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 Table of Contents  
CASE REPORT
Year : 2021  |  Volume : 1  |  Issue : 1  |  Page : 142-144

Restrictive strabismus in-patient with congenital third nerve palsy


Department of Ophthalmology, Government Medical College, Nagpur, Maharashtra, India

Date of Submission18-Apr-2020
Date of Acceptance29-Aug-2020
Date of Web Publication31-Dec-2020

Correspondence Address:
Dr. Rajesh Subhash Joshi
77, Panchatara Housing Society, Manish Nagar, Somalwada, Nagpur - 440 015, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_1010_20

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  Abstract 


In this study, we describe a case of restrictive exotropia in a 10-year-old female with amblyopia. The diagnosis of the accessory muscle was established through the magnetic resonance imaging (MRI) of the brain and orbit. A patient with restriction of all ocular movements in conjunction with enophthalmos of one eye or both eyes or the retraction of the eyeball should be suspected for an accessory ocular muscle and should be investigated accordingly.

Keywords: Accessory muscle, Duane's retraction syndrome, restrictive strabismus


How to cite this article:
Joshi RS, Jain DH, Hiremath VP. Restrictive strabismus in-patient with congenital third nerve palsy. Indian J Ophthalmol Case Rep 2021;1:142-4

How to cite this URL:
Joshi RS, Jain DH, Hiremath VP. Restrictive strabismus in-patient with congenital third nerve palsy. Indian J Ophthalmol Case Rep [serial online] 2021 [cited 2021 Feb 26];1:142-4. Available from: https://www.ijoreports.in/text.asp?2021/1/1/142/305469



The accessory muscle of the eye was first described by Nussbaum.[1] Lueder described it in patients with Duane retraction syndrome and congenital fibrosis of extraocular muscles.[2] The exact etiology and prevalence of the accessory muscle is unknown due to its rare presentation. Dobbs et al.[3] proposed the theory of disturbance in the mesodermal development of extraocular muscle. Pineles and Velez[4] suggested that the accessory muscle should be suspected in patients with atypical restrictive strabismus.


  Case Report Top


A 10-year-old female with a small left eye that deviated in an outward direction since birth was brought to the outpatient department of ophthalmology. She was a full-term baby and was delivered normally. At birth, she had normal birth weight and no congenital anomaly. The developmental history of the patient was normal.

On examination, the facial symmetry was also found to be normal. Head tilt was present toward the right side. The forehead and eyebrows were normal. The visual acuity of the right eye was 6/6, whereas that of the left eye was 6/24, with no improvement with pinhole. The enophthalmic left eye appeared smaller than the right eye [Figure 1]. The right eye and left eye had a vertical interpalpebral aperture of 12 and 7 mm, respectively, and a horizontal interpalpebral aperture of 30 and 29 mm horizontal, respectively. In the primary position, the left eye was exotropic by 30 Δ. The angle of the squint was measured by modified Krimsky's test. Uniocular and binocular movements of right eye were normal. A gross restriction of ocular movements of the left eye was observed in duction and version movements [Figure 2]. On examination, the rest of the anterior segment of both eyes was found to be normal. A dilated ophthalmoscopic examination reported both eyes to be normal. The cycloplegic refraction showed compound myopic astigmatism (–0.25 D sphere and −3.25 D cylinder at180°) in the left eye and emmetropia in the right eye. The patient was prescribed glasses and advised patching of the right eye 3 h daily for three months for amblyopia management without refractive adaptation. No other vision therapy was considered.
Figure 1: Showing enophthalmic and divergent left eye

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Figure 2: Showing resticted ocular movements in left eye

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The forced duction test of the left eye revealed a moderate restriction of adduction and no restriction of abduction. MRI of the brain and orbit presented with a hypointense band of the accessory extraocular muscle inserted close to the inferior rectus and lateral rectus [Figure 3]. The insertion appeared closer to the insertion of inferior rectus on coronal section [Figure 4]. The optic nerve was shifted medially. The band appeared to be originating from the apex of the orbit. A mild atrophy of the medial rectus was also observed on the affected side compared with the contralateral medial rectus [Figure 5].
Figure 3: MRI of the orbit showing hypointense band (Red circle) of the accessory extraocular muscle inserted close to the inferior rectus and lateral rectus in a sagittal section T2 weighed image

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Figure 4: Coronal section of the orbit showing insertion of accessory muscle closure to the inferior rectus (Arrow)

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Figure 5: Showing atrophic medial rectus (Red arrow) and medially shifted optic nerve (Yellow arrow)

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No treatment was advised to the patient, and parent counseling was conducted keeping in mind psychological impact of strabismus on parents and Childs' mind.


  Discussion Top


Restrictive strabismus due to the presence of an accessory extraocular muscle has been rarely reported. The prevalence of this condition is unknown due to its rare presentation and difficulty in identification during a routine strabismus surgery because accessory muscles are situated deep in the orbit.[5]

A series of retrospective record review study by Molinari et al.[6] described the accessory extraocular muscle to be a cause of restrictive strabismus in seven patients from six different countries, including one patient from India. To the best of our knowledge, this study described the second case of accessory muscle from India. In this case, an accessory muscle band was considered due to the complete restriction of ocular movements and presence of enophthalmos, which was confirmed through MRI.

Khitri and Demer[5] performed high-resolution orbital MRI in orthotropic patients and patients with strabismus. The accessory muscle band was observed in 11 patients (2.4%), of which 1 patient (0.8%) was orthotropic. Dobbs et al.[3] reported an anomalous extraocular muscle in a patient with strabismus who was operated for exotropia and did not present improvement after the surgical intervention. Park and Oh[7] described an accessory lateral rectus muscle in a patient with an exotropic eye concurrent with congenital third-nerve palsy. Pineles and Velez[4] described a patient having Duane syndrome with severe retraction and upshoot. The patient had 6 Δ of exotropia. During the surgery, two bands of the accessory muscle were observed, which doctors tried to recess, along with the lateral rectus, to 17 mm from the limbus in a V-shaped configuration. However, the normal preoperative abduction worsened postoperatively. In a series reporting seven cases of the accessory extraocular muscle by Molinari et al.[6] five patients underwent a surgical correction, of which only one patient presented partial improvement. Thus, we did not advise any treatment considering the literature[3],[4],[6] and the probability of worsening of the condition.


  Conclusion Top


The accessory muscle should be suspected in patients with atypical types of restrictive strabismus, those with severe upshoots or downshoots, or those with globe retraction. Radiologic evaluation (MRI) must be conducted in these patients because this anomaly is not amenable to surgical resection.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Nussbaum M. Vergleichend-anatomische beiträge zur kenntnis der augenmuskeln. Anat Anz 1893;8:208-10.  Back to cited text no. 1
    
2.
Lueder GT. Anomalous orbital structures resulting in unusual strabismus. Surv Ophthalmol 2002;47:27-35.  Back to cited text no. 2
    
3.
Dobbs MD, Mawn LA, Donahue SP. Anomalous extraocular muscles with strabismus. AJNR Am J Neuroradiol 2011;32:167-8.  Back to cited text no. 3
    
4.
Pineles SL, Velez FG. Accessory fibrotic lateral rectus muscles in exotropic Duane syndrome with severe retraction and upshoot. J AAPOS 2015;19:549-50.  Back to cited text no. 4
    
5.
Khitri MR, Demer JL. Magnetic resonance imaging of tissues compatible with supernumerary extraocular muscles. Am J Ophthalmol 2010;150:925-31.  Back to cited text no. 5
    
6.
Molinari A, Plager D, Merino P, Galan MM, Swaminathan M, Ramasuramanian S, et al. Accessory extraocular muscle as a cause of restrictive strabismus. Strabismus 2016;24:178-83.  Back to cited text no. 6
    
7.
Park CY, Oh SY. Accessory lateral rectus muscle in a patient with congenital third-nerve palsy. Am J Ophthalmol 2003;136:355-6.  Back to cited text no. 7
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]



 

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