown’s syndrome.2 Case 1 was performed before our recognition of this complication. Data recorded included (except where noted): visual acuity, preoperative and postoperative strabismus measurements in the 9 diagnostic fields of gaze plus head tilts, clinical estimate of degrees of head tilt or face turn, clinical grading of SO overaction (scored 1-4⫹), measure of fundus cyclotorsion as described by Guyton3 (scored 1-4⫹) or, if possible, by double Maddox rod (DMR), Worth 4-Dot (W4D), and Titmus stereo testing (Stereo Optical Inc, Chicago, IL). SO overaction was graded with the contralateral eye in level abduction: 1⫹ if the adducting eye depressed slightly on adduction, 2⫹ if more than half the cornea of the adducting eye was covered by the lower eyelid, 3⫹ if at most a small crescent of cornea was present in the adducting eye, and 4⫹ if the adducting eye rotated further downward so as to start abducting. Preoperative versus postoperative measurements of primary position hypotropia, SO overaction, and head tilts were compared using the Wilcoxon signed rank test.
surgery, the Tenon’s capsule posterior to the SO was violated and, within 48 hours, a significant orbital inflammatory response resulted. Oral prednisone treatment reduced the inflammation; however, a postoperative Brown’s syndrome resulted, with elevation limited in adduction. Despite this complication, the head tilt completely resolved, and the right face turn decreased to 15 degrees during the next 6 months. At last follow-up, 6 years after surgery, there was essentially no head tilt or face turn. The patient was orthophoric except for a mild residual Brown’s (right eye elevates up to 20 degrees in adduction). There was no SO overaction and no cyclotorsion by double Maddox rod. Titmus stereo showed 40 seconds arc and Worth 4-Dot (W4D) testing showed near and distance fusion. Case 2 A 7-year old girl with Down’s syndrome presented with a longstanding 30-40 degree right head tilt. (See Figures 1 and 2. Video available in the electronic journal format at www.mosby.com/jaapos.) Other than developmental delay, there were no neurologic abnormalities. She had been treated elsewhere at an early age for accommodative esotropia, with resulting excellent control and no amblyopia. There was essentially no eye crossing with or without glasses; however, an intermittent right hypotropia of 6 PD was present in right gaze and the primary position. The right hypotropia increased to 8 PD in left gaze and to 16 PD or more in left downgaze. The right hypotropia decreased to 4 PD in right head tilt, but increased to 12 PD in left head tilt. There was 3⫹ SO overaction on the right, and right fundus incyclotorsion was noted by indirect ophthalmoscopy but not graded. Sensory testing could not be performed. A 7- mm right SO tendon expander was placed, with significant reduction in the right head tilt within days of the surgery. Six months after surgery, a 15-degree right
SELECTED CASE REPORTS Case 1 A 21-month-old boy presented for evaluation of possible ocular torticollis. His vision was central, steady, and maintained in both eyes. He had a preferred head position in 30 degrees left face turn and 10 degrees right head tilt. He was orthophoric in right gaze but had a right hypotropia of 4 prism diopters (PD) in the primary position, increasing to 8 PD in left gaze. The right hypotropia measured 12 PD in left downgaze, with a small exotropia in downgaze only. The right hypotropia measured 4 PD in left head tilt but was not present on right head tilt. There was 2-3⫹ SO overaction on the right. Indirect funduscopy showed 2⫹ incyclotorsion on the right. A right IO paresis was diagnosed and treated by placement of a 7- mm right SO tendon expander. During
FIG 1. Case 2 preoperatively shows large right head tilt ocular torticollis. Preoperative ocular motility video may be viewed at www.mosby.com/jaapos.
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right SO overaction, with 2⫹ right fundus incyclotorsion by indirect ophthalmoscopy. Sensory testing was not performed because of patient age. The presumed right IO paresis was treated with a 7- mm right SO tendon expander. Two months postoperatively, her right hypotropia, SO overaction, and fundus incyclotorsion were all resolved. The right head tilt had resolved; however, a 15 degree left face turn persisted. A year later, the patient presented with a prominent right dissociative vertical deviation. She underwent recession 6.0 mm of the right SR. Two years after this surgery, her vision was 20/20 OU, with orthophoria in all fields of gaze. Her abnormal face turn had resolved. She still suppresses the W4D at distance, but fuses at near. FIG 2. Case 2 at 3 months after right SO tendon expander. Ocular torticollis markedly improved. Postoperative ocular motility video may be viewed at www.mosby.com/jaapos.
head tilt persisted, with a right hypotropia of 4 PD seen only in gaze to the left and in left head tilt. Two years after surgery, the patient was orthotropic in all fields, including tilts; however, the 15-degree right head tilt remained. There was no SO overaction and no fundus cyclotorsion. Case 5 A 24-year-old woman complained of diplopia despite wearing prisms in her glasses since the age of 9. Her vision was 20/20 OD and 20/25 OS, and there was no abnormal head position. She measured 4 PD right hypotropia on right gaze, with 6 PD in the primary position and in gaze to the left. The right hypotropia measured 14 PD in gaze down and to the left but only 8 PD up and to the left. There was 4 PD right hypotropia in right head tilt, and 8 PD on tilt to the left. There was 2⫹ right SO overaction and 8 degrees right incyclotorsion on DMR. Despite glasses with 3.5 PD base up OD and 3.0 PD base down OS, there was no fusion on W4D or Titmus stereo testing. The patient underwent a right 7- mm silicone SO tendon expander. Two weeks postoperatively, she was orthophoric in all fields. SO overaction had resolved and there was no cyclotorsion by DMR. Titmus stereo testing showed 40 seconds of arc. The findings were stable at 1 year follow up. Case 7 A 3-1/2-year old girl presented with strabismus and torticollis. Her vision was central, steady, and maintained OU. She preferred a 15-degree left face turn with 10-degree right head tilt position. She was orthophoric on gaze to the right but showed 2 PD of right hypotropia in the primary position, which increased to 10 PD on gaze to the left. The right hypotropia increased further to 20 PD on gaze down and to the left, but only measured 10 PD on gaze up and to the left. The hypotropia measured 8 PD on left head tilt, with orthophoria on right head tilt. There was 3⫹
RESULTS Mean preoperative primary position hypotropia was 6.5 ⫾ 2.8 PD; mean postoperative was 0.5 ⫾ 1.4 PD (P ⫽ 0.008). Seven of 8 patients had complete resolution of primary position hypotropia, whereas the eighth was reduced. Mean graded preoperative SO overaction was 3.0 ⫾ 0.7; all patients had postoperative resolution of SO overaction (P ⫽ 0.008; Table 1). Of 4 patients with preoperative ocular torticollis, mean head tilt was 9.3 ⫾ 12.4 degrees; postoperatively, mean tilt was 2.9 ⫾ 5.7 degrees (P ⫽ 0.125). Two patients’ head tilts had resolved, the other 2 showed improvement. Of the 2 patients with preoperative face turns, one resolved completely after tendon expander placement, whereas the second persisted. The second patient’s face turn did resolve after subsequent surgery for dissociative hypertropia, suggesting that the cause of the face turn may not have been IO paresis. All patients showed preoperative incylclotorsion of the hypotropic (paretic) eye; the inclyclotorsion resolved in all patients after the placement of a SO tendon expander. Four of 8 patients could cooperate for sensory testing preoperatively; none showed evidence of binocularity. At the most recent follow-up visit, 6 of the 8 could perform sensory testing; 5 of 6 showed binocularity by Titmus testing, Worth-4-Dot, or both.
DISCUSSION In this review, 8 cases of IO paresis were each treated with a SO tendon expander in the hypotropic (paretic) eye. Primary position hypotropia, SO overaction, and ocular incyclotorsion resolved in most of the patients, with the remainder showing definite improvement. Of 4 patients with preoperative compensatory head tilts toward the hypotropic (paretic) side, all had decreased head tilt postoperatively, although one with dissociative vertical deviation required a subsequent surgery to improve a face turn. Sensory fusion improved in most of those who could be tested. We believe the specific amount (or range) of primary position hypotropia corrected in this study may not be as
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344 Greenberg and Pollard TABLE 1. Patient data
Case no.
Age
FollowUp
1 2 3 4 5 6 7 8 Mean (SD)
21 mo 7 yr 8 yr 39 yr 24 yr 12 yr 3 yr 9 yr 12.9 yr (12.5)
6 yr 2 yr 2 mo 1 yr 1 yr 1 yr 3 yr 6 mo 1.8 yr (1.9)
Superior oblique overaction*
Primary position hypotropia (PD)
Head tilt (degrees)
Face turn (degrees)
Incyclotorsion†
Preop
Postop
Preop
Postop
Preop
Postop
Preop
Postop
Preop
Postop
4 6 6 8 6 10 2 10 6.5 PD (2.8)
0 0 0 4 0 0 0 0 0.5 PD (1.4)
2.5 3 2.5 4 2 3 3 4 3 (0.7)
0 0 0 0 0 0 0 0 0 (0)
10 35 0 0 0 10 10 n/a‡ 9.3 (12.4)
0 15 0 0 0 5 0 n/a‡ 2.9 (5.7)
30 0 0 0 0 0 15 n/a‡
0 0 0 0 0 0 15§ n/a‡
2⫹ ⫹¶ 2.5⫹ 5 deg 8 deg 5 deg 2⫹ 15 deg
0 0 0 0 0 0 0 3 deg
¶Incyclotorsion noted preop but not graded in records. *Superior oblique overaction graded 0 to 4 (see Methods). †Estimated 0 to 4 if Double Maddox Rod (degrees) could not be done. No mean given because of differing measurement scales. ‡n/a ⫽ measurements not recorded in patient’s chart. §Face turn resolved after subsequent dissociated hypertropia surgery. No mean given because small sample size.
important as the fact that SO overaction and ocular cyclotorsion resolved in nearly every case, allowing fusion in most cases. In case 5, for example, the adult patient could not fuse despite prism glasses corresponding to her primary position vertical strabismus. Lack of fusion may have resulted from the incomitance of the vertical strabismus, from the presence of cyclotorsion, or from both. After tendon expansion, all of these abnormalities were improved, and the patient’s high level stereopsis was recovered. IO paresis is a rare diagnosis and must be distinguished from several entities. Brown’s tendon sheath syndrome may simulate underaction of the IO muscle but typically does not show increased vertical deviation on head tilt testing. Brown’s syndrome also is more likely to show a Y-pattern strabismus rather than the A pattern, which may be seen in IO paresis. The sine quo non of Brown’s syndrome, however, is mechanical restriction to attempted forced elevation in adduction, and all patients presented here showed free rotations. Inferior rectus muscle paresis behaves like contralateral IO paresis on the first 2 steps of the 3-step test. Both show a hypotropia in the primary position, which increases with adduction of the hypotropic eye. The third step differentiates the entities; the vertical strabismus in IR paresis increases with head tilt toward the hypotropic eye, whereas in IO paresis, the strabismus increases in head tilt away from the hypotropia, as in all the patients reviewed here. Donahue et al4 noted that vertical skew deviation may exactly mimic IO paresis on the 3-step test, and may be clinically distinguished only on the basis of ocular cyclotorsion. They presented 6 such patients, each showing excyclotorsion of the hypotropic eye and incyclotorsion of the hypertropic eye. In contrast, the patients in this review with IO paresis all showed incyclotorsion of the hypotropic eyes. Additionally, the patients with skew deviation had significant neurologic events, like strokes or traumatic
brain injuries, as opposed to most patients with isolated IO paresis, including those presented in this study, who typically have no neurologic history. Demer et al5 have noted that some cases of presumed eye muscle palsies and/or overactions may actually be mechanical, rather than neurologic, in origin. They presented magnetic resonance imaging and computed tomography scan evidence of oculomotor muscle and orbital connective tissue anomalies to illustrate this principle. We use the terms “IO paresis” and “SO overaction” to describe specifically defined patterns of abnormal extraocular muscle movements, while recognizing that we cannot be completely certain of the true etiology of the strabismus we observed. Nevertheless, regardless of etiology, the tendon expander was a useful treatment modality in all of our cases presenting with the following clinical pattern of strabismus: positive 3-step test for IO paresis, incyclotorsion and SO overaction of the hypotropic eye, greatest vertical strabismus in the field of the overacting SO, and negative forced duction test for Brown’s syndrome. Scott and Nankin6 first reported using SO free tenectomy to treat 6 cases of isolated IO paresis. All 6 patients showed improvement initially; however, follow-up time was limited to a mean of 5 months in 5 of the 6 cases. Olivier and von Noorden7 subsequently reported 3 of 6 similar patients who developed consecutive iatrogenic SO paresis after SO tenectomy. Two of the 3 patients took 1-1/2 and 2 years, respectively, to require additional surgery, suggesting late overcorrection may be an issue. Kutschke and Scott8 later updated their experience with IO paresis and did eventually note iatrogenic SO palsies. In Pollard’s review of 25 isolated IO palsies, 2 of 16 patients treated with SO tenotomy developed consecutive SO palsy.9 Our previous report on SO tendon expanders showed successful resolution of A-pattern strabismus and bilateral SO overaction in 66 cases.2 Previously, when performing
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SO free tenectomies for A-pattern strabismus, we encountered frequent consecutive SO paresis, as well as torsional symptoms, in our patients. The use of the tendon expander has all but eliminated these complications in hundreds of subsequent cases, and we now consider this our technique of choice for bilaterally weakening overacting SO muscles. In our previous report,2 of the 5 patients with IO paresis treated with SO tendon expander, one did develop consecutive SO paresis. Combined with the results of this study, our incidence of SO paresis after IO pareses treated with the tendon expander is thus 1 in 13. Although this ratio is an improvement over previous reports, the small number of cases limits any firm statistical conclusions. However, on the basis of our experience of SO tendon expanders in bilateral A-pattern strabismus, we would predict the actual incidence of consecutive SO paresis will probably be even lower. Our study of the SO tendon expander in bilateral Apattern strabismus was limited to patients with 3⫹ and 4⫹ SO overaction, and all patients received 7- mm size tendon expanders. Although several cases treated successfully in this study had 2-3⫹ SO overaction, patients with IO paresis and milder SO overaction could receive shorter sized tendon expanders to reduce the chance of iatrogenic SO paresis. Additionally, should iatrogenic SO paresis occur after placement of the tendon expander, one potential treatment option would be to replace the expander with one of shorter length. In contrast, revision of a SO tenotomy or tenectomy following such a complication would be difficult, if not impossible, in most cases.
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In conclusion, our results suggest the SO tendon expander can be used to reduce hypotropia, ocular torsion, and unilateral SO overaction in the setting of IO paresis with SO overaction. Associated ocular torticollis and binocularity can also be improved. We believe the tendon expander offers many advantages over tenotomy or tenectomy and this is now our procedure of choice for treating cases of IO paresis with SO overaction.
References 1. Wright K. Superior oblique silicone expander for Brown syndrome and superior oblique overaction. J Pediatr Ophthalmol Strabismus 1991;28:101-7. 2. Pollard ZF, Greenberg MF. Results and complications in 66 cases using a silicone tendon expander on overaction superior obliques with A-pattern anisotropies. Binocul Vis Strabismus Q 2000;15: 113-20. 3. Guyton DL. Clinical assessment of ocular torsion. Am Orthoptic J 1983;33:7-15. 4. Donahue SP, Lavin PJM, Mohney B, Hamed L. Skew deviation and inferior oblique palsy. Am J Ophthalmol 2001;132:751-6. 5. Demer JL, Clark RA, Kono R, Wright W, Velez F, Rosenbaum AL. A 12-year, prospective study of extaocular muscle imaging in complex strabismus. JAAPOS 2002;6:337-47. 6. Scott WE, Nankin SJ. Isolated inferior oblique paresis. Arch Ophthalmol 1977;95:1586-93. 7. Olivier P, von Noorden GK. Results of superior oblique tenectomy in inferior oblique paresis. Arch Ophthalmol 1982;100:581-4. 8. Kutschke PJ, Scott WE. Postoperative results in inferior oblique palsy. J Pediatr Ophthalmol Strabismus 1996;33:72-8. 9. Pollard ZF. Diagnosis and treatment of inferior oblique palsy. J Pediatr Ophthalmol Strabismus 1993;30:15-8.
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From the Eye Consultants of Atlanta, Children’s Healthcare of Atlanta at Scottish Rite, Atlanta, Georgia. Presented at the AAPOS meeting Washington, DC, March 2004. Supported by a grant from the James Hall Foundation. Submitted March 9, 2004. Revision accepted April 4, 2005. Reprint requests: Marc Greenberg, MD, 5445 Meridian Mark Road, Suite 220, Atlanta, GA 30327. Copyright © 2005 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/2005/$35.00 ⫹ 0 doi:10.1016/j.jaapos.2005.04.003
Journal of AAPOS
thought to decrease the risk of causing SO paresis as compared with full SO tenotomy or tenectomy. We have previously reported a series of 71 patients with A-pattern strabismus in which overacting SO muscles were effectively weakened by use of a silicone tendon expander.2 In 66 patients with bilateral SO overaction, collapse of the A patterns and resolution of SO overaction were successful in all cases, with no iatrogenic SO pareses. In the same report,2 5 cases of IO paresis also were reported on briefly; 4 resolved successfully and 1 did have consecutive SO paresis. In this retrospective review, we examine cases of IO paresis treated with unilateral SO tendon expander subsequent to our previous report and report results with specific attention to vertical strabismus, ocular torticollis, cyclotorsion, and SO overaction.
SUBJECTS AND METHODS A retrospective review of both authors’ surgical logs was made to identify all patients with a diagnosis of IO paresis who were treated using SO tendon expanders between 1997 and 2002. Eight consecutive patients were identified. All had a positive 3-step test for IO paresis, as well as incyclotorsion and SO overaction of the hypotropic (paretic) eye. Unless noted, all patients were healthy. None had a history of head trauma or neurologic abnormality. Intraoperative forced duction testing of elevation in adduction revealed no Brown’s syndrome in any patient. All patients had surgical placement of a 7- mm long segAugust 2005
341
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342 Greenberg and Pollard ment of a 0.75- ⫻ 2-mm #40 silicone retina circling band (Baush and Lomb Surgical, St. Louis, MO) sutured between the severed ends of the SO tendon in the hypotropic (paretic) eye. The SO tendon was cut at least 5 mm nasal to the nasal border of the superior rectus muscle. Two 7-0 Prolene® (Ethicon, Inc., Somervile, NJ) double-armed sutures on a BV-1 needle were used to secure the tendon expander to the severed tendon ends. The #40 retina band used is smaller than the #240 band originally used by Wright1 and is more similar in size to the SO tendon itself. No other simultaneous strabismus surgery was performed. All cases, except case 1, were performed with particular attention to leaving an intact Tenon’s capsule between the tendon expander and the sclera because entering the subTenon’s space while placing a SO tendon expander may result in a severe postoperative sterile orbital inflammatory response and resultant iatrogenic Brown’s syndrome.2 Case 1 was performed before our recognition of this complication. Data recorded included (except where noted): visual acuity, preoperative and postoperative strabismus measurements in the 9 diagnostic fields of gaze plus head tilts, clinical estimate of degrees of head tilt or face turn, clinical grading of SO overaction (scored 1-4⫹), measure of fundus cyclotorsion as described by Guyton3 (scored 1-4⫹) or, if possible, by double Maddox rod (DMR), Worth 4-Dot (W4D), and Titmus stereo testing (Stereo Optical Inc, Chicago, IL). SO overaction was graded with the contralateral eye in level abduction: 1⫹ if the adducting eye depressed slightly on adduction, 2⫹ if more than half the cornea of the adducting eye was covered by the lower eyelid, 3⫹ if at most a small crescent of cornea was present in the adducting eye, and 4⫹ if the adducting eye rotated further downward so as to start abducting. Preoperative versus postoperative measurements of primary position hypotropia, SO overaction, and head tilts were compared using the Wilcoxon signed rank test.
surgery, the Tenon’s capsule posterior to the SO was violated and, within 48 hours, a significant orbital inflammatory response resulted. Oral prednisone treatment reduced the inflammation; however, a postoperative Brown’s syndrome resulted, with elevation limited in adduction. Despite this complication, the head tilt completely resolved, and the right face turn decreased to 15 degrees during the next 6 months. At last follow-up, 6 years after surgery, there was essentially no head tilt or face turn. The patient was orthophoric except for a mild residual Brown’s (right eye elevates up to 20 degrees in adduction). There was no SO overaction and no cyclotorsion by double Maddox rod. Titmus stereo showed 40 seconds arc and Worth 4-Dot (W4D) testing showed near and distance fusion. Case 2 A 7-year old girl with Down’s syndrome presented with a longstanding 30-40 degree right head tilt. (See Figures 1 and 2. Video available in the electronic journal format at www.mosby.com/jaapos.) Other than developmental delay, there were no neurologic abnormalities. She had been treated elsewhere at an early age for accommodative esotropia, with resulting excellent control and no amblyopia. There was essentially no eye crossing with or without glasses; however, an intermittent right hypotropia of 6 PD was present in right gaze and the primary position. The right hypotropia increased to 8 PD in left gaze and to 16 PD or more in left downgaze. The right hypotropia decreased to 4 PD in right head tilt, but increased to 12 PD in left head tilt. There was 3⫹ SO overaction on the right, and right fundus incyclotorsion was noted by indirect ophthalmoscopy but not graded. Sensory testing could not be performed. A 7- mm right SO tendon expander was placed, with significant reduction in the right head tilt within days of the surgery. Six months after surgery, a 15-degree right
SELECTED CASE REPORTS Case 1 A 21-month-old boy presented for evaluation of possible ocular torticollis. His vision was central, steady, and maintained in both eyes. He had a preferred head position in 30 degrees left face turn and 10 degrees right head tilt. He was orthophoric in right gaze but had a right hypotropia of 4 prism diopters (PD) in the primary position, increasing to 8 PD in left gaze. The right hypotropia measured 12 PD in left downgaze, with a small exotropia in downgaze only. The right hypotropia measured 4 PD in left head tilt but was not present on right head tilt. There was 2-3⫹ SO overaction on the right. Indirect funduscopy showed 2⫹ incyclotorsion on the right. A right IO paresis was diagnosed and treated by placement of a 7- mm right SO tendon expander. During
FIG 1. Case 2 preoperatively shows large right head tilt ocular torticollis. Preoperative ocular motility video may be viewed at www.mosby.com/jaapos.
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right SO overaction, with 2⫹ right fundus incyclotorsion by indirect ophthalmoscopy. Sensory testing was not performed because of patient age. The presumed right IO paresis was treated with a 7- mm right SO tendon expander. Two months postoperatively, her right hypotropia, SO overaction, and fundus incyclotorsion were all resolved. The right head tilt had resolved; however, a 15 degree left face turn persisted. A year later, the patient presented with a prominent right dissociative vertical deviation. She underwent recession 6.0 mm of the right SR. Two years after this surgery, her vision was 20/20 OU, with orthophoria in all fields of gaze. Her abnormal face turn had resolved. She still suppresses the W4D at distance, but fuses at near. FIG 2. Case 2 at 3 months after right SO tendon expander. Ocular torticollis markedly improved. Postoperative ocular motility video may be viewed at www.mosby.com/jaapos.
head tilt persisted, with a right hypotropia of 4 PD seen only in gaze to the left and in left head tilt. Two years after surgery, the patient was orthotropic in all fields, including tilts; however, the 15-degree right head tilt remained. There was no SO overaction and no fundus cyclotorsion. Case 5 A 24-year-old woman complained of diplopia despite wearing prisms in her glasses since the age of 9. Her vision was 20/20 OD and 20/25 OS, and there was no abnormal head position. She measured 4 PD right hypotropia on right gaze, with 6 PD in the primary position and in gaze to the left. The right hypotropia measured 14 PD in gaze down and to the left but only 8 PD up and to the left. There was 4 PD right hypotropia in right head tilt, and 8 PD on tilt to the left. There was 2⫹ right SO overaction and 8 degrees right incyclotorsion on DMR. Despite glasses with 3.5 PD base up OD and 3.0 PD base down OS, there was no fusion on W4D or Titmus stereo testing. The patient underwent a right 7- mm silicone SO tendon expander. Two weeks postoperatively, she was orthophoric in all fields. SO overaction had resolved and there was no cyclotorsion by DMR. Titmus stereo testing showed 40 seconds of arc. The findings were stable at 1 year follow up. Case 7 A 3-1/2-year old girl presented with strabismus and torticollis. Her vision was central, steady, and maintained OU. She preferred a 15-degree left face turn with 10-degree right head tilt position. She was orthophoric on gaze to the right but showed 2 PD of right hypotropia in the primary position, which increased to 10 PD on gaze to the left. The right hypotropia increased further to 20 PD on gaze down and to the left, but only measured 10 PD on gaze up and to the left. The hypotropia measured 8 PD on left head tilt, with orthophoria on right head tilt. There was 3⫹
RESULTS Mean preoperative primary position hypotropia was 6.5 ⫾ 2.8 PD; mean postoperative was 0.5 ⫾ 1.4 PD (P ⫽ 0.008). Seven of 8 patients had complete resolution of primary position hypotropia, whereas the eighth was reduced. Mean graded preoperative SO overaction was 3.0 ⫾ 0.7; all patients had postoperative resolution of SO overaction (P ⫽ 0.008; Table 1). Of 4 patients with preoperative ocular torticollis, mean head tilt was 9.3 ⫾ 12.4 degrees; postoperatively, mean tilt was 2.9 ⫾ 5.7 degrees (P ⫽ 0.125). Two patients’ head tilts had resolved, the other 2 showed improvement. Of the 2 patients with preoperative face turns, one resolved completely after tendon expander placement, whereas the second persisted. The second patient’s face turn did resolve after subsequent surgery for dissociative hypertropia, suggesting that the cause of the face turn may not have been IO paresis. All patients showed preoperative incylclotorsion of the hypotropic (paretic) eye; the inclyclotorsion resolved in all patients after the placement of a SO tendon expander. Four of 8 patients could cooperate for sensory testing preoperatively; none showed evidence of binocularity. At the most recent follow-up visit, 6 of the 8 could perform sensory testing; 5 of 6 showed binocularity by Titmus testing, Worth-4-Dot, or both.
DISCUSSION In this review, 8 cases of IO paresis were each treated with a SO tendon expander in the hypotropic (paretic) eye. Primary position hypotropia, SO overaction, and ocular incyclotorsion resolved in most of the patients, with the remainder showing definite improvement. Of 4 patients with preoperative compensatory head tilts toward the hypotropic (paretic) side, all had decreased head tilt postoperatively, although one with dissociative vertical deviation required a subsequent surgery to improve a face turn. Sensory fusion improved in most of those who could be tested. We believe the specific amount (or range) of primary position hypotropia corrected in this study may not be as
Journal of AAPOS Volume 9 Number 4 August 2005
344 Greenberg and Pollard TABLE 1. Patient data
Case no.
Age
FollowUp
1 2 3 4 5 6 7 8 Mean (SD)
21 mo 7 yr 8 yr 39 yr 24 yr 12 yr 3 yr 9 yr 12.9 yr (12.5)
6 yr 2 yr 2 mo 1 yr 1 yr 1 yr 3 yr 6 mo 1.8 yr (1.9)
Superior oblique overaction*
Primary position hypotropia (PD)
Head tilt (degrees)
Face turn (degrees)
Incyclotorsion†
Preop
Postop
Preop
Postop
Preop
Postop
Preop
Postop
Preop
Postop
4 6 6 8 6 10 2 10 6.5 PD (2.8)
0 0 0 4 0 0 0 0 0.5 PD (1.4)
2.5 3 2.5 4 2 3 3 4 3 (0.7)
0 0 0 0 0 0 0 0 0 (0)
10 35 0 0 0 10 10 n/a‡ 9.3 (12.4)
0 15 0 0 0 5 0 n/a‡ 2.9 (5.7)
30 0 0 0 0 0 15 n/a‡
0 0 0 0 0 0 15§ n/a‡
2⫹ ⫹¶ 2.5⫹ 5 deg 8 deg 5 deg 2⫹ 15 deg
0 0 0 0 0 0 0 3 deg
¶Incyclotorsion noted preop but not graded in records. *Superior oblique overaction graded 0 to 4 (see Methods). †Estimated 0 to 4 if Double Maddox Rod (degrees) could not be done. No mean given because of differing measurement scales. ‡n/a ⫽ measurements not recorded in patient’s chart. §Face turn resolved after subsequent dissociated hypertropia surgery. No mean given because small sample size.
important as the fact that SO overaction and ocular cyclotorsion resolved in nearly every case, allowing fusion in most cases. In case 5, for example, the adult patient could not fuse despite prism glasses corresponding to her primary position vertical strabismus. Lack of fusion may have resulted from the incomitance of the vertical strabismus, from the presence of cyclotorsion, or from both. After tendon expansion, all of these abnormalities were improved, and the patient’s high level stereopsis was recovered. IO paresis is a rare diagnosis and must be distinguished from several entities. Brown’s tendon sheath syndrome may simulate underaction of the IO muscle but typically does not show increased vertical deviation on head tilt testing. Brown’s syndrome also is more likely to show a Y-pattern strabismus rather than the A pattern, which may be seen in IO paresis. The sine quo non of Brown’s syndrome, however, is mechanical restriction to attempted forced elevation in adduction, and all patients presented here showed free rotations. Inferior rectus muscle paresis behaves like contralateral IO paresis on the first 2 steps of the 3-step test. Both show a hypotropia in the primary position, which increases with adduction of the hypotropic eye. The third step differentiates the entities; the vertical strabismus in IR paresis increases with head tilt toward the hypotropic eye, whereas in IO paresis, the strabismus increases in head tilt away from the hypotropia, as in all the patients reviewed here. Donahue et al4 noted that vertical skew deviation may exactly mimic IO paresis on the 3-step test, and may be clinically distinguished only on the basis of ocular cyclotorsion. They presented 6 such patients, each showing excyclotorsion of the hypotropic eye and incyclotorsion of the hypertropic eye. In contrast, the patients in this review with IO paresis all showed incyclotorsion of the hypotropic eyes. Additionally, the patients with skew deviation had significant neurologic events, like strokes or traumatic
brain injuries, as opposed to most patients with isolated IO paresis, including those presented in this study, who typically have no neurologic history. Demer et al5 have noted that some cases of presumed eye muscle palsies and/or overactions may actually be mechanical, rather than neurologic, in origin. They presented magnetic resonance imaging and computed tomography scan evidence of oculomotor muscle and orbital connective tissue anomalies to illustrate this principle. We use the terms “IO paresis” and “SO overaction” to describe specifically defined patterns of abnormal extraocular muscle movements, while recognizing that we cannot be completely certain of the true etiology of the strabismus we observed. Nevertheless, regardless of etiology, the tendon expander was a useful treatment modality in all of our cases presenting with the following clinical pattern of strabismus: positive 3-step test for IO paresis, incyclotorsion and SO overaction of the hypotropic eye, greatest vertical strabismus in the field of the overacting SO, and negative forced duction test for Brown’s syndrome. Scott and Nankin6 first reported using SO free tenectomy to treat 6 cases of isolated IO paresis. All 6 patients showed improvement initially; however, follow-up time was limited to a mean of 5 months in 5 of the 6 cases. Olivier and von Noorden7 subsequently reported 3 of 6 similar patients who developed consecutive iatrogenic SO paresis after SO tenectomy. Two of the 3 patients took 1-1/2 and 2 years, respectively, to require additional surgery, suggesting late overcorrection may be an issue. Kutschke and Scott8 later updated their experience with IO paresis and did eventually note iatrogenic SO palsies. In Pollard’s review of 25 isolated IO palsies, 2 of 16 patients treated with SO tenotomy developed consecutive SO palsy.9 Our previous report on SO tendon expanders showed successful resolution of A-pattern strabismus and bilateral SO overaction in 66 cases.2 Previously, when performing
Journal of AAPOS Volume 9 Number 4 August 2005
SO free tenectomies for A-pattern strabismus, we encountered frequent consecutive SO paresis, as well as torsional symptoms, in our patients. The use of the tendon expander has all but eliminated these complications in hundreds of subsequent cases, and we now consider this our technique of choice for bilaterally weakening overacting SO muscles. In our previous report,2 of the 5 patients with IO paresis treated with SO tendon expander, one did develop consecutive SO paresis. Combined with the results of this study, our incidence of SO paresis after IO pareses treated with the tendon expander is thus 1 in 13. Although this ratio is an improvement over previous reports, the small number of cases limits any firm statistical conclusions. However, on the basis of our experience of SO tendon expanders in bilateral A-pattern strabismus, we would predict the actual incidence of consecutive SO paresis will probably be even lower. Our study of the SO tendon expander in bilateral Apattern strabismus was limited to patients with 3⫹ and 4⫹ SO overaction, and all patients received 7- mm size tendon expanders. Although several cases treated successfully in this study had 2-3⫹ SO overaction, patients with IO paresis and milder SO overaction could receive shorter sized tendon expanders to reduce the chance of iatrogenic SO paresis. Additionally, should iatrogenic SO paresis occur after placement of the tendon expander, one potential treatment option would be to replace the expander with one of shorter length. In contrast, revision of a SO tenotomy or tenectomy following such a complication would be difficult, if not impossible, in most cases.
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In conclusion, our results suggest the SO tendon expander can be used to reduce hypotropia, ocular torsion, and unilateral SO overaction in the setting of IO paresis with SO overaction. Associated ocular torticollis and binocularity can also be improved. We believe the tendon expander offers many advantages over tenotomy or tenectomy and this is now our procedure of choice for treating cases of IO paresis with SO overaction.
References 1. Wright K. Superior oblique silicone expander for Brown syndrome and superior oblique overaction. J Pediatr Ophthalmol Strabismus 1991;28:101-7. 2. Pollard ZF, Greenberg MF. Results and complications in 66 cases using a silicone tendon expander on overaction superior obliques with A-pattern anisotropies. Binocul Vis Strabismus Q 2000;15: 113-20. 3. Guyton DL. Clinical assessment of ocular torsion. Am Orthoptic J 1983;33:7-15. 4. Donahue SP, Lavin PJM, Mohney B, Hamed L. Skew deviation and inferior oblique palsy. Am J Ophthalmol 2001;132:751-6. 5. Demer JL, Clark RA, Kono R, Wright W, Velez F, Rosenbaum AL. A 12-year, prospective study of extaocular muscle imaging in complex strabismus. JAAPOS 2002;6:337-47. 6. Scott WE, Nankin SJ. Isolated inferior oblique paresis. Arch Ophthalmol 1977;95:1586-93. 7. Olivier P, von Noorden GK. Results of superior oblique tenectomy in inferior oblique paresis. Arch Ophthalmol 1982;100:581-4. 8. Kutschke PJ, Scott WE. Postoperative results in inferior oblique palsy. J Pediatr Ophthalmol Strabismus 1996;33:72-8. 9. Pollard ZF. Diagnosis and treatment of inferior oblique palsy. J Pediatr Ophthalmol Strabismus 1993;30:15-8.