Congenital Superior Oblique Muscle Research Articles

Surgical Outcomes of Congenital Superior Oblique Muscle Palsy Operated in Adulthood

Purpose: To investigate the outcomes of patients who underwent surgical correction of congenital superior oblique muscle paralysis in adulthood.Methods: We retrospectively analyzed the medical records of 35 patients who underwent surgical correction of congenital superior oblique muscle paralysis after the age of 18 years. At the final follow-up, success was defined as residual hypertropia < 4 prism diopters (PD), whereas failure was defined as residual hypertropia ≥ 5 PD or overcorrection. Clinical features were compared between the success and failure groups to identify factors affecting the surgical outcome. At the final follow-up, the resolution of symptoms, such as head tilt and diplopia, was also recorded.Results: Of the 35 patients, 24 (68.6%) and 11 (31.4%) were classified into the success and failure groups, respectively. Preoperative vertical deviation was larger in the failure group compared to the success group (23.1 vs. 15.2 PD, respectively; <i>p</i> < 0.05). Of the 31 patients with preoperative head tilt, head tilt resolved in 29 (93.5%). Of the 19 patients with diplopia, it resolved in all except 1 who was overcorrected.Conclusions: The preoperative vertical angle of the superior oblique muscle may affect the outcome of surgery performed in adulthood for correcting congenital superior oblique paralysis. Head tilt, diplopia, and subjective symptoms are typically resolved postoperatively.

Facial Asymmetry in Unilateral Congenital Superior Oblique Muscle Palsy.

This study was conducted to evaluate facial asymmetry in unilateral congenital superior oblique muscle palsy (SOP). The results showed that all facial asymmetry parameters had a higher frequency in SOP patients compared with orthotropic individuals. This study aimed to evaluate the characteristics of facial asymmetry in unilateral congenital SOP and compare with orthotropic individuals. This cross-sectional comparative case series was conducted in 58 patients with ocular torticollis caused by SOP (mean ± standard deviation age, 18 ± 12 years) and 58 orthotropic individuals (mean ± standard deviation age, 19 ± 13 years). The exact form of torticollis was determined by direct observation from yaw, roll, and pitch axes. Four photographs were taken from patients: (1) with torticollis to calculate the amount of head tilt; (2) with the head in the straight position to calculate the facial angle and relative facial size (RFS); and (3 and 4) with the head positioned downward (to compare the cheek size) and upward (to assess columella deviation and nostril asymmetry). Twenty-nine patients (50%) had a head tilt, 23 (39.66%) had combined head tilt and a face turn, and 6 (10.44%) had a pure face turn. The mean ± standard deviation of head tilt, facial angle, and RFS was 10.11 ± 6.31°, 1.11 ± 1.67°, and 1.003 ± 0.126 in SOP patients, respectively, and the mean RFS and facial angle were significantly higher in SOP patients compared with orthotropic individuals (both P < .001). Facial hemihypoplasia, unilateral cheek compression, nostril asymmetry, and columella deviation were observed in 43 (74.1%), 31 (53.4%), 39 (67.2%), and 38 patients (65.5%), respectively, which were all significantly more common compared orthotropic individuals (P < .001). Facial asymmetry was seen in 52 patients (91.2%) and 17 orthotropic subjects (29.3%), respectively (P < .001). All quantitative and qualitative facial asymmetry parameters had a higher frequency in SOP patients compared with orthotropic subjects.

The Correlation between Hypertropia and Head Tilt in Congenital Unilateral Superior Oblique Muscle Palsy.

Purpose:To evaluate the correlation between the angle of deviation in different gazes and the amount of head tilt in patients with congenital unilateral superior oblique muscle palsy (SOP).Methods:This case series study was performed on 20 consecutive SOP patients with head tilt. Based on the Bielschowsky three-step test, the angle of deviation was measured in different gazes. Furthermore, the hypertropia difference between the two lateral gazes (gaze difference) and the two head tilt sides (bilateral head tilt difference) was calculated. For measuring head tilt, close-up pictures from 40 cm with a habitual abnormal head position were captured and analyzed by the Corel Draw X7 software.Results:The mean age of patients was 13 ± 9 years (range, 2.5–31 years). The mean angle of hypertropia in ipsilateral and contralateral head tilt was 24.5 Δ ± 7.1 Δ and 6.5 Δ ± 4.2 Δ, respectively (P < 0.001), and in ipsilateral and contralateral lateral gaze positions, it was 8.2 Δ ± 5.5 Δ and 22.5 Δ ± 6.1 Δ, respectively (P < 0.001). The mean of bilateral head tilt hypertropia difference was 18 Δ ± 5.3 Δ and gaze hypertropia difference was 14.3 Δ ± 6.16 Δ. There was a positive correlation between bilateral head tilt hypertropia difference and the amount of head tilt (R = 0.609, R2 = 0.371, P = 0.004, the amount of head tilt = 0.39 × [Bilateral head tilt hypertropia difference] +1.77). The amount of head tilt also had a positive correlation with the gaze hypertropia difference (R = 0.492, R2 = 0.242, P = 0.028, the amount of head tilt = 0.27 × [gaze hypertropia difference] +4.81).Conclusion:In SOP patients, the amount of head tilt had a positive correlation with bilateral head tilt hypertropia difference and also gaze hypertropia difference.

Phoria Adaptation: The Ghost in the Machine

ABSTRACT Importance Phoria adaptation is a central tonus mechanism that provides plasticity to binocular alignment. However, its slow dissipation inevitably adulterates our clinical strabismus measurements. Purpose To examine the role of phoria adaptation in normal binocular control, understand its neural substrate, and explore how it can alter our clinical measurements in common forms of strabismus. Methods Investigation into the role of phoria adaptation in maintaining binocular alignment and its role in altering clinical strabismus measurement. Results Phoria adaptation permeates all aspects of binocular alignment. It accounts for the stability of orthophoria, “latent” phorias, tenacious proximal fusion in intermittent exotropia, large fusional vertical amplitudes in congenital superior oblique muscle palsy, the “eating up” of prisms in accommodative esotropia, the smaller measured distance deviation in patients with high AC/A ratio or convergence excess, absence of physiologic skew deviation during head tilt, fusional divergence amplitudes, and spread of comitance. This binocular control system probably arises from a cerebellar learning mechanism that involves input via climbing fibers to the inferior olive, which provide a powerful timing and error signal to the cerebellar Purkinje cells to produce activity-dependent modification analogous to long-term potentiation. Conclusions Phoria adaptation is generated by a central neural integrator that provides inertia, plasticity, and positional stability to human binocular vision.

A case of surgical treatment for congenital superior oblique muscle agenesis

A case of surgical treatment for congenital superior oblique muscle agenesis

Double elevator weakening for unilateral congenital superior oblique palsy with ipsilateral superior rectus contracture and lax superior oblique tendon

In unilateral congenital superior oblique palsy, a large hypertropia is sometimes associated with ipsilateral contracture of the superior rectus muscle and apparent overaction of the contralateral superior oblique. Ipsilateral double elevator weakening is one surgical approach; however, this procedure could compromise supraduction. We report a series of three consecutive patients who underwent ipsilateral superior rectus and inferior oblique recessions for unilateral superior oblique palsy. Intraoperatively, all three patients were found to have a lax ipsilateral superior oblique tendon. Postoperatively, all three patients had satisfactory correction of the hypertropia and abnormal head position with minimal supraduction defect. This procedure seems to be an acceptable initial surgical option for treating congenital superior oblique muscle palsy with ipsilateral contracture of the superior rectus muscle, even when the ipsilateral superior oblique tendon is lax.

Residual Symptoms After Surgery for Unilateral Congenital Superior Oblique Palsy

To establish the surgical results and residual symptoms in 48 cases with unilateral congenital superior oblique muscle palsy that had surgical intervention to the vertical muscles alone. Myectomy and concomitant disinsertion of the inferior oblique (IO) muscle was performed in 38 cases and myectomy and concomitant IO disinsertion and recession of the superior rectus muscle in the ipsilateral eye was performed in 10 cases. The preoperative and postoperative vertical deviation values and surgical results were compared. Of the patients who had myectomy and concomitant IO disinsertion, 74% achieved an "excellent" result, 21% a "good" result, and 5% a "poor" result postoperatively. The difference in deviation between preoperative and postoperative values was statistically significant (P < .001). Of the patients who had myectomy and concomitant inferior oblique disinsertion and ipsilateral superior rectus recession, 50% achieved an "excellent" result, 20% a "good" result, and 30% a "poor" result postoperatively. The difference in deviation between preoperative and postoperative values was statistically significant (P < .001). Both procedures are effective and successful in patients with superior oblique muscle palsy, but a secondary surgery may be required.

Paretic Side/Normal Side Ratios of Cross-Sectional Areas of the Superior Oblique Muscle Vary Largely in Idiopathic Superior Oblique Palsy

To search for a new definition of muscle hypoplasia in congenital or idiopathic superior oblique muscle palsy. Retrospective case-control study. Cross-sectional areas of the superior oblique and 4 rectus muscles near the eye globe-optic nerve junction were measured by an image analysis software on magnetic resonance images of 50 patients with congenital or idiopathic superior oblique muscle palsy and 45 patients with other disease conditions serving as a control. The paretic side/contralateral normal side ratios of the cross-sectional areas and the left side/right side ratios were calculated for the superior oblique muscle palsy patients and the control patients, respectively. The 95% confidence intervals in paretic side/contralateral side ratios of cross-sectional areas of the superior oblique muscle were 0.55 to 0.80 in the right-side superior oblique muscle palsy, and 0.48 to 0.75 in the left-side palsy, while the 95% confidence interval in the left side/right side ratios was 0.99 to 1.00 in the control. The 95% confidence intervals in the left side/right side ratios of the 4 rectus muscles were 1.00, both in the superior oblique muscle palsy and in the control. The muscle hypoplasia could be defined as such when the paretic side/contralateral side ratios of cross-sectional areas of the superior oblique muscle on magnetic resonance images fell outside the 95% confidence interval of the ratios in normal controls.

When and how to strengthen the superior oblique muscle

To review the history of procedures used to strengthen the action of the superior oblique (SO) muscle and methods of quantifying surgical dosage and to determine the relationship between congenital onset and tendon laxity measured at the time of surgery. We reviewed medical records over a 10-year period of 30 patients who had undergone SO tendon tuck for SO muscle palsy using intraoperative assessment of forced ductions to determine surgical dosage. We also designed and tested a modified Bishop tucker, which can simultaneously measure tendon shortening and the force required. This allowed development of length tension curves between 0 and 200 g for individual SO tendons in patients with and without evidence of muscle palsy. In distinction to most other procedures on the extraocular muscles, intraoperative forced ductions are used to determine appropriate surgical dosage. Patients undergoing SO tendon tuck using a uniform and repeatable forced duction method receive a greater amount of tuck (mean, 3 mm) when there is known congenital onset. Patients with congenital SO muscle palsy received a mean tuck of 10.8 mm (range, 8-16 mm), whereas patients with equivocal or known adult-onset SO palsy received a mean of 7.8 mm (range, 4-12 mm; p = 0.002). Patients with congenital SO muscle palsy have increased tendon laxity when measured directly during SO tendon tuck. The excursion of presumed normal SO tendons through the trochlea is variable and may be less than previously thought. Modifying the Bishop tucker to provide length and tension data provides information that may be useful in determining surgical dosage.

001: When and how to strengthen the superior oblique muscle

Surgery to strengthen the action of the superior oblique muscle relies entirely on procedures to advance, resect, tuck, or redirect the reflected tendon. In distinction to most other procedures on the extraocular muscles, intraoperative assessment using forced ductions is usually required to determine appropriate surgical dosage, rather than a predetermined numerical value based on preoperative findings. Although the concept of a “lax tendon” has been proposed to help determine which patients may be candidates for superior oblique tendon tuck, the definition of lax or the relationship of tendon laxity to congenital onset superior oblique muscle palsy has not been unequivocally demonstrated.

Clinical features, ARIX and PHOX2B nucleotide changes in three families with congenital superior oblique muscle palsy.

We analyzed nucleotide changes in 3 genes, ARIX, PHOX2B, and KIF21A, in 6 patients of 3 families with congenital superior oblique muscle palsy. Three exons of ARIX, 3 exons of PHOX2B, and exons 8, 20, and 21 of KIF21A were amplified by polymerase chain reaction from genomic DNA isolated from the peripheral blood. The DNA fragments were directly sequenced in both directions. In 2 different families, a heterozygous nucleotide change, ARIX 153G>A, in the 5'.-untranslated region was found in common between a father and daughter with muscle palsy and between a mother and daughter with muscle palsy (Family No. 1 and No. 3). In the other family (Family No. 2), a heterozygous 15-nucleotide deletion, PHOX2B 1124del15, resulting in loss of 5 alanine residues in the alanine repeat of the protein, was found in the daughter with muscle palsy and her father with normal traits, but was not found in the mother with muscle palsy. No KIF21A nucleotide change was found in any patients. The ARIX 153G>A polymorphism might be a genetic risk factor for the development of congenital superior oblique muscle palsy.

Ist der einseitige Strabismus sursoadductorius eine paretische Störung? - Kernspintomographische Untersuchungen

Recent reports postulate that the concomitant vertical deviation found in congenital superior oblique palsy is due to mechanical abnormalities rather than a congenitally paretic muscle, and is overcome in most patients by fusion. On the basis of the clinical characteristics alone a primary paresis is indeed unlikely. Although intraoperatively a different elasticity of the superior oblique tendon exists in congenital versus acquired cases of superior oblique palsy, preoperatively performed MR imaging shows that the clinical findings in congenital superior oblique muscle malfunction could nevertheless be of paretic origin. Seventeen consecutive patients (males: n = 13; females: n = 4) were examined. The vertical deviation in adduction was concomitant in vertical versions, the excyclotropia was small and concomitant in all directions of gaze and was less than 10 degrees even after diagnostic occlusion. All patients showed a positive Bielschowsky head tilt phenomenon and large fusional ability. We performed preoperative MR imaging of both orbits in high resolution 3 mm sections in coronal and axial orientations with and without contrast enhancement. In sixteen patients we found a significant reduction in muscle volume or even total aplasia of the superior oblique muscle of the affected side in comparison to the sound muscle on the other side. In contrast, two patients had a full blown clinical picture of a congenital superior oblique palsy but showed symmetrical muscle volumes on both sides in all coronal sections. Hypoplasia or aplasia of the superior oblique muscle on magnetic resonance imaging provides evidence for a primary paretic cause for the vertical squint found with congenital superior oblique dysfunction. It is not clear, however, whether this is caused by a primary hypoplasia or is of neurogenic origin. Our data together with the consistent difference in tendon morphology of the congenital and acquired forms of superior oblique palsy seem to exclude a purely neurogenic cause for the affection.

ARIX and PHOX2B polymorphisms in patients with congenital superior oblique muscle palsy.

To identify ARIX gene and PHOX2B gene polymorphisms in patients with congenital superior oblique muscle palsy, 3 exons of the ARIX gene and PHOX2B gene were sequenced by genomic DNA amplification with polymerase chain reaction (PCR) and direct sequencing in 31 patients with congenital superior oblique muscle palsy and in 54 normal individuals. A family with a father and one daughter each having congenital superior oblique muscle palsy was also included in this study. Eleven patients with congenital superior oblique muscle palsy had heterozygous nucleotide changes in the ARIX gene, including 4 patients reported on previously. One patient with atrophy of the superior oblique muscle had a new change of T-4G in the promoter region of the ARIX gene. The other 6 patients had a heterozygous nucleotide change of G153A in the 5'-untranslated region (UTR) of the exon 1 of the ARIX gene. These nucleotide changes of the ARIX gene, taken together, had a significant association with congenital superior oblique muscle palsy(P = 0.0022). One patient and 5 patients had heterozygous nucleotide changes of A1106 C and A1121 C in exon 3 of the PHOX2B gene, respectively, while these changes were absent in the normal individuals. Two patients had both the G153A change in the 5'-UTR of exon 1 of the ARIX gene and the A1121 C change in exon 3 of the PHOX2B gene. In conclusion, the polymorphisms of the ARIX gene and PHOX2B gene may be genetic risk factors for the development of congenital superior oblique muscle palsy.

Paralytic strabismus

In the last year, published works on paralytic strabismus have concerned many topics. New advances have been made in the knowledge of epidemiology of ocular nerve palsies in children, muscular causes of paralytic strabismus, and neuroimaging management of patients with third nerve palsy who are at risk of cerebral aneurysms. The author describes reports on rare associations of oculomotor imbalances and neurologic diseases as well as atypical orbital localizations of tumors. He also discuss new neuroimaging findings in congenital superior oblique muscle palsy and new acquisitions on cyclofusion deterioration in acquired trochlear palsy.

Facial asymmetry in superior oblique muscle palsy and pulley heterotopy

Introduction: Some observers have considered facial asymmetry as characteristic of congenital superior oblique muscle (SO) palsy. However, recent orbital imaging studies have determined that incomitant vertical strabismus resembling SO palsy can be caused by heterotopic rectus muscle pulleys. This finding suggests that facial asymmetry may predict the presence of abnormal orbital anatomy rather than be secondary to ocular torticollis. Methods: Subjects who underwent orbital computed tomography or magnetic resonance imaging were divided into 5 groups based on clinical evaluation and previously established imaging criteria: (1) congenital SO palsy; (2) acquired SO palsy; (3) strabismus with pulley heterotopy; (4) strabismus without SO palsy or pulley heterotopy; and (5) orthotropic subjects. Frontal photographs were digitized and the following 3 facial morphometric features recorded: (1) angle of inclination of each orbit; (2) relative facial size; and (3) facial angle. Results: The 79 subjects who underwent imaging were divided into the 5 groups as follows: 6 with congenital SO palsy; 7 with acquired SO palsy; 20 with pulley heterotopy; 26 with strabismus without SO palsy or pulley heterotopy; and 20 control subjects. All subjects with either congenital or acquired SO palsy had torticollis. Multivariate analysis demonstrated no significant differences in any of the 3 facial morphometric features among any of the groups. Conclusion: Facial asymmetry as assessed by these 3 morphometric features is not useful in distinguishing between congenital SO palsy or pulley heterotopy and other acquired forms of strabismus. This finding casts doubt on the relationship between ocular torticollis and facial asymmetry. (J AAPOS 2000;4:233–9)

Should early strabismus surgery be performed for ocular torticollis to prevent facial asymmetry?

To help determine whether ocular torticollis causes facial asymmetry, we analyzed photographs of patients with long-standing head tilts for amounts of tilt and facial asymmetry. Significant facial asymmetry that correlated with the side of the head tilt was found in patients with congenital superior oblique muscle paresis, but not in patients with traumatic superior oblique muscle paresis nor in patients with dissociated vertical deviation. The mechanism explaining the development of facial asymmetry in these patients may be deformational molding of the face and skull from the infant's sleeping with its head turned predominantly to one side during the first 6 to 12 months of life. Early strabismus surgery to correct the head tilt may help prevent facial asymmetry, but ensuring that the infant sleeps with alternating head positions may be more important.

Facial asymmetry and tendon laxity in superior oblique palsy.

Both facial asymmetry and superior oblique tendon laxity are associated with congenital superior oblique muscle palsy (SOP). It is unknown whether facial asymmetry and tendon laxity are related to each other, perhaps even causally. We evaluated 29 patients with SOP for presence of facial symmetry, tendon laxity, or both, and correlated these findings with presence or absence of chronic head tilt. Sixteen of 21 (76%) unilateral congenital SOP patients had facial asymmetry and 17 (81%) had tendon asymmetry. Ninety-four percent had either or both abnormalities, but only 57% had tendon laxity (palsy) on the side opposite the facial hypoplasia. All patients with facial hypoplasia had a head tilt toward the hypoplastic side of the face, regardless of which side the palsy was on. These findings, along with previous studies of congenital muscular torticollis, infer that the two anatomic abnormalities associated with congenital SOP (facial asymmetry and tendon asymmetry) do not occur as part of the same developmental sequence, but the facial asymmetry develops as a consequence of a chronic head tilt from a young age.