Congenital unilateral fibrosis, blepharoptosis, and enophthalmos syndrome

Congenital orbital fibrosis: report of two cases and review of literature

A 7-year-old male child presented with complaints of lagophthalmos and lid retraction of the right eye since birth. Magnetic resonance imaging (MRI) showed diffuse thickening of right superior rectus and levator-palpebrae complex along with a hypointense, irregular, and ill-defined lesion in the adjoining fat abutting the lacrimal gland. Biopsy from the lesion showed diffuse orbital fibrosis. Another 3-year-old female child presented with complaints of her right eye appearing smaller and inability to move the right eye freely since birth. MRI showed thickening of right superior and medial recti with diffuse retrobulbar hypointense fibrotic strands. The findings were suggestive of orbital fibrosis. Congenital orbital fibrosis is an extremely rare orbital pathology with very few cases described in the literature. The most common clinical features are motility restriction, restrictive strabismus, upper lid retraction, enophthalmos, and proptosis. The diagnosis can be made on imaging but requires biopsy for confirmation. Management is mostly conservative in the form of refractive and amblyopia therapy.

A patient with congenitally restrictive strabismus and contralateral secondary muscle enlargement

AIM

To report the case of a congenital restrictive strabismus with a contralateral enlargement of extraocular muscles.

CASE

The clinical presentation, findings, and postoperative outcomes of a 4 years old boy referred to evaluation for presenting a left eye deviation since birth are detailed.

CONCLUSION

A unilateral congenital restrictive strabismus (congenital hypotropia and esotropia) can be the cause of contralateral secondary enlarged extraocular muscle and It must be included in the differential diagnosis.

Congenital Orbital Fibrosis With Spontaneous Regression of Orbital Tumor

Congenital orbital fibrosis (COF) is a rare disorder characterized by an infiltrating orbital mass with secondary involvement of the extraocular muscles that may present with extraocular muscle dysfunction, and globe and eyelid abnormalities in infancy. This condition is thought to be a nonprogressive process and literature on longitudinal assessment of COF is limited. The authors describe a case of COF which was followed for 15 years. The patient had stable symptoms of ocular dysmotility and ptosis but was noted to have spontaneous regression of the orbital mass on serial MRI.

Extraocular muscle enlargement of indeterminate cause in pediatric patients: case series and literature review

PURPOSE

To specify the clinical characteristics of enlarged extraocular muscles of indeterminate cause in pediatric patients based on a case series and literature review.

METHODS

The medical records of pediatric patients who presented between January 2019 and January 2022 with enlarged extraocular muscles, where the underlying cause could not be determined, were retrospectively reviewed.

RESULTS

Four patients were included. The main reason for presentation was evaluation of abnormal head posture. Head tilt or turn with duction deficit was observed in all patients. The age of onset ranged from 6 months to 1 year. Two patients presented with esotropia and hypotropia; the other 2 patients, with large-angle esotropia. Orbital imaging was performed in all cases and revealed unilateral rectus muscle enlargement sparing the muscle tendon. All 4 patients were found to have an enlarged medial rectus muscle. In the 2 patients with hypotropia, the inferior rectus muscle was also involved. No underlying systemic or orbital disease was found. There were no changes in the orbit or extraocular muscles on follow-up imaging test. The intraoperative forced duction test revealed severe restriction in the direction of gaze opposite to the primary field of action of the enlarged muscles.

CONCLUSIONS

Enlargement of extraocular muscles should be considered in the differential diagnosis when large-angle incomitant vertical or horizontal misalignment and abnormal head posture are observed in infancy.

Congenital Monocular Strabismus Fixus

PURPOSE

To investigate the clinical characteristics and magnetic resonance imaging (MRI) findings of the extraocular muscle and ocular motor nerves in congenital monocular strabismus fixus.

METHODS

The retrospective observational case series of three patients with congenital monocular strabismus fixus were reviewed between January 1, 2006, and December 31, 2016. Ophthalmologic examination and thin-sectioned MRI of the ocular motor nerve and the orbit were performed on the three patients.

RESULTS

Three patients presented with unilateral non-progressive strabismus fixus with marked limitations of movement in all directions since birth. Of the three patients, one presented with esotropia, one with a large degree of exotropia and hypertropia, and one with an almost normal primary position. All three patients had normal ocular motor nerves, but adherences among the extraocular muscles, posterior Tenon's capsule, and the globe within the muscle cone on MRI. Two patients underwent strabismus surgery, but there were no postoperative improvements in the primary position and eye movements.

CONCLUSIONS

Extensive adherences among the extraocular muscles, posterior Tenon's capsule, and globe may partially explain the cause of congenital monocular strabismus fixus and why strabismus surgery was ineffective. The findings further highlight the importance of MRI in detecting and characterizing atypical forms of strabismus. [J Pediatr Ophthalmol Strabismus. 2018;55(6):363-368.].

Congenital Orbital Fibrosis: Molecular Genetic Analysis by Whole-Exome and Mitochondrial Genome Sequencing

A 3-year-old girl presented with congenital orbital fibrosis. We performed molecular genetic analysis by whole exome and mitochondrial genome sequencing. No pathologic mutation was identified in the present case. To our best knowledge, this study presents the first report on the findings of mutational analysis of a patient with congenital orbital fibrosis.

Congenital cranial dysinnervation disorders

The European Neuromuscular Centre (ENMC) derived the term Congenital Cranial Dysinnervation Disorders in 2002 at an international workshop for a group of congenital neuromuscular diseases. CCDDs are congenital, non-progressive ophthalmoplegia with restriction of globe movement in one or more fields of gaze. This group of sporadic and familial strabismus syndromes was initially referred to as the 'congenital fibrosis syndromes' because it was assumed that the primary pathologic process starts in the muscles of eye motility. Over the last few decades, evidence has accumulated to support that the primary pathologic process of these disorders is neuropathic rather than myopathic. This is believed that for normal development of extra ocular muscles and for preservation of muscle fiber anatomy, normal intra-uterine development of the innervation to these muscles is essential. Congenital dysinnervation to these EOMs can lead to abnormal muscle structure depending upon the stage and the extent of such innervational defects. Over last few years new genes responsible for CCDD have been identified, permitting a better understanding of associated phenotypes, which can further lead to better classification of these disorders. Introduction of high-resolution MRI has led to detailed study of cranial nerves courses and muscles supplied by them. Thus, due to better understanding of pathophysiology and genetics of CCDDs, various treatment modalities can be developed to ensure good ocular alignment and better quality of life for patients suffering from the same.

Idiopathic Unilateral Enlargement of the Extraocular Muscles in an Infant

A 6-month-old boy presented with a unilateral motility deficit of the right eye in all fields of gaze. Neuroimaging revealed unilateral enlargement of the medial, lateral, and inferior rectus muscles with sparing of the tendons. An evaluation for thyroid eye disease, idiopathic orbital inflammation, myositis, inflammatory and neoplastic infiltration of the muscle, vascular anomalies, and metastatic neuroblastoma was unrevealing. Biopsy of the muscle revealed normal architecture with an absence of inflammation, infiltration, or fibrosis. A review of the literature reveals the exceptionally rare nature of this finding. While the authors cannot rule out an atypical case of congenital euthyroid eye disease, this constellation of findings is not consistent with thyroid eye disease and may represent previously described cases of idiopathic enlargement of the extraocular muscles.

Congenital orbital fibrosis associated with fibrosis of extraocular muscle

Congenital orbital fibrosis is a non-familial, unilateral, distinct clinical entity, characterised by the presence of a diffusely infiltrating orbital mass and is extremely a rare disease. Congenital orbital fibrosis with combined fibrosis of extraocular muscles have not been reported previously. We treated an 8-year-old boy with the presence of a diffusely infiltrating orbital mass and fibrosis of extraocular muscles with secondary involvement of extraocular muscles. Clinical examination revealed left exotropia, hypotropia and fibrosis of extraocular muscle, an irregular, retrobulbar mass located within the orbit, incorporating the optic nerve, medial, superior, inferior and lateral rectus muscle. The CT, MRI and light microscopic studies confirmed the diagnosis. We performed exploration of the orbit, release and biopsy of scar tissue and strabismus surgery. Unlike other reported cases, our case was a progressive congenital disorder with combined fibrosis of extraocular muscle.

Congenitally dysplastic inferior rectus muscle

The authors report an unusual presentation of an idiopathic congenitally dysplastic inferior rectus muscle that responded well to surgical correction. Isolated unilateral enlargement of extraocular muscles is rare in children, and there is no definite logical explanation for its cause. A 20-month-old child presented with a congenitally enlarged posterior part of the right inferior rectus muscle with prominent hypotropia and enophthalmos since 10 months of age. Systemic disease work-up, ultrasound B-scan, computed tomography of the orbit and brain, and inferior rectus muscle biopsy were performed. Preoperatively, the child had severe hypotropia of the right eye with retraction of the globe. Work-up for systemic diseases was negative. Computed tomography scan showed thickening of the posterior two-thirds of the inferior rectus muscle. Muscle biopsy showed non-specific fibrotic changes. Strabismus surgery was undertaken at 2 years of age. Hypotropia was reduced significantly postoperatively. Compensatory head position was eliminated.

Congenital fibrosis of the extraocular muscles type 1, distinctive conjunctival changes and intrapapillary disc colobomata

A 6-month-old boy presented with a congenital eye movement disorder consistent with congenital fibrosis of the extraocular muscles type 1 (CFEOM1). Mutational analysis confirmed the most common mutation in the CFEOM1 gene KIF21A. In addition to the typical findings in CFEOM1, distinctive conjunctival changes and small bilateral optic disc colobomata were also noted. It is suggested that optic disc colobomata represent a new association of CFEOM1.

Congenital orbital fibrosis: a distinct clinical entity

PURPOSE

To describe congenital orbital fibrosis as a distinct clinical entity, and highlight its constellation of features.

MATERIAL AND METHODS

Retrospective, noncomparative, interventional case series of 4 patients with congenital orbital fibrosis. One patient underwent exploration of the orbit, release and biopsy of scar tissue. Two patients underwent strabismus surgery. One of these also underwent upper eyelid lengthening. Blepharoptosis, eyelid retraction, enophthalmos, proptosis, presence of a diffusely infiltrating orbital mass with secondary involvement of extraocular muscles, and dysplasia of the affected bony orbit were identified.

RESULTS

One patient presented with eyelid retraction, 1 with ptosis, and the remaining 2 had normal eyelid height. Furthermore, one patient demonstrated true enophthalmos. Of the remaining 3, 1 had symmetrical exophthalmometry, and 2 presented with proptosis. The later 2 patients presented with ipsilateral facial hypoplasia, accompanying orbital wall dysplasia and decreased orbital volume, confirmed on computed tomography. In addition, all patients demonstrated an irregular, retrobulbar mass located medially within the orbit, incorporating the medial rectus muscle.

CONCLUSION

Congenital orbital fibrosis is a nonfamilial, nonprogressive, unilateral, distinct clinical entity, characterized by the presence of a diffusely infiltrating orbital mass with secondary involvement of extraocular muscles resulting in variable symptomatology due to the cicatricial process.

Non-traumatic enophthalmos: a review

Enophthalmos can be defined as a relative, posterior displacement of a normal-sized globe in relation to the bony orbital margin. Non-traumatic enophthalmos has a wide variety of clinical presentations and may be the first manifestation of a number of local or systemic conditions. It may present with cosmetic problems such as deep superior sulcus, pseudoptosis or eyelid retraction; or functional problems such as diplopia or exposure keratopathy. There are three main pathogenic mechanisms: structural alterations in the bony orbit; orbital fat atrophy; and retraction. Evaluation of enophthalmos patients includes orbital imaging and a thorough ophthalmic and systemic examination. In this review, we discuss the presenting features of non-traumatic enophthalmos and include a brief description of the more important causes. An approach to the clinical evaluation of these patients is also discussed together with a brief overview of the principles of management.

Unilateral restrictive ophthalmoplegia and enophthalmos associated with an intraorbital tissue band

Fibrosis of the extraocular muscles can be congenital or acquired. Acquired causes include trauma, myositis, thyroid eye disease, infection, and metastases. Congenital fibrosis of the extraocular muscles (CFEOM) runs in families and is known to have a genetic basis. It has been classified by Brown, Hansen, and Harley et al into the five following types: general fibrosis syndrome; fibrosis of the inferior rectus (IR) with blepharoptosis; strabismus fixus; vertical retraction syndrome; and unilateral fibrosis, blepharoptosis, and enophthalmos syndrome. In this report, a case of unilateral fibrosis with enophthalmos and blepharoptosis due to a fibrous band is described.

Diagnosis and management of enophthalmos

Enophthalmos is a relatively frequent and misdiagnosed clinical sign in orbital diseases. The knowledge of the different etiologies of enophthalmos and its adequate management are important, because in some cases, it could be the first sign revealing a life-threatening disease. This article provides a comprehensive review of the pathophysiology, evaluation, and management of enophthalmos. The main etiologies, such as trauma, chronic maxillary atelectasis (silent sinus syndrome), breast cancer metastasis, and orbital varix, will be discussed. Its objective is to enable the reader to recognize, assess, and treat the spectrum of disorders causing enophthalmos.

Management of congenital fibrosis of the inferior rectus muscle associated with high myopia: a case report

BACKGROUND

Congenital fibrosis of the extraocular muscles includes a wide spectrum of phenotypically heterogeneous disorders involving a single or multiple muscles.

METHODS

We present a case of congenital fibrosis of the inferior rectus associated with ipsilateral high myopia. First we tried to treat the hypotropia with inferior rectus weakening and superior rectus strengthening procedures, but this failed, so we proceeded with an ocular sling with fascia lata and a vertical Hummelsheim procedure.

RESULTS

Hypotropia improved completely after the last operation and some degree of upward movement appeared.

CONCLUSION

It seems that in a highly myopic globe with fibrotic muscles, classical methods for the correction of deviation may have poor response and more innovative procedures may be required to correct the deviation.

Die kongenitale Fibrose der äußeren Augenmuskeln (CFEOM) und andere Phänotypen der kongenitalen kranialen Dysinnervationssyndrome (CCDD)

Currently, different syndromes with congenital, nonprogressive, sporadic, or familial developmental abnormalities of the cranial nerves and its nuclei are classified as congenital cranial dysinnervation syndromes (CCDD). One of these syndromes, congenital fibrosis of extraocular muscles (CFEOM), is characterized mainly by bilateral ophthalmoplegia of the oculomotor and trochlear nerves. Within the scope of an overview, the case of a 60-year-old patient with congenital fibrosis of extraocular muscles type 1 (CFEOM1) with autosomal dominant inheritance and typical phenotype, but additional progression of the ocular symptoms, is presented. Symptoms were caused by the common C2860-->T mutation in exon 21 of the KIF21A gene on chromosome 12. Further CCDD syndromes include the following phenotypes: congenital ptosis, Duane syndrome, horizontal gaze palsy, Möbius' syndrome, and congenital facial palsy. There are 13 different known gene loci for one of these phenotypes. Five gene products have been identified: the kinesin motor protein Kif21a, the transcription factors ARIX and SALL4, and the carboxypeptidase CPAH.

Medical Imaging in Pediatric Neuro-Ophthalmology

This article provides an outline of the congenital and acquired conditions encountered in the practice of pediatric neuro-ophthalmology. Although some entities can be effectively evaluated clinically, CT and MR imaging studies may prove instrumental in many instances for detailed evaluation, narrowing of the differential diagnosis, or exclusion of underlying central nervous system pathologic findings.

Classification and surgical management of patients with familial and sporadic forms of congenital fibrosis of the extraocular muscles

PURPOSE

To outline the clinical features and surgical treatment of patients with familial and sporadic (simplex) forms of congenital fibrosis of extraocular muscles (CFEOM) from 2 countries, and to classify them according to phenotype and mode of inheritance.

DESIGN

Observational and experimental study.

METHODS

Twenty-eight affected individuals from 20 families with familial or sporadic CFEOM underwent assessment of ocular motility, visual acuity, slit-lamp biomicroscopy, tonometry, and ophthalmoscopy. Seventeen patients had a variety of eye muscle procedures and ptosis repair.

RESULTS

There were 1 Iranian family with autosomal dominant CFEOM, 4 Iranian families with autosomal recessive disease, and 15 simplex cases with various CFEOM phenotypes. Two simplex patients had unilateral disease. All other cases were bilateral. Inferior rectus recession improved hypotropia and Bell's phenomenon in the patients with infraducted eyes and chin elevation. Horizontal muscle recession, sometimes combined with opposite muscle resection, corrected horizontal strabismus satisfactorily in most cases. Ptosis was repaired by frontalis sling and/or levator resection.

CONCLUSION

Definite recessive CFEOM was present only in Iranian patients. American patients had the classic phenotype of dominant CFEOM, which was also observed in some of the Iranian patients. The surgical management of patients with CFEOM is challenging. Correction of vertical and horizontal strabismus was addressed using large muscle recessions. Ptosis repair should aim at placing the lid level 1 to 2 mm above the pupil in the primary position to avoid exposure keratopathy.

Clinical and surgical data of affected members of a classic CFEOM I family

BACKGROUND

Congenital fibiosis of the extraocular muscles (CFEOMI) refers to a group of congenital eye movement disorders that are characterized by non-progressive restrictive ophthalmoplegia. We present clinical and surgical data on affected members of a classic CFEOMI family.

METHODS

Ten members of a fifteen-member, three-generation Italian family affected by classic CFEOM participated in this study. Each affected family member underwent ophthalmologic (corrected visual acuity, pupillary function, anterior segment and fundus examination), orthoptic (cover test, cover-uncover test, prism alternate cover test), and preoperative examinations. Eight of the ten affected members had surgery and underwent postoperative examinations. Surgical procedures are listed.

RESULTS

All affected members were born with varying degrees of bilateral ptosis and ophthalmoplegia with both eyes fixed in a hypotropic position (classic CFEOM). The affected members clinical data prior to surgery, surgery procedures and postoperative outcomes are presented. On 14 operated eyes to correct ptosis there was an improvement in 12 eyes. In addition, the head position improved in all patients.

CONCLUSIONS

Surgery is effective at improving ptosis in the majority of patients with classic CFEOM. However, the surgical approach should be individualized to each patient, as inherited CFEOM exhibits variable expressivity and the clinical features may differ markedly between affected individuals, even within the same family.

Congenital retraction of the lower eyelid: two case reports

PURPOSE

Idiopathic congenital retraction of the lower eyelid is rare. To further define the clinical features of this condition, we describe two new cases.

METHODS

Retrospective chart review.

RESULTS

In both cases, eye movements were restricted ipsilaterally and the condition was nonprogressive. CT scans showed mildly enlarged inferior and medial rectus muscles in one patient and normal muscles in the other. All other orbital structures were normal.

CONCLUSIONS

No definite cause for the lower eyelid retraction could be found, but it appeared to be related to a tight inferior rectus muscle. These patients may represent a variant of ocular fibrosis syndrome.

Stimulus deprivation myopia in human congenital ptosis: a study of 95 patients

PURPOSE

To establish differences between the frequency of suspected deprivation myopia in unilateral and bilateral congenital ptosis with and without covered optical axis.

METHODS

Ametropia was evaluated in both eyes of 95 patients with congenital ptosis. The amount of refraction was documented as spherical equivalent (100% cycloplegia). Statistical analysis was performed using the chi-square and sign tests.

RESULTS

In unilateral ptosis, the frequency of myopia was lower (10/68: 15%) than that of hyperopia (58/68: 85%) in the ptotic eye (P <0.001). However, myopia occurred more often in the ptotic eye (10/68: 15%) than in the fellow eye (3/68: 4.4%). Myopic anisometropia was found only in the ptotic eye (5/68 vs 0/68), but was less frequent than hyperopic anisometropia (6/68 vs 8/68). In bilateral ptosis 7/54 myopia as compared with 47/54 hyperopia were observed and 1/27 myopic anisometropia vs 6/27 hyperopic anisometropia. Covered center of the pupil, in children < or = 8 years of age, was associated with myopia more frequently in bilateral than in unilateral ptosis (6/30 vs 1/27). We found a significantly higher rate of myopia <-1 diopter and hyperopia >2 diopter in comparison of children 5 to 7 years old with first-grade school children.

CONCLUSIONS

Two expected results were (1) compared with the normal population, an overall higher frequency of myopia in human congenital ptosis; (2) in unilateral ptosis, a higher frequency of myopia in the ptotic, than in the fellow eye.

Congenital fibrosis of the extraocular muscles associated with cortical dysplasia and maldevelopment of the basal ganglia

BACKGROUND

Congenital fibrosis of the extraocular muscles (CFEOM) is a rare condition that has been traditionally regarded as a primary eye muscle disease. Recent studies, however, suggest that CFEOM may be the result of a primary neuropathy with secondary myopathic changes.

PURPOSE

To describe a previously unrecognized association between congenital fibrosis of the extraocular muscles and structural abnormalities of the brain.

DESIGN

Small case series.

METHODS

Detailed clinical examinations and neuroradiologic studies were performed on the three affected family members. In addition, genetic analysis of the family was performed.

RESULTS

The three affected family members, mother and two children, have the ocular features of 'classic' congenital fibrosis of the extraocular muscles. All showed dilation of the left lateral ventricle secondary to hypoplasia of the body and tail of the ipsilateral caudate nucleus. There was fusion of an enlarged caudate nucleus head with the underlying putamen. Both children showed widespread bilateral cortical dysplasia. Genetic analysis of the family was inconclusive but consistent with linkage to the CFEOM1 locus on chromosome 12. Chromosomal analysis of the affected individuals did not show evidence of a deletion of chromosome 12 and haplotype analysis was not suggestive of a microdeletion.

CONCLUSIONS

Cerebral cortical and basal ganglia maldevelopment can be found in individuals with CFEOM. This suggests that neuroimaging should be considered in the initial diagnostic evaluation of these patients, particularly if there is developmental delay.

Hereditary external ophthalmoplegia synergistic divergence, jaw winking, and oculocutaneous hypopigmentation: a congenital fibrosis syndrome caused by deficient innervation to extraocular muscles

BACKGROUND

The congenital fibrosis syndrome is a hereditary form of external ophthalmoplegia that is considered to be a primary myopathy.

PURPOSE

To document the coexistence of two distinct forms of ocular motor synkinesis in a subgroup of patients with congenital fibrosis syndrome.

METHODS

Clinical and intraoperative examination results and extraocular muscle biopsy specimens from four patients with congenital fibrosis syndrome were studied.

RESULTS

Three patients displayed a variant of synergistic divergence characterized by simultaneous abduction with intorsion and depression of the synkinetically abducting eye. Three patients had variant of Marcus Gunn jaw winking characterized by elevation of a ptotic eyelid during mouth opening. Three patients had oculocutaneous hypopigmentation.

CONCLUSIONS

A subgroup of patients with congenital fibrosis syndrome display two distinct synkinetic ocular movements in conjunction with oculocutaneous hypopigmentation. The patterns of neuronal misdirection implicate a regional innervational disturbance involving cranial nerves III through VI as the underlying cause of diffuse hereditary ophthalmoplegia in these patients.

Congenital fibrosis of the vertically acting extraocular muscles. A new group of dominantly inherited ocular fibrosis with radiologic findings

BACKGROUND

The authors studied a family with a form of congenital fibrosis of the extraocular muscles different from any group previously reported.

METHODS

A careful examination was done of all affected and all, except one, unaffected members of a family of 15 members extending over three generations. The authors performed computed tomography on five affected and four unaffected family members.

RESULTS

All affected family members showed complete loss of vertical ocular movement but largely free horizontal movement except for variable restriction of adduction in some members. A variable degree of ptosis was present, ranging from gross to nil, but with poor levator function and an absent Bell phenomenon in all affected members. All affected members showed superficial keratopathy, many with corneal scarring. Ocular alignment showed considerable variation. Refractive error and amblyopia also were variable. Computed tomographic scan indicated reduction in size of the extraocular muscles, particularly the superior recti with intracranial ventricular asymmetry in three of five patients examined, and abnormality in shape of the eye globes in two patients.

CONCLUSIONS

The findings indicate a new group best described as dominantly inherited congenital fibrosis of the vertical-acting extraocular muscles, which is part of the syndrome of congenital ocular fibrosis. Computed tomographic scanning suggested that the clinical picture was produced by changes present in the orbit, but intracranial ventricular asymmetry also was present in some patients and asymmetry of the eye globes in others.

A case of unilateral congenitally enlarged extraocular muscles

BACKGROUND

Enlargement of extraocular muscles is an uncommon finding in children. Little has been written in the literature about possible causes.

METHODS

The authors present the clinical findings of a young girl who had unilateral congenitally enlarged extraocular muscles at 8 months of age. She underwent computed tomography (CT) and magnetic resonance imaging (MRI) scans, systemic assessment, and extraocular muscle biopsy to determine a cause for the enlarged muscles.

RESULTS

The patient had a unilateral left esotropia and hypotropia at birth that was nonprogressive. High-resolution CT and MRI scans showed enlargement of the left inferior rectus, lateral rectus, and medial rectus muscles. Strabismus surgery undertaken at 2 years of age showed that the affected muscles were restricted on forced duction testing but were macroscopically normal in appearance. A biopsy specimen of the left lateral rectus muscle was processed for histologic, histochemical, and electron microscopic studies, but no abnormal pathologic findings were found.

CONCLUSION

This patient's constellation of findings appears to be unique: it does not follow any previously reported pattern of disorders of extraocular muscle enlargement.