Superior oblique luxation and trochlear luxation as new concepts in superior oblique muscle weakening surgery

Acquired Brown Syndrome Treated With Traction of Superior Oblique Tendon

Brown syndrome is a rare strabismic disease characterized by a limited elevation in adduction of the eye. The lengthening/weakening of superior oblique muscle is the main way of surgical intervention for this disease. A 7-year-old boy was diagnosed as having acquired Brown syndrome in his right eye after injury in his face. We experienced successful release of this Brown syndrome through mere pulling outward of superior oblique tendon during surgical exploration. We briefly discuss why this manipulation of superior oblique tendon that we performed was successful.

Size of the Oblique Extraocular Muscles and Superior Oblique Muscle Contractility in Brown Syndrome

PURPOSE

This study employed magnetic resonance imaging (MRI) to investigate possible size and contractility changes in the superior oblique (SO) muscle, and possible isometric hypertrophy in the inferior oblique (IO) muscle, resulting from abnormal mechanical loading in Brown syndrome (BrS).

METHODS

High resolution orbital MRI was obtained in 4 congenital and 11 acquired cases of BrS, and compared with 44 normal subjects. Maximal cross-section areas and posterior partial volumes (PPVs) of the SO were analyzed in central gaze, supraduction, and infraduction [corrected] for the SO, and in central gaze only for the IO.

RESULTS

In congenital BrS, mean maximum SO cross-sectional areas were 24% and 20% less than normal in affected and unaffected eyes, respectively (P = 0.0002). Mean PPV in congenital BrS was also significantly subnormal bilaterally (29% and 34% less in affected and unaffected eyes, respectively, P = 0.001). However, SO muscle size and volume were normal in acquired cases. The SO muscle did not relax in supraduction in BrS, although there was normal contractile thickening in infraduction. The IO muscle had normal size bilaterally in BrS.

CONCLUSIONS

Congenital BrS may be associated with SO hypoplasia that could reflect hypoinnervation. However, unique isometric loading of oblique extraocular muscles due to restrictive hypotropia in adduction in BrS is generally not associated with changes in muscle bulk or in SO contractility. Unlike skeletal muscles, the bulk and contractility of extraocular muscles can therefore be regarded as independent of isometric exercise history. Restriction to elevation in BrS typically arises in the trochlea-tendon complex.

Trochlea surgery for acquired Brown syndrome

PURPOSE

To describe surgical treatment of acquired Brown syndrome by trochlea reconstruction and trochlea adhesiotomy.

METHODS

The medical records of patients with acquired Brown syndrome who underwent intraoperative forced duction testing under direct view of the trochlea from 2010 to 2012 were retrospectively reviewed. In all cases, the site of restricted movement was identified, after which either the trochlea was reconstructed or the trochlear adhesion was removed. Surgical results were assessed by means of the pre- and postoperative Hess chart scores and binocular single vision test scores.

RESULTS

Six eyes of 6 patients were included. In 4 patients the trochlea was reconstructed; in 2, the adhesion was removed. A significant improvement in the Hess chart scores was observed postoperatively in 5 of the 6 patients (P = 0.047). Binocular single vision test scores also significantly improved in 4 of 5 patients (P = 0.019). No iatrogenic superior oblique muscle paresis was observed in any of the patients.

CONCLUSIONS

Our technique of isolating the source of limitation of elevation and treating with trochlea reconstruction or adhesion removal successfully treated acquired Brown syndrome in these patients.

A new mechanism for Brown's syndrome

This case report describes a child who developed an acquired bilateral sequential Brown's syndrome, confirmed each time intraoperatively, that is likely the result of a new mechanism not previously described in the literature. Arguments are provided to support the premise of a new mechanism and a new measure of relative trochlear position is suggested to further elucidate the role of "desagittalization" of the superior oblique tendon in the spectrum of superior oblique dysfunction.

High-resolution magnetic resonance imaging of the normal extraocular musculature

PURPOSE

Magnetic resonance imaging (MRI) of the extraocular muscles has attracted growing interest for the evaluation of complex motility disorders. However, little information is available on the high-resolution MRI anatomy of the normal extraocular muscles and their connective tissue system. The study describes the imaging anatomy of the recti and oblique muscles and the levator palpebrae superioris muscle.

METHODS

MRI of the orbit at 1 tesla was performed in four normal volunteers using a surface coil.

RESULTS

Many anatomical details such as Zinn's tendinous annulus, the trochlea, the superior oblique tendon, the intermuscular septa, the check ligaments, Lockwood's ligament and the common sheath between the superior rectus muscle and the levator muscle were visualised. A striking imaging feature was the curved path of both the recti muscles and the levator palpebrae muscle. The inferior oblique muscle also showed a marked curvature in the region of Lockwood's ligament.

CONCLUSIONS

High-resolution MRI is capable of demonstrating the anatomy of the extraocular musculature and parts of its connective tissue system. The curved path of the extraocular muscles can be explained by the configuration of the orbital connective tissue system which couples each extraocular muscle with the adjacent orbital wall. We discuss the clinical implications of our findings and review previous radiological studies regarding the functional anatomy of the extraocular muscles.

Current status in the treatment of orbital myositis

PURPOSE

Orbital myositis is described as exquisitely sensitive to therapy with systemic corticosteroids. However, it may turn into a recurrent or chronic disease, requiring repeated courses or maintenance of corticotherapy that often is complicated with serious side effects. The authors conducted this study to evaluate their experience and the current status in the literature as to treatment of orbital myositis with corticosteroids and corticosteroid-sparing alternatives.

METHODS

The clinical records and computed tomography scans of patients with orbital myositis who presented at the Orbital Center Amsterdam between 1977 and 1991 were studied for the clinical course and therapeutic outcome. Recurrences were defined as a new attack of the same or another extraocular muscle as the primary affected, in the same or the other orbit.

RESULTS

The study group comprised 16 patients. All patients responded to initial treatment with oral corticosteroids (14/16) or nonsteroidal anti-inflammatory drugs (NSAID) (2/16). Of these 16 patients, 9 (56%) had 1 or more recurrences. Recurrences responded to repeated courses of corticosteroids, NSAID, or 20 Gy irradiation. Despite radiotherapy in six patients, recurrences continued to occur within a mean period of 2.7 years (range, 0.5 month-8.8 years). The mean follow-up after initial therapy in general was 9.7 years (range, 2.6-16.9 years), and after radiotherapy, in particular, was 7.4 years (range, 4.1-10.5 years).

CONCLUSIONS

Orbital myositis responds well to oral corticosteroids, but recurs in 50% of the cases. Based on a long-term follow-up of six patients who received irradiation of 20 Gy, radiotherapy appears ineffective in stopping recurrent orbital myositis.

Grave complications after superior oblique tenotomy or tenectomy for Brown syndrome

INTRODUCTION

Superior oblique tenotomy or tenectomy was the preferred procedure for Brown syndrome for decades. Superior oblique palsy was reported as a complication, but the complex nature of this palsy and the difficulty in treating it was not emphasized. We documented cases with distressing symptoms of unilateral and bilateral superior oblique palsy after a free tenotomy or tenectomy of the superior oblique tendon for Brown syndrome.

METHODS

Four cases referred for management of complex strabismus after superior oblique surgery for Brown syndrome were identified. Case histories, complications, and corresponding management are described in detail.

RESULTS

All cases presented with bothersome symptomatic superior oblique palsy-incomitant vertical deviation with significant torsion, diplopia worse in functional down gaze, and anomalous head postures. Although reanastomoses of the superior oblique tendon was attempted in all cases,the procedure was modestly successful in only one case. Superior oblique palsy could not be reversed. After three procedures, Case 1 was orthotropic in primary, right, and left gaze but had a small intermittent tropia in down gaze. Case 2 underwent bilateral superior oblique operations. Despite a unilateral reanastomosed superior oblique tendon, hypertropia in down and left gaze and 15 degrees chin down position persisted. Case 3 showed correction of head tilt and a negative cover test 1 week after the second operation for iatrogenic superior oblique palsy, but stability of the procedure could not be ascertained. Case 4 had a successful attempt at reanastomosis and regained control of the vertical deviation as a hyperphoria. Both anomalous head posture and torsion improved.

CONCLUSION

Superior oblique surgery for Brown syndrome may cause irreversible serious strabismus problems. Patients are left with distressing cyclovertical deviation worse in the functional position of gaze with significant torsional component that was resistant to therapy. Although adaptive mechanisms, such as an anomalous head posture, may develop, patients are left with a permanent disability that could not be reversed. One should scrupulously adhere to the indications for surgery in Brown syndrome. Preoperative assessment of superior oblique function is stressed. An alternative surgical procedure that is potentially reversible should be considered. This should include a reliable method to recover both ends of the tenotomized superior oblique tendon in case the procedure needs to be modified at a later date.