Unilateral Superior Oblique Palsy Research Articles

Predictive factors for corrective effect of inferior rectus recession for congenital superior oblique palsy.

To identify preoperative factors associated with the surgical corrective effect of contralateral inferior rectus recession (IRR) for vertical deviation in patients with congenital superior oblique palsy (SOP). This retrospective study included 20 treatment-naïve patients with unilateral congenital SOP (age range, 6-79years) who underwent contralateral IRR according to our basic policy to select IRR for paretic eye fixation. The corrective effect (°/mm) of IRR was defined as the difference in the vertical deviation at the primary gaze position between before and 6-18months after surgery per distance of recession. We also measured the preoperative vertical deviation at primary and secondary gaze positions, and vertical deviation with head-tilting, and calculated the difference in vertical deviation between these positions. We analyzed the correlation between the corrective effect of IRR and these study parameters. The mean corrective effect of IRR was 2.4±1.6°/mm, which had a significant correlation with preoperative differences in vertical deviation between the primary gaze position and the downward (P=0.004, r=-0.61) and contralateral gaze positions (P=0.03, r=-0.48); and the presence of preoperative stereopsis (P=0.02, r=-0.51). After excluding a statistical outlier, the correlation between the corrective effect and the difference between the primary and contralateral gaze positions was no longer significant (P=0.07), while the other two relationships remained significant. Our findings suggest that preoperative differences in vertical deviation between the primary and downward gaze positions and the presence of preoperative stereopsis are important considerations prior to performing IRR for congenital SOP, particularly with paretic eye fixation.

Ocular Torsion According to Trochlear Nerve Absence in Unilateral Superior Oblique Palsy.

To investigate the relationship between objective ocular torsion and the presence or absence of the trochlear nerve in subjects with unilateral superior oblique palsy (SOP). A total of 159 subjects with congenital and acquired unilateral SOP were reviewed. Eighty-four subjects who had a normal trochlear nerve (present group) and 75 subjects without a trochlear nerve (absent group) were included. Cyclovertical motility parameters and objective ocular torsion were compared between groups, and factors related to ocular torsion were evaluated. The degree of "net" excyclotorsion in the paretic eye was larger in the absent group compared to the present group (P = 0.002). The proportion of net excyclotorsion in the paretic eye was greater in the absent group (11% vs. 37%), while net incyclotorsion was greater in the present group (41% vs. 23%) (P < 0.001). Net excyclotorsion of the paretic eye was associated with absence of the trochlear nerve (P < 0.001) and smaller size of the paretic SO (P < 0.001). Net incyclotorsion of the paretic eye was related with a normal trochlear nerve (P = 0.005), larger size of the paretic SO (P = 0.002), and greater hypertropia during ipsilateral gaze (P = 0.024). The status of the trochlear nerve, paretic SO size, and hypertropia during ipsilateral gaze which reflects the tensile strength of the ipsilateral superior rectus, significantly contribute to ocular torsion in unilateral SOP.

Does Decreased Static Ocular Counter Rolling Account for Bielschowsky Head Tilt Test in Unilateral Superior Oblique Palsy?

To understand the relationship of static ocular counter rolling (s-OCR) and clinical manifestations in acquired unilateral superior oblique palsy subjects during the Bielschowsky head tilt test. Nineteen subjects that were diagnosed with acquired unilateral superior oblique palsy were included. Fundus photographs were obtained at different head tilt angles to evaluate static ocular counter rolling using a fundus camera with a cervical range of motion device. Using a graphics editing program, we calculated s-OCR from fundus photography. The incycloductional s-OCR (OCR-I) in the paretic eye was significantly smaller than the OCR-I in the fellow eye (P = 0.02, <0.001, 0.002 for 10°, 20°, and 30°, respectively, paired t-tests). In contrast, the excycloductional s-OCR (OCR-E) showed no significant difference between the paretic eye and the fellow eye for all angles. There was a significantly positive correlation between the amplitude of OCR-I in the paretic eye and the degree of hypertropia on ipsilesional head tilt (ρ = 0.612, 0.679, 0.474, P = 0.02, 0.002, 0.07 for 10°, 20°, and 30° respectively, Spearman's correlation). The amplitude of OCR-I in the paretic eye also showed a positive correlation with head tilt test difference, which is the degree of hyperdeviation difference between ipsilesional and contralesional head tilts (ρ = 0.445, 0.694, 0.579, P = 0.09, 0.002, 0.024 for 10°, 20°, and 30° respectively, Spearman's correlation). In unilateral SOP, OCR-I in the paretic eye was smaller than that in the fellow eye, and this was positively associated with the degree of hypertropia during ipsilesional head tilting, as well as the head tilt test difference.

The influence of ocular sighting dominance on Fundus torsion in patients with unilateral congenital superior oblique palsy.

The purpose of our study was to determine whether ocular sighting dominance may influence the ocular torsion in patients with unilateral congenital superior oblique palsy (UCSOP). This retrospective study included 22 UCSOP patients with radiologic evidence of unilateral superior oblique muscle hypoplasia on orbital magnetic resonance imaging and 66 healthy individuals with normal ocular motility as controls. Ocular torsion was assessed both quantitatively and qualitatively using digital fundus photography. The disc-fovea angle (DFA) was measured quantitatively using image software on a computer screen. All fundus photographs were qualitatively graded as normal torsion, extorsion, or intorsion in all subjects, based on the location of the optic disc relative to the fovea, according to the Bixenman and von Noorden's criteria. Ocular sighting dominance was assessed by the hole-in-the-card test and the pointing test. The Mann-Whitney U test and Fisher's exact test were used to determine the association between the ocular sighting dominance and the ocular torsion. The median DFA was significantly larger in the eyes of patients with UCSOP (9.1° in the paretic eyes and 9.3° in the non-paretic eyes) than the eyes of the control group (4.3°, p<0.001 for both). Ocular dominance tests displayed that, among 22 patients, 11 were paretic eye dominant and the other 11 were non-paretic eye dominant. The sighting-dominant eyes demonstrated significantly smaller median DFA than the non-dominant eyes (8.3° and 10.7°, respectively, p=0.033), regardless of which eyes were paretic. Ten eyes of ten patients had extorsion, none had intorsion, and all the eyes of remaining 12 patients had no abnormal torsion, qualitatively. All the eyes showing extorsion in fundus photography were non-dominant eyes, regardless of whether the eyes were paretic or non-paretic. Our findings illuminate the importance of considering ocular sighting dominance for properly assessing ocular torsion in patients with UCSOP. Ocular sighting dominance may have an influence on objective ocular torsion in a way that decreases the torsion in the dominant eye, thereby hindering the abnormal ocular torsion from appearing in that eye.

Are we overlooking masked bilateral congenital superior oblique palsy in children: is it possible to diagnose before surgery?

To describe the characteristics of children who had subsequent contralateral superior oblique underaction (SOUA) and inferior oblique overaction (IOOA) after unilateral inferior oblique weakening surgery and to identify suggestive clinical features for masked bilateral fourth nerve palsy. The medical records of children who underwent unilateral inferior oblique tenotomy as a single procedure for unilateral superior oblique palsy were all reviewed. Diagnosis was based on evaluation of ocular misalignment in nine diagnostic gaze positions and presence of SOUA, IOOA, and abnormal head position. The study was conducted with 29 children. All children had preoperative unilateral IOOA and SOUA. Eleven children (37.9%) had hyperesodeviation in the affected eye, while others (62.1%) had hyperexodeviation. The mean age at surgery was 6.66±1.87 (4-10) years. The mean vertical deviation, exodeviation, and the amount of IOOA were decreased postoperatively (p<0.001 for all). Among the 29 children, 22 had no residual ipsilateral IOOA, 2 had ipsilateral IOOA, and 5 had ipsilateral inferior oblique underaction (IOUA) at last visit. Three children had contralateral SOUA, IOOA, and hyperdeviation at follow-up visits, one of whom had IOUA on the operated eye. There was no difference of preoperative features between children with or without subsequent contralateral superior oblique palsy. Bilateral congenital superior oblique palsy may be overlooked in children in spite of detailed preoperative evaluation. Masked bilaterality should always be kept in mind in cases with unilateral pathology. Patients should be informed about the possibility of bilaterality.

Effect of modified graded recession and anteriorization on unilateral superior oblique palsy: a retrospective study

BackgroundSeveral inferior oblique (IO) weakening methods exist for correction of superior oblique palsy (SOP). A previously reported method involved recession and anteriorization according to IO overaction (IOOA) grade, which might be subjective and cause upgaze limitation and opposite vertical strabismus. Therefore, this study attempted to examine the efficacy of modified graded recession and anteriorization of the IO muscle in correction of unilateral SOP without resulting in upgaze limitation or opposite vertical strabismus.MethodsA total of 26 patients (male, 16; female, 10; age: 3–40 years) with SOP and head tilt or diplopia underwent modified graded recession and anteriorization. Patients were grouped by the position at which the IO muscle was attached inferior/temporal to the lateral border of the inferior rectus (IR) as follows: (1) 7.0/2.0 mm (4 patients), (2) 6.0/2.0 mm (3 patients), (3) 5.0/2.0 mm (3 patients), (4) 4.0/2.0 mm (11 patients), (5) 3.0/0.0 mm (2 patients), and (6) 2.0/0.0 mm (3 patients). Recession and anteriorization were matched to vertical deviation in the primary position at far distance. Remaining diplopia, head tilt, vertical deviation (≤3 prism diopter (PD), excellent; 4–7 PD, good; and ≥ 8 PD, poor), upgaze limitation, and opposite vertical strabismus were evaluated.ResultsThe average pre and postoperative 1-year vertical deviation angles in the primary position at far distance were 15.0 ± 5.6 PD and 1.2 ± 2.0 PD, respectively. At 1 year post-surgery, the vertical deviation angles were reduced by 6.8–21.0 PD from those at baseline. Few patients exhibited remaining head tilt, diplopia, upgaze limitation, or opposite vertical strabismus. Correction of hypertropia was excellent in 22 and good in 4 patients.ConclusionsModified graded recession and anteriorization of the IO muscle is an effective surgical method for treating unilateral SOP. It exhibits good results and reduces the incidence of opposite vertical strabismus.

The observation on efficacy of surgery for congenital unilateral superior oblique palsy

Objective To observe the efficacy of the surgery for congenital unilateral superior oblique palsy. Methods The medical records of 124 patients that underwent surgery for congennital unilateral superior oblique palsy from Oct. 2014 to Dec.2015 at Shanxi Eye Hospital were retrospectively reviewed. The chinical feature, the surgical procedures and efficacy were analyzed. Results The patients were followed up for 5-14 months after surgery. There were 110 cases recovered(88.71%), 12 cases improved(9.68%), and 2 cases invalid(1.61%). Conclusion Surgery is an effective method for congenital superior oblique palsy, the effectiveness rate is over 98%. Key words: Superior oblique palsy, congenital, unilateral; Surgery; efficacy

Extraocular Muscle Compartments in Superior Oblique Palsy.

PurposeTo investigate changes in volumes of extraocular muscle (EOM) compartments in unilateral superior oblique (SO) palsy using magnetic resonance imaging (MRI).MethodsHigh-resolution, surface-coil MRI was obtained in 19 patients with unilateral SO palsy and 19 age-matched orthotropic control subjects. Rectus EOMs and the SO were divided into two anatomic compartments for volume analysis in patients with unilateral SO palsy, allowing comparison of total compartmental volumes versus controls. Medial and lateral compartmental volumes of the SO muscle were compared in patients with isotropic (round shape) versus anisotropic (elongated shape) SO atrophy.ResultsThe medial and lateral compartments of the ipsilesional SO muscles were equally atrophic in isotropic SO palsy, whereas the lateral compartment was significantly smaller than the medial in anisotropic SO palsy (P = 0.01). In contrast to the SO, there were no differential compartmental volume changes in rectus EOMs; however, there was significant total muscle hypertrophy in the ipsilesional inferior rectus (IR) and lateral rectus (LR) muscles and contralesional superior rectus (SR) muscles. Medial rectus (MR) volume was normal both ipsi- and contralesionally.ConclusionsA subset of patients with SO palsy exhibit selective atrophy of the lateral, predominantly vertically acting SO compartment. Superior oblique atrophy is associated with whole-muscle volume changes in the ipsilesional IR, ipsilesional LR, and contralesional SR; however, SO muscle atrophy is not associated with compartmentally selective volume changes in the rectus EOMs. Selective compartmental SO pathology may provide an anatomic mechanism that explains some of the variability in clinical presentations of SO palsy.

The effect of superior oblique tucking on the Bielschowsky head tilt test

To investigate the effect of superior oblique tucking on the Bielschowsky head tilt test. A retrospective analysis of 22 patients with congenital unilateral superior oblique palsy, who underwent tucking of the superior oblique tendon in Tianjin Eye Hospital, depending on vertical deviation in the primary position, ocular motility, objective cyclotorsion and abnormal head posture. Bielschowsky head tilt test was evaluated quantitatively by the prism cover test. Α positive Bielschowsky head tilt test was defined as one in which the vertical deviation when the head tilt to the side of the paresis was at least 5. 0(△) greater than that on tilt to the uninvolved side. The follow-up period ranged from 3 to 12 months (mean 4.6 months). Kolmogorov-Smirnov (K-S), Rank sum test and Spearman correlation analysis statistical methods were used in this study. All patients had vertical deviation and significant abnormal head posture before operation. After the procedure of superior oblique tucking,vertical deviation and symptom of unacceptable abnormal head posture were ameliorated or disappeared. OBJECTIVE torsion was 15.62°±7.36° before the surgery, 9.91°±10.09°1d after the surgery and 11.25°±9.17°at the last follow-up visit, respectively (P<0.05). We found that there were positive correlations between the objective cyclotorsion and the vertical deviation difference value between the paralyzed side and uninvolved side at 1 d after the surgery and last follow-up visit(P<0.05). The vertical deviation of the paresised eye when the head tilted to the side of paresis side and uninvolved side difference were 5.00(△)-17.00(△), average 8.68(△)±3.23(△), 1.00(△)-8.00(△),average 3.36(△)±2.01(△) and 0.00(△)-14.00(△),average 3.77(△)±3.01(△), preoperatively, 1d after the surgery and at the last follow-up visit respectively. Using Rank sum test, the pre-and postoperative difference was statistically significant (Z=-4.64, P<0.01). A positive Bielschowsky head tilt test was found in all cases preoperatively. The results of Bielschowsky tilt test was still positive in 5 cases and negative in 17 cases (77.3%). In most cases with unilateral superior oblique paresis, the results of Bielschowsky tilt test became negative after superior oblique tucking. The long-standing results is worthy of observation. (Chin J Ophthalmol, 2016, 52: 589-595).

Incidence and pathophysiology of inferior oblique overaction after surgery for unilateral superior oblique palsy

Incidence and pathophysiology of inferior oblique overaction after surgery for unilateral superior oblique palsy

Surgical Outcomes of Inferior Oblique Myectomy in Unilateral Congenital Superior Oblique Palsy with or without Trochlear Nerve

ObjectivesTo compare the surgical outcomes of inferior oblique (IO) myectomy in congenital superior oblique palsy (SOP) according to the presence of the trochlear nerve identified with high-resolution MRI.Data ExtractionForty-one congenital SOP patients without a trochlear nerve (absent group) and 23 patients with a trochlear nerve (present group) who underwent IO myectomy as the primary surgical treatment were retrospectively reviewed. “Motor success” was defined as postoperative ipsilateral hypertropia ≤ 4 prism diopter (PD). “Head tilt improvement” was regarded as postoperative angle of head tilt < 5 degrees (°). Success rates for motor alignment and head tilt improvement, cumulative probabilities of success, and factors influencing surgical responses were evaluated.ResultsThe cumulative probabilities of motor success at 2 years after IO myectomy were 92% in patients with a trochlear nerve and 86% in patients without a trochlear nerve (P = 0.138). The cumulative probabilities of undercorrection and recurrence of hypertropia after 2 years were 0% in the present group versus 21% in the absent group (P = 0.014). The cumulative probabilities of persistent head tilt after 2 years were 14% in the present group and 20% in the absent group (P = 0.486). A younger age at operation was associated with reduced probabilities of motor success and head tilt improvement (P = 0.009, P = 0.022 respectively). A greater preoperative angle of head tilt was associated with persistent head tilt after surgery (P = 0.038).ConclusionsCongenital SOP without a trochlear nerve had a higher risk of hypertropia undercorrection after IO myectomy compared to patients with a trochlear nerve. A younger age at operation and larger preoperative head tilt was related to poor outcomes.

Rectus Pulley Displacements without Abnormal Oblique Contractility Explain Strabismus in Superior Oblique Palsy

Using high-resolution magnetic resonance imaging (MRI), we investigated whether rectus pulleys are significantly displaced in superior oblique (SO) palsy and whether displacements account for strabismus patterns. Prospective case-control study. Twenty-four patients diagnosed with SO palsy based on atrophy of the SO muscle on MRI and 19 age-matched orthotropic control subjects. High-resolution, surface coil MRI scans were obtained in multiple, contiguous, quasicoronal planes during monocular central gaze fixation. Pulley locations in oculocentric coordinates in the following subgroups of patients with SO palsy were compared with normal results in subgroups of patients with SO palsy: unilateral versus bilateral, congenital versus acquired, and isotropic (round) versus anisotropic (elongated) SO atrophy. Expected effects of pulley displacements were modeled using Orbit 1.8 (Eidactics, San Francisco, CA) computational simulation. Rectus pulley positions and ocular torsion. Rectus pulleys typically were displaced in SO palsy. In unilateral SO palsy, on average the medial rectus (MR) pulley was displaced 1.1 mm superiorly, the superior rectus (SR) pulley was displaced 0.8 mm temporally, and the inferior rectus (IR) pulley was displaced 0.6 mm superiorly and 0.9 mm nasally from normal. Displacements were similar in bilateral SO palsy, with the SR pulley additionally displaced 0.9 mm superiorly. However, the lateral rectus pulley was not displaced in either unilateral or bilateral SO palsy. The SR and MR pulleys were displaced in congenital SO palsy, whereas the IR and MR pulleys were displaced in acquired palsy. Pulley positions did not differ between isotropic and anisotropic palsy or between patients with cyclotropia of less than 7° versus cyclotropia of 7° or more. Simulations predicted that the observed pulley displacements alone could cause patterns of incomitant strabismus typical of SO palsy, without requiring any abnormality of SO or inferior oblique strength. Rectus pulley displacements alone, without abnormal oblique muscle contractility, can createthe clinical patterns of incomitant strabismus in SO palsy. This finding supports accumulating evidencethat clinical binocular misalignment patterns are not reliable indicators of contractile function of the SO muscle. Ocular torsion does not correlate with and thus cannot account for pulley displacements in SO palsy.

Surgical Management of Unilateral Superior Oblique Palsy: Thirty Years of Experience

Introduction and PurposeWe describe the clinical characteristics of 252 patients with unilateral superior oblique palsy who underwent strabismus surgery. We assess if a predetermined surgical strategy, based on preoperative alignment and motility measurements, was effective in treating these patients. On this basis, the patients were divided into three different treatment groups.MethodsTwo-hundred fifty-two patients were identified retrospectively and classified into three groups according to the performed procedures: 1) inferior oblique weakening; 2) inferior rectus recession; 3) combined inferior oblique weakening and inferior rectus recession. Demographic and clinical data were recorded. Criteria for surgical success included good postoperative alignment (distance, primary position alignment ≤5Δ), and improvement of diplopia and of abnormal head posture. Subgroup analyses of surgical outcome were performed for small (<12Δ) versus large (>20Δ) preoperative hypertropia in the group that underwent inferior oblique weakening, and for inferior oblique disinsertion-myectomy versus inferior oblique recession.ResultsMean forced primary position (PP) hypertropia decreased from 14.3Δ (range 3–37Δ) to 4.5Δ (range 0–30Δ) in Group 1, from 13Δ (range 1–30Δ) to 2Δ (range -20–20Δ) in Group 2, and from 25.7Δ (range 6–40Δ) to 1.3Δ (range -12–18Δ) in Group 3. Group 1 had the lowest re-operation rate (7.6%), followed by Group 2 (16%) and Group 3 (25.9%). Final surgical success rates were similar in three groups. Inferior oblique weakening was more predictable for small primary position hypertropia, but still yielded 85% success rate in large deviations. Inferior oblique disinsertion-myectomy resulted in more favorable results than inferior oblique recession (P < 0.05).ConclusionWhen a predetermined surgical strategy is applied to individual patients with unilateral superior oblique palsy, excellent functional improvement can be achieved in the majority of patients.

Graded recession with or without anterior transposition of the inferior oblique muscle for treatment of unilateral congenital superior oblique palsy

Graded recession with or without anterior transposition of the inferior oblique muscle for treatment of unilateral congenital superior oblique palsy

Effectiveness of prisms in relieving diplopia in superior oblique palsies

Aim: To study the effectiveness of prisms in relieving diplopia in patients with superior oblique palsies. Materials and Methods: This was a retrospective study of all patients with superior oblique palsies who were prescribed prisms for relief of symptomatic diplopia in our institute from September 2013 to March 2015. A detailed analysis was performed of demographic features of the patients; nature, onset, duration, and course of diplopia; measurement of deviation in all gazes; diplopia charting; assessment of torsion; systemic risk factors; and amount and type of prism given. The effectiveness of prisms was measured by an objective score by the examiner as well as a subjective score reported by the patient. Results: Among the total 25 patients, 21 patients had acquired superior oblique palsies and 4 patients had congenital causes. Males outnumbered females. Majority had unilateral involvement. Deviation in primary position ranged from 3 Prism Dioptre to 25 PD with 80% having less than 10 PD. Seventy-six percent had less than 10° torsion in primary gaze. Eighty-eight percent were given less than 10 PD prisms, 12% were given more than 10 PD, of which two were Fresnel Prisms. Seventy-six percent were satisfied with the prisms. Fifty-two percent had spontaneous improvement whereas 16% needed surgery. Conclusion: Prisms were effective in relieving diplopia in most of the acquired unilateral superior oblique palsies where the primary deviation was less than 10 PD and torsion was less than 10°.

Surgical outcomes for unilateral superior oblique palsy in Chinese population: a retrospective study.

To evaluate the outcome after surgery for unilateral superior oblique (SO) palsy in Chinese. The medical records of 39 patients that underwent surgery for unilateral SO palsy between January 2003 and December 2012 at Caritas Medical Centre, Hong Kong, were retrospectively reviewed. All surgeries were performed by a single surgeon. Pre-operative assessments for vertical deviation, cyclo-deviation, and Knapp's classification were obtained to determine the nature and degree of surgical correction. Vertical deviation was measured at 1wk; 1, 6mo and on last follow-up day post-operatively. Cyclo-deviation was measured on last follow-up day post-operatively. During the 10y period, 39 subjects were recruited. The most common etiology was congenital (94.9%). Knapp's Type III (66.7%) and Type I (12.8%) classifications were the most common subtypes. To treat SO palsy, the most common surgical procedures were: isolated inferior oblique (IO) anteriorization (41.0%), isolated IO myectomy (10.3%), and isolated IO recession (10.3%). At 3.5±2.1y post-operatively, the vertical deviation was significantly reduced (15.1±6.2 PD versus 0.5±1.4 PD, P<0.0001) without significant improvement in cyclo-deviation (P=0.5). Initial vertical deviation was correlated with cyclo-torsion (r=0.4, P=0.007). Those with over-correction had greater initial vertical deviation (19.4±7.2 PD versus 13.2±4.3 PD, P=0.003). After a single operation, 84.6% of subjects achieved a vertical deviation within ±3 PD. The majority of subjects achieved corrected vertical deviation after a single surgery although there was no improvement in cyclo-deviation. Those with over-correction of primary position deviation had greater preoperative vertical deviation and it may be related to simultaneous multiple muscle surgery.

Association of superior oblique muscle volumes with the presence or absence of the trochlear nerve on high-resolution MR imaging in congenital superior oblique palsy.

Congenital superior oblique palsy is known to relate to trochlear nerve absence and a variable degree of superior oblique muscle hypoplasia. The purpose of this study was to determine whether superior oblique muscle volume predicts trochlear nerve absence in congenital superior oblique palsy. A retrospective study of high-resolution MR imaging to evaluate the presence of the trochlear nerve and to measure superior oblique muscle areas and volumes with the image analysis tools of a PACS was performed in 128 consecutive patients with unilateral congenital superior oblique palsy and 34 age-matched healthy controls. Of the 128 patients with congenital superior oblique palsy, 88 had an ipsilateral trochlear nerve absence (absent group) and 40 had both trochlear nerves (present group). In patients with congenital superior oblique palsy, the paretic side superior oblique muscle volume was significantly smaller compared with the normal side only in the absent group (P < .001). The left and right side superior oblique muscle volumes were not significantly different in controls (P = .750), and the paretic and normal side superior oblique muscle volumes were not significantly different in the present group (P = .536). The cutoff value of the paretic/normal side superior oblique muscle volume ratio for diagnosing trochlear nerve absence was ≤0.75 (sensitivity 98.9%, specificity 95.0%) in patients with congenital superior oblique palsy. The ratio of paretic/normal side superior oblique muscle area and volume has an excellent predictability in diagnosing trochlear nerve absence in congenital superior oblique palsy.

Morphometry of the trochlear nerve and superior oblique muscle volume in congenital superior oblique palsy.

To infer the pathogenic mechanism of congenital superior oblique palsy (SOP) by evaluating trochlear nerve diameter (CN4D) and superior oblique muscle (SO) volume in patients with congenital SOP. The medical records of 125 patients diagnosed with unilateral congenital SOP and 34 age-matched healthy controls were reviewed retrospectively. Using thin-section high-resolution magnetic resonance imaging, we evaluated the presence of the trochlear nerve, CN4D, SO volume, and their relationship. Of the 125 patients with congenital SOP, 87 showed absence of the trochlear nerve (n = 87, 70%, absent group) and 38 showed bilateral presence of the trochlear nerve (n = 38, 30%, present group). The nonparetic side CN4D was smaller than controls in the absent group (P = 0.001), and larger than controls in the present group (P = 0.001). Trochlear nerve diameter positively correlated with SO volume in controls (P = 0.014, R(2) = 0.174) and in the nonparetic sides of congenital SOP (present group P = 0.023, R(2) = 0.135; absent group, P = 0.008, R(2) = 0.079). The paretic side SO volume did not show a linear correlation between CN4D and SO volume in the present group (P = 0.243). In congenital SOP patients without a trochlear nerve, the nonparetic side CN4D was also reduced in contrast to those with a trochlear nerve. The relatively weaker relationship of CN4D and nonparetic side SO volume in the absent group than that of the present group suggests different pathogenic mechanisms underlying these two entities of congenital SOP.

Masked bilateral superior oblique palsy in children.

Following surgery on an eye for unilateral superior oblique palsy, it is a well-recognized postoperative occurrence for the unoperated eye to develop superior oblique palsy, commonly referred to as masked bilateral superior oblique palsy. The purpose of this study was to describe this postoperative finding in children following unilateral inferior oblique weakening surgery. A retrospective review of records of children who underwent unilateral inferior oblique weakening surgery at Children's Hospital of Michigan, Detroit, Michigan, from 1987 to 2005, including information on the development of masked bilateral superior oblique palsy with contralateral inferior oblique overaction requiring a second surgical intervention. Of 50 children (25 boys and 25 girls, mean age: 5.6 years) who underwent unilateral inferior oblique weakening surgery (47 recessions and 3 myectomies), 9 (18%) manifested masked bilateral superior oblique palsy postoperatively, requiring subsequent surgical weakening of the inferior oblique muscle in the unoperated eye. Preoperative primary position hypertropia in children who were eventually diagnosed as having masked bilateral superior oblique palsy (5.56±4.22 prism diopters [PD]) was significantly smaller compared to children with unilateral superior oblique palsy (10.4±6.5 PD, P=.012), and preoperative primary position hypertropia of less than 5 PD was associated with an odds ratio of 8.2 (95% confidence interval: 1.7 to 38.5, P=.008) for requiring reoperation. Masked bilateral superior oblique palsy is a possible outcome after surgery for the correction of pediatric unilateral superior oblique palsy. Parents should be informed of this possible outcome, especially when primary position hypertropia is less than 5 PD.

Superior oblique tucking for treatment of superior oblique palsy.

To investigate the efficacy and safety of isolated superior oblique tucking in the treatment of congenital superior oblique palsy. Twenty-one patients with unilateral congenital superior oblique palsy and lax superior oblique tendon underwent isolated superior oblique tucking and retrospective analysis of the amount of tucking procedure, preoperative and postoperative vertical deviation in the primary position and reading position, abnormal head posture, ocular motility, and corrected objective torsion. Patients were evaluated before and 6 to 12 months after surgery. The average vertical deviation in the primary position was 10.9 ± 3.3 prism diopters (PD) before surgery and 1.5 ± 2.6 PD after surgery (n = 21, P < .05). The average vertical deviation in the reading position was 15.6 ± 3.6 PD before surgery and 2.6 ± 3.1 PD after surgery (P < .05). The average corrected vertical deviation was 9.9 ± 3.2 PD in the primary position and 13.0 ± 3.4 PD in the reading position (P < .05). The amount of tucking ranged from 5 to 12 mm (mean: 8.3 ± 2.3 mm), which was not related to the corrected vertical deviation in the primary and reading positions, the preoperative vertical deviation in the reading position, or the corrected objective torsion. After surgery, all patients had head posture that was normal or less than 5°. Unremarkable superior oblique underaction and negative head tilt test were found in all patients after surgery. All patients had mild Brown syndrome after surgery, but none were symptomatic. Isolated superior oblique tucking is an efficient and safe procedure for treatment of superior oblique palsy with hyperdeviation less than 15 PD in the primary position and remarkable superior oblique underaction. The superior oblique forced duction test was the most important criterion for planning surgery.