Intermittent exotropia course in frontonasal dysplasia and severe orbital hypertelorism: case report/Tok intermitentne egzotropije kod frontonazalne displazije sa izrazenim orbitalnim hipertelorizmom: prikaz slucaja.
Frontonasal dysplasia (FND), firstly described in 1967 as the median cleft face syndrome by De Myer, is presented by congenital structure malformations of the midface [1, 2]. FND is a rare condition and only about 100 cases have been reported in the scientific literature [3,4]. The etiology of the condition remains unknown, but seems to be linked to defective embryologic development . During the critical period between 4 and 8 weeks of human fetal development, the cell proliferation and tissue fusion to form the orbital, nasal, and oral structures were stopped. A disturbance to this developmental sequence causes FND, a very heterogeneous group of disorders [6, 7].
Most cases of FND are sporadic, but a few familial cases have been reported . There are at least three types of frontonasal dysplasia that are distinguished by their genetic causes and their signs and symptoms .
The clinical picture is highly variable, but the major characteristics include hypertelorism, primary telecanthus, median nasal cleft with a broad nasal root, and a widow's peak hairline [4,10]. Occasional abnormalities include median cleft hp and palate, basal encephalocele, and agenesis of the corpus callosum .
Ophthalmologic abnormalities have been estimated to occur in 87% of cases of FND and include optic nerve anomalies, ptosis, exophthalmos, orbital asymmetry, microphthalmia, cataract, dermoid, nystagmus, coloboma of iris, choroidea and optic disk, refractive errors, amblyopia, and strabismus .
Orbital hypertelorism (ORH) is a congenital anomaly of the skull characterized by an increased distance between the medial orbital walls. The ORH can occur in a variety of conditions such as craniofacial dysplasia, craniofacial clefts and some craniosynostosis syndromes . It has been reported that amblyopia and strabismus appeared in 58.3% of patients with ORH, exotropias being the most common .
We report a case of frontonasal dysplasia with severe hypertelorism and associated strabismus pattern.
A 15-year old boy presented with features characteristic of FND type I caused by ALX3 gene mutation, after the correction of severe hypertelorism, median nasal cleft with a broad nasal root and associated de-compensated intermittent exotropia with overaction of the inferior oblique muscles with V pattern. The pregnancy, delivery, and birth weight were normal. Family history revealed no ocular defects or any similar developmental defects.
Over the years various surgical procedures were performed to correct the physical deformities typical of FND. He underwent two skin procedures at the age of 2 years to close the nose defect as well as bilateral lateral rectus recessions of 6.0 mm for intermittent exotropia when he was six years old. The correction of hypertelorism was performed with orbital "box osteotomy" technique when he was thirteen years old, and a year later, he underwent the corrective surgery for telecanthus and eyebrows transfer.
The ocular alignment improved for some time after strabismus surgery, but it deteriorated gradually. After the orbital rotation surgery aimed at correcting hipertelorism, the ocular alignment improved; however, intermittent exotropia deteriorated again after six to seven months.
On the last ophthalmologic examination, he had ocular alignment on the level of small angle exotropia and associated hypertropia and occasionally even small angle esotropia at near. Ductions and versions were full, with bilateral overaction in adduction and V pattern, which remained unchanged after extensive facial bones surgical procedures. Randot forms, Lang I as well as Wirth stereo tests were negative.
He wore prescription glasses to correct mild compound myopic astigmatism. The best corrected visual acuity was 1.0 and 0.8 in the right and in the left eye, respectively. The interpupillary distance after orbital rotation surgery was 65 mm.
His overall facial appearance was significantly improved and acceptable (Figures 1 and 2).
Our case is consistent with earlier findings that hypertelorism is frequently associated with exodeviations [14, 15].
The larger interpupillary distance to a certain extent, the greater is the angle of visual disparity and the greater is the stereoscopic potential .
Improving of intermittent exotropia after reduction of severe hypertelorism with orbital rotation surgery indicates that interpupillary distance within normal limits facilitates the ocular alignment.
Early start and long duration of manifest deviation resulted in the absence of normal binocular vision in our patient. Associated overelevation in adduction with V pattern prevented a better horizontal alignment and binocular vision at the level of small angle deviation. Bilateral inferior oblique weakening procedure is planned to enable fusional amplitudes and improve horizontal alignment.
Many theories have been suggested to clarify the etiology of patterns consisting of orbital factors such as craniofacial anomalies or heterotopia of muscle pulleys, anomalies of extraocular muscles, and disruption of fusion . Some previous studies have reported a significant association between V-pattern strabismus and excyclorotation of the muscle cone due to orbital malformations [17, 18]. When a vertical deviation is greatest in adduction (overelevation in adduction), the primary oblique muscle overaction could be the commonest cause .
Our case with frontonasal dysplasia shows that severe hypertelorism is frequently associated with exodeviations. It seems that a smaller interpupillary distance after the reduction of hypertelorism, leads to an improved ocular alignment. An associated vertical deviation contributes to the dissociation of horizontal deviation. The high incidence of ocular abnormalities indicates that the early assessment by an ophthalmologist should be a part of the initial evaluation of patients with frontonasal dysplasia to detect treatable visual or ocular problems.
Abbreviations FND --frontonasal dysplasia ORH --orbital hypertelorism
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Rad je primljen 9. VI 2016.
Recenziran 17. VI 2016.
Prihvacen za stampu 20.VI 2016.
Zorana B. PAVLOVIC (1) and Branislav R. STANKOVIC (2, 3)
General Hospital "Saint Luke", Doboj, Republic of Srpska (1)
University of Belgrade, Faculty of Medicine (2)
Clinical Centre of Serbia, Belgrade
Institute for Ophthalmology (3)
Corresponding Author: Dr Zorana Pavlovic, Opsta bolnica "Sveti apostol Luka", 74000 Doboj, Pop Ljubina bb, Republika Srpska, E-mail:email@example.com
Caption: Figure 1. Facial appearance before orbital rotation surgery. Severe hypertelorism Slika 1. Izgled lica pre orbitorotacije. Izrazen hipertielorizam
Caption: Figure 2. Facial appearance after orbital rotation surgery Slika 2. Izgled lica posle orbitorotacije
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|Title Annotation:||Case report/Prikaz slucaja|
|Author:||Pavlovic, Zorana B.; Stankovic, Branislav R.|
|Date:||Sep 1, 2016|
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