Mims et al, Anti elevation syndrome after anterior transposition of the ...

Journal of AAPOSVolume 3 Number 6 December 1999Mims and Wood 335TABLE 1. AES cases corresponding to each degree of anterior transposition and lateral displacement of the IO musclemm temporal to lateral end of IR muscle(X, lateral displacement) 1 mm 2 mm 3 mm 4 mm 5 mmmm anterior to lateral end of IR muscle 4 mm 0/1 0/0 0/6 1/4 1/4(Y, anterior transposition) 3 mm 0/0 0/1 0/4 1/5 0/32 mm 0/15* 0/1 5/46 3/30 5†/171 mm 0/31* 0/0 0/1 0/1 0/10 mm 0/29*The numerator of each fraction is the number of cases of AES; the denominator is the total cases with a specific level of anterior transposition (mm anterior to a line drawn laterallyfrom the IR muscle insertion) and lateral spreading (mm lateral to the lateral end of the IR muscle insertion).*All of these cases are from Kushner. 2†Two of these 5 cases are from Kushner. 2TABLE 2. Various group characteristics among Mims’ patients (N = 123)Comparisons of those who did and did not have AESMo of follow-up* Patient age at MROU (mo) Patient age at ATIO (mo) OAIOAll who did not have AES (N = 109)87.2 ± 4.2 22.4 ± 2.0 35.5 ± 2.3 1.9 ± 0.07All who did have AES (N = 14)45.5 ± 4.3 18.2 ± 3.8 29.4 ± 4.4 2.0 ± 0.14Comparisons among those whose IO muscleswere placed 2 mm or more anterior to aline drawn laterally from the insertion of theIR muscle with 3, 4, or 5 mm of lateral displacementMo of follow-up* Patient age at MROU (mo) Patient age at ATIO (mo) OAIO3 mm: posterior IO muscle insertion placed at X,Y of 3,4 or 3,3 or 3,2. (N = 56)81.8 ± 5.4 24.7 ± 3.1 44.8 ± 5.0 1.8 ± 0.14 mm: posterior IO muscle insertion placed at X,Y of 4,4 or 4,3 or 4,2. (N = 39)69.8 ± 6.3 21.7 ± 2.9 31.6 ± 3.7 1.8 ± 0.095 mm: posterior IO muscle insertion placed at X,Y of 5,4 or 5,4 or 5,2. (N = 22)97.9 ± 10.8 15.1 ± 3.4 43.2 ± 5.4 2.2 ± 0.16The ± designates ± 1 SE of the mean.*Months of follow-up is after the ATIO and extends to either the surgical date for AES or to the last visit in the office.MROU, Bilateral medial rectus muscle recession.Kushner 2 extended this idea to explain an abnormalmotility pattern he observed in some patients after bilateralATIO. This pattern resembles marked recurrent OAIOassociated with a Y or V pattern and exotropia in upgaze.Small alternating hypertropias (right hypertropia in leftgaze and left hypertropia in right gaze) may be present infar side gazes, but these hypertropias are much smallerthan those seen in cases of primary OAIO with a similarappearance on version testing. A limitation of elevation ofthe abducting eye is frequently demonstrable. Kushner 2has hypothesized that this complication of ATIO is producedprimarily by the posterior fibers of the IO muscle.In this study, all 16 patients with AES had receivedbilateral anterior transposition of the posterior fibers ofthe IO muscle to at least 2 mm anterior to the lateral endof the IR muscle, with displacement 3 to 5 mm lateral tothe lateral end of the IR muscle insertion. Is the incidenceof AES increased with more lateral displacement of theTABLE 3. AES: dependence on amount of anterior transposition and lateraltransposition (percentages of patients with AES after ATIO)X (lateral displacement)Y (anterior transposition) 0-2 mm 3 mm 4 mm 5 mm0-1 mm 0% 0% 0% 0%2-4 mm 0% 8.9% 12.8% 25%These percentages were derived from the data in Table 1.This progression in incidence of AES with more spreading out of the new IO muscleinsertion laterally was significant (P = .011).posterior fibers of the IO muscle? When we combined ourpatients with those previously reported on by Kushner, 2we found that for those patients with posterior fibers of theIO muscle placed at least 2 mm directly anterior to the lateralend of the IR muscle, the amount of lateral displacementof the new IO muscle insertion significantly